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llvm-project/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

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//===------ SimplifyLibCalls.cpp - Library calls simplifier ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the library calls simplifier. It does not implement
// any pass, but can't be used by other passes to do simplifications.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
using namespace llvm;
using namespace PatternMatch;
static cl::opt<bool>
EnableUnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
cl::init(false),
cl::desc("Enable unsafe double to float "
"shrinking for math lib calls"));
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
static bool ignoreCallingConv(LibFunc Func) {
return Func == LibFunc_abs || Func == LibFunc_labs ||
Func == LibFunc_llabs || Func == LibFunc_strlen;
}
/// Return true if it is only used in equality comparisons with With.
static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) {
for (User *U : V->users()) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(U))
if (IC->isEquality() && IC->getOperand(1) == With)
continue;
// Unknown instruction.
return false;
}
return true;
}
static bool callHasFloatingPointArgument(const CallInst *CI) {
return any_of(CI->operands(), [](const Use &OI) {
return OI->getType()->isFloatingPointTy();
});
}
static bool callHasFP128Argument(const CallInst *CI) {
return any_of(CI->operands(), [](const Use &OI) {
return OI->getType()->isFP128Ty();
});
}
// Convert the entire string Str representing an integer in Base, up to
// the terminating nul if present, to a constant according to the rules
// of strtoul[l] or, when AsSigned is set, of strtol[l]. On success
// return the result, otherwise null.
// The function assumes the string is encoded in ASCII and carefully
// avoids converting sequences (including "") that the corresponding
// library call might fail and set errno for.
static Value *convertStrToInt(CallInst *CI, StringRef &Str, Value *EndPtr,
uint64_t Base, bool AsSigned, IRBuilderBase &B) {
if (Base < 2 || Base > 36)
if (Base != 0)
// Fail for an invalid base (required by POSIX).
return nullptr;
// Current offset into the original string to reflect in EndPtr.
size_t Offset = 0;
// Strip leading whitespace.
for ( ; Offset != Str.size(); ++Offset)
if (!isSpace((unsigned char)Str[Offset])) {
Str = Str.substr(Offset);
break;
}
if (Str.empty())
// Fail for empty subject sequences (POSIX allows but doesn't require
// strtol[l]/strtoul[l] to fail with EINVAL).
return nullptr;
// Strip but remember the sign.
bool Negate = Str[0] == '-';
if (Str[0] == '-' || Str[0] == '+') {
Str = Str.drop_front();
if (Str.empty())
// Fail for a sign with nothing after it.
return nullptr;
++Offset;
}
// Set Max to the absolute value of the minimum (for signed), or
// to the maximum (for unsigned) value representable in the type.
Type *RetTy = CI->getType();
unsigned NBits = RetTy->getPrimitiveSizeInBits();
uint64_t Max = AsSigned && Negate ? 1 : 0;
Max += AsSigned ? maxIntN(NBits) : maxUIntN(NBits);
// Autodetect Base if it's zero and consume the "0x" prefix.
if (Str.size() > 1) {
if (Str[0] == '0') {
if (toUpper((unsigned char)Str[1]) == 'X') {
if (Str.size() == 2 || (Base && Base != 16))
// Fail if Base doesn't allow the "0x" prefix or for the prefix
// alone that implementations like BSD set errno to EINVAL for.
return nullptr;
Str = Str.drop_front(2);
Offset += 2;
Base = 16;
}
else if (Base == 0)
Base = 8;
} else if (Base == 0)
Base = 10;
}
else if (Base == 0)
Base = 10;
// Convert the rest of the subject sequence, not including the sign,
// to its uint64_t representation (this assumes the source character
// set is ASCII).
uint64_t Result = 0;
for (unsigned i = 0; i != Str.size(); ++i) {
unsigned char DigVal = Str[i];
if (isDigit(DigVal))
DigVal = DigVal - '0';
else {
DigVal = toUpper(DigVal);
if (isAlpha(DigVal))
DigVal = DigVal - 'A' + 10;
else
return nullptr;
}
if (DigVal >= Base)
// Fail if the digit is not valid in the Base.
return nullptr;
// Add the digit and fail if the result is not representable in
// the (unsigned form of the) destination type.
bool VFlow;
Result = SaturatingMultiplyAdd(Result, Base, (uint64_t)DigVal, &VFlow);
if (VFlow || Result > Max)
return nullptr;
}
if (EndPtr) {
// Store the pointer to the end.
Value *Off = B.getInt64(Offset + Str.size());
Value *StrBeg = CI->getArgOperand(0);
Value *StrEnd = B.CreateInBoundsGEP(B.getInt8Ty(), StrBeg, Off, "endptr");
B.CreateStore(StrEnd, EndPtr);
}
if (Negate)
// Unsigned negation doesn't overflow.
Result = -Result;
return ConstantInt::get(RetTy, Result);
}
static bool isOnlyUsedInComparisonWithZero(Value *V) {
for (User *U : V->users()) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(U))
if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
if (C->isNullValue())
continue;
// Unknown instruction.
return false;
}
return true;
}
static bool canTransformToMemCmp(CallInst *CI, Value *Str, uint64_t Len,
const DataLayout &DL) {
if (!isOnlyUsedInComparisonWithZero(CI))
return false;
if (!isDereferenceableAndAlignedPointer(Str, Align(1), APInt(64, Len), DL))
return false;
if (CI->getFunction()->hasFnAttribute(Attribute::SanitizeMemory))
return false;
return true;
}
static void annotateDereferenceableBytes(CallInst *CI,
ArrayRef<unsigned> ArgNos,
uint64_t DereferenceableBytes) {
const Function *F = CI->getCaller();
if (!F)
return;
for (unsigned ArgNo : ArgNos) {
uint64_t DerefBytes = DereferenceableBytes;
unsigned AS = CI->getArgOperand(ArgNo)->getType()->getPointerAddressSpace();
if (!llvm::NullPointerIsDefined(F, AS) ||
CI->paramHasAttr(ArgNo, Attribute::NonNull))
DerefBytes = std::max(CI->getParamDereferenceableOrNullBytes(ArgNo),
DereferenceableBytes);
if (CI->getParamDereferenceableBytes(ArgNo) < DerefBytes) {
CI->removeParamAttr(ArgNo, Attribute::Dereferenceable);
if (!llvm::NullPointerIsDefined(F, AS) ||
CI->paramHasAttr(ArgNo, Attribute::NonNull))
CI->removeParamAttr(ArgNo, Attribute::DereferenceableOrNull);
CI->addParamAttr(ArgNo, Attribute::getWithDereferenceableBytes(
CI->getContext(), DerefBytes));
}
}
}
static void annotateNonNullNoUndefBasedOnAccess(CallInst *CI,
ArrayRef<unsigned> ArgNos) {
Function *F = CI->getCaller();
if (!F)
return;
for (unsigned ArgNo : ArgNos) {
if (!CI->paramHasAttr(ArgNo, Attribute::NoUndef))
CI->addParamAttr(ArgNo, Attribute::NoUndef);
if (CI->paramHasAttr(ArgNo, Attribute::NonNull))
continue;
unsigned AS = CI->getArgOperand(ArgNo)->getType()->getPointerAddressSpace();
if (llvm::NullPointerIsDefined(F, AS))
continue;
CI->addParamAttr(ArgNo, Attribute::NonNull);
annotateDereferenceableBytes(CI, ArgNo, 1);
}
}
static void annotateNonNullAndDereferenceable(CallInst *CI, ArrayRef<unsigned> ArgNos,
Value *Size, const DataLayout &DL) {
if (ConstantInt *LenC = dyn_cast<ConstantInt>(Size)) {
annotateNonNullNoUndefBasedOnAccess(CI, ArgNos);
annotateDereferenceableBytes(CI, ArgNos, LenC->getZExtValue());
} else if (isKnownNonZero(Size, DL)) {
annotateNonNullNoUndefBasedOnAccess(CI, ArgNos);
const APInt *X, *Y;
uint64_t DerefMin = 1;
if (match(Size, m_Select(m_Value(), m_APInt(X), m_APInt(Y)))) {
DerefMin = std::min(X->getZExtValue(), Y->getZExtValue());
annotateDereferenceableBytes(CI, ArgNos, DerefMin);
}
}
}
// Copy CallInst "flags" like musttail, notail, and tail. Return New param for
// easier chaining. Calls to emit* and B.createCall should probably be wrapped
// in this function when New is created to replace Old. Callers should take
// care to check Old.isMustTailCall() if they aren't replacing Old directly
// with New.
static Value *copyFlags(const CallInst &Old, Value *New) {
assert(!Old.isMustTailCall() && "do not copy musttail call flags");
assert(!Old.isNoTailCall() && "do not copy notail call flags");
if (auto *NewCI = dyn_cast_or_null<CallInst>(New))
NewCI->setTailCallKind(Old.getTailCallKind());
return New;
}
// Helper to avoid truncating the length if size_t is 32-bits.
static StringRef substr(StringRef Str, uint64_t Len) {
return Len >= Str.size() ? Str : Str.substr(0, Len);
}
//===----------------------------------------------------------------------===//
// String and Memory Library Call Optimizations
//===----------------------------------------------------------------------===//
Value *LibCallSimplifier::optimizeStrCat(CallInst *CI, IRBuilderBase &B) {
// Extract some information from the instruction
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
--Len; // Unbias length.
// Handle the simple, do-nothing case: strcat(x, "") -> x
if (Len == 0)
return Dst;
return copyFlags(*CI, emitStrLenMemCpy(Src, Dst, Len, B));
}
Value *LibCallSimplifier::emitStrLenMemCpy(Value *Src, Value *Dst, uint64_t Len,
IRBuilderBase &B) {
// We need to find the end of the destination string. That's where the
// memory is to be moved to. We just generate a call to strlen.
Value *DstLen = emitStrLen(Dst, B, DL, TLI);
if (!DstLen)
return nullptr;
// Now that we have the destination's length, we must index into the
// destination's pointer to get the actual memcpy destination (end of
// the string .. we're concatenating).
Value *CpyDst = B.CreateInBoundsGEP(B.getInt8Ty(), Dst, DstLen, "endptr");
// We have enough information to now generate the memcpy call to do the
// concatenation for us. Make a memcpy to copy the nul byte with align = 1.
B.CreateMemCpy(
CpyDst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(Src->getContext()), Len + 1));
return Dst;
}
Value *LibCallSimplifier::optimizeStrNCat(CallInst *CI, IRBuilderBase &B) {
// Extract some information from the instruction.
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
uint64_t Len;
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, 1);
// We don't do anything if length is not constant.
ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size);
if (LengthArg) {
Len = LengthArg->getZExtValue();
// strncat(x, c, 0) -> x
if (!Len)
return Dst;
} else {
return nullptr;
}
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen) {
annotateDereferenceableBytes(CI, 1, SrcLen);
--SrcLen; // Unbias length.
} else {
return nullptr;
}
// strncat(x, "", c) -> x
if (SrcLen == 0)
return Dst;
// We don't optimize this case.
if (Len < SrcLen)
return nullptr;
// strncat(x, s, c) -> strcat(x, s)
// s is constant so the strcat can be optimized further.
return copyFlags(*CI, emitStrLenMemCpy(Src, Dst, SrcLen, B));
}
// Helper to transform memchr(S, C, N) == S to N && *S == C and, when
// NBytes is null, strchr(S, C) to *S == C. A precondition of the function
// is that either S is dereferenceable or the value of N is nonzero.
static Value* memChrToCharCompare(CallInst *CI, Value *NBytes,
IRBuilderBase &B, const DataLayout &DL)
{
Value *Src = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
// Fold memchr(A, C, N) == A to N && *A == C.
Type *CharTy = B.getInt8Ty();
Value *Char0 = B.CreateLoad(CharTy, Src);
CharVal = B.CreateTrunc(CharVal, CharTy);
Value *Cmp = B.CreateICmpEQ(Char0, CharVal, "char0cmp");
if (NBytes) {
Value *Zero = ConstantInt::get(NBytes->getType(), 0);
Value *And = B.CreateICmpNE(NBytes, Zero);
Cmp = B.CreateLogicalAnd(And, Cmp);
}
Value *NullPtr = Constant::getNullValue(CI->getType());
return B.CreateSelect(Cmp, Src, NullPtr);
}
Value *LibCallSimplifier::optimizeStrChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
return memChrToCharCompare(CI, nullptr, B, DL);
// If the second operand is non-constant, see if we can compute the length
// of the input string and turn this into memchr.
ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal);
if (!CharC) {
uint64_t Len = GetStringLength(SrcStr);
if (Len)
annotateDereferenceableBytes(CI, 0, Len);
else
return nullptr;
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
if (!FT->getParamType(1)->isIntegerTy(32)) // memchr needs i32.
return nullptr;
return copyFlags(
*CI,
emitMemChr(SrcStr, CharVal, // include nul.
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len), B,
DL, TLI));
}
if (CharC->isZero()) {
Value *NullPtr = Constant::getNullValue(CI->getType());
if (isOnlyUsedInEqualityComparison(CI, NullPtr))
// Pre-empt the transformation to strlen below and fold
// strchr(A, '\0') == null to false.
return B.CreateIntToPtr(B.getTrue(), CI->getType());
}
// Otherwise, the character is a constant, see if the first argument is
// a string literal. If so, we can constant fold.
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
if (CharC->isZero()) // strchr(p, 0) -> p + strlen(p)
if (Value *StrLen = emitStrLen(SrcStr, B, DL, TLI))
return B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, StrLen, "strchr");
return nullptr;
}
// Compute the offset, make sure to handle the case when we're searching for
// zero (a weird way to spell strlen).
size_t I = (0xFF & CharC->getSExtValue()) == 0
? Str.size()
: Str.find(CharC->getSExtValue());
if (I == StringRef::npos) // Didn't find the char. strchr returns null.
return Constant::getNullValue(CI->getType());
// strchr(s+n,c) -> gep(s+n+i,c)
return B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strchr");
}
Value *LibCallSimplifier::optimizeStrRChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *CharVal = CI->getArgOperand(1);
ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
// strrchr(s, 0) -> strchr(s, 0)
if (CharC && CharC->isZero())
return copyFlags(*CI, emitStrChr(SrcStr, '\0', B, TLI));
return nullptr;
}
// Try to expand strrchr to the memrchr nonstandard extension if it's
// available, or simply fail otherwise.
uint64_t NBytes = Str.size() + 1; // Include the terminating nul.
Type *IntPtrType = DL.getIntPtrType(CI->getContext());
Value *Size = ConstantInt::get(IntPtrType, NBytes);
return copyFlags(*CI, emitMemRChr(SrcStr, CharVal, Size, B, DL, TLI));
}
Value *LibCallSimplifier::optimizeStrCmp(CallInst *CI, IRBuilderBase &B) {
Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1);
if (Str1P == Str2P) // strcmp(x,x) -> 0
return ConstantInt::get(CI->getType(), 0);
StringRef Str1, Str2;
bool HasStr1 = getConstantStringInfo(Str1P, Str1);
bool HasStr2 = getConstantStringInfo(Str2P, Str2);
// strcmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(), Str1.compare(Str2));
if (HasStr1 && Str1.empty()) // strcmp("", x) -> -*x
return B.CreateNeg(B.CreateZExt(
B.CreateLoad(B.getInt8Ty(), Str2P, "strcmpload"), CI->getType()));
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(B.getInt8Ty(), Str1P, "strcmpload"),
CI->getType());
// strcmp(P, "x") -> memcmp(P, "x", 2)
uint64_t Len1 = GetStringLength(Str1P);
if (Len1)
annotateDereferenceableBytes(CI, 0, Len1);
uint64_t Len2 = GetStringLength(Str2P);
if (Len2)
annotateDereferenceableBytes(CI, 1, Len2);
if (Len1 && Len2) {
return copyFlags(
*CI, emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
std::min(Len1, Len2)),
B, DL, TLI));
}
// strcmp to memcmp
if (!HasStr1 && HasStr2) {
if (canTransformToMemCmp(CI, Str1P, Len2, DL))
return copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len2),
B, DL, TLI));
} else if (HasStr1 && !HasStr2) {
if (canTransformToMemCmp(CI, Str2P, Len1, DL))
return copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len1),
B, DL, TLI));
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
// Optimize a memcmp or, when StrNCmp is true, strncmp call CI with constant
// arrays LHS and RHS and nonconstant Size.
static Value *optimizeMemCmpVarSize(CallInst *CI, Value *LHS, Value *RHS,
Value *Size, bool StrNCmp,
IRBuilderBase &B, const DataLayout &DL);
Value *LibCallSimplifier::optimizeStrNCmp(CallInst *CI, IRBuilderBase &B) {
Value *Str1P = CI->getArgOperand(0);
Value *Str2P = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
if (Str1P == Str2P) // strncmp(x,x,n) -> 0
return ConstantInt::get(CI->getType(), 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// Get the length argument if it is constant.
uint64_t Length;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size))
Length = LengthArg->getZExtValue();
else
return optimizeMemCmpVarSize(CI, Str1P, Str2P, Size, true, B, DL);
if (Length == 0) // strncmp(x,y,0) -> 0
return ConstantInt::get(CI->getType(), 0);
if (Length == 1) // strncmp(x,y,1) -> memcmp(x,y,1)
return copyFlags(*CI, emitMemCmp(Str1P, Str2P, Size, B, DL, TLI));
StringRef Str1, Str2;
bool HasStr1 = getConstantStringInfo(Str1P, Str1);
bool HasStr2 = getConstantStringInfo(Str2P, Str2);
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2) {
// Avoid truncating the 64-bit Length to 32 bits in ILP32.
StringRef SubStr1 = substr(Str1, Length);
StringRef SubStr2 = substr(Str2, Length);
return ConstantInt::get(CI->getType(), SubStr1.compare(SubStr2));
}
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> -*x
return B.CreateNeg(B.CreateZExt(
B.CreateLoad(B.getInt8Ty(), Str2P, "strcmpload"), CI->getType()));
if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
return B.CreateZExt(B.CreateLoad(B.getInt8Ty(), Str1P, "strcmpload"),
CI->getType());
uint64_t Len1 = GetStringLength(Str1P);
if (Len1)
annotateDereferenceableBytes(CI, 0, Len1);
uint64_t Len2 = GetStringLength(Str2P);
if (Len2)
annotateDereferenceableBytes(CI, 1, Len2);
// strncmp to memcmp
if (!HasStr1 && HasStr2) {
Len2 = std::min(Len2, Length);
if (canTransformToMemCmp(CI, Str1P, Len2, DL))
return copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len2),
B, DL, TLI));
} else if (HasStr1 && !HasStr2) {
Len1 = std::min(Len1, Length);
if (canTransformToMemCmp(CI, Str2P, Len1, DL))
return copyFlags(
*CI,
emitMemCmp(Str1P, Str2P,
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len1),
B, DL, TLI));
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrNDup(CallInst *CI, IRBuilderBase &B) {
Value *Src = CI->getArgOperand(0);
ConstantInt *Size = dyn_cast<ConstantInt>(CI->getArgOperand(1));
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen && Size) {
annotateDereferenceableBytes(CI, 0, SrcLen);
if (SrcLen <= Size->getZExtValue() + 1)
return copyFlags(*CI, emitStrDup(Src, B, TLI));
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
if (Dst == Src) // strcpy(x,x) -> x
return Src;
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
// We have enough information to now generate the memcpy call to do the
// copy for us. Make a memcpy to copy the nul byte with align = 1.
CallInst *NewCI =
B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return Dst;
}
Value *LibCallSimplifier::optimizeStpCpy(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
// stpcpy(d,s) -> strcpy(d,s) if the result is not used.
if (CI->use_empty())
return copyFlags(*CI, emitStrCpy(Dst, Src, B, TLI));
if (Dst == Src) { // stpcpy(x,x) -> x+strlen(x)
Value *StrLen = emitStrLen(Src, B, DL, TLI);
return StrLen ? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, StrLen) : nullptr;
}
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
Type *PT = Callee->getFunctionType()->getParamType(0);
Value *LenV = ConstantInt::get(DL.getIntPtrType(PT), Len);
Value *DstEnd = B.CreateInBoundsGEP(
B.getInt8Ty(), Dst, ConstantInt::get(DL.getIntPtrType(PT), Len - 1));
// We have enough information to now generate the memcpy call to do the
// copy for us. Make a memcpy to copy the nul byte with align = 1.
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1), LenV);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return DstEnd;
}
// Optimize a call to size_t strlcpy(char*, const char*, size_t).
Value *LibCallSimplifier::optimizeStrLCpy(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
if (isKnownNonZero(Size, DL))
// Like snprintf, the function stores into the destination only when
// the size argument is nonzero.
annotateNonNullNoUndefBasedOnAccess(CI, 0);
// The function reads the source argument regardless of Size (it returns
// its length).
annotateNonNullNoUndefBasedOnAccess(CI, 1);
uint64_t NBytes;
if (ConstantInt *SizeC = dyn_cast<ConstantInt>(Size))
NBytes = SizeC->getZExtValue();
else
return nullptr;
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
if (NBytes <= 1) {
if (NBytes == 1)
// For a call to strlcpy(D, S, 1) first store a nul in *D.
B.CreateStore(B.getInt8(0), Dst);
// Transform strlcpy(D, S, 0) to a call to strlen(S).
return copyFlags(*CI, emitStrLen(Src, B, DL, TLI));
}
// Try to determine the length of the source, substituting its size
// when it's not nul-terminated (as it's required to be) to avoid
// reading past its end.
StringRef Str;
if (!getConstantStringInfo(Src, Str, 0, /*TrimAtNul=*/false))
return nullptr;
uint64_t SrcLen = Str.find('\0');
// Set if the terminating nul should be copied by the call to memcpy
// below.
bool NulTerm = SrcLen < NBytes;
if (NulTerm)
// Overwrite NBytes with the number of bytes to copy, including
// the terminating nul.
NBytes = SrcLen + 1;
else {
// Set the length of the source for the function to return to its
// size, and cap NBytes at the same.
SrcLen = std::min(SrcLen, uint64_t(Str.size()));
NBytes = std::min(NBytes - 1, SrcLen);
}
if (SrcLen == 0) {
// Transform strlcpy(D, "", N) to (*D = '\0, 0).
B.CreateStore(B.getInt8(0), Dst);
return ConstantInt::get(CI->getType(), 0);
}
Function *Callee = CI->getCalledFunction();
Type *PT = Callee->getFunctionType()->getParamType(0);
// Transform strlcpy(D, S, N) to memcpy(D, S, N') where N' is the lower
// bound on strlen(S) + 1 and N, optionally followed by a nul store to
// D[N' - 1] if necessary.
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(PT), NBytes));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
if (!NulTerm) {
Value *EndOff = ConstantInt::get(CI->getType(), NBytes);
Value *EndPtr = B.CreateInBoundsGEP(B.getInt8Ty(), Dst, EndOff);
B.CreateStore(B.getInt8(0), EndPtr);
}
// Like snprintf, strlcpy returns the number of nonzero bytes that would
// have been copied if the bound had been sufficiently big (which in this
// case is strlen(Src)).
return ConstantInt::get(CI->getType(), SrcLen);
}
// Optimize a call to strncpy.
Value *LibCallSimplifier::optimizeStrNCpy(CallInst *CI, IRBuilderBase &B) {
Function *Callee = CI->getCalledFunction();
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isKnownNonZero(Size, DL))
annotateNonNullNoUndefBasedOnAccess(CI, 1);
uint64_t Len;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(Size))
Len = LengthArg->getZExtValue();
else
return nullptr;
// strncpy(x, y, 0) -> x
if (Len == 0)
return Dst;
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen) {
annotateDereferenceableBytes(CI, 1, SrcLen);
--SrcLen; // Unbias length.
} else {
return nullptr;
}
if (SrcLen == 0) {
// strncpy(x, "", y) -> memset(x, '\0', y)
Align MemSetAlign =
CI->getAttributes().getParamAttrs(0).getAlignment().valueOrOne();
CallInst *NewCI = B.CreateMemSet(Dst, B.getInt8('\0'), Size, MemSetAlign);
AttrBuilder ArgAttrs(CI->getContext(), CI->getAttributes().getParamAttrs(0));
NewCI->setAttributes(NewCI->getAttributes().addParamAttributes(
CI->getContext(), 0, ArgAttrs));
copyFlags(*CI, NewCI);
return Dst;
}
// strncpy(a, "a", 4) - > memcpy(a, "a\0\0\0", 4)
if (Len > SrcLen + 1) {
if (Len <= 128) {
StringRef Str;
if (!getConstantStringInfo(Src, Str))
return nullptr;
std::string SrcStr = Str.str();
SrcStr.resize(Len, '\0');
Src = B.CreateGlobalString(SrcStr, "str");
} else {
return nullptr;
}
}
Type *PT = Callee->getFunctionType()->getParamType(0);
// strncpy(x, s, c) -> memcpy(align 1 x, align 1 s, c) [s and c are constant]
CallInst *NewCI = B.CreateMemCpy(Dst, Align(1), Src, Align(1),
ConstantInt::get(DL.getIntPtrType(PT), Len));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return Dst;
}
Value *LibCallSimplifier::optimizeStringLength(CallInst *CI, IRBuilderBase &B,
unsigned CharSize,
Value *Bound) {
Value *Src = CI->getArgOperand(0);
Type *CharTy = B.getIntNTy(CharSize);
if (isOnlyUsedInZeroEqualityComparison(CI) &&
(!Bound || isKnownNonZero(Bound, DL))) {
// Fold strlen:
// strlen(x) != 0 --> *x != 0
// strlen(x) == 0 --> *x == 0
// and likewise strnlen with constant N > 0:
// strnlen(x, N) != 0 --> *x != 0
// strnlen(x, N) == 0 --> *x == 0
return B.CreateZExt(B.CreateLoad(CharTy, Src, "char0"),
CI->getType());
}
if (Bound) {
if (ConstantInt *BoundCst = dyn_cast<ConstantInt>(Bound)) {
if (BoundCst->isZero())
// Fold strnlen(s, 0) -> 0 for any s, constant or otherwise.
return ConstantInt::get(CI->getType(), 0);
if (BoundCst->isOne()) {
// Fold strnlen(s, 1) -> *s ? 1 : 0 for any s.
Value *CharVal = B.CreateLoad(CharTy, Src, "strnlen.char0");
Value *ZeroChar = ConstantInt::get(CharTy, 0);
Value *Cmp = B.CreateICmpNE(CharVal, ZeroChar, "strnlen.char0cmp");
return B.CreateZExt(Cmp, CI->getType());
}
}
}
if (uint64_t Len = GetStringLength(Src, CharSize)) {
Value *LenC = ConstantInt::get(CI->getType(), Len - 1);
// Fold strlen("xyz") -> 3 and strnlen("xyz", 2) -> 2
// and strnlen("xyz", Bound) -> min(3, Bound) for nonconstant Bound.
if (Bound)
return B.CreateBinaryIntrinsic(Intrinsic::umin, LenC, Bound);
return LenC;
}
if (Bound)
// Punt for strnlen for now.
return nullptr;
// If s is a constant pointer pointing to a string literal, we can fold
// strlen(s + x) to strlen(s) - x, when x is known to be in the range
// [0, strlen(s)] or the string has a single null terminator '\0' at the end.
// We only try to simplify strlen when the pointer s points to an array
// of i8. Otherwise, we would need to scale the offset x before doing the
// subtraction. This will make the optimization more complex, and it's not
// very useful because calling strlen for a pointer of other types is
// very uncommon.
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Src)) {
// TODO: Handle subobjects.
if (!isGEPBasedOnPointerToString(GEP, CharSize))
return nullptr;
ConstantDataArraySlice Slice;
if (getConstantDataArrayInfo(GEP->getOperand(0), Slice, CharSize)) {
uint64_t NullTermIdx;
if (Slice.Array == nullptr) {
NullTermIdx = 0;
} else {
NullTermIdx = ~((uint64_t)0);
for (uint64_t I = 0, E = Slice.Length; I < E; ++I) {
if (Slice.Array->getElementAsInteger(I + Slice.Offset) == 0) {
NullTermIdx = I;
break;
}
}
// If the string does not have '\0', leave it to strlen to compute
// its length.
if (NullTermIdx == ~((uint64_t)0))
return nullptr;
}
Value *Offset = GEP->getOperand(2);
KnownBits Known = computeKnownBits(Offset, DL, 0, nullptr, CI, nullptr);
uint64_t ArrSize =
cast<ArrayType>(GEP->getSourceElementType())->getNumElements();
// If Offset is not provably in the range [0, NullTermIdx], we can still
// optimize if we can prove that the program has undefined behavior when
// Offset is outside that range. That is the case when GEP->getOperand(0)
// is a pointer to an object whose memory extent is NullTermIdx+1.
if ((Known.isNonNegative() && Known.getMaxValue().ule(NullTermIdx)) ||
(isa<GlobalVariable>(GEP->getOperand(0)) &&
NullTermIdx == ArrSize - 1)) {
Offset = B.CreateSExtOrTrunc(Offset, CI->getType());
return B.CreateSub(ConstantInt::get(CI->getType(), NullTermIdx),
Offset);
}
}
}
// strlen(x?"foo":"bars") --> x ? 3 : 4
if (SelectInst *SI = dyn_cast<SelectInst>(Src)) {
uint64_t LenTrue = GetStringLength(SI->getTrueValue(), CharSize);
uint64_t LenFalse = GetStringLength(SI->getFalseValue(), CharSize);
if (LenTrue && LenFalse) {
ORE.emit([&]() {
return OptimizationRemark("instcombine", "simplify-libcalls", CI)
<< "folded strlen(select) to select of constants";
});
return B.CreateSelect(SI->getCondition(),
ConstantInt::get(CI->getType(), LenTrue - 1),
ConstantInt::get(CI->getType(), LenFalse - 1));
}
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrLen(CallInst *CI, IRBuilderBase &B) {
if (Value *V = optimizeStringLength(CI, B, 8))
return V;
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeStrNLen(CallInst *CI, IRBuilderBase &B) {
Value *Bound = CI->getArgOperand(1);
if (Value *V = optimizeStringLength(CI, B, 8, Bound))
return V;
if (isKnownNonZero(Bound, DL))
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeWcslen(CallInst *CI, IRBuilderBase &B) {
Module &M = *CI->getModule();
unsigned WCharSize = TLI->getWCharSize(M) * 8;
// We cannot perform this optimization without wchar_size metadata.
if (WCharSize == 0)
return nullptr;
return optimizeStringLength(CI, B, WCharSize);
}
Value *LibCallSimplifier::optimizeStrPBrk(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strpbrk(s, "") -> nullptr
// strpbrk("", s) -> nullptr
if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t I = S1.find_first_of(S2);
if (I == StringRef::npos) // No match.
return Constant::getNullValue(CI->getType());
return B.CreateInBoundsGEP(B.getInt8Ty(), CI->getArgOperand(0),
B.getInt64(I), "strpbrk");
}
// strpbrk(s, "a") -> strchr(s, 'a')
if (HasS2 && S2.size() == 1)
return copyFlags(*CI, emitStrChr(CI->getArgOperand(0), S2[0], B, TLI));
return nullptr;
}
Value *LibCallSimplifier::optimizeStrTo(CallInst *CI, IRBuilderBase &B) {
Value *EndPtr = CI->getArgOperand(1);
if (isa<ConstantPointerNull>(EndPtr)) {
// With a null EndPtr, this function won't capture the main argument.
// It would be readonly too, except that it still may write to errno.
CI->addParamAttr(0, Attribute::NoCapture);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrSpn(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strspn(s, "") -> 0
// strspn("", s) -> 0
if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t Pos = S1.find_first_not_of(S2);
if (Pos == StringRef::npos)
Pos = S1.size();
return ConstantInt::get(CI->getType(), Pos);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeStrCSpn(CallInst *CI, IRBuilderBase &B) {
StringRef S1, S2;
bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
// strcspn("", s) -> 0
if (HasS1 && S1.empty())
return Constant::getNullValue(CI->getType());
// Constant folding.
if (HasS1 && HasS2) {
size_t Pos = S1.find_first_of(S2);
if (Pos == StringRef::npos)
Pos = S1.size();
return ConstantInt::get(CI->getType(), Pos);
}
// strcspn(s, "") -> strlen(s)
if (HasS2 && S2.empty())
return copyFlags(*CI, emitStrLen(CI->getArgOperand(0), B, DL, TLI));
return nullptr;
}
Value *LibCallSimplifier::optimizeStrStr(CallInst *CI, IRBuilderBase &B) {
// fold strstr(x, x) -> x.
if (CI->getArgOperand(0) == CI->getArgOperand(1))
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
if (isOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {
Value *StrLen = emitStrLen(CI->getArgOperand(1), B, DL, TLI);
if (!StrLen)
return nullptr;
Value *StrNCmp = emitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),
StrLen, B, DL, TLI);
if (!StrNCmp)
return nullptr;
for (User *U : llvm::make_early_inc_range(CI->users())) {
ICmpInst *Old = cast<ICmpInst>(U);
Value *Cmp =
B.CreateICmp(Old->getPredicate(), StrNCmp,
ConstantInt::getNullValue(StrNCmp->getType()), "cmp");
replaceAllUsesWith(Old, Cmp);
}
return CI;
}
// See if either input string is a constant string.
StringRef SearchStr, ToFindStr;
bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr);
bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr);
// fold strstr(x, "") -> x.
if (HasStr2 && ToFindStr.empty())
return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
// If both strings are known, constant fold it.
if (HasStr1 && HasStr2) {
size_t Offset = SearchStr.find(ToFindStr);
if (Offset == StringRef::npos) // strstr("foo", "bar") -> null
return Constant::getNullValue(CI->getType());
// strstr("abcd", "bc") -> gep((char*)"abcd", 1)
Value *Result = castToCStr(CI->getArgOperand(0), B);
Result =
B.CreateConstInBoundsGEP1_64(B.getInt8Ty(), Result, Offset, "strstr");
return B.CreateBitCast(Result, CI->getType());
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1) {
Value *StrChr = emitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TLI);
return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : nullptr;
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
Value *LibCallSimplifier::optimizeMemRChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
Value *CharVal = CI->getArgOperand(1);
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
Value *NullPtr = Constant::getNullValue(CI->getType());
if (LenC) {
if (LenC->isZero())
// Fold memrchr(x, y, 0) --> null.
return NullPtr;
if (LenC->isOne()) {
// Fold memrchr(x, y, 1) --> *x == y ? x : null for any x and y,
// constant or otherwise.
Value *Val = B.CreateLoad(B.getInt8Ty(), SrcStr, "memrchr.char0");
// Slice off the character's high end bits.
CharVal = B.CreateTrunc(CharVal, B.getInt8Ty());
Value *Cmp = B.CreateICmpEQ(Val, CharVal, "memrchr.char0cmp");
return B.CreateSelect(Cmp, SrcStr, NullPtr, "memrchr.sel");
}
}
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str, 0, /*TrimAtNul=*/false))
return nullptr;
if (Str.size() == 0)
// If the array is empty fold memrchr(A, C, N) to null for any value
// of C and N on the basis that the only valid value of N is zero
// (otherwise the call is undefined).
return NullPtr;
uint64_t EndOff = UINT64_MAX;
if (LenC) {
EndOff = LenC->getZExtValue();
if (Str.size() < EndOff)
// Punt out-of-bounds accesses to sanitizers and/or libc.
return nullptr;
}
if (ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal)) {
// Fold memrchr(S, C, N) for a constant C.
size_t Pos = Str.rfind(CharC->getZExtValue(), EndOff);
if (Pos == StringRef::npos)
// When the character is not in the source array fold the result
// to null regardless of Size.
return NullPtr;
if (LenC)
// Fold memrchr(s, c, N) --> s + Pos for constant N > Pos.
return B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(Pos));
if (Str.find(Str[Pos]) == Pos) {
// When there is just a single occurrence of C in S, i.e., the one
// in Str[Pos], fold
// memrchr(s, c, N) --> N <= Pos ? null : s + Pos
// for nonconstant N.
Value *Cmp = B.CreateICmpULE(Size, ConstantInt::get(Size->getType(), Pos),
"memrchr.cmp");
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr,
B.getInt64(Pos), "memrchr.ptr_plus");
return B.CreateSelect(Cmp, NullPtr, SrcPlus, "memrchr.sel");
}
}
// Truncate the string to search at most EndOff characters.
Str = Str.substr(0, EndOff);
if (Str.find_first_not_of(Str[0]) != StringRef::npos)
return nullptr;
// If the source array consists of all equal characters, then for any
// C and N (whether in bounds or not), fold memrchr(S, C, N) to
// N != 0 && *S == C ? S + N - 1 : null
Type *SizeTy = Size->getType();
Type *Int8Ty = B.getInt8Ty();
Value *NNeZ = B.CreateICmpNE(Size, ConstantInt::get(SizeTy, 0));
// Slice off the sought character's high end bits.
CharVal = B.CreateTrunc(CharVal, Int8Ty);
Value *CEqS0 = B.CreateICmpEQ(ConstantInt::get(Int8Ty, Str[0]), CharVal);
Value *And = B.CreateLogicalAnd(NNeZ, CEqS0);
Value *SizeM1 = B.CreateSub(Size, ConstantInt::get(SizeTy, 1));
Value *SrcPlus =
B.CreateInBoundsGEP(Int8Ty, SrcStr, SizeM1, "memrchr.ptr_plus");
return B.CreateSelect(And, SrcPlus, NullPtr, "memrchr.sel");
}
Value *LibCallSimplifier::optimizeMemChr(CallInst *CI, IRBuilderBase &B) {
Value *SrcStr = CI->getArgOperand(0);
Value *Size = CI->getArgOperand(2);
if (isKnownNonZero(Size, DL)) {
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
return memChrToCharCompare(CI, Size, B, DL);
}
Value *CharVal = CI->getArgOperand(1);
ConstantInt *CharC = dyn_cast<ConstantInt>(CharVal);
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
Value *NullPtr = Constant::getNullValue(CI->getType());
// memchr(x, y, 0) -> null
if (LenC) {
if (LenC->isZero())
return NullPtr;
if (LenC->isOne()) {
// Fold memchr(x, y, 1) --> *x == y ? x : null for any x and y,
// constant or otherwise.
Value *Val = B.CreateLoad(B.getInt8Ty(), SrcStr, "memchr.char0");
// Slice off the character's high end bits.
CharVal = B.CreateTrunc(CharVal, B.getInt8Ty());
Value *Cmp = B.CreateICmpEQ(Val, CharVal, "memchr.char0cmp");
return B.CreateSelect(Cmp, SrcStr, NullPtr, "memchr.sel");
}
}
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str, 0, /*TrimAtNul=*/false))
return nullptr;
if (CharC) {
size_t Pos = Str.find(CharC->getZExtValue());
if (Pos == StringRef::npos)
// When the character is not in the source array fold the result
// to null regardless of Size.
return NullPtr;
// Fold memchr(s, c, n) -> n <= Pos ? null : s + Pos
// When the constant Size is less than or equal to the character
// position also fold the result to null.
Value *Cmp = B.CreateICmpULE(Size, ConstantInt::get(Size->getType(), Pos),
"memchr.cmp");
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, B.getInt64(Pos),
"memchr.ptr");
return B.CreateSelect(Cmp, NullPtr, SrcPlus);
}
if (Str.size() == 0)
// If the array is empty fold memchr(A, C, N) to null for any value
// of C and N on the basis that the only valid value of N is zero
// (otherwise the call is undefined).
return NullPtr;
if (LenC)
Str = substr(Str, LenC->getZExtValue());
size_t Pos = Str.find_first_not_of(Str[0]);
if (Pos == StringRef::npos
|| Str.find_first_not_of(Str[Pos], Pos) == StringRef::npos) {
// If the source array consists of at most two consecutive sequences
// of the same characters, then for any C and N (whether in bounds or
// not), fold memchr(S, C, N) to
// N != 0 && *S == C ? S : null
// or for the two sequences to:
// N != 0 && *S == C ? S : (N > Pos && S[Pos] == C ? S + Pos : null)
// ^Sel2 ^Sel1 are denoted above.
// The latter makes it also possible to fold strchr() calls with strings
// of the same characters.
Type *SizeTy = Size->getType();
Type *Int8Ty = B.getInt8Ty();
// Slice off the sought character's high end bits.
CharVal = B.CreateTrunc(CharVal, Int8Ty);
Value *Sel1 = NullPtr;
if (Pos != StringRef::npos) {
// Handle two consecutive sequences of the same characters.
Value *PosVal = ConstantInt::get(SizeTy, Pos);
Value *StrPos = ConstantInt::get(Int8Ty, Str[Pos]);
Value *CEqSPos = B.CreateICmpEQ(CharVal, StrPos);
Value *NGtPos = B.CreateICmp(ICmpInst::ICMP_UGT, Size, PosVal);
Value *And = B.CreateAnd(CEqSPos, NGtPos);
Value *SrcPlus = B.CreateInBoundsGEP(B.getInt8Ty(), SrcStr, PosVal);
Sel1 = B.CreateSelect(And, SrcPlus, NullPtr, "memchr.sel1");
}
Value *Str0 = ConstantInt::get(Int8Ty, Str[0]);
Value *CEqS0 = B.CreateICmpEQ(Str0, CharVal);
Value *NNeZ = B.CreateICmpNE(Size, ConstantInt::get(SizeTy, 0));
Value *And = B.CreateAnd(NNeZ, CEqS0);
return B.CreateSelect(And, SrcStr, Sel1, "memchr.sel2");
}
if (!LenC) {
if (isOnlyUsedInEqualityComparison(CI, SrcStr))
// S is dereferenceable so it's safe to load from it and fold
// memchr(S, C, N) == S to N && *S == C for any C and N.
// TODO: This is safe even even for nonconstant S.
return memChrToCharCompare(CI, Size, B, DL);
// From now on we need a constant length and constant array.
return nullptr;
}
// If the char is variable but the input str and length are not we can turn
// this memchr call into a simple bit field test. Of course this only works
// when the return value is only checked against null.
//
// It would be really nice to reuse switch lowering here but we can't change
// the CFG at this point.
//
// memchr("\r\n", C, 2) != nullptr -> (1 << C & ((1 << '\r') | (1 << '\n')))
// != 0
// after bounds check.
if (Str.empty() || !isOnlyUsedInZeroEqualityComparison(CI))
return nullptr;
unsigned char Max =
*std::max_element(reinterpret_cast<const unsigned char *>(Str.begin()),
reinterpret_cast<const unsigned char *>(Str.end()));
// Make sure the bit field we're about to create fits in a register on the
// target.
// FIXME: On a 64 bit architecture this prevents us from using the
// interesting range of alpha ascii chars. We could do better by emitting
// two bitfields or shifting the range by 64 if no lower chars are used.
if (!DL.fitsInLegalInteger(Max + 1))
return nullptr;
// For the bit field use a power-of-2 type with at least 8 bits to avoid
// creating unnecessary illegal types.
unsigned char Width = NextPowerOf2(std::max((unsigned char)7, Max));
// Now build the bit field.
APInt Bitfield(Width, 0);
for (char C : Str)
Bitfield.setBit((unsigned char)C);
Value *BitfieldC = B.getInt(Bitfield);
// Adjust width of "C" to the bitfield width, then mask off the high bits.
Value *C = B.CreateZExtOrTrunc(CharVal, BitfieldC->getType());
C = B.CreateAnd(C, B.getIntN(Width, 0xFF));
// First check that the bit field access is within bounds.
Value *Bounds = B.CreateICmp(ICmpInst::ICMP_ULT, C, B.getIntN(Width, Width),
"memchr.bounds");
// Create code that checks if the given bit is set in the field.
Value *Shl = B.CreateShl(B.getIntN(Width, 1ULL), C);
Value *Bits = B.CreateIsNotNull(B.CreateAnd(Shl, BitfieldC), "memchr.bits");
// Finally merge both checks and cast to pointer type. The inttoptr
// implicitly zexts the i1 to intptr type.
return B.CreateIntToPtr(B.CreateLogicalAnd(Bounds, Bits, "memchr"),
CI->getType());
}
// Optimize a memcmp or, when StrNCmp is true, strncmp call CI with constant
// arrays LHS and RHS and nonconstant Size.
static Value *optimizeMemCmpVarSize(CallInst *CI, Value *LHS, Value *RHS,
Value *Size, bool StrNCmp,
IRBuilderBase &B, const DataLayout &DL) {
if (LHS == RHS) // memcmp(s,s,x) -> 0
return Constant::getNullValue(CI->getType());
StringRef LStr, RStr;
if (!getConstantStringInfo(LHS, LStr, 0, /*TrimAtNul=*/false) ||
!getConstantStringInfo(RHS, RStr, 0, /*TrimAtNul=*/false))
return nullptr;
// If the contents of both constant arrays are known, fold a call to
// memcmp(A, B, N) to
// N <= Pos ? 0 : (A < B ? -1 : B < A ? +1 : 0)
// where Pos is the first mismatch between A and B, determined below.
uint64_t Pos = 0;
Value *Zero = ConstantInt::get(CI->getType(), 0);
for (uint64_t MinSize = std::min(LStr.size(), RStr.size()); ; ++Pos) {
if (Pos == MinSize ||
(StrNCmp && (LStr[Pos] == '\0' && RStr[Pos] == '\0'))) {
// One array is a leading part of the other of equal or greater
// size, or for strncmp, the arrays are equal strings.
// Fold the result to zero. Size is assumed to be in bounds, since
// otherwise the call would be undefined.
return Zero;
}
if (LStr[Pos] != RStr[Pos])
break;
}
// Normalize the result.
typedef unsigned char UChar;
int IRes = UChar(LStr[Pos]) < UChar(RStr[Pos]) ? -1 : 1;
Value *MaxSize = ConstantInt::get(Size->getType(), Pos);
Value *Cmp = B.CreateICmp(ICmpInst::ICMP_ULE, Size, MaxSize);
Value *Res = ConstantInt::get(CI->getType(), IRes);
return B.CreateSelect(Cmp, Zero, Res);
}
// Optimize a memcmp call CI with constant size Len.
static Value *optimizeMemCmpConstantSize(CallInst *CI, Value *LHS, Value *RHS,
uint64_t Len, IRBuilderBase &B,
const DataLayout &DL) {
if (Len == 0) // memcmp(s1,s2,0) -> 0
return Constant::getNullValue(CI->getType());
// memcmp(S1,S2,1) -> *(unsigned char*)LHS - *(unsigned char*)RHS
if (Len == 1) {
Value *LHSV =
B.CreateZExt(B.CreateLoad(B.getInt8Ty(), castToCStr(LHS, B), "lhsc"),
CI->getType(), "lhsv");
Value *RHSV =
B.CreateZExt(B.CreateLoad(B.getInt8Ty(), castToCStr(RHS, B), "rhsc"),
CI->getType(), "rhsv");
return B.CreateSub(LHSV, RHSV, "chardiff");
}
// memcmp(S1,S2,N/8)==0 -> (*(intN_t*)S1 != *(intN_t*)S2)==0
// TODO: The case where both inputs are constants does not need to be limited
// to legal integers or equality comparison. See block below this.
if (DL.isLegalInteger(Len * 8) && isOnlyUsedInZeroEqualityComparison(CI)) {
IntegerType *IntType = IntegerType::get(CI->getContext(), Len * 8);
unsigned PrefAlignment = DL.getPrefTypeAlignment(IntType);
// First, see if we can fold either argument to a constant.
Value *LHSV = nullptr;
if (auto *LHSC = dyn_cast<Constant>(LHS)) {
LHSC = ConstantExpr::getBitCast(LHSC, IntType->getPointerTo());
LHSV = ConstantFoldLoadFromConstPtr(LHSC, IntType, DL);
}
Value *RHSV = nullptr;
if (auto *RHSC = dyn_cast<Constant>(RHS)) {
RHSC = ConstantExpr::getBitCast(RHSC, IntType->getPointerTo());
RHSV = ConstantFoldLoadFromConstPtr(RHSC, IntType, DL);
}
// Don't generate unaligned loads. If either source is constant data,
// alignment doesn't matter for that source because there is no load.
if ((LHSV || getKnownAlignment(LHS, DL, CI) >= PrefAlignment) &&
(RHSV || getKnownAlignment(RHS, DL, CI) >= PrefAlignment)) {
if (!LHSV) {
Type *LHSPtrTy =
IntType->getPointerTo(LHS->getType()->getPointerAddressSpace());
LHSV = B.CreateLoad(IntType, B.CreateBitCast(LHS, LHSPtrTy), "lhsv");
}
if (!RHSV) {
Type *RHSPtrTy =
IntType->getPointerTo(RHS->getType()->getPointerAddressSpace());
RHSV = B.CreateLoad(IntType, B.CreateBitCast(RHS, RHSPtrTy), "rhsv");
}
return B.CreateZExt(B.CreateICmpNE(LHSV, RHSV), CI->getType(), "memcmp");
}
}
return nullptr;
}
// Most simplifications for memcmp also apply to bcmp.
Value *LibCallSimplifier::optimizeMemCmpBCmpCommon(CallInst *CI,
IRBuilderBase &B) {
Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (Value *Res = optimizeMemCmpVarSize(CI, LHS, RHS, Size, false, B, DL))
return Res;
// Handle constant Size.
ConstantInt *LenC = dyn_cast<ConstantInt>(Size);
if (!LenC)
return nullptr;
return optimizeMemCmpConstantSize(CI, LHS, RHS, LenC->getZExtValue(), B, DL);
}
Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
if (Value *V = optimizeMemCmpBCmpCommon(CI, B))
return V;
// memcmp(x, y, Len) == 0 -> bcmp(x, y, Len) == 0
// bcmp can be more efficient than memcmp because it only has to know that
// there is a difference, not how different one is to the other.
if (isLibFuncEmittable(M, TLI, LibFunc_bcmp) &&
isOnlyUsedInZeroEqualityComparison(CI)) {
Value *LHS = CI->getArgOperand(0);
Value *RHS = CI->getArgOperand(1);
Value *Size = CI->getArgOperand(2);
return copyFlags(*CI, emitBCmp(LHS, RHS, Size, B, DL, TLI));
}
return nullptr;
}
Value *LibCallSimplifier::optimizeBCmp(CallInst *CI, IRBuilderBase &B) {
return optimizeMemCmpBCmpCommon(CI, B);
}
Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// memcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n)
CallInst *NewCI = B.CreateMemCpy(CI->getArgOperand(0), Align(1),
CI->getArgOperand(1), Align(1), Size);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeMemCCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0);
Value *Src = CI->getArgOperand(1);
ConstantInt *StopChar = dyn_cast<ConstantInt>(CI->getArgOperand(2));
ConstantInt *N = dyn_cast<ConstantInt>(CI->getArgOperand(3));
StringRef SrcStr;
if (CI->use_empty() && Dst == Src)
return Dst;
// memccpy(d, s, c, 0) -> nullptr
if (N) {
if (N->isNullValue())
return Constant::getNullValue(CI->getType());
if (!getConstantStringInfo(Src, SrcStr, /*Offset=*/0,
/*TrimAtNul=*/false) ||
// TODO: Handle zeroinitializer.
!StopChar)
return nullptr;
} else {
return nullptr;
}
// Wrap arg 'c' of type int to char
size_t Pos = SrcStr.find(StopChar->getSExtValue() & 0xFF);
if (Pos == StringRef::npos) {
if (N->getZExtValue() <= SrcStr.size()) {
copyFlags(*CI, B.CreateMemCpy(Dst, Align(1), Src, Align(1),
CI->getArgOperand(3)));
return Constant::getNullValue(CI->getType());
}
return nullptr;
}
Value *NewN =
ConstantInt::get(N->getType(), std::min(uint64_t(Pos + 1), N->getZExtValue()));
// memccpy -> llvm.memcpy
copyFlags(*CI, B.CreateMemCpy(Dst, Align(1), Src, Align(1), NewN));
return Pos + 1 <= N->getZExtValue()
? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, NewN)
: Constant::getNullValue(CI->getType());
}
Value *LibCallSimplifier::optimizeMemPCpy(CallInst *CI, IRBuilderBase &B) {
Value *Dst = CI->getArgOperand(0);
Value *N = CI->getArgOperand(2);
// mempcpy(x, y, n) -> llvm.memcpy(align 1 x, align 1 y, n), x + n
CallInst *NewCI =
B.CreateMemCpy(Dst, Align(1), CI->getArgOperand(1), Align(1), N);
// Propagate attributes, but memcpy has no return value, so make sure that
// any return attributes are compliant.
// TODO: Attach return value attributes to the 1st operand to preserve them?
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return B.CreateInBoundsGEP(B.getInt8Ty(), Dst, N);
}
Value *LibCallSimplifier::optimizeMemMove(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, {0, 1}, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// memmove(x, y, n) -> llvm.memmove(align 1 x, align 1 y, n)
CallInst *NewCI = B.CreateMemMove(CI->getArgOperand(0), Align(1),
CI->getArgOperand(1), Align(1), Size);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilderBase &B) {
Value *Size = CI->getArgOperand(2);
annotateNonNullAndDereferenceable(CI, 0, Size, DL);
if (isa<IntrinsicInst>(CI))
return nullptr;
// memset(p, v, n) -> llvm.memset(align 1 p, v, n)
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
CallInst *NewCI = B.CreateMemSet(CI->getArgOperand(0), Val, Size, Align(1));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
Value *LibCallSimplifier::optimizeRealloc(CallInst *CI, IRBuilderBase &B) {
if (isa<ConstantPointerNull>(CI->getArgOperand(0)))
return copyFlags(*CI, emitMalloc(CI->getArgOperand(1), B, DL, TLI));
return nullptr;
}
//===----------------------------------------------------------------------===//
// Math Library Optimizations
//===----------------------------------------------------------------------===//
// Replace a libcall \p CI with a call to intrinsic \p IID
static Value *replaceUnaryCall(CallInst *CI, IRBuilderBase &B,
Intrinsic::ID IID) {
// Propagate fast-math flags from the existing call to the new call.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
Module *M = CI->getModule();
Value *V = CI->getArgOperand(0);
Function *F = Intrinsic::getDeclaration(M, IID, CI->getType());
CallInst *NewCall = B.CreateCall(F, V);
NewCall->takeName(CI);
return copyFlags(*CI, NewCall);
}
/// Return a variant of Val with float type.
/// Currently this works in two cases: If Val is an FPExtension of a float
/// value to something bigger, simply return the operand.
/// If Val is a ConstantFP but can be converted to a float ConstantFP without
/// loss of precision do so.
static Value *valueHasFloatPrecision(Value *Val) {
if (FPExtInst *Cast = dyn_cast<FPExtInst>(Val)) {
Value *Op = Cast->getOperand(0);
if (Op->getType()->isFloatTy())
return Op;
}
if (ConstantFP *Const = dyn_cast<ConstantFP>(Val)) {
APFloat F = Const->getValueAPF();
bool losesInfo;
(void)F.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
&losesInfo);
if (!losesInfo)
return ConstantFP::get(Const->getContext(), F);
}
return nullptr;
}
/// Shrink double -> float functions.
static Value *optimizeDoubleFP(CallInst *CI, IRBuilderBase &B,
bool isBinary, const TargetLibraryInfo *TLI,
bool isPrecise = false) {
Function *CalleeFn = CI->getCalledFunction();
if (!CI->getType()->isDoubleTy() || !CalleeFn)
return nullptr;
// If not all the uses of the function are converted to float, then bail out.
// This matters if the precision of the result is more important than the
// precision of the arguments.
if (isPrecise)
for (User *U : CI->users()) {
FPTruncInst *Cast = dyn_cast<FPTruncInst>(U);
if (!Cast || !Cast->getType()->isFloatTy())
return nullptr;
}
// If this is something like 'g((double) float)', convert to 'gf(float)'.
Value *V[2];
V[0] = valueHasFloatPrecision(CI->getArgOperand(0));
V[1] = isBinary ? valueHasFloatPrecision(CI->getArgOperand(1)) : nullptr;
if (!V[0] || (isBinary && !V[1]))
return nullptr;
// If call isn't an intrinsic, check that it isn't within a function with the
// same name as the float version of this call, otherwise the result is an
// infinite loop. For example, from MinGW-w64:
//
// float expf(float val) { return (float) exp((double) val); }
StringRef CalleeName = CalleeFn->getName();
bool IsIntrinsic = CalleeFn->isIntrinsic();
if (!IsIntrinsic) {
StringRef CallerName = CI->getFunction()->getName();
if (!CallerName.empty() && CallerName.back() == 'f' &&
CallerName.size() == (CalleeName.size() + 1) &&
CallerName.startswith(CalleeName))
return nullptr;
}
// Propagate the math semantics from the current function to the new function.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
// g((double) float) -> (double) gf(float)
Value *R;
if (IsIntrinsic) {
Module *M = CI->getModule();
Intrinsic::ID IID = CalleeFn->getIntrinsicID();
Function *Fn = Intrinsic::getDeclaration(M, IID, B.getFloatTy());
R = isBinary ? B.CreateCall(Fn, V) : B.CreateCall(Fn, V[0]);
} else {
AttributeList CalleeAttrs = CalleeFn->getAttributes();
R = isBinary ? emitBinaryFloatFnCall(V[0], V[1], TLI, CalleeName, B,
CalleeAttrs)
: emitUnaryFloatFnCall(V[0], TLI, CalleeName, B, CalleeAttrs);
}
return B.CreateFPExt(R, B.getDoubleTy());
}
/// Shrink double -> float for unary functions.
static Value *optimizeUnaryDoubleFP(CallInst *CI, IRBuilderBase &B,
const TargetLibraryInfo *TLI,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, false, TLI, isPrecise);
}
/// Shrink double -> float for binary functions.
static Value *optimizeBinaryDoubleFP(CallInst *CI, IRBuilderBase &B,
const TargetLibraryInfo *TLI,
bool isPrecise = false) {
return optimizeDoubleFP(CI, B, true, TLI, isPrecise);
}
// cabs(z) -> sqrt((creal(z)*creal(z)) + (cimag(z)*cimag(z)))
Value *LibCallSimplifier::optimizeCAbs(CallInst *CI, IRBuilderBase &B) {
if (!CI->isFast())
return nullptr;
// Propagate fast-math flags from the existing call to new instructions.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(CI->getFastMathFlags());
Value *Real, *Imag;
if (CI->arg_size() == 1) {
Value *Op = CI->getArgOperand(0);
assert(Op->getType()->isArrayTy() && "Unexpected signature for cabs!");
Real = B.CreateExtractValue(Op, 0, "real");
Imag = B.CreateExtractValue(Op, 1, "imag");
} else {
assert(CI->arg_size() == 2 && "Unexpected signature for cabs!");
Real = CI->getArgOperand(0);
Imag = CI->getArgOperand(1);
}
Value *RealReal = B.CreateFMul(Real, Real);
Value *ImagImag = B.CreateFMul(Imag, Imag);
Function *FSqrt = Intrinsic::getDeclaration(CI->getModule(), Intrinsic::sqrt,
CI->getType());
return copyFlags(
*CI, B.CreateCall(FSqrt, B.CreateFAdd(RealReal, ImagImag), "cabs"));
}
static Value *optimizeTrigReflections(CallInst *Call, LibFunc Func,
IRBuilderBase &B) {
if (!isa<FPMathOperator>(Call))
return nullptr;
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(Call->getFastMathFlags());
// TODO: Can this be shared to also handle LLVM intrinsics?
Value *X;
switch (Func) {
case LibFunc_sin:
case LibFunc_sinf:
case LibFunc_sinl:
case LibFunc_tan:
case LibFunc_tanf:
case LibFunc_tanl:
// sin(-X) --> -sin(X)
// tan(-X) --> -tan(X)
if (match(Call->getArgOperand(0), m_OneUse(m_FNeg(m_Value(X)))))
return B.CreateFNeg(
copyFlags(*Call, B.CreateCall(Call->getCalledFunction(), X)));
break;
case LibFunc_cos:
case LibFunc_cosf:
case LibFunc_cosl:
// cos(-X) --> cos(X)
if (match(Call->getArgOperand(0), m_FNeg(m_Value(X))))
return copyFlags(*Call,
B.CreateCall(Call->getCalledFunction(), X, "cos"));
break;
default:
break;
}
return nullptr;
}
// Return a properly extended integer (DstWidth bits wide) if the operation is
// an itofp.
static Value *getIntToFPVal(Value *I2F, IRBuilderBase &B, unsigned DstWidth) {
if (isa<SIToFPInst>(I2F) || isa<UIToFPInst>(I2F)) {
Value *Op = cast<Instruction>(I2F)->getOperand(0);
// Make sure that the exponent fits inside an "int" of size DstWidth,
// thus avoiding any range issues that FP has not.
unsigned BitWidth = Op->getType()->getPrimitiveSizeInBits();
if (BitWidth < DstWidth ||
(BitWidth == DstWidth && isa<SIToFPInst>(I2F)))
return isa<SIToFPInst>(I2F) ? B.CreateSExt(Op, B.getIntNTy(DstWidth))
: B.CreateZExt(Op, B.getIntNTy(DstWidth));
}
return nullptr;
}
/// Use exp{,2}(x * y) for pow(exp{,2}(x), y);
/// ldexp(1.0, x) for pow(2.0, itofp(x)); exp2(n * x) for pow(2.0 ** n, x);
/// exp10(x) for pow(10.0, x); exp2(log2(n) * x) for pow(n, x).
Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilderBase &B) {
Module *M = Pow->getModule();
Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs; // Attributes are only meaningful on the original call
Module *Mod = Pow->getModule();
Type *Ty = Pow->getType();
bool Ignored;
// Evaluate special cases related to a nested function as the base.
// pow(exp(x), y) -> exp(x * y)
// pow(exp2(x), y) -> exp2(x * y)
// If exp{,2}() is used only once, it is better to fold two transcendental
// math functions into one. If used again, exp{,2}() would still have to be
// called with the original argument, then keep both original transcendental
// functions. However, this transformation is only safe with fully relaxed
// math semantics, since, besides rounding differences, it changes overflow
// and underflow behavior quite dramatically. For example:
// pow(exp(1000), 0.001) = pow(inf, 0.001) = inf
// Whereas:
// exp(1000 * 0.001) = exp(1)
// TODO: Loosen the requirement for fully relaxed math semantics.
// TODO: Handle exp10() when more targets have it available.
CallInst *BaseFn = dyn_cast<CallInst>(Base);
if (BaseFn && BaseFn->hasOneUse() && BaseFn->isFast() && Pow->isFast()) {
LibFunc LibFn;
Function *CalleeFn = BaseFn->getCalledFunction();
if (CalleeFn &&
TLI->getLibFunc(CalleeFn->getName(), LibFn) &&
isLibFuncEmittable(M, TLI, LibFn)) {
StringRef ExpName;
Intrinsic::ID ID;
Value *ExpFn;
LibFunc LibFnFloat, LibFnDouble, LibFnLongDouble;
switch (LibFn) {
default:
return nullptr;
case LibFunc_expf: case LibFunc_exp: case LibFunc_expl:
ExpName = TLI->getName(LibFunc_exp);
ID = Intrinsic::exp;
LibFnFloat = LibFunc_expf;
LibFnDouble = LibFunc_exp;
LibFnLongDouble = LibFunc_expl;
break;
case LibFunc_exp2f: case LibFunc_exp2: case LibFunc_exp2l:
ExpName = TLI->getName(LibFunc_exp2);
ID = Intrinsic::exp2;
LibFnFloat = LibFunc_exp2f;
LibFnDouble = LibFunc_exp2;
LibFnLongDouble = LibFunc_exp2l;
break;
}
// Create new exp{,2}() with the product as its argument.
Value *FMul = B.CreateFMul(BaseFn->getArgOperand(0), Expo, "mul");
ExpFn = BaseFn->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, ID, Ty),
FMul, ExpName)
: emitUnaryFloatFnCall(FMul, TLI, LibFnDouble, LibFnFloat,
LibFnLongDouble, B,
BaseFn->getAttributes());
// Since the new exp{,2}() is different from the original one, dead code
// elimination cannot be trusted to remove it, since it may have side
// effects (e.g., errno). When the only consumer for the original
// exp{,2}() is pow(), then it has to be explicitly erased.
substituteInParent(BaseFn, ExpFn);
return ExpFn;
}
}
// Evaluate special cases related to a constant base.
const APFloat *BaseF;
if (!match(Pow->getArgOperand(0), m_APFloat(BaseF)))
return nullptr;
// pow(2.0, itofp(x)) -> ldexp(1.0, x)
if (match(Base, m_SpecificFP(2.0)) &&
(isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo)) &&
hasFloatFn(M, TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *ExpoI = getIntToFPVal(Expo, B, TLI->getIntSize()))
return copyFlags(*Pow,
emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), ExpoI,
TLI, LibFunc_ldexp, LibFunc_ldexpf,
LibFunc_ldexpl, B, Attrs));
}
// pow(2.0 ** n, x) -> exp2(n * x)
if (hasFloatFn(M, TLI, Ty, LibFunc_exp2, LibFunc_exp2f, LibFunc_exp2l)) {
APFloat BaseR = APFloat(1.0);
BaseR.convert(BaseF->getSemantics(), APFloat::rmTowardZero, &Ignored);
BaseR = BaseR / *BaseF;
bool IsInteger = BaseF->isInteger(), IsReciprocal = BaseR.isInteger();
const APFloat *NF = IsReciprocal ? &BaseR : BaseF;
APSInt NI(64, false);
if ((IsInteger || IsReciprocal) &&
NF->convertToInteger(NI, APFloat::rmTowardZero, &Ignored) ==
APFloat::opOK &&
NI > 1 && NI.isPowerOf2()) {
double N = NI.logBase2() * (IsReciprocal ? -1.0 : 1.0);
Value *FMul = B.CreateFMul(Expo, ConstantFP::get(Ty, N), "mul");
if (Pow->doesNotAccessMemory())
return copyFlags(*Pow, B.CreateCall(Intrinsic::getDeclaration(
Mod, Intrinsic::exp2, Ty),
FMul, "exp2"));
else
return copyFlags(*Pow, emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2,
LibFunc_exp2f,
LibFunc_exp2l, B, Attrs));
}
}
// pow(10.0, x) -> exp10(x)
// TODO: There is no exp10() intrinsic yet, but some day there shall be one.
if (match(Base, m_SpecificFP(10.0)) &&
hasFloatFn(M, TLI, Ty, LibFunc_exp10, LibFunc_exp10f, LibFunc_exp10l))
return copyFlags(*Pow, emitUnaryFloatFnCall(Expo, TLI, LibFunc_exp10,
LibFunc_exp10f, LibFunc_exp10l,
B, Attrs));
// pow(x, y) -> exp2(log2(x) * y)
if (Pow->hasApproxFunc() && Pow->hasNoNaNs() && BaseF->isFiniteNonZero() &&
!BaseF->isNegative()) {
// pow(1, inf) is defined to be 1 but exp2(log2(1) * inf) evaluates to NaN.
// Luckily optimizePow has already handled the x == 1 case.
assert(!match(Base, m_FPOne()) &&
"pow(1.0, y) should have been simplified earlier!");
Value *Log = nullptr;
if (Ty->isFloatTy())
Log = ConstantFP::get(Ty, std::log2(BaseF->convertToFloat()));
else if (Ty->isDoubleTy())
Log = ConstantFP::get(Ty, std::log2(BaseF->convertToDouble()));
if (Log) {
Value *FMul = B.CreateFMul(Log, Expo, "mul");
if (Pow->doesNotAccessMemory())
return copyFlags(*Pow, B.CreateCall(Intrinsic::getDeclaration(
Mod, Intrinsic::exp2, Ty),
FMul, "exp2"));
else if (hasFloatFn(M, TLI, Ty, LibFunc_exp2, LibFunc_exp2f,
LibFunc_exp2l))
return copyFlags(*Pow, emitUnaryFloatFnCall(FMul, TLI, LibFunc_exp2,
LibFunc_exp2f,
LibFunc_exp2l, B, Attrs));
}
}
return nullptr;
}
static Value *getSqrtCall(Value *V, AttributeList Attrs, bool NoErrno,
Module *M, IRBuilderBase &B,
const TargetLibraryInfo *TLI) {
// If errno is never set, then use the intrinsic for sqrt().
if (NoErrno) {
Function *SqrtFn =
Intrinsic::getDeclaration(M, Intrinsic::sqrt, V->getType());
return B.CreateCall(SqrtFn, V, "sqrt");
}
// Otherwise, use the libcall for sqrt().
if (hasFloatFn(M, TLI, V->getType(), LibFunc_sqrt, LibFunc_sqrtf,
LibFunc_sqrtl))
// TODO: We also should check that the target can in fact lower the sqrt()
// libcall. We currently have no way to ask this question, so we ask if
// the target has a sqrt() libcall, which is not exactly the same.
return emitUnaryFloatFnCall(V, TLI, LibFunc_sqrt, LibFunc_sqrtf,
LibFunc_sqrtl, B, Attrs);
return nullptr;
}
/// Use square root in place of pow(x, +/-0.5).
Value *LibCallSimplifier::replacePowWithSqrt(CallInst *Pow, IRBuilderBase &B) {
Value *Sqrt, *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs; // Attributes are only meaningful on the original call
Module *Mod = Pow->getModule();
Type *Ty = Pow->getType();
const APFloat *ExpoF;
if (!match(Expo, m_APFloat(ExpoF)) ||
(!ExpoF->isExactlyValue(0.5) && !ExpoF->isExactlyValue(-0.5)))
return nullptr;
// Converting pow(X, -0.5) to 1/sqrt(X) may introduce an extra rounding step,
// so that requires fast-math-flags (afn or reassoc).
if (ExpoF->isNegative() && (!Pow->hasApproxFunc() && !Pow->hasAllowReassoc()))
return nullptr;
// If we have a pow() library call (accesses memory) and we can't guarantee
// that the base is not an infinity, give up:
// pow(-Inf, 0.5) is optionally required to have a result of +Inf (not setting
// errno), but sqrt(-Inf) is required by various standards to set errno.
if (!Pow->doesNotAccessMemory() && !Pow->hasNoInfs() &&
!isKnownNeverInfinity(Base, TLI))
return nullptr;
Sqrt = getSqrtCall(Base, Attrs, Pow->doesNotAccessMemory(), Mod, B, TLI);
if (!Sqrt)
return nullptr;
// Handle signed zero base by expanding to fabs(sqrt(x)).
if (!Pow->hasNoSignedZeros()) {
Function *FAbsFn = Intrinsic::getDeclaration(Mod, Intrinsic::fabs, Ty);
Sqrt = B.CreateCall(FAbsFn, Sqrt, "abs");
}
Sqrt = copyFlags(*Pow, Sqrt);
// Handle non finite base by expanding to
// (x == -infinity ? +infinity : sqrt(x)).
if (!Pow->hasNoInfs()) {
Value *PosInf = ConstantFP::getInfinity(Ty),
*NegInf = ConstantFP::getInfinity(Ty, true);
Value *FCmp = B.CreateFCmpOEQ(Base, NegInf, "isinf");
Sqrt = B.CreateSelect(FCmp, PosInf, Sqrt);
}
// If the exponent is negative, then get the reciprocal.
if (ExpoF->isNegative())
Sqrt = B.CreateFDiv(ConstantFP::get(Ty, 1.0), Sqrt, "reciprocal");
return Sqrt;
}
static Value *createPowWithIntegerExponent(Value *Base, Value *Expo, Module *M,
IRBuilderBase &B) {
Value *Args[] = {Base, Expo};
Type *Types[] = {Base->getType(), Expo->getType()};
Function *F = Intrinsic::getDeclaration(M, Intrinsic::powi, Types);
return B.CreateCall(F, Args);
}
Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilderBase &B) {
Value *Base = Pow->getArgOperand(0);
Value *Expo = Pow->getArgOperand(1);
Function *Callee = Pow->getCalledFunction();
StringRef Name = Callee->getName();
Type *Ty = Pow->getType();
Module *M = Pow->getModule();
bool AllowApprox = Pow->hasApproxFunc();
bool Ignored;
// Propagate the math semantics from the call to any created instructions.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(Pow->getFastMathFlags());
// Evaluate special cases related to the base.
// pow(1.0, x) -> 1.0
if (match(Base, m_FPOne()))
return Base;
if (Value *Exp = replacePowWithExp(Pow, B))
return Exp;
// Evaluate special cases related to the exponent.
// pow(x, -1.0) -> 1.0 / x
if (match(Expo, m_SpecificFP(-1.0)))
return B.CreateFDiv(ConstantFP::get(Ty, 1.0), Base, "reciprocal");
// pow(x, +/-0.0) -> 1.0
if (match(Expo, m_AnyZeroFP()))
return ConstantFP::get(Ty, 1.0);
// pow(x, 1.0) -> x
if (match(Expo, m_FPOne()))
return Base;
// pow(x, 2.0) -> x * x
if (match(Expo, m_SpecificFP(2.0)))
return B.CreateFMul(Base, Base, "square");
if (Value *Sqrt = replacePowWithSqrt(Pow, B))
return Sqrt;
// If we can approximate pow:
// pow(x, n) -> powi(x, n) * sqrt(x) if n has exactly a 0.5 fraction
// pow(x, n) -> powi(x, n) if n is a constant signed integer value
const APFloat *ExpoF;
if (AllowApprox && match(Expo, m_APFloat(ExpoF)) &&
!ExpoF->isExactlyValue(0.5) && !ExpoF->isExactlyValue(-0.5)) {
APFloat ExpoA(abs(*ExpoF));
APFloat ExpoI(*ExpoF);
Value *Sqrt = nullptr;
if (!ExpoA.isInteger()) {
APFloat Expo2 = ExpoA;
// To check if ExpoA is an integer + 0.5, we add it to itself. If there
// is no floating point exception and the result is an integer, then
// ExpoA == integer + 0.5
if (Expo2.add(ExpoA, APFloat::rmNearestTiesToEven) != APFloat::opOK)
return nullptr;
if (!Expo2.isInteger())
return nullptr;
if (ExpoI.roundToIntegral(APFloat::rmTowardNegative) !=
APFloat::opInexact)
return nullptr;
if (!ExpoI.isInteger())
return nullptr;
ExpoF = &ExpoI;
Sqrt = getSqrtCall(Base, Pow->getCalledFunction()->getAttributes(),
Pow->doesNotAccessMemory(), M, B, TLI);
if (!Sqrt)
return nullptr;
}
// 0.5 fraction is now optionally handled.
// Do pow -> powi for remaining integer exponent
APSInt IntExpo(TLI->getIntSize(), /*isUnsigned=*/false);
if (ExpoF->isInteger() &&
ExpoF->convertToInteger(IntExpo, APFloat::rmTowardZero, &Ignored) ==
APFloat::opOK) {
Value *PowI = copyFlags(
*Pow,
createPowWithIntegerExponent(
Base, ConstantInt::get(B.getIntNTy(TLI->getIntSize()), IntExpo),
M, B));
if (PowI && Sqrt)
return B.CreateFMul(PowI, Sqrt);
return PowI;
}
}
// powf(x, itofp(y)) -> powi(x, y)
if (AllowApprox && (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo))) {
if (Value *ExpoI = getIntToFPVal(Expo, B, TLI->getIntSize()))
return copyFlags(*Pow, createPowWithIntegerExponent(Base, ExpoI, M, B));
}
// Shrink pow() to powf() if the arguments are single precision,
// unless the result is expected to be double precision.
if (UnsafeFPShrink && Name == TLI->getName(LibFunc_pow) &&
hasFloatVersion(M, Name)) {
if (Value *Shrunk = optimizeBinaryDoubleFP(Pow, B, TLI, true))
return Shrunk;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
AttributeList Attrs; // Attributes are only meaningful on the original call
StringRef Name = Callee->getName();
Value *Ret = nullptr;
if (UnsafeFPShrink && Name == TLI->getName(LibFunc_exp2) &&
hasFloatVersion(M, Name))
Ret = optimizeUnaryDoubleFP(CI, B, TLI, true);
Type *Ty = CI->getType();
Value *Op = CI->getArgOperand(0);
// Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= IntSize
// Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < IntSize
if ((isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) &&
hasFloatFn(M, TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
if (Value *Exp = getIntToFPVal(Op, B, TLI->getIntSize()))
return emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), Exp, TLI,
LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl,
B, Attrs);
}
return Ret;
}
Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
// If we can shrink the call to a float function rather than a double
// function, do that first.
Function *Callee = CI->getCalledFunction();
StringRef Name = Callee->getName();
if ((Name == "fmin" || Name == "fmax") && hasFloatVersion(M, Name))
if (Value *Ret = optimizeBinaryDoubleFP(CI, B, TLI))
return Ret;
// The LLVM intrinsics minnum/maxnum correspond to fmin/fmax. Canonicalize to
// the intrinsics for improved optimization (for example, vectorization).
// No-signed-zeros is implied by the definitions of fmax/fmin themselves.
// From the C standard draft WG14/N1256:
// "Ideally, fmax would be sensitive to the sign of zero, for example
// fmax(-0.0, +0.0) would return +0; however, implementation in software
// might be impractical."
IRBuilderBase::FastMathFlagGuard Guard(B);
FastMathFlags FMF = CI->getFastMathFlags();
FMF.setNoSignedZeros();
B.setFastMathFlags(FMF);
Intrinsic::ID IID = Callee->getName().startswith("fmin") ? Intrinsic::minnum
: Intrinsic::maxnum;
Function *F = Intrinsic::getDeclaration(CI->getModule(), IID, CI->getType());
return copyFlags(
*CI, B.CreateCall(F, {CI->getArgOperand(0), CI->getArgOperand(1)}));
}
Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilderBase &B) {
Function *LogFn = Log->getCalledFunction();
AttributeList Attrs; // Attributes are only meaningful on the original call
StringRef LogNm = LogFn->getName();
Intrinsic::ID LogID = LogFn->getIntrinsicID();
Module *Mod = Log->getModule();
Type *Ty = Log->getType();
Value *Ret = nullptr;
if (UnsafeFPShrink && hasFloatVersion(Mod, LogNm))
Ret = optimizeUnaryDoubleFP(Log, B, TLI, true);
// The earlier call must also be 'fast' in order to do these transforms.
CallInst *Arg = dyn_cast<CallInst>(Log->getArgOperand(0));
if (!Log->isFast() || !Arg || !Arg->isFast() || !Arg->hasOneUse())
return Ret;
LibFunc LogLb, ExpLb, Exp2Lb, Exp10Lb, PowLb;
// This is only applicable to log(), log2(), log10().
if (TLI->getLibFunc(LogNm, LogLb))
switch (LogLb) {
case LibFunc_logf:
LogID = Intrinsic::log;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log:
LogID = Intrinsic::log;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_logl:
LogID = Intrinsic::log;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log2f:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log2:
LogID = Intrinsic::log2;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log2l:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log10f:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log10:
LogID = Intrinsic::log10;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log10l:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
default:
return Ret;
}
else if (LogID == Intrinsic::log || LogID == Intrinsic::log2 ||
LogID == Intrinsic::log10) {
if (Ty->getScalarType()->isFloatTy()) {
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
} else if (Ty->getScalarType()->isDoubleTy()) {
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
} else
return Ret;
} else
return Ret;
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(FastMathFlags::getFast());
Intrinsic::ID ArgID = Arg->getIntrinsicID();
LibFunc ArgLb = NotLibFunc;
TLI->getLibFunc(*Arg, ArgLb);
// log(pow(x,y)) -> y*log(x)
if (ArgLb == PowLb || ArgID == Intrinsic::pow) {
Value *LogX =
Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Arg->getOperand(0), "log")
: emitUnaryFloatFnCall(Arg->getOperand(0), TLI, LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(1), LogX, "mul");
// Since pow() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
// log(exp{,2,10}(y)) -> y*log({e,2,10})
// TODO: There is no exp10() intrinsic yet.
if (ArgLb == ExpLb || ArgLb == Exp2Lb || ArgLb == Exp10Lb ||
ArgID == Intrinsic::exp || ArgID == Intrinsic::exp2) {
Constant *Eul;
if (ArgLb == ExpLb || ArgID == Intrinsic::exp)
// FIXME: Add more precise value of e for long double.
Eul = ConstantFP::get(Log->getType(), numbers::e);
else if (ArgLb == Exp2Lb || ArgID == Intrinsic::exp2)
Eul = ConstantFP::get(Log->getType(), 2.0);
else
Eul = ConstantFP::get(Log->getType(), 10.0);
Value *LogE = Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Eul, "log")
: emitUnaryFloatFnCall(Eul, TLI, LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(0), LogE, "mul");
// Since exp() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
return Ret;
}
Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
Value *Ret = nullptr;
// TODO: Once we have a way (other than checking for the existince of the
// libcall) to tell whether our target can lower @llvm.sqrt, relax the
// condition below.
if (isLibFuncEmittable(M, TLI, LibFunc_sqrtf) &&
(Callee->getName() == "sqrt" ||
Callee->getIntrinsicID() == Intrinsic::sqrt))
Ret = optimizeUnaryDoubleFP(CI, B, TLI, true);
if (!CI->isFast())
return Ret;
Instruction *I = dyn_cast<Instruction>(CI->getArgOperand(0));
if (!I || I->getOpcode() != Instruction::FMul || !I->isFast())
return Ret;
// We're looking for a repeated factor in a multiplication tree,
// so we can do this fold: sqrt(x * x) -> fabs(x);
// or this fold: sqrt((x * x) * y) -> fabs(x) * sqrt(y).
Value *Op0 = I->getOperand(0);
Value *Op1 = I->getOperand(1);
Value *RepeatOp = nullptr;
Value *OtherOp = nullptr;
if (Op0 == Op1) {
// Simple match: the operands of the multiply are identical.
RepeatOp = Op0;
} else {
// Look for a more complicated pattern: one of the operands is itself
// a multiply, so search for a common factor in that multiply.
// Note: We don't bother looking any deeper than this first level or for
// variations of this pattern because instcombine's visitFMUL and/or the
// reassociation pass should give us this form.
Value *OtherMul0, *OtherMul1;
if (match(Op0, m_FMul(m_Value(OtherMul0), m_Value(OtherMul1)))) {
// Pattern: sqrt((x * y) * z)
if (OtherMul0 == OtherMul1 && cast<Instruction>(Op0)->isFast()) {
// Matched: sqrt((x * x) * z)
RepeatOp = OtherMul0;
OtherOp = Op1;
}
}
}
if (!RepeatOp)
return Ret;
// Fast math flags for any created instructions should match the sqrt
// and multiply.
IRBuilderBase::FastMathFlagGuard Guard(B);
B.setFastMathFlags(I->getFastMathFlags());
// If we found a repeated factor, hoist it out of the square root and
// replace it with the fabs of that factor.
Type *ArgType = I->getType();
Function *Fabs = Intrinsic::getDeclaration(M, Intrinsic::fabs, ArgType);
Value *FabsCall = B.CreateCall(Fabs, RepeatOp, "fabs");
if (OtherOp) {
// If we found a non-repeated factor, we still need to get its square
// root. We then multiply that by the value that was simplified out
// of the square root calculation.
Function *Sqrt = Intrinsic::getDeclaration(M, Intrinsic::sqrt, ArgType);
Value *SqrtCall = B.CreateCall(Sqrt, OtherOp, "sqrt");
return copyFlags(*CI, B.CreateFMul(FabsCall, SqrtCall));
}
return copyFlags(*CI, FabsCall);
}
// TODO: Generalize to handle any trig function and its inverse.
Value *LibCallSimplifier::optimizeTan(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
Value *Ret = nullptr;
StringRef Name = Callee->getName();
if (UnsafeFPShrink && Name == "tan" && hasFloatVersion(M, Name))
Ret = optimizeUnaryDoubleFP(CI, B, TLI, true);
Value *Op1 = CI->getArgOperand(0);
auto *OpC = dyn_cast<CallInst>(Op1);
if (!OpC)
return Ret;
// Both calls must be 'fast' in order to remove them.
if (!CI->isFast() || !OpC->isFast())
return Ret;
// tan(atan(x)) -> x
// tanf(atanf(x)) -> x
// tanl(atanl(x)) -> x
LibFunc Func;
Function *F = OpC->getCalledFunction();
if (F && TLI->getLibFunc(F->getName(), Func) &&
isLibFuncEmittable(M, TLI, Func) &&
((Func == LibFunc_atan && Callee->getName() == "tan") ||
(Func == LibFunc_atanf && Callee->getName() == "tanf") ||
(Func == LibFunc_atanl && Callee->getName() == "tanl")))
Ret = OpC->getArgOperand(0);
return Ret;
}
static bool isTrigLibCall(CallInst *CI) {
// We can only hope to do anything useful if we can ignore things like errno
// and floating-point exceptions.
// We already checked the prototype.
return CI->hasFnAttr(Attribute::NoUnwind) &&
CI->hasFnAttr(Attribute::ReadNone);
}
static bool insertSinCosCall(IRBuilderBase &B, Function *OrigCallee, Value *Arg,
bool UseFloat, Value *&Sin, Value *&Cos,
Value *&SinCos, const TargetLibraryInfo *TLI) {
Module *M = OrigCallee->getParent();
Type *ArgTy = Arg->getType();
Type *ResTy;
StringRef Name;
Triple T(OrigCallee->getParent()->getTargetTriple());
if (UseFloat) {
Name = "__sincospif_stret";
assert(T.getArch() != Triple::x86 && "x86 messy and unsupported for now");
// x86_64 can't use {float, float} since that would be returned in both
// xmm0 and xmm1, which isn't what a real struct would do.
ResTy = T.getArch() == Triple::x86_64
? static_cast<Type *>(FixedVectorType::get(ArgTy, 2))
: static_cast<Type *>(StructType::get(ArgTy, ArgTy));
} else {
Name = "__sincospi_stret";
ResTy = StructType::get(ArgTy, ArgTy);
}
if (!isLibFuncEmittable(M, TLI, Name))
return false;
LibFunc TheLibFunc;
TLI->getLibFunc(Name, TheLibFunc);
FunctionCallee Callee = getOrInsertLibFunc(
M, *TLI, TheLibFunc, OrigCallee->getAttributes(), ResTy, ArgTy);
if (Instruction *ArgInst = dyn_cast<Instruction>(Arg)) {
// If the argument is an instruction, it must dominate all uses so put our
// sincos call there.
B.SetInsertPoint(ArgInst->getParent(), ++ArgInst->getIterator());
} else {
// Otherwise (e.g. for a constant) the beginning of the function is as
// good a place as any.
BasicBlock &EntryBB = B.GetInsertBlock()->getParent()->getEntryBlock();
B.SetInsertPoint(&EntryBB, EntryBB.begin());
}
SinCos = B.CreateCall(Callee, Arg, "sincospi");
if (SinCos->getType()->isStructTy()) {
Sin = B.CreateExtractValue(SinCos, 0, "sinpi");
Cos = B.CreateExtractValue(SinCos, 1, "cospi");
} else {
Sin = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 0),
"sinpi");
Cos = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 1),
"cospi");
}
return true;
}
Value *LibCallSimplifier::optimizeSinCosPi(CallInst *CI, IRBuilderBase &B) {
// Make sure the prototype is as expected, otherwise the rest of the
// function is probably invalid and likely to abort.
if (!isTrigLibCall(CI))
return nullptr;
Value *Arg = CI->getArgOperand(0);
SmallVector<CallInst *, 1> SinCalls;
SmallVector<CallInst *, 1> CosCalls;
SmallVector<CallInst *, 1> SinCosCalls;
bool IsFloat = Arg->getType()->isFloatTy();
// Look for all compatible sinpi, cospi and sincospi calls with the same
// argument. If there are enough (in some sense) we can make the
// substitution.
Function *F = CI->getFunction();
for (User *U : Arg->users())
classifyArgUse(U, F, IsFloat, SinCalls, CosCalls, SinCosCalls);
// It's only worthwhile if both sinpi and cospi are actually used.
if (SinCalls.empty() || CosCalls.empty())
return nullptr;
Value *Sin, *Cos, *SinCos;
if (!insertSinCosCall(B, CI->getCalledFunction(), Arg, IsFloat, Sin, Cos,
SinCos, TLI))
return nullptr;
auto replaceTrigInsts = [this](SmallVectorImpl<CallInst *> &Calls,
Value *Res) {
for (CallInst *C : Calls)
replaceAllUsesWith(C, Res);
};
replaceTrigInsts(SinCalls, Sin);
replaceTrigInsts(CosCalls, Cos);
replaceTrigInsts(SinCosCalls, SinCos);
return nullptr;
}
void LibCallSimplifier::classifyArgUse(
Value *Val, Function *F, bool IsFloat,
SmallVectorImpl<CallInst *> &SinCalls,
SmallVectorImpl<CallInst *> &CosCalls,
SmallVectorImpl<CallInst *> &SinCosCalls) {
CallInst *CI = dyn_cast<CallInst>(Val);
Module *M = CI->getModule();
if (!CI || CI->use_empty())
return;
// Don't consider calls in other functions.
if (CI->getFunction() != F)
return;
Function *Callee = CI->getCalledFunction();
LibFunc Func;
if (!Callee || !TLI->getLibFunc(*Callee, Func) ||
!isLibFuncEmittable(M, TLI, Func) ||
!isTrigLibCall(CI))
return;
if (IsFloat) {
if (Func == LibFunc_sinpif)
SinCalls.push_back(CI);
else if (Func == LibFunc_cospif)
CosCalls.push_back(CI);
else if (Func == LibFunc_sincospif_stret)
SinCosCalls.push_back(CI);
} else {
if (Func == LibFunc_sinpi)
SinCalls.push_back(CI);
else if (Func == LibFunc_cospi)
CosCalls.push_back(CI);
else if (Func == LibFunc_sincospi_stret)
SinCosCalls.push_back(CI);
}
}
//===----------------------------------------------------------------------===//
// Integer Library Call Optimizations
//===----------------------------------------------------------------------===//
Value *LibCallSimplifier::optimizeFFS(CallInst *CI, IRBuilderBase &B) {
// All variants of ffs return int which need not be 32 bits wide.
// ffs{,l,ll}(x) -> x != 0 ? (int)llvm.cttz(x)+1 : 0
Type *RetType = CI->getType();
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Function *F = Intrinsic::getDeclaration(CI->getCalledFunction()->getParent(),
Intrinsic::cttz, ArgType);
Value *V = B.CreateCall(F, {Op, B.getTrue()}, "cttz");
V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1));
V = B.CreateIntCast(V, RetType, false);
Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType));
return B.CreateSelect(Cond, V, ConstantInt::get(RetType, 0));
}
Value *LibCallSimplifier::optimizeFls(CallInst *CI, IRBuilderBase &B) {
// All variants of fls return int which need not be 32 bits wide.
// fls{,l,ll}(x) -> (int)(sizeInBits(x) - llvm.ctlz(x, false))
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Function *F = Intrinsic::getDeclaration(CI->getCalledFunction()->getParent(),
Intrinsic::ctlz, ArgType);
Value *V = B.CreateCall(F, {Op, B.getFalse()}, "ctlz");
V = B.CreateSub(ConstantInt::get(V->getType(), ArgType->getIntegerBitWidth()),
V);
return B.CreateIntCast(V, CI->getType(), false);
}
Value *LibCallSimplifier::optimizeAbs(CallInst *CI, IRBuilderBase &B) {
// abs(x) -> x <s 0 ? -x : x
// The negation has 'nsw' because abs of INT_MIN is undefined.
Value *X = CI->getArgOperand(0);
Value *IsNeg = B.CreateIsNeg(X);
Value *NegX = B.CreateNSWNeg(X, "neg");
return B.CreateSelect(IsNeg, NegX, X);
}
Value *LibCallSimplifier::optimizeIsDigit(CallInst *CI, IRBuilderBase &B) {
// isdigit(c) -> (c-'0') <u 10
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Op = B.CreateSub(Op, ConstantInt::get(ArgType, '0'), "isdigittmp");
Op = B.CreateICmpULT(Op, ConstantInt::get(ArgType, 10), "isdigit");
return B.CreateZExt(Op, CI->getType());
}
Value *LibCallSimplifier::optimizeIsAscii(CallInst *CI, IRBuilderBase &B) {
// isascii(c) -> c <u 128
Value *Op = CI->getArgOperand(0);
Type *ArgType = Op->getType();
Op = B.CreateICmpULT(Op, ConstantInt::get(ArgType, 128), "isascii");
return B.CreateZExt(Op, CI->getType());
}
Value *LibCallSimplifier::optimizeToAscii(CallInst *CI, IRBuilderBase &B) {
// toascii(c) -> c & 0x7f
return B.CreateAnd(CI->getArgOperand(0),
ConstantInt::get(CI->getType(), 0x7F));
}
// Fold calls to atoi, atol, and atoll.
Value *LibCallSimplifier::optimizeAtoi(CallInst *CI, IRBuilderBase &B) {
CI->addParamAttr(0, Attribute::NoCapture);
StringRef Str;
if (!getConstantStringInfo(CI->getArgOperand(0), Str))
return nullptr;
return convertStrToInt(CI, Str, nullptr, 10, /*AsSigned=*/true, B);
}
// Fold calls to strtol, strtoll, strtoul, and strtoull.
Value *LibCallSimplifier::optimizeStrToInt(CallInst *CI, IRBuilderBase &B,
bool AsSigned) {
Value *EndPtr = CI->getArgOperand(1);
if (isa<ConstantPointerNull>(EndPtr)) {
// With a null EndPtr, this function won't capture the main argument.
// It would be readonly too, except that it still may write to errno.
CI->addParamAttr(0, Attribute::NoCapture);
EndPtr = nullptr;
} else if (!isKnownNonZero(EndPtr, DL))
return nullptr;
StringRef Str;
if (!getConstantStringInfo(CI->getArgOperand(0), Str))
return nullptr;
if (ConstantInt *CInt = dyn_cast<ConstantInt>(CI->getArgOperand(2))) {
return convertStrToInt(CI, Str, EndPtr, CInt->getSExtValue(), AsSigned, B);
}
return nullptr;
}
//===----------------------------------------------------------------------===//
// Formatting and IO Library Call Optimizations
//===----------------------------------------------------------------------===//
static bool isReportingError(Function *Callee, CallInst *CI, int StreamArg);
Value *LibCallSimplifier::optimizeErrorReporting(CallInst *CI, IRBuilderBase &B,
int StreamArg) {
Function *Callee = CI->getCalledFunction();
// Error reporting calls should be cold, mark them as such.
// This applies even to non-builtin calls: it is only a hint and applies to
// functions that the frontend might not understand as builtins.
// This heuristic was suggested in:
// Improving Static Branch Prediction in a Compiler
// Brian L. Deitrich, Ben-Chung Cheng, Wen-mei W. Hwu
// Proceedings of PACT'98, Oct. 1998, IEEE
if (!CI->hasFnAttr(Attribute::Cold) &&
isReportingError(Callee, CI, StreamArg)) {
CI->addFnAttr(Attribute::Cold);
}
return nullptr;
}
static bool isReportingError(Function *Callee, CallInst *CI, int StreamArg) {
if (!Callee || !Callee->isDeclaration())
return false;
if (StreamArg < 0)
return true;
// These functions might be considered cold, but only if their stream
// argument is stderr.
if (StreamArg >= (int)CI->arg_size())
return false;
LoadInst *LI = dyn_cast<LoadInst>(CI->getArgOperand(StreamArg));
if (!LI)
return false;
GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getPointerOperand());
if (!GV || !GV->isDeclaration())
return false;
return GV->getName() == "stderr";
}
Value *LibCallSimplifier::optimizePrintFString(CallInst *CI, IRBuilderBase &B) {
// Check for a fixed format string.
StringRef FormatStr;
if (!getConstantStringInfo(CI->getArgOperand(0), FormatStr))
return nullptr;
// Empty format string -> noop.
if (FormatStr.empty()) // Tolerate printf's declared void.
return CI->use_empty() ? (Value *)CI : ConstantInt::get(CI->getType(), 0);
// Do not do any of the following transformations if the printf return value
// is used, in general the printf return value is not compatible with either
// putchar() or puts().
if (!CI->use_empty())
return nullptr;
Type *IntTy = CI->getType();
// printf("x") -> putchar('x'), even for "%" and "%%".
if (FormatStr.size() == 1 || FormatStr == "%%") {
// Convert the character to unsigned char before passing it to putchar
// to avoid host-specific sign extension in the IR. Putchar converts
// it to unsigned char regardless.
Value *IntChar = ConstantInt::get(IntTy, (unsigned char)FormatStr[0]);
return copyFlags(*CI, emitPutChar(IntChar, B, TLI));
}
// Try to remove call or emit putchar/puts.
if (FormatStr == "%s" && CI->arg_size() > 1) {
StringRef OperandStr;
if (!getConstantStringInfo(CI->getOperand(1), OperandStr))
return nullptr;
// printf("%s", "") --> NOP
if (OperandStr.empty())
return (Value *)CI;
// printf("%s", "a") --> putchar('a')
if (OperandStr.size() == 1) {
// Convert the character to unsigned char before passing it to putchar
// to avoid host-specific sign extension in the IR. Putchar converts
// it to unsigned char regardless.
Value *IntChar = ConstantInt::get(IntTy, (unsigned char)OperandStr[0]);
return copyFlags(*CI, emitPutChar(IntChar, B, TLI));
}
// printf("%s", str"\n") --> puts(str)
if (OperandStr.back() == '\n') {
OperandStr = OperandStr.drop_back();
Value *GV = B.CreateGlobalString(OperandStr, "str");
return copyFlags(*CI, emitPutS(GV, B, TLI));
}
return nullptr;
}
// printf("foo\n") --> puts("foo")
if (FormatStr.back() == '\n' &&
!FormatStr.contains('%')) { // No format characters.
// Create a string literal with no \n on it. We expect the constant merge
// pass to be run after this pass, to merge duplicate strings.
FormatStr = FormatStr.drop_back();
Value *GV = B.CreateGlobalString(FormatStr, "str");
return copyFlags(*CI, emitPutS(GV, B, TLI));
}
// Optimize specific format strings.
// printf("%c", chr) --> putchar(chr)
if (FormatStr == "%c" && CI->arg_size() > 1 &&
CI->getArgOperand(1)->getType()->isIntegerTy()) {
// Convert the argument to the type expected by putchar, i.e., int, which
// need not be 32 bits wide but which is the same as printf's return type.
Value *IntChar = B.CreateIntCast(CI->getArgOperand(1), IntTy, false);
return copyFlags(*CI, emitPutChar(IntChar, B, TLI));
}
// printf("%s\n", str) --> puts(str)
if (FormatStr == "%s\n" && CI->arg_size() > 1 &&
CI->getArgOperand(1)->getType()->isPointerTy())
return copyFlags(*CI, emitPutS(CI->getArgOperand(1), B, TLI));
return nullptr;
}
Value *LibCallSimplifier::optimizePrintF(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
if (Value *V = optimizePrintFString(CI, B)) {
return V;
}
// printf(format, ...) -> iprintf(format, ...) if no floating point
// arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_iprintf) &&
!callHasFloatingPointArgument(CI)) {
FunctionCallee IPrintFFn = getOrInsertLibFunc(M, *TLI, LibFunc_iprintf, FT,
Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(IPrintFFn);
B.Insert(New);
return New;
}
// printf(format, ...) -> __small_printf(format, ...) if no 128-bit floating point
// arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_small_printf) &&
!callHasFP128Argument(CI)) {
auto SmallPrintFFn = getOrInsertLibFunc(M, *TLI, LibFunc_small_printf, FT,
Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(SmallPrintFFn);
B.Insert(New);
return New;
}
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI,
IRBuilderBase &B) {
// Check for a fixed format string.
StringRef FormatStr;
if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
return nullptr;
// If we just have a format string (nothing else crazy) transform it.
Value *Dest = CI->getArgOperand(0);
if (CI->arg_size() == 2) {
// Make sure there's no % in the constant array. We could try to handle
// %% -> % in the future if we cared.
if (FormatStr.contains('%'))
return nullptr; // we found a format specifier, bail out.
// sprintf(str, fmt) -> llvm.memcpy(align 1 str, align 1 fmt, strlen(fmt)+1)
B.CreateMemCpy(
Dest, Align(1), CI->getArgOperand(1), Align(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
FormatStr.size() + 1)); // Copy the null byte.
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->arg_size() < 3)
return nullptr;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!CI->getArgOperand(2)->getType()->isIntegerTy())
return nullptr;
Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char");
Value *Ptr = castToCStr(Dest, B);
B.CreateStore(V, Ptr);
Ptr = B.CreateInBoundsGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul");
B.CreateStore(B.getInt8(0), Ptr);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// sprintf(dest, "%s", str) -> llvm.memcpy(align 1 dest, align 1 str,
// strlen(str)+1)
if (!CI->getArgOperand(2)->getType()->isPointerTy())
return nullptr;
if (CI->use_empty())
// sprintf(dest, "%s", str) -> strcpy(dest, str)
return copyFlags(*CI, emitStrCpy(Dest, CI->getArgOperand(2), B, TLI));
uint64_t SrcLen = GetStringLength(CI->getArgOperand(2));
if (SrcLen) {
B.CreateMemCpy(
Dest, Align(1), CI->getArgOperand(2), Align(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()), SrcLen));
// Returns total number of characters written without null-character.
return ConstantInt::get(CI->getType(), SrcLen - 1);
} else if (Value *V = emitStpCpy(Dest, CI->getArgOperand(2), B, TLI)) {
// sprintf(dest, "%s", str) -> stpcpy(dest, str) - dest
// Handle mismatched pointer types (goes away with typeless pointers?).
V = B.CreatePointerCast(V, B.getInt8PtrTy());
Dest = B.CreatePointerCast(Dest, B.getInt8PtrTy());
Value *PtrDiff = B.CreatePtrDiff(B.getInt8Ty(), V, Dest);
return B.CreateIntCast(PtrDiff, CI->getType(), false);
}
bool OptForSize = CI->getFunction()->hasOptSize() ||
llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI,
PGSOQueryType::IRPass);
if (OptForSize)
return nullptr;
Value *Len = emitStrLen(CI->getArgOperand(2), B, DL, TLI);
if (!Len)
return nullptr;
Value *IncLen =
B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), "leninc");
B.CreateMemCpy(Dest, Align(1), CI->getArgOperand(2), Align(1), IncLen);
// The sprintf result is the unincremented number of bytes in the string.
return B.CreateIntCast(Len, CI->getType(), false);
}
return nullptr;
}
Value *LibCallSimplifier::optimizeSPrintF(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
if (Value *V = optimizeSPrintFString(CI, B)) {
return V;
}
// sprintf(str, format, ...) -> siprintf(str, format, ...) if no floating
// point arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_siprintf) &&
!callHasFloatingPointArgument(CI)) {
FunctionCallee SIPrintFFn = getOrInsertLibFunc(M, *TLI, LibFunc_siprintf,
FT, Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(SIPrintFFn);
B.Insert(New);
return New;
}
// sprintf(str, format, ...) -> __small_sprintf(str, format, ...) if no 128-bit
// floating point arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_small_sprintf) &&
!callHasFP128Argument(CI)) {
auto SmallSPrintFFn = getOrInsertLibFunc(M, *TLI, LibFunc_small_sprintf, FT,
Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(SmallSPrintFFn);
B.Insert(New);
return New;
}
annotateNonNullNoUndefBasedOnAccess(CI, {0, 1});
return nullptr;
}
// Transform an snprintf call CI with the bound N to format the string Str
// either to a call to memcpy, or to single character a store, or to nothing,
// and fold the result to a constant. A nonnull StrArg refers to the string
// argument being formatted. Otherwise the call is one with N < 2 and
// the "%c" directive to format a single character.
Value *LibCallSimplifier::emitSnPrintfMemCpy(CallInst *CI, Value *StrArg,
StringRef Str, uint64_t N,
IRBuilderBase &B) {
assert(StrArg || (N < 2 && Str.size() == 1));
unsigned IntBits = TLI->getIntSize();
uint64_t IntMax = maxIntN(IntBits);
if (Str.size() > IntMax)
// Bail if the string is longer than INT_MAX. POSIX requires
// implementations to set errno to EOVERFLOW in this case, in
// addition to when N is larger than that (checked by the caller).
return nullptr;
Value *StrLen = ConstantInt::get(CI->getType(), Str.size());
if (N == 0)
return StrLen;
// Set to the number of bytes to copy fron StrArg which is also
// the offset of the terinating nul.
uint64_t NCopy;
if (N > Str.size())
// Copy the full string, including the terminating nul (which must
// be present regardless of the bound).
NCopy = Str.size() + 1;
else
NCopy = N - 1;
Value *DstArg = CI->getArgOperand(0);
if (NCopy && StrArg)
// Transform the call to lvm.memcpy(dst, fmt, N).
copyFlags(
*CI,
B.CreateMemCpy(
DstArg, Align(1), StrArg, Align(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()), NCopy)));
if (N > Str.size())
// Return early when the whole format string, including the final nul,
// has been copied.
return StrLen;
// Otherwise, when truncating the string append a terminating nul.
Type *Int8Ty = B.getInt8Ty();
Value *NulOff = B.getIntN(IntBits, NCopy);
Value *DstEnd = B.CreateInBoundsGEP(Int8Ty, DstArg, NulOff, "endptr");
B.CreateStore(ConstantInt::get(Int8Ty, 0), DstEnd);
return StrLen;
}
Value *LibCallSimplifier::optimizeSnPrintFString(CallInst *CI,
IRBuilderBase &B) {
// Check for size
ConstantInt *Size = dyn_cast<ConstantInt>(CI->getArgOperand(1));
if (!Size)
return nullptr;
uint64_t N = Size->getZExtValue();
uint64_t IntMax = maxIntN(TLI->getIntSize());
if (N > IntMax)
// Bail if the bound exceeds INT_MAX. POSIX requires implementations
// to set errno to EOVERFLOW in this case.
return nullptr;
Value *DstArg = CI->getArgOperand(0);
Value *FmtArg = CI->getArgOperand(2);
// Check for a fixed format string.
StringRef FormatStr;
if (!getConstantStringInfo(FmtArg, FormatStr))
return nullptr;
// If we just have a format string (nothing else crazy) transform it.
if (CI->arg_size() == 3) {
if (FormatStr.contains('%'))
// Bail if the format string contains a directive and there are
// no arguments. We could handle "%%" in the future.
return nullptr;
return emitSnPrintfMemCpy(CI, FmtArg, FormatStr, N, B);
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->arg_size() != 4)
return nullptr;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
if (N <= 1) {
// Use an arbitary string of length 1 to transform the call into
// either a nul store (N == 1) or a no-op (N == 0) and fold it
// to one.
StringRef CharStr("*");
return emitSnPrintfMemCpy(CI, nullptr, CharStr, N, B);
}
// snprintf(dst, size, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!CI->getArgOperand(3)->getType()->isIntegerTy())
return nullptr;
Value *V = B.CreateTrunc(CI->getArgOperand(3), B.getInt8Ty(), "char");
Value *Ptr = castToCStr(DstArg, B);
B.CreateStore(V, Ptr);
Ptr = B.CreateInBoundsGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul");
B.CreateStore(B.getInt8(0), Ptr);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] != 's')
return nullptr;
Value *StrArg = CI->getArgOperand(3);
// snprintf(dest, size, "%s", str) to llvm.memcpy(dest, str, len+1, 1)
StringRef Str;
if (!getConstantStringInfo(StrArg, Str))
return nullptr;
return emitSnPrintfMemCpy(CI, StrArg, Str, N, B);
}
Value *LibCallSimplifier::optimizeSnPrintF(CallInst *CI, IRBuilderBase &B) {
if (Value *V = optimizeSnPrintFString(CI, B)) {
return V;
}
if (isKnownNonZero(CI->getOperand(1), DL))
annotateNonNullNoUndefBasedOnAccess(CI, 0);
return nullptr;
}
Value *LibCallSimplifier::optimizeFPrintFString(CallInst *CI,
IRBuilderBase &B) {
optimizeErrorReporting(CI, B, 0);
// All the optimizations depend on the format string.
StringRef FormatStr;
if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
return nullptr;
// Do not do any of the following transformations if the fprintf return
// value is used, in general the fprintf return value is not compatible
// with fwrite(), fputc() or fputs().
if (!CI->use_empty())
return nullptr;
// fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
if (CI->arg_size() == 2) {
// Could handle %% -> % if we cared.
if (FormatStr.contains('%'))
return nullptr; // We found a format specifier.
return copyFlags(
*CI, emitFWrite(CI->getArgOperand(1),
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
FormatStr.size()),
CI->getArgOperand(0), B, DL, TLI));
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->arg_size() < 3)
return nullptr;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// fprintf(F, "%c", chr) --> fputc(chr, F)
if (!CI->getArgOperand(2)->getType()->isIntegerTy())
return nullptr;
return copyFlags(
*CI, emitFPutC(CI->getArgOperand(2), CI->getArgOperand(0), B, TLI));
}
if (FormatStr[1] == 's') {
// fprintf(F, "%s", str) --> fputs(str, F)
if (!CI->getArgOperand(2)->getType()->isPointerTy())
return nullptr;
return copyFlags(
*CI, emitFPutS(CI->getArgOperand(2), CI->getArgOperand(0), B, TLI));
}
return nullptr;
}
Value *LibCallSimplifier::optimizeFPrintF(CallInst *CI, IRBuilderBase &B) {
Module *M = CI->getModule();
Function *Callee = CI->getCalledFunction();
FunctionType *FT = Callee->getFunctionType();
if (Value *V = optimizeFPrintFString(CI, B)) {
return V;
}
// fprintf(stream, format, ...) -> fiprintf(stream, format, ...) if no
// floating point arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_fiprintf) &&
!callHasFloatingPointArgument(CI)) {
FunctionCallee FIPrintFFn = getOrInsertLibFunc(M, *TLI, LibFunc_fiprintf,
FT, Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(FIPrintFFn);
B.Insert(New);
return New;
}
// fprintf(stream, format, ...) -> __small_fprintf(stream, format, ...) if no
// 128-bit floating point arguments.
if (isLibFuncEmittable(M, TLI, LibFunc_small_fprintf) &&
!callHasFP128Argument(CI)) {
auto SmallFPrintFFn =
getOrInsertLibFunc(M, *TLI, LibFunc_small_fprintf, FT,
Callee->getAttributes());
CallInst *New = cast<CallInst>(CI->clone());
New->setCalledFunction(SmallFPrintFFn);
B.Insert(New);
return New;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeFWrite(CallInst *CI, IRBuilderBase &B) {
optimizeErrorReporting(CI, B, 3);
// Get the element size and count.
ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
if (SizeC && CountC) {
uint64_t Bytes = SizeC->getZExtValue() * CountC->getZExtValue();
// If this is writing zero records, remove the call (it's a noop).
if (Bytes == 0)
return ConstantInt::get(CI->getType(), 0);
// If this is writing one byte, turn it into fputc.
// This optimisation is only valid, if the return value is unused.
if (Bytes == 1 && CI->use_empty()) { // fwrite(S,1,1,F) -> fputc(S[0],F)
Value *Char = B.CreateLoad(B.getInt8Ty(),
castToCStr(CI->getArgOperand(0), B), "char");
Value *NewCI = emitFPutC(Char, CI->getArgOperand(3), B, TLI);
return NewCI ? ConstantInt::get(CI->getType(), 1) : nullptr;
}
}
return nullptr;
}
Value *LibCallSimplifier::optimizeFPuts(CallInst *CI, IRBuilderBase &B) {
optimizeErrorReporting(CI, B, 1);
// Don't rewrite fputs to fwrite when optimising for size because fwrite
// requires more arguments and thus extra MOVs are required.
bool OptForSize = CI->getFunction()->hasOptSize() ||
llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI,
PGSOQueryType::IRPass);
if (OptForSize)
return nullptr;
// We can't optimize if return value is used.
if (!CI->use_empty())
return nullptr;
// fputs(s,F) --> fwrite(s,strlen(s),1,F)
uint64_t Len = GetStringLength(CI->getArgOperand(0));
if (!Len)
return nullptr;
// Known to have no uses (see above).
return copyFlags(
*CI,
emitFWrite(CI->getArgOperand(0),
ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len - 1),
CI->getArgOperand(1), B, DL, TLI));
}
Value *LibCallSimplifier::optimizePuts(CallInst *CI, IRBuilderBase &B) {
annotateNonNullNoUndefBasedOnAccess(CI, 0);
if (!CI->use_empty())
return nullptr;
// Check for a constant string.
// puts("") -> putchar('\n')
StringRef Str;
if (getConstantStringInfo(CI->getArgOperand(0), Str) && Str.empty()) {
// putchar takes an argument of the same type as puts returns, i.e.,
// int, which need not be 32 bits wide.
Type *IntTy = CI->getType();
return copyFlags(*CI, emitPutChar(ConstantInt::get(IntTy, '\n'), B, TLI));
}
return nullptr;
}
Value *LibCallSimplifier::optimizeBCopy(CallInst *CI, IRBuilderBase &B) {
// bcopy(src, dst, n) -> llvm.memmove(dst, src, n)
return copyFlags(*CI, B.CreateMemMove(CI->getArgOperand(1), Align(1),
CI->getArgOperand(0), Align(1),
CI->getArgOperand(2)));
}
bool LibCallSimplifier::hasFloatVersion(const Module *M, StringRef FuncName) {
SmallString<20> FloatFuncName = FuncName;
FloatFuncName += 'f';
return isLibFuncEmittable(M, TLI, FloatFuncName);
}
Value *LibCallSimplifier::optimizeStringMemoryLibCall(CallInst *CI,
IRBuilderBase &Builder) {
Module *M = CI->getModule();
LibFunc Func;
Function *Callee = CI->getCalledFunction();
// Check for string/memory library functions.
if (TLI->getLibFunc(*Callee, Func) && isLibFuncEmittable(M, TLI, Func)) {
// Make sure we never change the calling convention.
assert(
(ignoreCallingConv(Func) ||
TargetLibraryInfoImpl::isCallingConvCCompatible(CI)) &&
"Optimizing string/memory libcall would change the calling convention");
switch (Func) {
case LibFunc_strcat:
return optimizeStrCat(CI, Builder);
case LibFunc_strncat:
return optimizeStrNCat(CI, Builder);
case LibFunc_strchr:
return optimizeStrChr(CI, Builder);
case LibFunc_strrchr:
return optimizeStrRChr(CI, Builder);
case LibFunc_strcmp:
return optimizeStrCmp(CI, Builder);
case LibFunc_strncmp:
return optimizeStrNCmp(CI, Builder);
case LibFunc_strcpy:
return optimizeStrCpy(CI, Builder);
case LibFunc_stpcpy:
return optimizeStpCpy(CI, Builder);
case LibFunc_strlcpy:
return optimizeStrLCpy(CI, Builder);
case LibFunc_strncpy:
return optimizeStrNCpy(CI, Builder);
case LibFunc_strlen:
return optimizeStrLen(CI, Builder);
case LibFunc_strnlen:
return optimizeStrNLen(CI, Builder);
case LibFunc_strpbrk:
return optimizeStrPBrk(CI, Builder);
case LibFunc_strndup:
return optimizeStrNDup(CI, Builder);
case LibFunc_strtol:
case LibFunc_strtod:
case LibFunc_strtof:
case LibFunc_strtoul:
case LibFunc_strtoll:
case LibFunc_strtold:
case LibFunc_strtoull:
return optimizeStrTo(CI, Builder);
case LibFunc_strspn:
return optimizeStrSpn(CI, Builder);
case LibFunc_strcspn:
return optimizeStrCSpn(CI, Builder);
case LibFunc_strstr:
return optimizeStrStr(CI, Builder);
case LibFunc_memchr:
return optimizeMemChr(CI, Builder);
case LibFunc_memrchr:
return optimizeMemRChr(CI, Builder);
case LibFunc_bcmp:
return optimizeBCmp(CI, Builder);
case LibFunc_memcmp:
return optimizeMemCmp(CI, Builder);
case LibFunc_memcpy:
return optimizeMemCpy(CI, Builder);
case LibFunc_memccpy:
return optimizeMemCCpy(CI, Builder);
case LibFunc_mempcpy:
return optimizeMemPCpy(CI, Builder);
case LibFunc_memmove:
return optimizeMemMove(CI, Builder);
case LibFunc_memset:
return optimizeMemSet(CI, Builder);
case LibFunc_realloc:
return optimizeRealloc(CI, Builder);
case LibFunc_wcslen:
return optimizeWcslen(CI, Builder);
case LibFunc_bcopy:
return optimizeBCopy(CI, Builder);
default:
break;
}
}
return nullptr;
}
Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
LibFunc Func,
IRBuilderBase &Builder) {
const Module *M = CI->getModule();
// Don't optimize calls that require strict floating point semantics.
if (CI->isStrictFP())
return nullptr;
if (Value *V = optimizeTrigReflections(CI, Func, Builder))
return V;
switch (Func) {
case LibFunc_sinpif:
case LibFunc_sinpi:
case LibFunc_cospif:
case LibFunc_cospi:
return optimizeSinCosPi(CI, Builder);
case LibFunc_powf:
case LibFunc_pow:
case LibFunc_powl:
return optimizePow(CI, Builder);
case LibFunc_exp2l:
case LibFunc_exp2:
case LibFunc_exp2f:
return optimizeExp2(CI, Builder);
case LibFunc_fabsf:
case LibFunc_fabs:
case LibFunc_fabsl:
return replaceUnaryCall(CI, Builder, Intrinsic::fabs);
case LibFunc_sqrtf:
case LibFunc_sqrt:
case LibFunc_sqrtl:
return optimizeSqrt(CI, Builder);
case LibFunc_logf:
case LibFunc_log:
case LibFunc_logl:
case LibFunc_log10f:
case LibFunc_log10:
case LibFunc_log10l:
case LibFunc_log1pf:
case LibFunc_log1p:
case LibFunc_log1pl:
case LibFunc_log2f:
case LibFunc_log2:
case LibFunc_log2l:
case LibFunc_logbf:
case LibFunc_logb:
case LibFunc_logbl:
return optimizeLog(CI, Builder);
case LibFunc_tan:
case LibFunc_tanf:
case LibFunc_tanl:
return optimizeTan(CI, Builder);
case LibFunc_ceil:
return replaceUnaryCall(CI, Builder, Intrinsic::ceil);
case LibFunc_floor:
return replaceUnaryCall(CI, Builder, Intrinsic::floor);
case LibFunc_round:
return replaceUnaryCall(CI, Builder, Intrinsic::round);
case LibFunc_roundeven:
return replaceUnaryCall(CI, Builder, Intrinsic::roundeven);
case LibFunc_nearbyint:
return replaceUnaryCall(CI, Builder, Intrinsic::nearbyint);
case LibFunc_rint:
return replaceUnaryCall(CI, Builder, Intrinsic::rint);
case LibFunc_trunc:
return replaceUnaryCall(CI, Builder, Intrinsic::trunc);
case LibFunc_acos:
case LibFunc_acosh:
case LibFunc_asin:
case LibFunc_asinh:
case LibFunc_atan:
case LibFunc_atanh:
case LibFunc_cbrt:
case LibFunc_cosh:
case LibFunc_exp:
case LibFunc_exp10:
case LibFunc_expm1:
case LibFunc_cos:
case LibFunc_sin:
case LibFunc_sinh:
case LibFunc_tanh:
if (UnsafeFPShrink && hasFloatVersion(M, CI->getCalledFunction()->getName()))
return optimizeUnaryDoubleFP(CI, Builder, TLI, true);
return nullptr;
case LibFunc_copysign:
if (hasFloatVersion(M, CI->getCalledFunction()->getName()))
return optimizeBinaryDoubleFP(CI, Builder, TLI);
return nullptr;
case LibFunc_fminf:
case LibFunc_fmin:
case LibFunc_fminl:
case LibFunc_fmaxf:
case LibFunc_fmax:
case LibFunc_fmaxl:
return optimizeFMinFMax(CI, Builder);
case LibFunc_cabs:
case LibFunc_cabsf:
case LibFunc_cabsl:
return optimizeCAbs(CI, Builder);
default:
return nullptr;
}
}
Value *LibCallSimplifier::optimizeCall(CallInst *CI, IRBuilderBase &Builder) {
Module *M = CI->getModule();
assert(!CI->isMustTailCall() && "These transforms aren't musttail safe.");
// TODO: Split out the code below that operates on FP calls so that
// we can all non-FP calls with the StrictFP attribute to be
// optimized.
if (CI->isNoBuiltin())
return nullptr;
LibFunc Func;
Function *Callee = CI->getCalledFunction();
bool IsCallingConvC = TargetLibraryInfoImpl::isCallingConvCCompatible(CI);
SmallVector<OperandBundleDef, 2> OpBundles;
CI->getOperandBundlesAsDefs(OpBundles);
IRBuilderBase::OperandBundlesGuard Guard(Builder);
Builder.setDefaultOperandBundles(OpBundles);
// Command-line parameter overrides instruction attribute.
// This can't be moved to optimizeFloatingPointLibCall() because it may be
// used by the intrinsic optimizations.
if (EnableUnsafeFPShrink.getNumOccurrences() > 0)
UnsafeFPShrink = EnableUnsafeFPShrink;
else if (isa<FPMathOperator>(CI) && CI->isFast())
UnsafeFPShrink = true;
// First, check for intrinsics.
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
if (!IsCallingConvC)
return nullptr;
// The FP intrinsics have corresponding constrained versions so we don't
// need to check for the StrictFP attribute here.
switch (II->getIntrinsicID()) {
case Intrinsic::pow:
return optimizePow(CI, Builder);
case Intrinsic::exp2:
return optimizeExp2(CI, Builder);
case Intrinsic::log:
case Intrinsic::log2:
case Intrinsic::log10:
return optimizeLog(CI, Builder);
case Intrinsic::sqrt:
return optimizeSqrt(CI, Builder);
case Intrinsic::memset:
return optimizeMemSet(CI, Builder);
case Intrinsic::memcpy:
return optimizeMemCpy(CI, Builder);
case Intrinsic::memmove:
return optimizeMemMove(CI, Builder);
default:
return nullptr;
}
}
// Also try to simplify calls to fortified library functions.
if (Value *SimplifiedFortifiedCI =
FortifiedSimplifier.optimizeCall(CI, Builder)) {
// Try to further simplify the result.
CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI);
if (SimplifiedCI && SimplifiedCI->getCalledFunction()) {
// Ensure that SimplifiedCI's uses are complete, since some calls have
// their uses analyzed.
replaceAllUsesWith(CI, SimplifiedCI);
// Set insertion point to SimplifiedCI to guarantee we reach all uses
// we might replace later on.
IRBuilderBase::InsertPointGuard Guard(Builder);
Builder.SetInsertPoint(SimplifiedCI);
if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, Builder)) {
// If we were able to further simplify, remove the now redundant call.
substituteInParent(SimplifiedCI, V);
return V;
}
}
return SimplifiedFortifiedCI;
}
// Then check for known library functions.
if (TLI->getLibFunc(*Callee, Func) && isLibFuncEmittable(M, TLI, Func)) {
// We never change the calling convention.
if (!ignoreCallingConv(Func) && !IsCallingConvC)
return nullptr;
if (Value *V = optimizeStringMemoryLibCall(CI, Builder))
return V;
if (Value *V = optimizeFloatingPointLibCall(CI, Func, Builder))
return V;
switch (Func) {
case LibFunc_ffs:
case LibFunc_ffsl:
case LibFunc_ffsll:
return optimizeFFS(CI, Builder);
case LibFunc_fls:
case LibFunc_flsl:
case LibFunc_flsll:
return optimizeFls(CI, Builder);
case LibFunc_abs:
case LibFunc_labs:
case LibFunc_llabs:
return optimizeAbs(CI, Builder);
case LibFunc_isdigit:
return optimizeIsDigit(CI, Builder);
case LibFunc_isascii:
return optimizeIsAscii(CI, Builder);
case LibFunc_toascii:
return optimizeToAscii(CI, Builder);
case LibFunc_atoi:
case LibFunc_atol:
case LibFunc_atoll:
return optimizeAtoi(CI, Builder);
case LibFunc_strtol:
case LibFunc_strtoll:
return optimizeStrToInt(CI, Builder, /*AsSigned=*/true);
case LibFunc_strtoul:
case LibFunc_strtoull:
return optimizeStrToInt(CI, Builder, /*AsSigned=*/false);
case LibFunc_printf:
return optimizePrintF(CI, Builder);
case LibFunc_sprintf:
return optimizeSPrintF(CI, Builder);
case LibFunc_snprintf:
return optimizeSnPrintF(CI, Builder);
case LibFunc_fprintf:
return optimizeFPrintF(CI, Builder);
case LibFunc_fwrite:
return optimizeFWrite(CI, Builder);
case LibFunc_fputs:
return optimizeFPuts(CI, Builder);
case LibFunc_puts:
return optimizePuts(CI, Builder);
case LibFunc_perror:
return optimizeErrorReporting(CI, Builder);
case LibFunc_vfprintf:
case LibFunc_fiprintf:
return optimizeErrorReporting(CI, Builder, 0);
default:
return nullptr;
}
}
return nullptr;
}
LibCallSimplifier::LibCallSimplifier(
const DataLayout &DL, const TargetLibraryInfo *TLI,
OptimizationRemarkEmitter &ORE,
BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
function_ref<void(Instruction *, Value *)> Replacer,
function_ref<void(Instruction *)> Eraser)
: FortifiedSimplifier(TLI), DL(DL), TLI(TLI), ORE(ORE), BFI(BFI), PSI(PSI),
Replacer(Replacer), Eraser(Eraser) {}
void LibCallSimplifier::replaceAllUsesWith(Instruction *I, Value *With) {
// Indirect through the replacer used in this instance.
Replacer(I, With);
}
void LibCallSimplifier::eraseFromParent(Instruction *I) {
Eraser(I);
}
// TODO:
// Additional cases that we need to add to this file:
//
// cbrt:
// * cbrt(expN(X)) -> expN(x/3)
// * cbrt(sqrt(x)) -> pow(x,1/6)
// * cbrt(cbrt(x)) -> pow(x,1/9)
//
// exp, expf, expl:
// * exp(log(x)) -> x
//
// log, logf, logl:
// * log(exp(x)) -> x
// * log(exp(y)) -> y*log(e)
// * log(exp10(y)) -> y*log(10)
// * log(sqrt(x)) -> 0.5*log(x)
//
// pow, powf, powl:
// * pow(sqrt(x),y) -> pow(x,y*0.5)
// * pow(pow(x,y),z)-> pow(x,y*z)
//
// signbit:
// * signbit(cnst) -> cnst'
// * signbit(nncst) -> 0 (if pstv is a non-negative constant)
//
// sqrt, sqrtf, sqrtl:
// * sqrt(expN(x)) -> expN(x*0.5)
// * sqrt(Nroot(x)) -> pow(x,1/(2*N))
// * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
//
//===----------------------------------------------------------------------===//
// Fortified Library Call Optimizations
//===----------------------------------------------------------------------===//
bool
FortifiedLibCallSimplifier::isFortifiedCallFoldable(CallInst *CI,
unsigned ObjSizeOp,
Optional<unsigned> SizeOp,
Optional<unsigned> StrOp,
Optional<unsigned> FlagOp) {
// If this function takes a flag argument, the implementation may use it to
// perform extra checks. Don't fold into the non-checking variant.
if (FlagOp) {
ConstantInt *Flag = dyn_cast<ConstantInt>(CI->getArgOperand(*FlagOp));
if (!Flag || !Flag->isZero())
return false;
}
if (SizeOp && CI->getArgOperand(ObjSizeOp) == CI->getArgOperand(*SizeOp))
return true;
if (ConstantInt *ObjSizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(ObjSizeOp))) {
if (ObjSizeCI->isMinusOne())
return true;
// If the object size wasn't -1 (unknown), bail out if we were asked to.
if (OnlyLowerUnknownSize)
return false;
if (StrOp) {
uint64_t Len = GetStringLength(CI->getArgOperand(*StrOp));
// If the length is 0 we don't know how long it is and so we can't
// remove the check.
if (Len)
annotateDereferenceableBytes(CI, *StrOp, Len);
else
return false;
return ObjSizeCI->getZExtValue() >= Len;
}
if (SizeOp) {
if (ConstantInt *SizeCI =
dyn_cast<ConstantInt>(CI->getArgOperand(*SizeOp)))
return ObjSizeCI->getZExtValue() >= SizeCI->getZExtValue();
}
}
return false;
}
Value *FortifiedLibCallSimplifier::optimizeMemCpyChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3, 2)) {
CallInst *NewCI =
B.CreateMemCpy(CI->getArgOperand(0), Align(1), CI->getArgOperand(1),
Align(1), CI->getArgOperand(2));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemMoveChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3, 2)) {
CallInst *NewCI =
B.CreateMemMove(CI->getArgOperand(0), Align(1), CI->getArgOperand(1),
Align(1), CI->getArgOperand(2));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemSetChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3, 2)) {
Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
CallInst *NewCI = B.CreateMemSet(CI->getArgOperand(0), Val,
CI->getArgOperand(2), Align(1));
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
copyFlags(*CI, NewCI);
return CI->getArgOperand(0);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemPCpyChk(CallInst *CI,
IRBuilderBase &B) {
const DataLayout &DL = CI->getModule()->getDataLayout();
if (isFortifiedCallFoldable(CI, 3, 2))
if (Value *Call = emitMemPCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, DL, TLI)) {
CallInst *NewCI = cast<CallInst>(Call);
NewCI->setAttributes(CI->getAttributes());
NewCI->removeRetAttrs(AttributeFuncs::typeIncompatible(NewCI->getType()));
return copyFlags(*CI, NewCI);
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrpCpyChk(CallInst *CI,
IRBuilderBase &B,
LibFunc Func) {
const DataLayout &DL = CI->getModule()->getDataLayout();
Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1),
*ObjSize = CI->getArgOperand(2);
// __stpcpy_chk(x,x,...) -> x+strlen(x)
if (Func == LibFunc_stpcpy_chk && !OnlyLowerUnknownSize && Dst == Src) {
Value *StrLen = emitStrLen(Src, B, DL, TLI);
return StrLen ? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, StrLen) : nullptr;
}
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
// st[rp]cpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFortifiedCallFoldable(CI, 2, None, 1)) {
if (Func == LibFunc_strcpy_chk)
return copyFlags(*CI, emitStrCpy(Dst, Src, B, TLI));
else
return copyFlags(*CI, emitStpCpy(Dst, Src, B, TLI));
}
if (OnlyLowerUnknownSize)
return nullptr;
// Maybe we can stil fold __st[rp]cpy_chk to __memcpy_chk.
uint64_t Len = GetStringLength(Src);
if (Len)
annotateDereferenceableBytes(CI, 1, Len);
else
return nullptr;
// FIXME: There is really no guarantee that sizeof(size_t) is equal to
// sizeof(int*) for every target. So the assumption used here to derive the
// SizeTBits based on the size of an integer pointer in address space zero
// isn't always valid.
Type *SizeTTy = DL.getIntPtrType(CI->getContext(), /*AddressSpace=*/0);
Value *LenV = ConstantInt::get(SizeTTy, Len);
Value *Ret = emitMemCpyChk(Dst, Src, LenV, ObjSize, B, DL, TLI);
// If the function was an __stpcpy_chk, and we were able to fold it into
// a __memcpy_chk, we still need to return the correct end pointer.
if (Ret && Func == LibFunc_stpcpy_chk)
return B.CreateInBoundsGEP(B.getInt8Ty(), Dst,
ConstantInt::get(SizeTTy, Len - 1));
return copyFlags(*CI, cast<CallInst>(Ret));
}
Value *FortifiedLibCallSimplifier::optimizeStrLenChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 1, None, 0))
return copyFlags(*CI, emitStrLen(CI->getArgOperand(0), B,
CI->getModule()->getDataLayout(), TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrpNCpyChk(CallInst *CI,
IRBuilderBase &B,
LibFunc Func) {
if (isFortifiedCallFoldable(CI, 3, 2)) {
if (Func == LibFunc_strncpy_chk)
return copyFlags(*CI,
emitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TLI));
else
return copyFlags(*CI,
emitStpNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TLI));
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeMemCCpyChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 4, 3))
return copyFlags(
*CI, emitMemCCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), CI->getArgOperand(3), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeSNPrintfChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3, 1, None, 2)) {
SmallVector<Value *, 8> VariadicArgs(drop_begin(CI->args(), 5));
return copyFlags(*CI,
emitSNPrintf(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(4), VariadicArgs, B, TLI));
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeSPrintfChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 2, None, None, 1)) {
SmallVector<Value *, 8> VariadicArgs(drop_begin(CI->args(), 4));
return copyFlags(*CI,
emitSPrintf(CI->getArgOperand(0), CI->getArgOperand(3),
VariadicArgs, B, TLI));
}
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrCatChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 2))
return copyFlags(
*CI, emitStrCat(CI->getArgOperand(0), CI->getArgOperand(1), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrLCat(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3))
return copyFlags(*CI,
emitStrLCat(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrNCatChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3))
return copyFlags(*CI,
emitStrNCat(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeStrLCpyChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3))
return copyFlags(*CI,
emitStrLCpy(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(2), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeVSNPrintfChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 3, 1, None, 2))
return copyFlags(
*CI, emitVSNPrintf(CI->getArgOperand(0), CI->getArgOperand(1),
CI->getArgOperand(4), CI->getArgOperand(5), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeVSPrintfChk(CallInst *CI,
IRBuilderBase &B) {
if (isFortifiedCallFoldable(CI, 2, None, None, 1))
return copyFlags(*CI,
emitVSPrintf(CI->getArgOperand(0), CI->getArgOperand(3),
CI->getArgOperand(4), B, TLI));
return nullptr;
}
Value *FortifiedLibCallSimplifier::optimizeCall(CallInst *CI,
IRBuilderBase &Builder) {
// FIXME: We shouldn't be changing "nobuiltin" or TLI unavailable calls here.
// Some clang users checked for _chk libcall availability using:
// __has_builtin(__builtin___memcpy_chk)
// When compiling with -fno-builtin, this is always true.
// When passing -ffreestanding/-mkernel, which both imply -fno-builtin, we
// end up with fortified libcalls, which isn't acceptable in a freestanding
// environment which only provides their non-fortified counterparts.
//
// Until we change clang and/or teach external users to check for availability
// differently, disregard the "nobuiltin" attribute and TLI::has.
//
// PR23093.
LibFunc Func;
Function *Callee = CI->getCalledFunction();
bool IsCallingConvC = TargetLibraryInfoImpl::isCallingConvCCompatible(CI);
SmallVector<OperandBundleDef, 2> OpBundles;
CI->getOperandBundlesAsDefs(OpBundles);
IRBuilderBase::OperandBundlesGuard Guard(Builder);
Builder.setDefaultOperandBundles(OpBundles);
// First, check that this is a known library functions and that the prototype
// is correct.
if (!TLI->getLibFunc(*Callee, Func))
return nullptr;
// We never change the calling convention.
if (!ignoreCallingConv(Func) && !IsCallingConvC)
return nullptr;
switch (Func) {
case LibFunc_memcpy_chk:
return optimizeMemCpyChk(CI, Builder);
case LibFunc_mempcpy_chk:
return optimizeMemPCpyChk(CI, Builder);
case LibFunc_memmove_chk:
return optimizeMemMoveChk(CI, Builder);
case LibFunc_memset_chk:
return optimizeMemSetChk(CI, Builder);
case LibFunc_stpcpy_chk:
case LibFunc_strcpy_chk:
return optimizeStrpCpyChk(CI, Builder, Func);
case LibFunc_strlen_chk:
return optimizeStrLenChk(CI, Builder);
case LibFunc_stpncpy_chk:
case LibFunc_strncpy_chk:
return optimizeStrpNCpyChk(CI, Builder, Func);
case LibFunc_memccpy_chk:
return optimizeMemCCpyChk(CI, Builder);
case LibFunc_snprintf_chk:
return optimizeSNPrintfChk(CI, Builder);
case LibFunc_sprintf_chk:
return optimizeSPrintfChk(CI, Builder);
case LibFunc_strcat_chk:
return optimizeStrCatChk(CI, Builder);
case LibFunc_strlcat_chk:
return optimizeStrLCat(CI, Builder);
case LibFunc_strncat_chk:
return optimizeStrNCatChk(CI, Builder);
case LibFunc_strlcpy_chk:
return optimizeStrLCpyChk(CI, Builder);
case LibFunc_vsnprintf_chk:
return optimizeVSNPrintfChk(CI, Builder);
case LibFunc_vsprintf_chk:
return optimizeVSPrintfChk(CI, Builder);
default:
break;
}
return nullptr;
}
FortifiedLibCallSimplifier::FortifiedLibCallSimplifier(
const TargetLibraryInfo *TLI, bool OnlyLowerUnknownSize)
: TLI(TLI), OnlyLowerUnknownSize(OnlyLowerUnknownSize) {}
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