forked from OSchip/llvm-project
2217 lines
83 KiB
C++
2217 lines
83 KiB
C++
//===-- Local.cpp - Functions to perform local transformations ------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This family of functions perform various local transformations to the
|
|
// program.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Utils/Local.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/ADT/DenseSet.h"
|
|
#include "llvm/ADT/Hashing.h"
|
|
#include "llvm/ADT/STLExtras.h"
|
|
#include "llvm/ADT/SetVector.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Analysis/EHPersonalities.h"
|
|
#include "llvm/Analysis/InstructionSimplify.h"
|
|
#include "llvm/Analysis/LazyValueInfo.h"
|
|
#include "llvm/Analysis/MemoryBuiltins.h"
|
|
#include "llvm/Analysis/ValueTracking.h"
|
|
#include "llvm/IR/CFG.h"
|
|
#include "llvm/IR/ConstantRange.h"
|
|
#include "llvm/IR/Constants.h"
|
|
#include "llvm/IR/DIBuilder.h"
|
|
#include "llvm/IR/DataLayout.h"
|
|
#include "llvm/IR/DebugInfo.h"
|
|
#include "llvm/IR/DerivedTypes.h"
|
|
#include "llvm/IR/Dominators.h"
|
|
#include "llvm/IR/GetElementPtrTypeIterator.h"
|
|
#include "llvm/IR/GlobalAlias.h"
|
|
#include "llvm/IR/GlobalVariable.h"
|
|
#include "llvm/IR/IRBuilder.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/IR/IntrinsicInst.h"
|
|
#include "llvm/IR/Intrinsics.h"
|
|
#include "llvm/IR/MDBuilder.h"
|
|
#include "llvm/IR/Metadata.h"
|
|
#include "llvm/IR/Operator.h"
|
|
#include "llvm/IR/PatternMatch.h"
|
|
#include "llvm/IR/ValueHandle.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/KnownBits.h"
|
|
#include "llvm/Support/MathExtras.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
using namespace llvm;
|
|
using namespace llvm::PatternMatch;
|
|
|
|
#define DEBUG_TYPE "local"
|
|
|
|
STATISTIC(NumRemoved, "Number of unreachable basic blocks removed");
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Local constant propagation.
|
|
//
|
|
|
|
/// ConstantFoldTerminator - If a terminator instruction is predicated on a
|
|
/// constant value, convert it into an unconditional branch to the constant
|
|
/// destination. This is a nontrivial operation because the successors of this
|
|
/// basic block must have their PHI nodes updated.
|
|
/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
|
|
/// conditions and indirectbr addresses this might make dead if
|
|
/// DeleteDeadConditions is true.
|
|
bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
|
|
const TargetLibraryInfo *TLI) {
|
|
TerminatorInst *T = BB->getTerminator();
|
|
IRBuilder<> Builder(T);
|
|
|
|
// Branch - See if we are conditional jumping on constant
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(T)) {
|
|
if (BI->isUnconditional()) return false; // Can't optimize uncond branch
|
|
BasicBlock *Dest1 = BI->getSuccessor(0);
|
|
BasicBlock *Dest2 = BI->getSuccessor(1);
|
|
|
|
if (ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition())) {
|
|
// Are we branching on constant?
|
|
// YES. Change to unconditional branch...
|
|
BasicBlock *Destination = Cond->getZExtValue() ? Dest1 : Dest2;
|
|
BasicBlock *OldDest = Cond->getZExtValue() ? Dest2 : Dest1;
|
|
|
|
//cerr << "Function: " << T->getParent()->getParent()
|
|
// << "\nRemoving branch from " << T->getParent()
|
|
// << "\n\nTo: " << OldDest << endl;
|
|
|
|
// Let the basic block know that we are letting go of it. Based on this,
|
|
// it will adjust it's PHI nodes.
|
|
OldDest->removePredecessor(BB);
|
|
|
|
// Replace the conditional branch with an unconditional one.
|
|
Builder.CreateBr(Destination);
|
|
BI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
if (Dest2 == Dest1) { // Conditional branch to same location?
|
|
// This branch matches something like this:
|
|
// br bool %cond, label %Dest, label %Dest
|
|
// and changes it into: br label %Dest
|
|
|
|
// Let the basic block know that we are letting go of one copy of it.
|
|
assert(BI->getParent() && "Terminator not inserted in block!");
|
|
Dest1->removePredecessor(BI->getParent());
|
|
|
|
// Replace the conditional branch with an unconditional one.
|
|
Builder.CreateBr(Dest1);
|
|
Value *Cond = BI->getCondition();
|
|
BI->eraseFromParent();
|
|
if (DeleteDeadConditions)
|
|
RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (SwitchInst *SI = dyn_cast<SwitchInst>(T)) {
|
|
// If we are switching on a constant, we can convert the switch to an
|
|
// unconditional branch.
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
|
|
BasicBlock *DefaultDest = SI->getDefaultDest();
|
|
BasicBlock *TheOnlyDest = DefaultDest;
|
|
|
|
// If the default is unreachable, ignore it when searching for TheOnlyDest.
|
|
if (isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg()) &&
|
|
SI->getNumCases() > 0) {
|
|
TheOnlyDest = SI->case_begin()->getCaseSuccessor();
|
|
}
|
|
|
|
// Figure out which case it goes to.
|
|
for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
|
|
// Found case matching a constant operand?
|
|
if (i->getCaseValue() == CI) {
|
|
TheOnlyDest = i->getCaseSuccessor();
|
|
break;
|
|
}
|
|
|
|
// Check to see if this branch is going to the same place as the default
|
|
// dest. If so, eliminate it as an explicit compare.
|
|
if (i->getCaseSuccessor() == DefaultDest) {
|
|
MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
|
|
unsigned NCases = SI->getNumCases();
|
|
// Fold the case metadata into the default if there will be any branches
|
|
// left, unless the metadata doesn't match the switch.
|
|
if (NCases > 1 && MD && MD->getNumOperands() == 2 + NCases) {
|
|
// Collect branch weights into a vector.
|
|
SmallVector<uint32_t, 8> Weights;
|
|
for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e;
|
|
++MD_i) {
|
|
auto *CI = mdconst::extract<ConstantInt>(MD->getOperand(MD_i));
|
|
Weights.push_back(CI->getValue().getZExtValue());
|
|
}
|
|
// Merge weight of this case to the default weight.
|
|
unsigned idx = i->getCaseIndex();
|
|
Weights[0] += Weights[idx+1];
|
|
// Remove weight for this case.
|
|
std::swap(Weights[idx+1], Weights.back());
|
|
Weights.pop_back();
|
|
SI->setMetadata(LLVMContext::MD_prof,
|
|
MDBuilder(BB->getContext()).
|
|
createBranchWeights(Weights));
|
|
}
|
|
// Remove this entry.
|
|
DefaultDest->removePredecessor(SI->getParent());
|
|
i = SI->removeCase(i);
|
|
e = SI->case_end();
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, check to see if the switch only branches to one destination.
|
|
// We do this by reseting "TheOnlyDest" to null when we find two non-equal
|
|
// destinations.
|
|
if (i->getCaseSuccessor() != TheOnlyDest)
|
|
TheOnlyDest = nullptr;
|
|
|
|
// Increment this iterator as we haven't removed the case.
|
|
++i;
|
|
}
|
|
|
|
if (CI && !TheOnlyDest) {
|
|
// Branching on a constant, but not any of the cases, go to the default
|
|
// successor.
|
|
TheOnlyDest = SI->getDefaultDest();
|
|
}
|
|
|
|
// If we found a single destination that we can fold the switch into, do so
|
|
// now.
|
|
if (TheOnlyDest) {
|
|
// Insert the new branch.
|
|
Builder.CreateBr(TheOnlyDest);
|
|
BasicBlock *BB = SI->getParent();
|
|
|
|
// Remove entries from PHI nodes which we no longer branch to...
|
|
for (BasicBlock *Succ : SI->successors()) {
|
|
// Found case matching a constant operand?
|
|
if (Succ == TheOnlyDest)
|
|
TheOnlyDest = nullptr; // Don't modify the first branch to TheOnlyDest
|
|
else
|
|
Succ->removePredecessor(BB);
|
|
}
|
|
|
|
// Delete the old switch.
|
|
Value *Cond = SI->getCondition();
|
|
SI->eraseFromParent();
|
|
if (DeleteDeadConditions)
|
|
RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
|
|
return true;
|
|
}
|
|
|
|
if (SI->getNumCases() == 1) {
|
|
// Otherwise, we can fold this switch into a conditional branch
|
|
// instruction if it has only one non-default destination.
|
|
auto FirstCase = *SI->case_begin();
|
|
Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
|
|
FirstCase.getCaseValue(), "cond");
|
|
|
|
// Insert the new branch.
|
|
BranchInst *NewBr = Builder.CreateCondBr(Cond,
|
|
FirstCase.getCaseSuccessor(),
|
|
SI->getDefaultDest());
|
|
MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
|
|
if (MD && MD->getNumOperands() == 3) {
|
|
ConstantInt *SICase =
|
|
mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
|
|
ConstantInt *SIDef =
|
|
mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
|
|
assert(SICase && SIDef);
|
|
// The TrueWeight should be the weight for the single case of SI.
|
|
NewBr->setMetadata(LLVMContext::MD_prof,
|
|
MDBuilder(BB->getContext()).
|
|
createBranchWeights(SICase->getValue().getZExtValue(),
|
|
SIDef->getValue().getZExtValue()));
|
|
}
|
|
|
|
// Update make.implicit metadata to the newly-created conditional branch.
|
|
MDNode *MakeImplicitMD = SI->getMetadata(LLVMContext::MD_make_implicit);
|
|
if (MakeImplicitMD)
|
|
NewBr->setMetadata(LLVMContext::MD_make_implicit, MakeImplicitMD);
|
|
|
|
// Delete the old switch.
|
|
SI->eraseFromParent();
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(T)) {
|
|
// indirectbr blockaddress(@F, @BB) -> br label @BB
|
|
if (BlockAddress *BA =
|
|
dyn_cast<BlockAddress>(IBI->getAddress()->stripPointerCasts())) {
|
|
BasicBlock *TheOnlyDest = BA->getBasicBlock();
|
|
// Insert the new branch.
|
|
Builder.CreateBr(TheOnlyDest);
|
|
|
|
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
|
|
if (IBI->getDestination(i) == TheOnlyDest)
|
|
TheOnlyDest = nullptr;
|
|
else
|
|
IBI->getDestination(i)->removePredecessor(IBI->getParent());
|
|
}
|
|
Value *Address = IBI->getAddress();
|
|
IBI->eraseFromParent();
|
|
if (DeleteDeadConditions)
|
|
RecursivelyDeleteTriviallyDeadInstructions(Address, TLI);
|
|
|
|
// If we didn't find our destination in the IBI successor list, then we
|
|
// have undefined behavior. Replace the unconditional branch with an
|
|
// 'unreachable' instruction.
|
|
if (TheOnlyDest) {
|
|
BB->getTerminator()->eraseFromParent();
|
|
new UnreachableInst(BB->getContext(), BB);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Local dead code elimination.
|
|
//
|
|
|
|
/// isInstructionTriviallyDead - Return true if the result produced by the
|
|
/// instruction is not used, and the instruction has no side effects.
|
|
///
|
|
bool llvm::isInstructionTriviallyDead(Instruction *I,
|
|
const TargetLibraryInfo *TLI) {
|
|
if (!I->use_empty())
|
|
return false;
|
|
return wouldInstructionBeTriviallyDead(I, TLI);
|
|
}
|
|
|
|
bool llvm::wouldInstructionBeTriviallyDead(Instruction *I,
|
|
const TargetLibraryInfo *TLI) {
|
|
if (isa<TerminatorInst>(I))
|
|
return false;
|
|
|
|
// We don't want the landingpad-like instructions removed by anything this
|
|
// general.
|
|
if (I->isEHPad())
|
|
return false;
|
|
|
|
// We don't want debug info removed by anything this general, unless
|
|
// debug info is empty.
|
|
if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) {
|
|
if (DDI->getAddress())
|
|
return false;
|
|
return true;
|
|
}
|
|
if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) {
|
|
if (DVI->getValue())
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
if (!I->mayHaveSideEffects())
|
|
return true;
|
|
|
|
// Special case intrinsics that "may have side effects" but can be deleted
|
|
// when dead.
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
|
|
// Safe to delete llvm.stacksave if dead.
|
|
if (II->getIntrinsicID() == Intrinsic::stacksave)
|
|
return true;
|
|
|
|
// Lifetime intrinsics are dead when their right-hand is undef.
|
|
if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
|
|
II->getIntrinsicID() == Intrinsic::lifetime_end)
|
|
return isa<UndefValue>(II->getArgOperand(1));
|
|
|
|
// Assumptions are dead if their condition is trivially true. Guards on
|
|
// true are operationally no-ops. In the future we can consider more
|
|
// sophisticated tradeoffs for guards considering potential for check
|
|
// widening, but for now we keep things simple.
|
|
if (II->getIntrinsicID() == Intrinsic::assume ||
|
|
II->getIntrinsicID() == Intrinsic::experimental_guard) {
|
|
if (ConstantInt *Cond = dyn_cast<ConstantInt>(II->getArgOperand(0)))
|
|
return !Cond->isZero();
|
|
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (isAllocLikeFn(I, TLI))
|
|
return true;
|
|
|
|
if (CallInst *CI = isFreeCall(I, TLI))
|
|
if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
|
|
return C->isNullValue() || isa<UndefValue>(C);
|
|
|
|
if (CallSite CS = CallSite(I))
|
|
if (isMathLibCallNoop(CS, TLI))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
|
|
/// trivially dead instruction, delete it. If that makes any of its operands
|
|
/// trivially dead, delete them too, recursively. Return true if any
|
|
/// instructions were deleted.
|
|
bool
|
|
llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
|
|
const TargetLibraryInfo *TLI) {
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I || !I->use_empty() || !isInstructionTriviallyDead(I, TLI))
|
|
return false;
|
|
|
|
SmallVector<Instruction*, 16> DeadInsts;
|
|
DeadInsts.push_back(I);
|
|
|
|
do {
|
|
I = DeadInsts.pop_back_val();
|
|
|
|
// Null out all of the instruction's operands to see if any operand becomes
|
|
// dead as we go.
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
|
|
Value *OpV = I->getOperand(i);
|
|
I->setOperand(i, nullptr);
|
|
|
|
if (!OpV->use_empty()) continue;
|
|
|
|
// If the operand is an instruction that became dead as we nulled out the
|
|
// operand, and if it is 'trivially' dead, delete it in a future loop
|
|
// iteration.
|
|
if (Instruction *OpI = dyn_cast<Instruction>(OpV))
|
|
if (isInstructionTriviallyDead(OpI, TLI))
|
|
DeadInsts.push_back(OpI);
|
|
}
|
|
|
|
I->eraseFromParent();
|
|
} while (!DeadInsts.empty());
|
|
|
|
return true;
|
|
}
|
|
|
|
/// areAllUsesEqual - Check whether the uses of a value are all the same.
|
|
/// This is similar to Instruction::hasOneUse() except this will also return
|
|
/// true when there are no uses or multiple uses that all refer to the same
|
|
/// value.
|
|
static bool areAllUsesEqual(Instruction *I) {
|
|
Value::user_iterator UI = I->user_begin();
|
|
Value::user_iterator UE = I->user_end();
|
|
if (UI == UE)
|
|
return true;
|
|
|
|
User *TheUse = *UI;
|
|
for (++UI; UI != UE; ++UI) {
|
|
if (*UI != TheUse)
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
|
|
/// dead PHI node, due to being a def-use chain of single-use nodes that
|
|
/// either forms a cycle or is terminated by a trivially dead instruction,
|
|
/// delete it. If that makes any of its operands trivially dead, delete them
|
|
/// too, recursively. Return true if a change was made.
|
|
bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN,
|
|
const TargetLibraryInfo *TLI) {
|
|
SmallPtrSet<Instruction*, 4> Visited;
|
|
for (Instruction *I = PN; areAllUsesEqual(I) && !I->mayHaveSideEffects();
|
|
I = cast<Instruction>(*I->user_begin())) {
|
|
if (I->use_empty())
|
|
return RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
|
|
|
|
// If we find an instruction more than once, we're on a cycle that
|
|
// won't prove fruitful.
|
|
if (!Visited.insert(I).second) {
|
|
// Break the cycle and delete the instruction and its operands.
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
(void)RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static bool
|
|
simplifyAndDCEInstruction(Instruction *I,
|
|
SmallSetVector<Instruction *, 16> &WorkList,
|
|
const DataLayout &DL,
|
|
const TargetLibraryInfo *TLI) {
|
|
if (isInstructionTriviallyDead(I, TLI)) {
|
|
// Null out all of the instruction's operands to see if any operand becomes
|
|
// dead as we go.
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
|
|
Value *OpV = I->getOperand(i);
|
|
I->setOperand(i, nullptr);
|
|
|
|
if (!OpV->use_empty() || I == OpV)
|
|
continue;
|
|
|
|
// If the operand is an instruction that became dead as we nulled out the
|
|
// operand, and if it is 'trivially' dead, delete it in a future loop
|
|
// iteration.
|
|
if (Instruction *OpI = dyn_cast<Instruction>(OpV))
|
|
if (isInstructionTriviallyDead(OpI, TLI))
|
|
WorkList.insert(OpI);
|
|
}
|
|
|
|
I->eraseFromParent();
|
|
|
|
return true;
|
|
}
|
|
|
|
if (Value *SimpleV = SimplifyInstruction(I, DL)) {
|
|
// Add the users to the worklist. CAREFUL: an instruction can use itself,
|
|
// in the case of a phi node.
|
|
for (User *U : I->users()) {
|
|
if (U != I) {
|
|
WorkList.insert(cast<Instruction>(U));
|
|
}
|
|
}
|
|
|
|
// Replace the instruction with its simplified value.
|
|
bool Changed = false;
|
|
if (!I->use_empty()) {
|
|
I->replaceAllUsesWith(SimpleV);
|
|
Changed = true;
|
|
}
|
|
if (isInstructionTriviallyDead(I, TLI)) {
|
|
I->eraseFromParent();
|
|
Changed = true;
|
|
}
|
|
return Changed;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
|
|
/// simplify any instructions in it and recursively delete dead instructions.
|
|
///
|
|
/// This returns true if it changed the code, note that it can delete
|
|
/// instructions in other blocks as well in this block.
|
|
bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB,
|
|
const TargetLibraryInfo *TLI) {
|
|
bool MadeChange = false;
|
|
const DataLayout &DL = BB->getModule()->getDataLayout();
|
|
|
|
#ifndef NDEBUG
|
|
// In debug builds, ensure that the terminator of the block is never replaced
|
|
// or deleted by these simplifications. The idea of simplification is that it
|
|
// cannot introduce new instructions, and there is no way to replace the
|
|
// terminator of a block without introducing a new instruction.
|
|
AssertingVH<Instruction> TerminatorVH(&BB->back());
|
|
#endif
|
|
|
|
SmallSetVector<Instruction *, 16> WorkList;
|
|
// Iterate over the original function, only adding insts to the worklist
|
|
// if they actually need to be revisited. This avoids having to pre-init
|
|
// the worklist with the entire function's worth of instructions.
|
|
for (BasicBlock::iterator BI = BB->begin(), E = std::prev(BB->end());
|
|
BI != E;) {
|
|
assert(!BI->isTerminator());
|
|
Instruction *I = &*BI;
|
|
++BI;
|
|
|
|
// We're visiting this instruction now, so make sure it's not in the
|
|
// worklist from an earlier visit.
|
|
if (!WorkList.count(I))
|
|
MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
|
|
}
|
|
|
|
while (!WorkList.empty()) {
|
|
Instruction *I = WorkList.pop_back_val();
|
|
MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Control Flow Graph Restructuring.
|
|
//
|
|
|
|
|
|
/// RemovePredecessorAndSimplify - Like BasicBlock::removePredecessor, this
|
|
/// method is called when we're about to delete Pred as a predecessor of BB. If
|
|
/// BB contains any PHI nodes, this drops the entries in the PHI nodes for Pred.
|
|
///
|
|
/// Unlike the removePredecessor method, this attempts to simplify uses of PHI
|
|
/// nodes that collapse into identity values. For example, if we have:
|
|
/// x = phi(1, 0, 0, 0)
|
|
/// y = and x, z
|
|
///
|
|
/// .. and delete the predecessor corresponding to the '1', this will attempt to
|
|
/// recursively fold the and to 0.
|
|
void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred) {
|
|
// This only adjusts blocks with PHI nodes.
|
|
if (!isa<PHINode>(BB->begin()))
|
|
return;
|
|
|
|
// Remove the entries for Pred from the PHI nodes in BB, but do not simplify
|
|
// them down. This will leave us with single entry phi nodes and other phis
|
|
// that can be removed.
|
|
BB->removePredecessor(Pred, true);
|
|
|
|
WeakTrackingVH PhiIt = &BB->front();
|
|
while (PHINode *PN = dyn_cast<PHINode>(PhiIt)) {
|
|
PhiIt = &*++BasicBlock::iterator(cast<Instruction>(PhiIt));
|
|
Value *OldPhiIt = PhiIt;
|
|
|
|
if (!recursivelySimplifyInstruction(PN))
|
|
continue;
|
|
|
|
// If recursive simplification ended up deleting the next PHI node we would
|
|
// iterate to, then our iterator is invalid, restart scanning from the top
|
|
// of the block.
|
|
if (PhiIt != OldPhiIt) PhiIt = &BB->front();
|
|
}
|
|
}
|
|
|
|
|
|
/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its
|
|
/// predecessor is known to have one successor (DestBB!). Eliminate the edge
|
|
/// between them, moving the instructions in the predecessor into DestBB and
|
|
/// deleting the predecessor block.
|
|
///
|
|
void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT) {
|
|
// If BB has single-entry PHI nodes, fold them.
|
|
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
|
|
Value *NewVal = PN->getIncomingValue(0);
|
|
// Replace self referencing PHI with undef, it must be dead.
|
|
if (NewVal == PN) NewVal = UndefValue::get(PN->getType());
|
|
PN->replaceAllUsesWith(NewVal);
|
|
PN->eraseFromParent();
|
|
}
|
|
|
|
BasicBlock *PredBB = DestBB->getSinglePredecessor();
|
|
assert(PredBB && "Block doesn't have a single predecessor!");
|
|
|
|
// Zap anything that took the address of DestBB. Not doing this will give the
|
|
// address an invalid value.
|
|
if (DestBB->hasAddressTaken()) {
|
|
BlockAddress *BA = BlockAddress::get(DestBB);
|
|
Constant *Replacement =
|
|
ConstantInt::get(llvm::Type::getInt32Ty(BA->getContext()), 1);
|
|
BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
|
|
BA->getType()));
|
|
BA->destroyConstant();
|
|
}
|
|
|
|
// Anything that branched to PredBB now branches to DestBB.
|
|
PredBB->replaceAllUsesWith(DestBB);
|
|
|
|
// Splice all the instructions from PredBB to DestBB.
|
|
PredBB->getTerminator()->eraseFromParent();
|
|
DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
|
|
|
|
// If the PredBB is the entry block of the function, move DestBB up to
|
|
// become the entry block after we erase PredBB.
|
|
if (PredBB == &DestBB->getParent()->getEntryBlock())
|
|
DestBB->moveAfter(PredBB);
|
|
|
|
if (DT) {
|
|
BasicBlock *PredBBIDom = DT->getNode(PredBB)->getIDom()->getBlock();
|
|
DT->changeImmediateDominator(DestBB, PredBBIDom);
|
|
DT->eraseNode(PredBB);
|
|
}
|
|
// Nuke BB.
|
|
PredBB->eraseFromParent();
|
|
}
|
|
|
|
/// CanMergeValues - Return true if we can choose one of these values to use
|
|
/// in place of the other. Note that we will always choose the non-undef
|
|
/// value to keep.
|
|
static bool CanMergeValues(Value *First, Value *Second) {
|
|
return First == Second || isa<UndefValue>(First) || isa<UndefValue>(Second);
|
|
}
|
|
|
|
/// CanPropagatePredecessorsForPHIs - Return true if we can fold BB, an
|
|
/// almost-empty BB ending in an unconditional branch to Succ, into Succ.
|
|
///
|
|
/// Assumption: Succ is the single successor for BB.
|
|
///
|
|
static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
|
|
assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
|
|
|
|
DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into "
|
|
<< Succ->getName() << "\n");
|
|
// Shortcut, if there is only a single predecessor it must be BB and merging
|
|
// is always safe
|
|
if (Succ->getSinglePredecessor()) return true;
|
|
|
|
// Make a list of the predecessors of BB
|
|
SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
|
|
|
|
// Look at all the phi nodes in Succ, to see if they present a conflict when
|
|
// merging these blocks
|
|
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
|
|
PHINode *PN = cast<PHINode>(I);
|
|
|
|
// If the incoming value from BB is again a PHINode in
|
|
// BB which has the same incoming value for *PI as PN does, we can
|
|
// merge the phi nodes and then the blocks can still be merged
|
|
PHINode *BBPN = dyn_cast<PHINode>(PN->getIncomingValueForBlock(BB));
|
|
if (BBPN && BBPN->getParent() == BB) {
|
|
for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
|
|
BasicBlock *IBB = PN->getIncomingBlock(PI);
|
|
if (BBPreds.count(IBB) &&
|
|
!CanMergeValues(BBPN->getIncomingValueForBlock(IBB),
|
|
PN->getIncomingValue(PI))) {
|
|
DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
|
|
<< Succ->getName() << " is conflicting with "
|
|
<< BBPN->getName() << " with regard to common predecessor "
|
|
<< IBB->getName() << "\n");
|
|
return false;
|
|
}
|
|
}
|
|
} else {
|
|
Value* Val = PN->getIncomingValueForBlock(BB);
|
|
for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
|
|
// See if the incoming value for the common predecessor is equal to the
|
|
// one for BB, in which case this phi node will not prevent the merging
|
|
// of the block.
|
|
BasicBlock *IBB = PN->getIncomingBlock(PI);
|
|
if (BBPreds.count(IBB) &&
|
|
!CanMergeValues(Val, PN->getIncomingValue(PI))) {
|
|
DEBUG(dbgs() << "Can't fold, phi node " << PN->getName() << " in "
|
|
<< Succ->getName() << " is conflicting with regard to common "
|
|
<< "predecessor " << IBB->getName() << "\n");
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
typedef SmallVector<BasicBlock *, 16> PredBlockVector;
|
|
typedef DenseMap<BasicBlock *, Value *> IncomingValueMap;
|
|
|
|
/// \brief Determines the value to use as the phi node input for a block.
|
|
///
|
|
/// Select between \p OldVal any value that we know flows from \p BB
|
|
/// to a particular phi on the basis of which one (if either) is not
|
|
/// undef. Update IncomingValues based on the selected value.
|
|
///
|
|
/// \param OldVal The value we are considering selecting.
|
|
/// \param BB The block that the value flows in from.
|
|
/// \param IncomingValues A map from block-to-value for other phi inputs
|
|
/// that we have examined.
|
|
///
|
|
/// \returns the selected value.
|
|
static Value *selectIncomingValueForBlock(Value *OldVal, BasicBlock *BB,
|
|
IncomingValueMap &IncomingValues) {
|
|
if (!isa<UndefValue>(OldVal)) {
|
|
assert((!IncomingValues.count(BB) ||
|
|
IncomingValues.find(BB)->second == OldVal) &&
|
|
"Expected OldVal to match incoming value from BB!");
|
|
|
|
IncomingValues.insert(std::make_pair(BB, OldVal));
|
|
return OldVal;
|
|
}
|
|
|
|
IncomingValueMap::const_iterator It = IncomingValues.find(BB);
|
|
if (It != IncomingValues.end()) return It->second;
|
|
|
|
return OldVal;
|
|
}
|
|
|
|
/// \brief Create a map from block to value for the operands of a
|
|
/// given phi.
|
|
///
|
|
/// Create a map from block to value for each non-undef value flowing
|
|
/// into \p PN.
|
|
///
|
|
/// \param PN The phi we are collecting the map for.
|
|
/// \param IncomingValues [out] The map from block to value for this phi.
|
|
static void gatherIncomingValuesToPhi(PHINode *PN,
|
|
IncomingValueMap &IncomingValues) {
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
|
|
BasicBlock *BB = PN->getIncomingBlock(i);
|
|
Value *V = PN->getIncomingValue(i);
|
|
|
|
if (!isa<UndefValue>(V))
|
|
IncomingValues.insert(std::make_pair(BB, V));
|
|
}
|
|
}
|
|
|
|
/// \brief Replace the incoming undef values to a phi with the values
|
|
/// from a block-to-value map.
|
|
///
|
|
/// \param PN The phi we are replacing the undefs in.
|
|
/// \param IncomingValues A map from block to value.
|
|
static void replaceUndefValuesInPhi(PHINode *PN,
|
|
const IncomingValueMap &IncomingValues) {
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
|
|
Value *V = PN->getIncomingValue(i);
|
|
|
|
if (!isa<UndefValue>(V)) continue;
|
|
|
|
BasicBlock *BB = PN->getIncomingBlock(i);
|
|
IncomingValueMap::const_iterator It = IncomingValues.find(BB);
|
|
if (It == IncomingValues.end()) continue;
|
|
|
|
PN->setIncomingValue(i, It->second);
|
|
}
|
|
}
|
|
|
|
/// \brief Replace a value flowing from a block to a phi with
|
|
/// potentially multiple instances of that value flowing from the
|
|
/// block's predecessors to the phi.
|
|
///
|
|
/// \param BB The block with the value flowing into the phi.
|
|
/// \param BBPreds The predecessors of BB.
|
|
/// \param PN The phi that we are updating.
|
|
static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
|
|
const PredBlockVector &BBPreds,
|
|
PHINode *PN) {
|
|
Value *OldVal = PN->removeIncomingValue(BB, false);
|
|
assert(OldVal && "No entry in PHI for Pred BB!");
|
|
|
|
IncomingValueMap IncomingValues;
|
|
|
|
// We are merging two blocks - BB, and the block containing PN - and
|
|
// as a result we need to redirect edges from the predecessors of BB
|
|
// to go to the block containing PN, and update PN
|
|
// accordingly. Since we allow merging blocks in the case where the
|
|
// predecessor and successor blocks both share some predecessors,
|
|
// and where some of those common predecessors might have undef
|
|
// values flowing into PN, we want to rewrite those values to be
|
|
// consistent with the non-undef values.
|
|
|
|
gatherIncomingValuesToPhi(PN, IncomingValues);
|
|
|
|
// If this incoming value is one of the PHI nodes in BB, the new entries
|
|
// in the PHI node are the entries from the old PHI.
|
|
if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
|
|
PHINode *OldValPN = cast<PHINode>(OldVal);
|
|
for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i) {
|
|
// Note that, since we are merging phi nodes and BB and Succ might
|
|
// have common predecessors, we could end up with a phi node with
|
|
// identical incoming branches. This will be cleaned up later (and
|
|
// will trigger asserts if we try to clean it up now, without also
|
|
// simplifying the corresponding conditional branch).
|
|
BasicBlock *PredBB = OldValPN->getIncomingBlock(i);
|
|
Value *PredVal = OldValPN->getIncomingValue(i);
|
|
Value *Selected = selectIncomingValueForBlock(PredVal, PredBB,
|
|
IncomingValues);
|
|
|
|
// And add a new incoming value for this predecessor for the
|
|
// newly retargeted branch.
|
|
PN->addIncoming(Selected, PredBB);
|
|
}
|
|
} else {
|
|
for (unsigned i = 0, e = BBPreds.size(); i != e; ++i) {
|
|
// Update existing incoming values in PN for this
|
|
// predecessor of BB.
|
|
BasicBlock *PredBB = BBPreds[i];
|
|
Value *Selected = selectIncomingValueForBlock(OldVal, PredBB,
|
|
IncomingValues);
|
|
|
|
// And add a new incoming value for this predecessor for the
|
|
// newly retargeted branch.
|
|
PN->addIncoming(Selected, PredBB);
|
|
}
|
|
}
|
|
|
|
replaceUndefValuesInPhi(PN, IncomingValues);
|
|
}
|
|
|
|
/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
|
|
/// unconditional branch, and contains no instructions other than PHI nodes,
|
|
/// potential side-effect free intrinsics and the branch. If possible,
|
|
/// eliminate BB by rewriting all the predecessors to branch to the successor
|
|
/// block and return true. If we can't transform, return false.
|
|
bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
|
|
assert(BB != &BB->getParent()->getEntryBlock() &&
|
|
"TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
|
|
|
|
// We can't eliminate infinite loops.
|
|
BasicBlock *Succ = cast<BranchInst>(BB->getTerminator())->getSuccessor(0);
|
|
if (BB == Succ) return false;
|
|
|
|
// Check to see if merging these blocks would cause conflicts for any of the
|
|
// phi nodes in BB or Succ. If not, we can safely merge.
|
|
if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
|
|
|
|
// Check for cases where Succ has multiple predecessors and a PHI node in BB
|
|
// has uses which will not disappear when the PHI nodes are merged. It is
|
|
// possible to handle such cases, but difficult: it requires checking whether
|
|
// BB dominates Succ, which is non-trivial to calculate in the case where
|
|
// Succ has multiple predecessors. Also, it requires checking whether
|
|
// constructing the necessary self-referential PHI node doesn't introduce any
|
|
// conflicts; this isn't too difficult, but the previous code for doing this
|
|
// was incorrect.
|
|
//
|
|
// Note that if this check finds a live use, BB dominates Succ, so BB is
|
|
// something like a loop pre-header (or rarely, a part of an irreducible CFG);
|
|
// folding the branch isn't profitable in that case anyway.
|
|
if (!Succ->getSinglePredecessor()) {
|
|
BasicBlock::iterator BBI = BB->begin();
|
|
while (isa<PHINode>(*BBI)) {
|
|
for (Use &U : BBI->uses()) {
|
|
if (PHINode* PN = dyn_cast<PHINode>(U.getUser())) {
|
|
if (PN->getIncomingBlock(U) != BB)
|
|
return false;
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
++BBI;
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
|
|
|
|
if (isa<PHINode>(Succ->begin())) {
|
|
// If there is more than one pred of succ, and there are PHI nodes in
|
|
// the successor, then we need to add incoming edges for the PHI nodes
|
|
//
|
|
const PredBlockVector BBPreds(pred_begin(BB), pred_end(BB));
|
|
|
|
// Loop over all of the PHI nodes in the successor of BB.
|
|
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
|
|
PHINode *PN = cast<PHINode>(I);
|
|
|
|
redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN);
|
|
}
|
|
}
|
|
|
|
if (Succ->getSinglePredecessor()) {
|
|
// BB is the only predecessor of Succ, so Succ will end up with exactly
|
|
// the same predecessors BB had.
|
|
|
|
// Copy over any phi, debug or lifetime instruction.
|
|
BB->getTerminator()->eraseFromParent();
|
|
Succ->getInstList().splice(Succ->getFirstNonPHI()->getIterator(),
|
|
BB->getInstList());
|
|
} else {
|
|
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
|
|
// We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
|
|
assert(PN->use_empty() && "There shouldn't be any uses here!");
|
|
PN->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
// If the unconditional branch we replaced contains llvm.loop metadata, we
|
|
// add the metadata to the branch instructions in the predecessors.
|
|
unsigned LoopMDKind = BB->getContext().getMDKindID("llvm.loop");
|
|
Instruction *TI = BB->getTerminator();
|
|
if (TI)
|
|
if (MDNode *LoopMD = TI->getMetadata(LoopMDKind))
|
|
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
|
|
BasicBlock *Pred = *PI;
|
|
Pred->getTerminator()->setMetadata(LoopMDKind, LoopMD);
|
|
}
|
|
|
|
// Everything that jumped to BB now goes to Succ.
|
|
BB->replaceAllUsesWith(Succ);
|
|
if (!Succ->hasName()) Succ->takeName(BB);
|
|
BB->eraseFromParent(); // Delete the old basic block.
|
|
return true;
|
|
}
|
|
|
|
/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
|
|
/// nodes in this block. This doesn't try to be clever about PHI nodes
|
|
/// which differ only in the order of the incoming values, but instcombine
|
|
/// orders them so it usually won't matter.
|
|
///
|
|
bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
|
|
// This implementation doesn't currently consider undef operands
|
|
// specially. Theoretically, two phis which are identical except for
|
|
// one having an undef where the other doesn't could be collapsed.
|
|
|
|
struct PHIDenseMapInfo {
|
|
static PHINode *getEmptyKey() {
|
|
return DenseMapInfo<PHINode *>::getEmptyKey();
|
|
}
|
|
static PHINode *getTombstoneKey() {
|
|
return DenseMapInfo<PHINode *>::getTombstoneKey();
|
|
}
|
|
static unsigned getHashValue(PHINode *PN) {
|
|
// Compute a hash value on the operands. Instcombine will likely have
|
|
// sorted them, which helps expose duplicates, but we have to check all
|
|
// the operands to be safe in case instcombine hasn't run.
|
|
return static_cast<unsigned>(hash_combine(
|
|
hash_combine_range(PN->value_op_begin(), PN->value_op_end()),
|
|
hash_combine_range(PN->block_begin(), PN->block_end())));
|
|
}
|
|
static bool isEqual(PHINode *LHS, PHINode *RHS) {
|
|
if (LHS == getEmptyKey() || LHS == getTombstoneKey() ||
|
|
RHS == getEmptyKey() || RHS == getTombstoneKey())
|
|
return LHS == RHS;
|
|
return LHS->isIdenticalTo(RHS);
|
|
}
|
|
};
|
|
|
|
// Set of unique PHINodes.
|
|
DenseSet<PHINode *, PHIDenseMapInfo> PHISet;
|
|
|
|
// Examine each PHI.
|
|
bool Changed = false;
|
|
for (auto I = BB->begin(); PHINode *PN = dyn_cast<PHINode>(I++);) {
|
|
auto Inserted = PHISet.insert(PN);
|
|
if (!Inserted.second) {
|
|
// A duplicate. Replace this PHI with its duplicate.
|
|
PN->replaceAllUsesWith(*Inserted.first);
|
|
PN->eraseFromParent();
|
|
Changed = true;
|
|
|
|
// The RAUW can change PHIs that we already visited. Start over from the
|
|
// beginning.
|
|
PHISet.clear();
|
|
I = BB->begin();
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// enforceKnownAlignment - If the specified pointer points to an object that
|
|
/// we control, modify the object's alignment to PrefAlign. This isn't
|
|
/// often possible though. If alignment is important, a more reliable approach
|
|
/// is to simply align all global variables and allocation instructions to
|
|
/// their preferred alignment from the beginning.
|
|
///
|
|
static unsigned enforceKnownAlignment(Value *V, unsigned Align,
|
|
unsigned PrefAlign,
|
|
const DataLayout &DL) {
|
|
assert(PrefAlign > Align);
|
|
|
|
V = V->stripPointerCasts();
|
|
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
|
|
// TODO: ideally, computeKnownBits ought to have used
|
|
// AllocaInst::getAlignment() in its computation already, making
|
|
// the below max redundant. But, as it turns out,
|
|
// stripPointerCasts recurses through infinite layers of bitcasts,
|
|
// while computeKnownBits is not allowed to traverse more than 6
|
|
// levels.
|
|
Align = std::max(AI->getAlignment(), Align);
|
|
if (PrefAlign <= Align)
|
|
return Align;
|
|
|
|
// If the preferred alignment is greater than the natural stack alignment
|
|
// then don't round up. This avoids dynamic stack realignment.
|
|
if (DL.exceedsNaturalStackAlignment(PrefAlign))
|
|
return Align;
|
|
AI->setAlignment(PrefAlign);
|
|
return PrefAlign;
|
|
}
|
|
|
|
if (auto *GO = dyn_cast<GlobalObject>(V)) {
|
|
// TODO: as above, this shouldn't be necessary.
|
|
Align = std::max(GO->getAlignment(), Align);
|
|
if (PrefAlign <= Align)
|
|
return Align;
|
|
|
|
// If there is a large requested alignment and we can, bump up the alignment
|
|
// of the global. If the memory we set aside for the global may not be the
|
|
// memory used by the final program then it is impossible for us to reliably
|
|
// enforce the preferred alignment.
|
|
if (!GO->canIncreaseAlignment())
|
|
return Align;
|
|
|
|
GO->setAlignment(PrefAlign);
|
|
return PrefAlign;
|
|
}
|
|
|
|
return Align;
|
|
}
|
|
|
|
unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
|
|
const DataLayout &DL,
|
|
const Instruction *CxtI,
|
|
AssumptionCache *AC,
|
|
const DominatorTree *DT) {
|
|
assert(V->getType()->isPointerTy() &&
|
|
"getOrEnforceKnownAlignment expects a pointer!");
|
|
|
|
KnownBits Known = computeKnownBits(V, DL, 0, AC, CxtI, DT);
|
|
unsigned TrailZ = Known.countMinTrailingZeros();
|
|
|
|
// Avoid trouble with ridiculously large TrailZ values, such as
|
|
// those computed from a null pointer.
|
|
TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1));
|
|
|
|
unsigned Align = 1u << std::min(Known.getBitWidth() - 1, TrailZ);
|
|
|
|
// LLVM doesn't support alignments larger than this currently.
|
|
Align = std::min(Align, +Value::MaximumAlignment);
|
|
|
|
if (PrefAlign > Align)
|
|
Align = enforceKnownAlignment(V, Align, PrefAlign, DL);
|
|
|
|
// We don't need to make any adjustment.
|
|
return Align;
|
|
}
|
|
|
|
///===---------------------------------------------------------------------===//
|
|
/// Dbg Intrinsic utilities
|
|
///
|
|
|
|
/// See if there is a dbg.value intrinsic for DIVar before I.
|
|
static bool LdStHasDebugValue(DILocalVariable *DIVar, DIExpression *DIExpr,
|
|
Instruction *I) {
|
|
// Since we can't guarantee that the original dbg.declare instrinsic
|
|
// is removed by LowerDbgDeclare(), we need to make sure that we are
|
|
// not inserting the same dbg.value intrinsic over and over.
|
|
llvm::BasicBlock::InstListType::iterator PrevI(I);
|
|
if (PrevI != I->getParent()->getInstList().begin()) {
|
|
--PrevI;
|
|
if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(PrevI))
|
|
if (DVI->getValue() == I->getOperand(0) &&
|
|
DVI->getVariable() == DIVar &&
|
|
DVI->getExpression() == DIExpr)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// See if there is a dbg.value intrinsic for DIVar for the PHI node.
|
|
static bool PhiHasDebugValue(DILocalVariable *DIVar,
|
|
DIExpression *DIExpr,
|
|
PHINode *APN) {
|
|
// Since we can't guarantee that the original dbg.declare instrinsic
|
|
// is removed by LowerDbgDeclare(), we need to make sure that we are
|
|
// not inserting the same dbg.value intrinsic over and over.
|
|
SmallVector<DbgValueInst *, 1> DbgValues;
|
|
findDbgValues(DbgValues, APN);
|
|
for (auto *DVI : DbgValues) {
|
|
assert(DVI->getValue() == APN);
|
|
if ((DVI->getVariable() == DIVar) && (DVI->getExpression() == DIExpr))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
|
|
/// that has an associated llvm.dbg.decl intrinsic.
|
|
void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
|
|
StoreInst *SI, DIBuilder &Builder) {
|
|
auto *DIVar = DDI->getVariable();
|
|
assert(DIVar && "Missing variable");
|
|
auto *DIExpr = DDI->getExpression();
|
|
Value *DV = SI->getOperand(0);
|
|
|
|
// If an argument is zero extended then use argument directly. The ZExt
|
|
// may be zapped by an optimization pass in future.
|
|
Argument *ExtendedArg = nullptr;
|
|
if (ZExtInst *ZExt = dyn_cast<ZExtInst>(SI->getOperand(0)))
|
|
ExtendedArg = dyn_cast<Argument>(ZExt->getOperand(0));
|
|
if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0)))
|
|
ExtendedArg = dyn_cast<Argument>(SExt->getOperand(0));
|
|
if (ExtendedArg) {
|
|
// If this DDI was already describing only a fragment of a variable, ensure
|
|
// that fragment is appropriately narrowed here.
|
|
// But if a fragment wasn't used, describe the value as the original
|
|
// argument (rather than the zext or sext) so that it remains described even
|
|
// if the sext/zext is optimized away. This widens the variable description,
|
|
// leaving it up to the consumer to know how the smaller value may be
|
|
// represented in a larger register.
|
|
if (auto Fragment = DIExpr->getFragmentInfo()) {
|
|
unsigned FragmentOffset = Fragment->OffsetInBits;
|
|
SmallVector<uint64_t, 3> Ops(DIExpr->elements_begin(),
|
|
DIExpr->elements_end() - 3);
|
|
Ops.push_back(dwarf::DW_OP_LLVM_fragment);
|
|
Ops.push_back(FragmentOffset);
|
|
const DataLayout &DL = DDI->getModule()->getDataLayout();
|
|
Ops.push_back(DL.getTypeSizeInBits(ExtendedArg->getType()));
|
|
DIExpr = Builder.createExpression(Ops);
|
|
}
|
|
DV = ExtendedArg;
|
|
}
|
|
if (!LdStHasDebugValue(DIVar, DIExpr, SI))
|
|
Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, DDI->getDebugLoc(),
|
|
SI);
|
|
}
|
|
|
|
/// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
|
|
/// that has an associated llvm.dbg.decl intrinsic.
|
|
void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
|
|
LoadInst *LI, DIBuilder &Builder) {
|
|
auto *DIVar = DDI->getVariable();
|
|
auto *DIExpr = DDI->getExpression();
|
|
assert(DIVar && "Missing variable");
|
|
|
|
if (LdStHasDebugValue(DIVar, DIExpr, LI))
|
|
return;
|
|
|
|
// We are now tracking the loaded value instead of the address. In the
|
|
// future if multi-location support is added to the IR, it might be
|
|
// preferable to keep tracking both the loaded value and the original
|
|
// address in case the alloca can not be elided.
|
|
Instruction *DbgValue = Builder.insertDbgValueIntrinsic(
|
|
LI, DIVar, DIExpr, DDI->getDebugLoc(), (Instruction *)nullptr);
|
|
DbgValue->insertAfter(LI);
|
|
}
|
|
|
|
/// Inserts a llvm.dbg.value intrinsic after a phi
|
|
/// that has an associated llvm.dbg.decl intrinsic.
|
|
void llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
|
|
PHINode *APN, DIBuilder &Builder) {
|
|
auto *DIVar = DDI->getVariable();
|
|
auto *DIExpr = DDI->getExpression();
|
|
assert(DIVar && "Missing variable");
|
|
|
|
if (PhiHasDebugValue(DIVar, DIExpr, APN))
|
|
return;
|
|
|
|
BasicBlock *BB = APN->getParent();
|
|
auto InsertionPt = BB->getFirstInsertionPt();
|
|
|
|
// The block may be a catchswitch block, which does not have a valid
|
|
// insertion point.
|
|
// FIXME: Insert dbg.value markers in the successors when appropriate.
|
|
if (InsertionPt != BB->end())
|
|
Builder.insertDbgValueIntrinsic(APN, DIVar, DIExpr, DDI->getDebugLoc(),
|
|
&*InsertionPt);
|
|
}
|
|
|
|
/// Determine whether this alloca is either a VLA or an array.
|
|
static bool isArray(AllocaInst *AI) {
|
|
return AI->isArrayAllocation() ||
|
|
AI->getType()->getElementType()->isArrayTy();
|
|
}
|
|
|
|
/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
|
|
/// of llvm.dbg.value intrinsics.
|
|
bool llvm::LowerDbgDeclare(Function &F) {
|
|
DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
|
|
SmallVector<DbgDeclareInst *, 4> Dbgs;
|
|
for (auto &FI : F)
|
|
for (Instruction &BI : FI)
|
|
if (auto DDI = dyn_cast<DbgDeclareInst>(&BI))
|
|
Dbgs.push_back(DDI);
|
|
|
|
if (Dbgs.empty())
|
|
return false;
|
|
|
|
for (auto &I : Dbgs) {
|
|
DbgDeclareInst *DDI = I;
|
|
AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
|
|
// If this is an alloca for a scalar variable, insert a dbg.value
|
|
// at each load and store to the alloca and erase the dbg.declare.
|
|
// The dbg.values allow tracking a variable even if it is not
|
|
// stored on the stack, while the dbg.declare can only describe
|
|
// the stack slot (and at a lexical-scope granularity). Later
|
|
// passes will attempt to elide the stack slot.
|
|
if (AI && !isArray(AI)) {
|
|
for (auto &AIUse : AI->uses()) {
|
|
User *U = AIUse.getUser();
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
|
|
if (AIUse.getOperandNo() == 1)
|
|
ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
|
|
ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
|
|
} else if (CallInst *CI = dyn_cast<CallInst>(U)) {
|
|
// This is a call by-value or some other instruction that
|
|
// takes a pointer to the variable. Insert a *value*
|
|
// intrinsic that describes the alloca.
|
|
DIB.insertDbgValueIntrinsic(AI, DDI->getVariable(),
|
|
DDI->getExpression(), DDI->getDebugLoc(),
|
|
CI);
|
|
}
|
|
}
|
|
DDI->eraseFromParent();
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// FindAllocaDbgDeclare - Finds the llvm.dbg.declare intrinsic describing the
|
|
/// alloca 'V', if any.
|
|
DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
|
|
if (auto *L = LocalAsMetadata::getIfExists(V))
|
|
if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L))
|
|
for (User *U : MDV->users())
|
|
if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U))
|
|
return DDI;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
void llvm::findDbgValues(SmallVectorImpl<DbgValueInst *> &DbgValues, Value *V) {
|
|
if (auto *L = LocalAsMetadata::getIfExists(V))
|
|
if (auto *MDV = MetadataAsValue::getIfExists(V->getContext(), L))
|
|
for (User *U : MDV->users())
|
|
if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(U))
|
|
DbgValues.push_back(DVI);
|
|
}
|
|
|
|
|
|
bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
|
|
Instruction *InsertBefore, DIBuilder &Builder,
|
|
bool Deref, int Offset) {
|
|
DbgDeclareInst *DDI = FindAllocaDbgDeclare(Address);
|
|
if (!DDI)
|
|
return false;
|
|
DebugLoc Loc = DDI->getDebugLoc();
|
|
auto *DIVar = DDI->getVariable();
|
|
auto *DIExpr = DDI->getExpression();
|
|
assert(DIVar && "Missing variable");
|
|
DIExpr = DIExpression::prepend(DIExpr, Deref, Offset);
|
|
// Insert llvm.dbg.declare immediately after the original alloca, and remove
|
|
// old llvm.dbg.declare.
|
|
Builder.insertDeclare(NewAddress, DIVar, DIExpr, Loc, InsertBefore);
|
|
DDI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
|
|
DIBuilder &Builder, bool Deref, int Offset) {
|
|
return replaceDbgDeclare(AI, NewAllocaAddress, AI->getNextNode(), Builder,
|
|
Deref, Offset);
|
|
}
|
|
|
|
static void replaceOneDbgValueForAlloca(DbgValueInst *DVI, Value *NewAddress,
|
|
DIBuilder &Builder, int Offset) {
|
|
DebugLoc Loc = DVI->getDebugLoc();
|
|
auto *DIVar = DVI->getVariable();
|
|
auto *DIExpr = DVI->getExpression();
|
|
assert(DIVar && "Missing variable");
|
|
|
|
// This is an alloca-based llvm.dbg.value. The first thing it should do with
|
|
// the alloca pointer is dereference it. Otherwise we don't know how to handle
|
|
// it and give up.
|
|
if (!DIExpr || DIExpr->getNumElements() < 1 ||
|
|
DIExpr->getElement(0) != dwarf::DW_OP_deref)
|
|
return;
|
|
|
|
// Insert the offset immediately after the first deref.
|
|
// We could just change the offset argument of dbg.value, but it's unsigned...
|
|
if (Offset) {
|
|
SmallVector<uint64_t, 4> Ops;
|
|
Ops.push_back(dwarf::DW_OP_deref);
|
|
DIExpression::appendOffset(Ops, Offset);
|
|
Ops.append(DIExpr->elements_begin() + 1, DIExpr->elements_end());
|
|
DIExpr = Builder.createExpression(Ops);
|
|
}
|
|
|
|
Builder.insertDbgValueIntrinsic(NewAddress, DIVar, DIExpr, Loc, DVI);
|
|
DVI->eraseFromParent();
|
|
}
|
|
|
|
void llvm::replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
|
|
DIBuilder &Builder, int Offset) {
|
|
if (auto *L = LocalAsMetadata::getIfExists(AI))
|
|
if (auto *MDV = MetadataAsValue::getIfExists(AI->getContext(), L))
|
|
for (auto UI = MDV->use_begin(), UE = MDV->use_end(); UI != UE;) {
|
|
Use &U = *UI++;
|
|
if (auto *DVI = dyn_cast<DbgValueInst>(U.getUser()))
|
|
replaceOneDbgValueForAlloca(DVI, NewAllocaAddress, Builder, Offset);
|
|
}
|
|
}
|
|
|
|
void llvm::salvageDebugInfo(Instruction &I) {
|
|
SmallVector<DbgValueInst *, 1> DbgValues;
|
|
auto &M = *I.getModule();
|
|
|
|
auto MDWrap = [&](Value *V) {
|
|
return MetadataAsValue::get(I.getContext(), ValueAsMetadata::get(V));
|
|
};
|
|
|
|
if (isa<BitCastInst>(&I)) {
|
|
findDbgValues(DbgValues, &I);
|
|
for (auto *DVI : DbgValues) {
|
|
// Bitcasts are entirely irrelevant for debug info. Rewrite the dbg.value
|
|
// to use the cast's source.
|
|
DVI->setOperand(0, MDWrap(I.getOperand(0)));
|
|
DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n');
|
|
}
|
|
} else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
|
|
findDbgValues(DbgValues, &I);
|
|
for (auto *DVI : DbgValues) {
|
|
unsigned BitWidth =
|
|
M.getDataLayout().getPointerSizeInBits(GEP->getPointerAddressSpace());
|
|
APInt Offset(BitWidth, 0);
|
|
// Rewrite a constant GEP into a DIExpression. Since we are performing
|
|
// arithmetic to compute the variable's *value* in the DIExpression, we
|
|
// need to mark the expression with a DW_OP_stack_value.
|
|
if (GEP->accumulateConstantOffset(M.getDataLayout(), Offset)) {
|
|
auto *DIExpr = DVI->getExpression();
|
|
DIBuilder DIB(M, /*AllowUnresolved*/ false);
|
|
// GEP offsets are i32 and thus always fit into an int64_t.
|
|
DIExpr = DIExpression::prepend(DIExpr, DIExpression::NoDeref,
|
|
Offset.getSExtValue(),
|
|
DIExpression::WithStackValue);
|
|
DVI->setOperand(0, MDWrap(I.getOperand(0)));
|
|
DVI->setOperand(2, MetadataAsValue::get(I.getContext(), DIExpr));
|
|
DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n');
|
|
}
|
|
}
|
|
} else if (isa<LoadInst>(&I)) {
|
|
findDbgValues(DbgValues, &I);
|
|
for (auto *DVI : DbgValues) {
|
|
// Rewrite the load into DW_OP_deref.
|
|
auto *DIExpr = DVI->getExpression();
|
|
DIBuilder DIB(M, /*AllowUnresolved*/ false);
|
|
DIExpr = DIExpression::prepend(DIExpr, DIExpression::WithDeref);
|
|
DVI->setOperand(0, MDWrap(I.getOperand(0)));
|
|
DVI->setOperand(2, MetadataAsValue::get(I.getContext(), DIExpr));
|
|
DEBUG(dbgs() << "SALVAGE: " << *DVI << '\n');
|
|
}
|
|
}
|
|
}
|
|
|
|
unsigned llvm::removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB) {
|
|
unsigned NumDeadInst = 0;
|
|
// Delete the instructions backwards, as it has a reduced likelihood of
|
|
// having to update as many def-use and use-def chains.
|
|
Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
|
|
while (EndInst != &BB->front()) {
|
|
// Delete the next to last instruction.
|
|
Instruction *Inst = &*--EndInst->getIterator();
|
|
if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
|
|
Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
|
|
if (Inst->isEHPad() || Inst->getType()->isTokenTy()) {
|
|
EndInst = Inst;
|
|
continue;
|
|
}
|
|
if (!isa<DbgInfoIntrinsic>(Inst))
|
|
++NumDeadInst;
|
|
Inst->eraseFromParent();
|
|
}
|
|
return NumDeadInst;
|
|
}
|
|
|
|
unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap,
|
|
bool PreserveLCSSA) {
|
|
BasicBlock *BB = I->getParent();
|
|
// Loop over all of the successors, removing BB's entry from any PHI
|
|
// nodes.
|
|
for (BasicBlock *Successor : successors(BB))
|
|
Successor->removePredecessor(BB, PreserveLCSSA);
|
|
|
|
// Insert a call to llvm.trap right before this. This turns the undefined
|
|
// behavior into a hard fail instead of falling through into random code.
|
|
if (UseLLVMTrap) {
|
|
Function *TrapFn =
|
|
Intrinsic::getDeclaration(BB->getParent()->getParent(), Intrinsic::trap);
|
|
CallInst *CallTrap = CallInst::Create(TrapFn, "", I);
|
|
CallTrap->setDebugLoc(I->getDebugLoc());
|
|
}
|
|
new UnreachableInst(I->getContext(), I);
|
|
|
|
// All instructions after this are dead.
|
|
unsigned NumInstrsRemoved = 0;
|
|
BasicBlock::iterator BBI = I->getIterator(), BBE = BB->end();
|
|
while (BBI != BBE) {
|
|
if (!BBI->use_empty())
|
|
BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
|
|
BB->getInstList().erase(BBI++);
|
|
++NumInstrsRemoved;
|
|
}
|
|
return NumInstrsRemoved;
|
|
}
|
|
|
|
/// changeToCall - Convert the specified invoke into a normal call.
|
|
static void changeToCall(InvokeInst *II) {
|
|
SmallVector<Value*, 8> Args(II->arg_begin(), II->arg_end());
|
|
SmallVector<OperandBundleDef, 1> OpBundles;
|
|
II->getOperandBundlesAsDefs(OpBundles);
|
|
CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args, OpBundles,
|
|
"", II);
|
|
NewCall->takeName(II);
|
|
NewCall->setCallingConv(II->getCallingConv());
|
|
NewCall->setAttributes(II->getAttributes());
|
|
NewCall->setDebugLoc(II->getDebugLoc());
|
|
II->replaceAllUsesWith(NewCall);
|
|
|
|
// Follow the call by a branch to the normal destination.
|
|
BranchInst::Create(II->getNormalDest(), II);
|
|
|
|
// Update PHI nodes in the unwind destination
|
|
II->getUnwindDest()->removePredecessor(II->getParent());
|
|
II->eraseFromParent();
|
|
}
|
|
|
|
BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
|
|
BasicBlock *UnwindEdge) {
|
|
BasicBlock *BB = CI->getParent();
|
|
|
|
// Convert this function call into an invoke instruction. First, split the
|
|
// basic block.
|
|
BasicBlock *Split =
|
|
BB->splitBasicBlock(CI->getIterator(), CI->getName() + ".noexc");
|
|
|
|
// Delete the unconditional branch inserted by splitBasicBlock
|
|
BB->getInstList().pop_back();
|
|
|
|
// Create the new invoke instruction.
|
|
SmallVector<Value *, 8> InvokeArgs(CI->arg_begin(), CI->arg_end());
|
|
SmallVector<OperandBundleDef, 1> OpBundles;
|
|
|
|
CI->getOperandBundlesAsDefs(OpBundles);
|
|
|
|
// Note: we're round tripping operand bundles through memory here, and that
|
|
// can potentially be avoided with a cleverer API design that we do not have
|
|
// as of this time.
|
|
|
|
InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split, UnwindEdge,
|
|
InvokeArgs, OpBundles, CI->getName(), BB);
|
|
II->setDebugLoc(CI->getDebugLoc());
|
|
II->setCallingConv(CI->getCallingConv());
|
|
II->setAttributes(CI->getAttributes());
|
|
|
|
// Make sure that anything using the call now uses the invoke! This also
|
|
// updates the CallGraph if present, because it uses a WeakTrackingVH.
|
|
CI->replaceAllUsesWith(II);
|
|
|
|
// Delete the original call
|
|
Split->getInstList().pop_front();
|
|
return Split;
|
|
}
|
|
|
|
static bool markAliveBlocks(Function &F,
|
|
SmallPtrSetImpl<BasicBlock*> &Reachable) {
|
|
|
|
SmallVector<BasicBlock*, 128> Worklist;
|
|
BasicBlock *BB = &F.front();
|
|
Worklist.push_back(BB);
|
|
Reachable.insert(BB);
|
|
bool Changed = false;
|
|
do {
|
|
BB = Worklist.pop_back_val();
|
|
|
|
// Do a quick scan of the basic block, turning any obviously unreachable
|
|
// instructions into LLVM unreachable insts. The instruction combining pass
|
|
// canonicalizes unreachable insts into stores to null or undef.
|
|
for (Instruction &I : *BB) {
|
|
// Assumptions that are known to be false are equivalent to unreachable.
|
|
// Also, if the condition is undefined, then we make the choice most
|
|
// beneficial to the optimizer, and choose that to also be unreachable.
|
|
if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
|
|
if (II->getIntrinsicID() == Intrinsic::assume) {
|
|
if (match(II->getArgOperand(0), m_CombineOr(m_Zero(), m_Undef()))) {
|
|
// Don't insert a call to llvm.trap right before the unreachable.
|
|
changeToUnreachable(II, false);
|
|
Changed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (II->getIntrinsicID() == Intrinsic::experimental_guard) {
|
|
// A call to the guard intrinsic bails out of the current compilation
|
|
// unit if the predicate passed to it is false. If the predicate is a
|
|
// constant false, then we know the guard will bail out of the current
|
|
// compile unconditionally, so all code following it is dead.
|
|
//
|
|
// Note: unlike in llvm.assume, it is not "obviously profitable" for
|
|
// guards to treat `undef` as `false` since a guard on `undef` can
|
|
// still be useful for widening.
|
|
if (match(II->getArgOperand(0), m_Zero()))
|
|
if (!isa<UnreachableInst>(II->getNextNode())) {
|
|
changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/ false);
|
|
Changed = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (auto *CI = dyn_cast<CallInst>(&I)) {
|
|
Value *Callee = CI->getCalledValue();
|
|
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
|
|
changeToUnreachable(CI, /*UseLLVMTrap=*/false);
|
|
Changed = true;
|
|
break;
|
|
}
|
|
if (CI->doesNotReturn()) {
|
|
// If we found a call to a no-return function, insert an unreachable
|
|
// instruction after it. Make sure there isn't *already* one there
|
|
// though.
|
|
if (!isa<UnreachableInst>(CI->getNextNode())) {
|
|
// Don't insert a call to llvm.trap right before the unreachable.
|
|
changeToUnreachable(CI->getNextNode(), false);
|
|
Changed = true;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Store to undef and store to null are undefined and used to signal that
|
|
// they should be changed to unreachable by passes that can't modify the
|
|
// CFG.
|
|
if (auto *SI = dyn_cast<StoreInst>(&I)) {
|
|
// Don't touch volatile stores.
|
|
if (SI->isVolatile()) continue;
|
|
|
|
Value *Ptr = SI->getOperand(1);
|
|
|
|
if (isa<UndefValue>(Ptr) ||
|
|
(isa<ConstantPointerNull>(Ptr) &&
|
|
SI->getPointerAddressSpace() == 0)) {
|
|
changeToUnreachable(SI, true);
|
|
Changed = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
TerminatorInst *Terminator = BB->getTerminator();
|
|
if (auto *II = dyn_cast<InvokeInst>(Terminator)) {
|
|
// Turn invokes that call 'nounwind' functions into ordinary calls.
|
|
Value *Callee = II->getCalledValue();
|
|
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
|
|
changeToUnreachable(II, true);
|
|
Changed = true;
|
|
} else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
|
|
if (II->use_empty() && II->onlyReadsMemory()) {
|
|
// jump to the normal destination branch.
|
|
BranchInst::Create(II->getNormalDest(), II);
|
|
II->getUnwindDest()->removePredecessor(II->getParent());
|
|
II->eraseFromParent();
|
|
} else
|
|
changeToCall(II);
|
|
Changed = true;
|
|
}
|
|
} else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Terminator)) {
|
|
// Remove catchpads which cannot be reached.
|
|
struct CatchPadDenseMapInfo {
|
|
static CatchPadInst *getEmptyKey() {
|
|
return DenseMapInfo<CatchPadInst *>::getEmptyKey();
|
|
}
|
|
static CatchPadInst *getTombstoneKey() {
|
|
return DenseMapInfo<CatchPadInst *>::getTombstoneKey();
|
|
}
|
|
static unsigned getHashValue(CatchPadInst *CatchPad) {
|
|
return static_cast<unsigned>(hash_combine_range(
|
|
CatchPad->value_op_begin(), CatchPad->value_op_end()));
|
|
}
|
|
static bool isEqual(CatchPadInst *LHS, CatchPadInst *RHS) {
|
|
if (LHS == getEmptyKey() || LHS == getTombstoneKey() ||
|
|
RHS == getEmptyKey() || RHS == getTombstoneKey())
|
|
return LHS == RHS;
|
|
return LHS->isIdenticalTo(RHS);
|
|
}
|
|
};
|
|
|
|
// Set of unique CatchPads.
|
|
SmallDenseMap<CatchPadInst *, detail::DenseSetEmpty, 4,
|
|
CatchPadDenseMapInfo, detail::DenseSetPair<CatchPadInst *>>
|
|
HandlerSet;
|
|
detail::DenseSetEmpty Empty;
|
|
for (CatchSwitchInst::handler_iterator I = CatchSwitch->handler_begin(),
|
|
E = CatchSwitch->handler_end();
|
|
I != E; ++I) {
|
|
BasicBlock *HandlerBB = *I;
|
|
auto *CatchPad = cast<CatchPadInst>(HandlerBB->getFirstNonPHI());
|
|
if (!HandlerSet.insert({CatchPad, Empty}).second) {
|
|
CatchSwitch->removeHandler(I);
|
|
--I;
|
|
--E;
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
Changed |= ConstantFoldTerminator(BB, true);
|
|
for (BasicBlock *Successor : successors(BB))
|
|
if (Reachable.insert(Successor).second)
|
|
Worklist.push_back(Successor);
|
|
} while (!Worklist.empty());
|
|
return Changed;
|
|
}
|
|
|
|
void llvm::removeUnwindEdge(BasicBlock *BB) {
|
|
TerminatorInst *TI = BB->getTerminator();
|
|
|
|
if (auto *II = dyn_cast<InvokeInst>(TI)) {
|
|
changeToCall(II);
|
|
return;
|
|
}
|
|
|
|
TerminatorInst *NewTI;
|
|
BasicBlock *UnwindDest;
|
|
|
|
if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
|
|
NewTI = CleanupReturnInst::Create(CRI->getCleanupPad(), nullptr, CRI);
|
|
UnwindDest = CRI->getUnwindDest();
|
|
} else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(TI)) {
|
|
auto *NewCatchSwitch = CatchSwitchInst::Create(
|
|
CatchSwitch->getParentPad(), nullptr, CatchSwitch->getNumHandlers(),
|
|
CatchSwitch->getName(), CatchSwitch);
|
|
for (BasicBlock *PadBB : CatchSwitch->handlers())
|
|
NewCatchSwitch->addHandler(PadBB);
|
|
|
|
NewTI = NewCatchSwitch;
|
|
UnwindDest = CatchSwitch->getUnwindDest();
|
|
} else {
|
|
llvm_unreachable("Could not find unwind successor");
|
|
}
|
|
|
|
NewTI->takeName(TI);
|
|
NewTI->setDebugLoc(TI->getDebugLoc());
|
|
UnwindDest->removePredecessor(BB);
|
|
TI->replaceAllUsesWith(NewTI);
|
|
TI->eraseFromParent();
|
|
}
|
|
|
|
/// removeUnreachableBlocks - Remove blocks that are not reachable, even
|
|
/// if they are in a dead cycle. Return true if a change was made, false
|
|
/// otherwise. If `LVI` is passed, this function preserves LazyValueInfo
|
|
/// after modifying the CFG.
|
|
bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI) {
|
|
SmallPtrSet<BasicBlock*, 16> Reachable;
|
|
bool Changed = markAliveBlocks(F, Reachable);
|
|
|
|
// If there are unreachable blocks in the CFG...
|
|
if (Reachable.size() == F.size())
|
|
return Changed;
|
|
|
|
assert(Reachable.size() < F.size());
|
|
NumRemoved += F.size()-Reachable.size();
|
|
|
|
// Loop over all of the basic blocks that are not reachable, dropping all of
|
|
// their internal references...
|
|
for (Function::iterator BB = ++F.begin(), E = F.end(); BB != E; ++BB) {
|
|
if (Reachable.count(&*BB))
|
|
continue;
|
|
|
|
for (BasicBlock *Successor : successors(&*BB))
|
|
if (Reachable.count(Successor))
|
|
Successor->removePredecessor(&*BB);
|
|
if (LVI)
|
|
LVI->eraseBlock(&*BB);
|
|
BB->dropAllReferences();
|
|
}
|
|
|
|
for (Function::iterator I = ++F.begin(); I != F.end();)
|
|
if (!Reachable.count(&*I))
|
|
I = F.getBasicBlockList().erase(I);
|
|
else
|
|
++I;
|
|
|
|
return true;
|
|
}
|
|
|
|
void llvm::combineMetadata(Instruction *K, const Instruction *J,
|
|
ArrayRef<unsigned> KnownIDs) {
|
|
SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
|
|
K->dropUnknownNonDebugMetadata(KnownIDs);
|
|
K->getAllMetadataOtherThanDebugLoc(Metadata);
|
|
for (const auto &MD : Metadata) {
|
|
unsigned Kind = MD.first;
|
|
MDNode *JMD = J->getMetadata(Kind);
|
|
MDNode *KMD = MD.second;
|
|
|
|
switch (Kind) {
|
|
default:
|
|
K->setMetadata(Kind, nullptr); // Remove unknown metadata
|
|
break;
|
|
case LLVMContext::MD_dbg:
|
|
llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg");
|
|
case LLVMContext::MD_tbaa:
|
|
K->setMetadata(Kind, MDNode::getMostGenericTBAA(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_alias_scope:
|
|
K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_noalias:
|
|
case LLVMContext::MD_mem_parallel_loop_access:
|
|
K->setMetadata(Kind, MDNode::intersect(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_range:
|
|
K->setMetadata(Kind, MDNode::getMostGenericRange(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_fpmath:
|
|
K->setMetadata(Kind, MDNode::getMostGenericFPMath(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_invariant_load:
|
|
// Only set the !invariant.load if it is present in both instructions.
|
|
K->setMetadata(Kind, JMD);
|
|
break;
|
|
case LLVMContext::MD_nonnull:
|
|
// Only set the !nonnull if it is present in both instructions.
|
|
K->setMetadata(Kind, JMD);
|
|
break;
|
|
case LLVMContext::MD_invariant_group:
|
|
// Preserve !invariant.group in K.
|
|
break;
|
|
case LLVMContext::MD_align:
|
|
K->setMetadata(Kind,
|
|
MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
|
|
break;
|
|
case LLVMContext::MD_dereferenceable:
|
|
case LLVMContext::MD_dereferenceable_or_null:
|
|
K->setMetadata(Kind,
|
|
MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
|
|
break;
|
|
}
|
|
}
|
|
// Set !invariant.group from J if J has it. If both instructions have it
|
|
// then we will just pick it from J - even when they are different.
|
|
// Also make sure that K is load or store - f.e. combining bitcast with load
|
|
// could produce bitcast with invariant.group metadata, which is invalid.
|
|
// FIXME: we should try to preserve both invariant.group md if they are
|
|
// different, but right now instruction can only have one invariant.group.
|
|
if (auto *JMD = J->getMetadata(LLVMContext::MD_invariant_group))
|
|
if (isa<LoadInst>(K) || isa<StoreInst>(K))
|
|
K->setMetadata(LLVMContext::MD_invariant_group, JMD);
|
|
}
|
|
|
|
void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J) {
|
|
unsigned KnownIDs[] = {
|
|
LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
|
|
LLVMContext::MD_noalias, LLVMContext::MD_range,
|
|
LLVMContext::MD_invariant_load, LLVMContext::MD_nonnull,
|
|
LLVMContext::MD_invariant_group, LLVMContext::MD_align,
|
|
LLVMContext::MD_dereferenceable,
|
|
LLVMContext::MD_dereferenceable_or_null};
|
|
combineMetadata(K, J, KnownIDs);
|
|
}
|
|
|
|
template <typename RootType, typename DominatesFn>
|
|
static unsigned replaceDominatedUsesWith(Value *From, Value *To,
|
|
const RootType &Root,
|
|
const DominatesFn &Dominates) {
|
|
assert(From->getType() == To->getType());
|
|
|
|
unsigned Count = 0;
|
|
for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
|
|
UI != UE;) {
|
|
Use &U = *UI++;
|
|
if (!Dominates(Root, U))
|
|
continue;
|
|
U.set(To);
|
|
DEBUG(dbgs() << "Replace dominated use of '" << From->getName() << "' as "
|
|
<< *To << " in " << *U << "\n");
|
|
++Count;
|
|
}
|
|
return Count;
|
|
}
|
|
|
|
unsigned llvm::replaceNonLocalUsesWith(Instruction *From, Value *To) {
|
|
assert(From->getType() == To->getType());
|
|
auto *BB = From->getParent();
|
|
unsigned Count = 0;
|
|
|
|
for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
|
|
UI != UE;) {
|
|
Use &U = *UI++;
|
|
auto *I = cast<Instruction>(U.getUser());
|
|
if (I->getParent() == BB)
|
|
continue;
|
|
U.set(To);
|
|
++Count;
|
|
}
|
|
return Count;
|
|
}
|
|
|
|
unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
|
|
DominatorTree &DT,
|
|
const BasicBlockEdge &Root) {
|
|
auto Dominates = [&DT](const BasicBlockEdge &Root, const Use &U) {
|
|
return DT.dominates(Root, U);
|
|
};
|
|
return ::replaceDominatedUsesWith(From, To, Root, Dominates);
|
|
}
|
|
|
|
unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
|
|
DominatorTree &DT,
|
|
const BasicBlock *BB) {
|
|
auto ProperlyDominates = [&DT](const BasicBlock *BB, const Use &U) {
|
|
auto *I = cast<Instruction>(U.getUser())->getParent();
|
|
return DT.properlyDominates(BB, I);
|
|
};
|
|
return ::replaceDominatedUsesWith(From, To, BB, ProperlyDominates);
|
|
}
|
|
|
|
bool llvm::callsGCLeafFunction(ImmutableCallSite CS,
|
|
const TargetLibraryInfo &TLI) {
|
|
// Check if the function is specifically marked as a gc leaf function.
|
|
if (CS.hasFnAttr("gc-leaf-function"))
|
|
return true;
|
|
if (const Function *F = CS.getCalledFunction()) {
|
|
if (F->hasFnAttribute("gc-leaf-function"))
|
|
return true;
|
|
|
|
if (auto IID = F->getIntrinsicID())
|
|
// Most LLVM intrinsics do not take safepoints.
|
|
return IID != Intrinsic::experimental_gc_statepoint &&
|
|
IID != Intrinsic::experimental_deoptimize;
|
|
}
|
|
|
|
// Lib calls can be materialized by some passes, and won't be
|
|
// marked as 'gc-leaf-function.' All available Libcalls are
|
|
// GC-leaf.
|
|
LibFunc LF;
|
|
if (TLI.getLibFunc(CS, LF)) {
|
|
return TLI.has(LF);
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void llvm::copyNonnullMetadata(const LoadInst &OldLI, MDNode *N,
|
|
LoadInst &NewLI) {
|
|
auto *NewTy = NewLI.getType();
|
|
|
|
// This only directly applies if the new type is also a pointer.
|
|
if (NewTy->isPointerTy()) {
|
|
NewLI.setMetadata(LLVMContext::MD_nonnull, N);
|
|
return;
|
|
}
|
|
|
|
// The only other translation we can do is to integral loads with !range
|
|
// metadata.
|
|
if (!NewTy->isIntegerTy())
|
|
return;
|
|
|
|
MDBuilder MDB(NewLI.getContext());
|
|
const Value *Ptr = OldLI.getPointerOperand();
|
|
auto *ITy = cast<IntegerType>(NewTy);
|
|
auto *NullInt = ConstantExpr::getPtrToInt(
|
|
ConstantPointerNull::get(cast<PointerType>(Ptr->getType())), ITy);
|
|
auto *NonNullInt = ConstantExpr::getAdd(NullInt, ConstantInt::get(ITy, 1));
|
|
NewLI.setMetadata(LLVMContext::MD_range,
|
|
MDB.createRange(NonNullInt, NullInt));
|
|
}
|
|
|
|
void llvm::copyRangeMetadata(const DataLayout &DL, const LoadInst &OldLI,
|
|
MDNode *N, LoadInst &NewLI) {
|
|
auto *NewTy = NewLI.getType();
|
|
|
|
// Give up unless it is converted to a pointer where there is a single very
|
|
// valuable mapping we can do reliably.
|
|
// FIXME: It would be nice to propagate this in more ways, but the type
|
|
// conversions make it hard.
|
|
if (!NewTy->isPointerTy())
|
|
return;
|
|
|
|
unsigned BitWidth = DL.getTypeSizeInBits(NewTy);
|
|
if (!getConstantRangeFromMetadata(*N).contains(APInt(BitWidth, 0))) {
|
|
MDNode *NN = MDNode::get(OldLI.getContext(), None);
|
|
NewLI.setMetadata(LLVMContext::MD_nonnull, NN);
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
/// A potential constituent of a bitreverse or bswap expression. See
|
|
/// collectBitParts for a fuller explanation.
|
|
struct BitPart {
|
|
BitPart(Value *P, unsigned BW) : Provider(P) {
|
|
Provenance.resize(BW);
|
|
}
|
|
|
|
/// The Value that this is a bitreverse/bswap of.
|
|
Value *Provider;
|
|
/// The "provenance" of each bit. Provenance[A] = B means that bit A
|
|
/// in Provider becomes bit B in the result of this expression.
|
|
SmallVector<int8_t, 32> Provenance; // int8_t means max size is i128.
|
|
|
|
enum { Unset = -1 };
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
/// Analyze the specified subexpression and see if it is capable of providing
|
|
/// pieces of a bswap or bitreverse. The subexpression provides a potential
|
|
/// piece of a bswap or bitreverse if it can be proven that each non-zero bit in
|
|
/// the output of the expression came from a corresponding bit in some other
|
|
/// value. This function is recursive, and the end result is a mapping of
|
|
/// bitnumber to bitnumber. It is the caller's responsibility to validate that
|
|
/// the bitnumber to bitnumber mapping is correct for a bswap or bitreverse.
|
|
///
|
|
/// For example, if the current subexpression if "(shl i32 %X, 24)" then we know
|
|
/// that the expression deposits the low byte of %X into the high byte of the
|
|
/// result and that all other bits are zero. This expression is accepted and a
|
|
/// BitPart is returned with Provider set to %X and Provenance[24-31] set to
|
|
/// [0-7].
|
|
///
|
|
/// To avoid revisiting values, the BitPart results are memoized into the
|
|
/// provided map. To avoid unnecessary copying of BitParts, BitParts are
|
|
/// constructed in-place in the \c BPS map. Because of this \c BPS needs to
|
|
/// store BitParts objects, not pointers. As we need the concept of a nullptr
|
|
/// BitParts (Value has been analyzed and the analysis failed), we an Optional
|
|
/// type instead to provide the same functionality.
|
|
///
|
|
/// Because we pass around references into \c BPS, we must use a container that
|
|
/// does not invalidate internal references (std::map instead of DenseMap).
|
|
///
|
|
static const Optional<BitPart> &
|
|
collectBitParts(Value *V, bool MatchBSwaps, bool MatchBitReversals,
|
|
std::map<Value *, Optional<BitPart>> &BPS) {
|
|
auto I = BPS.find(V);
|
|
if (I != BPS.end())
|
|
return I->second;
|
|
|
|
auto &Result = BPS[V] = None;
|
|
auto BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
|
|
|
|
if (Instruction *I = dyn_cast<Instruction>(V)) {
|
|
// If this is an or instruction, it may be an inner node of the bswap.
|
|
if (I->getOpcode() == Instruction::Or) {
|
|
auto &A = collectBitParts(I->getOperand(0), MatchBSwaps,
|
|
MatchBitReversals, BPS);
|
|
auto &B = collectBitParts(I->getOperand(1), MatchBSwaps,
|
|
MatchBitReversals, BPS);
|
|
if (!A || !B)
|
|
return Result;
|
|
|
|
// Try and merge the two together.
|
|
if (!A->Provider || A->Provider != B->Provider)
|
|
return Result;
|
|
|
|
Result = BitPart(A->Provider, BitWidth);
|
|
for (unsigned i = 0; i < A->Provenance.size(); ++i) {
|
|
if (A->Provenance[i] != BitPart::Unset &&
|
|
B->Provenance[i] != BitPart::Unset &&
|
|
A->Provenance[i] != B->Provenance[i])
|
|
return Result = None;
|
|
|
|
if (A->Provenance[i] == BitPart::Unset)
|
|
Result->Provenance[i] = B->Provenance[i];
|
|
else
|
|
Result->Provenance[i] = A->Provenance[i];
|
|
}
|
|
|
|
return Result;
|
|
}
|
|
|
|
// If this is a logical shift by a constant, recurse then shift the result.
|
|
if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
|
|
unsigned BitShift =
|
|
cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
|
|
// Ensure the shift amount is defined.
|
|
if (BitShift > BitWidth)
|
|
return Result;
|
|
|
|
auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps,
|
|
MatchBitReversals, BPS);
|
|
if (!Res)
|
|
return Result;
|
|
Result = Res;
|
|
|
|
// Perform the "shift" on BitProvenance.
|
|
auto &P = Result->Provenance;
|
|
if (I->getOpcode() == Instruction::Shl) {
|
|
P.erase(std::prev(P.end(), BitShift), P.end());
|
|
P.insert(P.begin(), BitShift, BitPart::Unset);
|
|
} else {
|
|
P.erase(P.begin(), std::next(P.begin(), BitShift));
|
|
P.insert(P.end(), BitShift, BitPart::Unset);
|
|
}
|
|
|
|
return Result;
|
|
}
|
|
|
|
// If this is a logical 'and' with a mask that clears bits, recurse then
|
|
// unset the appropriate bits.
|
|
if (I->getOpcode() == Instruction::And &&
|
|
isa<ConstantInt>(I->getOperand(1))) {
|
|
APInt Bit(I->getType()->getPrimitiveSizeInBits(), 1);
|
|
const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
|
|
|
|
// Check that the mask allows a multiple of 8 bits for a bswap, for an
|
|
// early exit.
|
|
unsigned NumMaskedBits = AndMask.countPopulation();
|
|
if (!MatchBitReversals && NumMaskedBits % 8 != 0)
|
|
return Result;
|
|
|
|
auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps,
|
|
MatchBitReversals, BPS);
|
|
if (!Res)
|
|
return Result;
|
|
Result = Res;
|
|
|
|
for (unsigned i = 0; i < BitWidth; ++i, Bit <<= 1)
|
|
// If the AndMask is zero for this bit, clear the bit.
|
|
if ((AndMask & Bit) == 0)
|
|
Result->Provenance[i] = BitPart::Unset;
|
|
return Result;
|
|
}
|
|
|
|
// If this is a zext instruction zero extend the result.
|
|
if (I->getOpcode() == Instruction::ZExt) {
|
|
auto &Res = collectBitParts(I->getOperand(0), MatchBSwaps,
|
|
MatchBitReversals, BPS);
|
|
if (!Res)
|
|
return Result;
|
|
|
|
Result = BitPart(Res->Provider, BitWidth);
|
|
auto NarrowBitWidth =
|
|
cast<IntegerType>(cast<ZExtInst>(I)->getSrcTy())->getBitWidth();
|
|
for (unsigned i = 0; i < NarrowBitWidth; ++i)
|
|
Result->Provenance[i] = Res->Provenance[i];
|
|
for (unsigned i = NarrowBitWidth; i < BitWidth; ++i)
|
|
Result->Provenance[i] = BitPart::Unset;
|
|
return Result;
|
|
}
|
|
}
|
|
|
|
// Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
|
|
// the input value to the bswap/bitreverse.
|
|
Result = BitPart(V, BitWidth);
|
|
for (unsigned i = 0; i < BitWidth; ++i)
|
|
Result->Provenance[i] = i;
|
|
return Result;
|
|
}
|
|
|
|
static bool bitTransformIsCorrectForBSwap(unsigned From, unsigned To,
|
|
unsigned BitWidth) {
|
|
if (From % 8 != To % 8)
|
|
return false;
|
|
// Convert from bit indices to byte indices and check for a byte reversal.
|
|
From >>= 3;
|
|
To >>= 3;
|
|
BitWidth >>= 3;
|
|
return From == BitWidth - To - 1;
|
|
}
|
|
|
|
static bool bitTransformIsCorrectForBitReverse(unsigned From, unsigned To,
|
|
unsigned BitWidth) {
|
|
return From == BitWidth - To - 1;
|
|
}
|
|
|
|
/// Given an OR instruction, check to see if this is a bitreverse
|
|
/// idiom. If so, insert the new intrinsic and return true.
|
|
bool llvm::recognizeBSwapOrBitReverseIdiom(
|
|
Instruction *I, bool MatchBSwaps, bool MatchBitReversals,
|
|
SmallVectorImpl<Instruction *> &InsertedInsts) {
|
|
if (Operator::getOpcode(I) != Instruction::Or)
|
|
return false;
|
|
if (!MatchBSwaps && !MatchBitReversals)
|
|
return false;
|
|
IntegerType *ITy = dyn_cast<IntegerType>(I->getType());
|
|
if (!ITy || ITy->getBitWidth() > 128)
|
|
return false; // Can't do vectors or integers > 128 bits.
|
|
unsigned BW = ITy->getBitWidth();
|
|
|
|
unsigned DemandedBW = BW;
|
|
IntegerType *DemandedTy = ITy;
|
|
if (I->hasOneUse()) {
|
|
if (TruncInst *Trunc = dyn_cast<TruncInst>(I->user_back())) {
|
|
DemandedTy = cast<IntegerType>(Trunc->getType());
|
|
DemandedBW = DemandedTy->getBitWidth();
|
|
}
|
|
}
|
|
|
|
// Try to find all the pieces corresponding to the bswap.
|
|
std::map<Value *, Optional<BitPart>> BPS;
|
|
auto Res = collectBitParts(I, MatchBSwaps, MatchBitReversals, BPS);
|
|
if (!Res)
|
|
return false;
|
|
auto &BitProvenance = Res->Provenance;
|
|
|
|
// Now, is the bit permutation correct for a bswap or a bitreverse? We can
|
|
// only byteswap values with an even number of bytes.
|
|
bool OKForBSwap = DemandedBW % 16 == 0, OKForBitReverse = true;
|
|
for (unsigned i = 0; i < DemandedBW; ++i) {
|
|
OKForBSwap &=
|
|
bitTransformIsCorrectForBSwap(BitProvenance[i], i, DemandedBW);
|
|
OKForBitReverse &=
|
|
bitTransformIsCorrectForBitReverse(BitProvenance[i], i, DemandedBW);
|
|
}
|
|
|
|
Intrinsic::ID Intrin;
|
|
if (OKForBSwap && MatchBSwaps)
|
|
Intrin = Intrinsic::bswap;
|
|
else if (OKForBitReverse && MatchBitReversals)
|
|
Intrin = Intrinsic::bitreverse;
|
|
else
|
|
return false;
|
|
|
|
if (ITy != DemandedTy) {
|
|
Function *F = Intrinsic::getDeclaration(I->getModule(), Intrin, DemandedTy);
|
|
Value *Provider = Res->Provider;
|
|
IntegerType *ProviderTy = cast<IntegerType>(Provider->getType());
|
|
// We may need to truncate the provider.
|
|
if (DemandedTy != ProviderTy) {
|
|
auto *Trunc = CastInst::Create(Instruction::Trunc, Provider, DemandedTy,
|
|
"trunc", I);
|
|
InsertedInsts.push_back(Trunc);
|
|
Provider = Trunc;
|
|
}
|
|
auto *CI = CallInst::Create(F, Provider, "rev", I);
|
|
InsertedInsts.push_back(CI);
|
|
auto *ExtInst = CastInst::Create(Instruction::ZExt, CI, ITy, "zext", I);
|
|
InsertedInsts.push_back(ExtInst);
|
|
return true;
|
|
}
|
|
|
|
Function *F = Intrinsic::getDeclaration(I->getModule(), Intrin, ITy);
|
|
InsertedInsts.push_back(CallInst::Create(F, Res->Provider, "rev", I));
|
|
return true;
|
|
}
|
|
|
|
// CodeGen has special handling for some string functions that may replace
|
|
// them with target-specific intrinsics. Since that'd skip our interceptors
|
|
// in ASan/MSan/TSan/DFSan, and thus make us miss some memory accesses,
|
|
// we mark affected calls as NoBuiltin, which will disable optimization
|
|
// in CodeGen.
|
|
void llvm::maybeMarkSanitizerLibraryCallNoBuiltin(
|
|
CallInst *CI, const TargetLibraryInfo *TLI) {
|
|
Function *F = CI->getCalledFunction();
|
|
LibFunc Func;
|
|
if (F && !F->hasLocalLinkage() && F->hasName() &&
|
|
TLI->getLibFunc(F->getName(), Func) && TLI->hasOptimizedCodeGen(Func) &&
|
|
!F->doesNotAccessMemory())
|
|
CI->addAttribute(AttributeList::FunctionIndex, Attribute::NoBuiltin);
|
|
}
|
|
|
|
bool llvm::canReplaceOperandWithVariable(const Instruction *I, unsigned OpIdx) {
|
|
// We can't have a PHI with a metadata type.
|
|
if (I->getOperand(OpIdx)->getType()->isMetadataTy())
|
|
return false;
|
|
|
|
// Early exit.
|
|
if (!isa<Constant>(I->getOperand(OpIdx)))
|
|
return true;
|
|
|
|
switch (I->getOpcode()) {
|
|
default:
|
|
return true;
|
|
case Instruction::Call:
|
|
case Instruction::Invoke:
|
|
// Can't handle inline asm. Skip it.
|
|
if (isa<InlineAsm>(ImmutableCallSite(I).getCalledValue()))
|
|
return false;
|
|
// Many arithmetic intrinsics have no issue taking a
|
|
// variable, however it's hard to distingish these from
|
|
// specials such as @llvm.frameaddress that require a constant.
|
|
if (isa<IntrinsicInst>(I))
|
|
return false;
|
|
|
|
// Constant bundle operands may need to retain their constant-ness for
|
|
// correctness.
|
|
if (ImmutableCallSite(I).isBundleOperand(OpIdx))
|
|
return false;
|
|
return true;
|
|
case Instruction::ShuffleVector:
|
|
// Shufflevector masks are constant.
|
|
return OpIdx != 2;
|
|
case Instruction::Switch:
|
|
case Instruction::ExtractValue:
|
|
// All operands apart from the first are constant.
|
|
return OpIdx == 0;
|
|
case Instruction::InsertValue:
|
|
// All operands apart from the first and the second are constant.
|
|
return OpIdx < 2;
|
|
case Instruction::Alloca:
|
|
// Static allocas (constant size in the entry block) are handled by
|
|
// prologue/epilogue insertion so they're free anyway. We definitely don't
|
|
// want to make them non-constant.
|
|
return !dyn_cast<AllocaInst>(I)->isStaticAlloca();
|
|
case Instruction::GetElementPtr:
|
|
if (OpIdx == 0)
|
|
return true;
|
|
gep_type_iterator It = gep_type_begin(I);
|
|
for (auto E = std::next(It, OpIdx); It != E; ++It)
|
|
if (It.isStruct())
|
|
return false;
|
|
return true;
|
|
}
|
|
}
|