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llvm-project/llvm/lib/CodeGen/StackMaps.cpp

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//===---------------------------- StackMaps.cpp ---------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOpcodes.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include <iterator>
using namespace llvm;
#define DEBUG_TYPE "stackmaps"
PatchPointOpers::PatchPointOpers(const MachineInstr *MI)
: MI(MI),
HasDef(MI->getOperand(0).isReg() && MI->getOperand(0).isDef() &&
!MI->getOperand(0).isImplicit()),
IsAnyReg(MI->getOperand(getMetaIdx(CCPos)).getImm() == CallingConv::AnyReg)
{
#ifndef NDEBUG
unsigned CheckStartIdx = 0, e = MI->getNumOperands();
while (CheckStartIdx < e && MI->getOperand(CheckStartIdx).isReg() &&
MI->getOperand(CheckStartIdx).isDef() &&
!MI->getOperand(CheckStartIdx).isImplicit())
++CheckStartIdx;
assert(getMetaIdx() == CheckStartIdx &&
"Unexpected additional definition in Patchpoint intrinsic.");
#endif
}
unsigned PatchPointOpers::getNextScratchIdx(unsigned StartIdx) const {
if (!StartIdx)
StartIdx = getVarIdx();
// Find the next scratch register (implicit def and early clobber)
unsigned ScratchIdx = StartIdx, e = MI->getNumOperands();
while (ScratchIdx < e &&
!(MI->getOperand(ScratchIdx).isReg() &&
MI->getOperand(ScratchIdx).isDef() &&
MI->getOperand(ScratchIdx).isImplicit() &&
MI->getOperand(ScratchIdx).isEarlyClobber()))
++ScratchIdx;
assert(ScratchIdx != e && "No scratch register available");
return ScratchIdx;
}
MachineInstr::const_mop_iterator
StackMaps::parseOperand(MachineInstr::const_mop_iterator MOI,
MachineInstr::const_mop_iterator MOE,
LocationVec &Locs, LiveOutVec &LiveOuts) const {
if (MOI->isImm()) {
switch (MOI->getImm()) {
default: llvm_unreachable("Unrecognized operand type.");
case StackMaps::DirectMemRefOp: {
unsigned Size = AP.TM.getDataLayout()->getPointerSizeInBits();
assert((Size % 8) == 0 && "Need pointer size in bytes.");
Size /= 8;
unsigned Reg = (++MOI)->getReg();
int64_t Imm = (++MOI)->getImm();
Locs.push_back(Location(StackMaps::Location::Direct, Size, Reg, Imm));
break;
}
case StackMaps::IndirectMemRefOp: {
int64_t Size = (++MOI)->getImm();
assert(Size > 0 && "Need a valid size for indirect memory locations.");
unsigned Reg = (++MOI)->getReg();
int64_t Imm = (++MOI)->getImm();
Locs.push_back(Location(StackMaps::Location::Indirect, Size, Reg, Imm));
break;
}
case StackMaps::ConstantOp: {
++MOI;
assert(MOI->isImm() && "Expected constant operand.");
int64_t Imm = MOI->getImm();
Locs.push_back(Location(Location::Constant, sizeof(int64_t), 0, Imm));
break;
}
}
return ++MOI;
}
// The physical register number will ultimately be encoded as a DWARF regno.
// The stack map also records the size of a spill slot that can hold the
// register content. (The runtime can track the actual size of the data type
// if it needs to.)
if (MOI->isReg()) {
// Skip implicit registers (this includes our scratch registers)
if (MOI->isImplicit())
return ++MOI;
assert(TargetRegisterInfo::isPhysicalRegister(MOI->getReg()) &&
"Virtreg operands should have been rewritten before now.");
const TargetRegisterClass *RC =
AP.TM.getRegisterInfo()->getMinimalPhysRegClass(MOI->getReg());
assert(!MOI->getSubReg() && "Physical subreg still around.");
Locs.push_back(
Location(Location::Register, RC->getSize(), MOI->getReg(), 0));
return ++MOI;
}
if (MOI->isRegLiveOut())
LiveOuts = parseRegisterLiveOutMask(MOI->getRegLiveOut());
return ++MOI;
}
/// Go up the super-register chain until we hit a valid dwarf register number.
static unsigned getDwarfRegNum(unsigned Reg, const TargetRegisterInfo *TRI) {
int RegNo = TRI->getDwarfRegNum(Reg, false);
for (MCSuperRegIterator SR(Reg, TRI); SR.isValid() && RegNo < 0; ++SR)
RegNo = TRI->getDwarfRegNum(*SR, false);
assert(RegNo >= 0 && "Invalid Dwarf register number.");
return (unsigned) RegNo;
}
/// Create a live-out register record for the given register Reg.
StackMaps::LiveOutReg
StackMaps::createLiveOutReg(unsigned Reg, const TargetRegisterInfo *TRI) const {
unsigned RegNo = getDwarfRegNum(Reg, TRI);
unsigned Size = TRI->getMinimalPhysRegClass(Reg)->getSize();
return LiveOutReg(Reg, RegNo, Size);
}
/// Parse the register live-out mask and return a vector of live-out registers
/// that need to be recorded in the stackmap.
StackMaps::LiveOutVec
StackMaps::parseRegisterLiveOutMask(const uint32_t *Mask) const {
assert(Mask && "No register mask specified");
const TargetRegisterInfo *TRI = AP.TM.getRegisterInfo();
LiveOutVec LiveOuts;
// Create a LiveOutReg for each bit that is set in the register mask.
for (unsigned Reg = 0, NumRegs = TRI->getNumRegs(); Reg != NumRegs; ++Reg)
if ((Mask[Reg / 32] >> Reg % 32) & 1)
LiveOuts.push_back(createLiveOutReg(Reg, TRI));
// We don't need to keep track of a register if its super-register is already
// in the list. Merge entries that refer to the same dwarf register and use
// the maximum size that needs to be spilled.
std::sort(LiveOuts.begin(), LiveOuts.end());
for (LiveOutVec::iterator I = LiveOuts.begin(), E = LiveOuts.end();
I != E; ++I) {
for (LiveOutVec::iterator II = std::next(I); II != E; ++II) {
if (I->RegNo != II->RegNo) {
// Skip all the now invalid entries.
I = --II;
break;
}
I->Size = std::max(I->Size, II->Size);
if (TRI->isSuperRegister(I->Reg, II->Reg))
I->Reg = II->Reg;
II->MarkInvalid();
}
}
LiveOuts.erase(std::remove_if(LiveOuts.begin(), LiveOuts.end(),
LiveOutReg::IsInvalid), LiveOuts.end());
return LiveOuts;
}
void StackMaps::recordStackMapOpers(const MachineInstr &MI, uint64_t ID,
MachineInstr::const_mop_iterator MOI,
MachineInstr::const_mop_iterator MOE,
bool recordResult) {
MCContext &OutContext = AP.OutStreamer.getContext();
MCSymbol *MILabel = OutContext.CreateTempSymbol();
AP.OutStreamer.EmitLabel(MILabel);
LocationVec Locations;
LiveOutVec LiveOuts;
if (recordResult) {
assert(PatchPointOpers(&MI).hasDef() && "Stackmap has no return value.");
parseOperand(MI.operands_begin(), std::next(MI.operands_begin()),
Locations, LiveOuts);
}
// Parse operands.
while (MOI != MOE) {
MOI = parseOperand(MOI, MOE, Locations, LiveOuts);
}
// Move large constants into the constant pool.
for (LocationVec::iterator I = Locations.begin(), E = Locations.end();
I != E; ++I) {
// Constants are encoded as sign-extended integers.
// -1 is directly encoded as .long 0xFFFFFFFF with no constant pool.
if (I->LocType == Location::Constant &&
((I->Offset + (int64_t(1)<<31)) >> 32) != 0) {
I->LocType = Location::ConstantIndex;
I->Offset = ConstPool.getConstantIndex(I->Offset);
}
}
// Create an expression to calculate the offset of the callsite from function
// entry.
const MCExpr *CSOffsetExpr = MCBinaryExpr::CreateSub(
MCSymbolRefExpr::Create(MILabel, OutContext),
MCSymbolRefExpr::Create(AP.CurrentFnSym, OutContext),
OutContext);
CSInfos.push_back(CallsiteInfo(CSOffsetExpr, ID, Locations, LiveOuts));
// Record the stack size of the current function.
const MachineFrameInfo *MFI = AP.MF->getFrameInfo();
FnStackSize[AP.CurrentFnSym] =
MFI->hasVarSizedObjects() ? UINT64_MAX : MFI->getStackSize();
}
void StackMaps::recordStackMap(const MachineInstr &MI) {
assert(MI.getOpcode() == TargetOpcode::STACKMAP && "expected stackmap");
int64_t ID = MI.getOperand(0).getImm();
recordStackMapOpers(MI, ID, std::next(MI.operands_begin(), 2),
MI.operands_end());
}
void StackMaps::recordPatchPoint(const MachineInstr &MI) {
assert(MI.getOpcode() == TargetOpcode::PATCHPOINT && "expected patchpoint");
PatchPointOpers opers(&MI);
int64_t ID = opers.getMetaOper(PatchPointOpers::IDPos).getImm();
MachineInstr::const_mop_iterator MOI =
std::next(MI.operands_begin(), opers.getStackMapStartIdx());
recordStackMapOpers(MI, ID, MOI, MI.operands_end(),
opers.isAnyReg() && opers.hasDef());
#ifndef NDEBUG
// verify anyregcc
LocationVec &Locations = CSInfos.back().Locations;
if (opers.isAnyReg()) {
unsigned NArgs = opers.getMetaOper(PatchPointOpers::NArgPos).getImm();
for (unsigned i = 0, e = (opers.hasDef() ? NArgs+1 : NArgs); i != e; ++i)
assert(Locations[i].LocType == Location::Register &&
"anyreg arg must be in reg.");
}
#endif
}
/// serializeToStackMapSection conceptually populates the following fields:
///
/// Header {
/// uint8 : Stack Map Version (currently 1)
/// uint8 : Reserved (expected to be 0)
/// uint16 : Reserved (expected to be 0)
/// }
/// uint32 : NumFunctions
/// uint32 : NumConstants
/// uint32 : NumRecords
/// StkSizeRecord[NumFunctions] {
/// uint64 : Function Address
/// uint64 : Stack Size
/// }
/// int64 : Constants[NumConstants]
/// StkMapRecord[NumRecords] {
/// uint64 : PatchPoint ID
/// uint32 : Instruction Offset
/// uint16 : Reserved (record flags)
/// uint16 : NumLocations
/// Location[NumLocations] {
/// uint8 : Register | Direct | Indirect | Constant | ConstantIndex
/// uint8 : Size in Bytes
/// uint16 : Dwarf RegNum
/// int32 : Offset
/// }
/// uint16 : Padding
/// uint16 : NumLiveOuts
/// LiveOuts[NumLiveOuts] {
/// uint16 : Dwarf RegNum
/// uint8 : Reserved
/// uint8 : Size in Bytes
/// }
/// uint32 : Padding (only if required to align to 8 byte)
/// }
///
/// Location Encoding, Type, Value:
/// 0x1, Register, Reg (value in register)
/// 0x2, Direct, Reg + Offset (frame index)
/// 0x3, Indirect, [Reg + Offset] (spilled value)
/// 0x4, Constant, Offset (small constant)
/// 0x5, ConstIndex, Constants[Offset] (large constant)
///
void StackMaps::serializeToStackMapSection() {
// Bail out if there's no stack map data.
if (CSInfos.empty())
return;
MCContext &OutContext = AP.OutStreamer.getContext();
const TargetRegisterInfo *TRI = AP.TM.getRegisterInfo();
// Create the section.
const MCSection *StackMapSection =
OutContext.getObjectFileInfo()->getStackMapSection();
AP.OutStreamer.SwitchSection(StackMapSection);
// Emit a dummy symbol to force section inclusion.
AP.OutStreamer.EmitLabel(
OutContext.GetOrCreateSymbol(Twine("__LLVM_StackMaps")));
// Serialize data.
const char *WSMP = "Stack Maps: ";
(void)WSMP;
DEBUG(dbgs() << "********** Stack Map Output **********\n");
// Header.
AP.OutStreamer.EmitIntValue(1, 1); // Version.
AP.OutStreamer.EmitIntValue(0, 1); // Reserved.
AP.OutStreamer.EmitIntValue(0, 2); // Reserved.
// Num functions.
DEBUG(dbgs() << WSMP << "#functions = " << FnStackSize.size() << '\n');
AP.OutStreamer.EmitIntValue(FnStackSize.size(), 4);
// Num constants.
DEBUG(dbgs() << WSMP << "#constants = " << ConstPool.getNumConstants()
<< '\n');
AP.OutStreamer.EmitIntValue(ConstPool.getNumConstants(), 4);
// Num callsites.
DEBUG(dbgs() << WSMP << "#callsites = " << CSInfos.size() << '\n');
AP.OutStreamer.EmitIntValue(CSInfos.size(), 4);
// Function stack size entries.
for (FnStackSizeMap::iterator I = FnStackSize.begin(), E = FnStackSize.end();
I != E; ++I) {
AP.OutStreamer.EmitSymbolValue(I->first, 8);
AP.OutStreamer.EmitIntValue(I->second, 8);
}
// Constant pool entries.
for (unsigned i = 0; i < ConstPool.getNumConstants(); ++i)
AP.OutStreamer.EmitIntValue(ConstPool.getConstant(i), 8);
// Callsite entries.
for (CallsiteInfoList::const_iterator CSII = CSInfos.begin(),
CSIE = CSInfos.end(); CSII != CSIE; ++CSII) {
uint64_t CallsiteID = CSII->ID;
const LocationVec &CSLocs = CSII->Locations;
const LiveOutVec &LiveOuts = CSII->LiveOuts;
DEBUG(dbgs() << WSMP << "callsite " << CallsiteID << "\n");
// Verify stack map entry. It's better to communicate a problem to the
// runtime than crash in case of in-process compilation. Currently, we do
// simple overflow checks, but we may eventually communicate other
// compilation errors this way.
if (CSLocs.size() > UINT16_MAX || LiveOuts.size() > UINT16_MAX) {
AP.OutStreamer.EmitIntValue(UINT64_MAX, 8); // Invalid ID.
AP.OutStreamer.EmitValue(CSII->CSOffsetExpr, 4);
AP.OutStreamer.EmitIntValue(0, 2); // Reserved.
AP.OutStreamer.EmitIntValue(0, 2); // 0 locations.
AP.OutStreamer.EmitIntValue(0, 2); // padding.
AP.OutStreamer.EmitIntValue(0, 2); // 0 live-out registers.
AP.OutStreamer.EmitIntValue(0, 4); // padding.
continue;
}
AP.OutStreamer.EmitIntValue(CallsiteID, 8);
AP.OutStreamer.EmitValue(CSII->CSOffsetExpr, 4);
// Reserved for flags.
AP.OutStreamer.EmitIntValue(0, 2);
DEBUG(dbgs() << WSMP << " has " << CSLocs.size() << " locations\n");
AP.OutStreamer.EmitIntValue(CSLocs.size(), 2);
unsigned operIdx = 0;
for (LocationVec::const_iterator LocI = CSLocs.begin(), LocE = CSLocs.end();
LocI != LocE; ++LocI, ++operIdx) {
const Location &Loc = *LocI;
unsigned RegNo = 0;
int Offset = Loc.Offset;
if(Loc.Reg) {
RegNo = getDwarfRegNum(Loc.Reg, TRI);
// If this is a register location, put the subregister byte offset in
// the location offset.
if (Loc.LocType == Location::Register) {
assert(!Loc.Offset && "Register location should have zero offset");
unsigned LLVMRegNo = TRI->getLLVMRegNum(RegNo, false);
unsigned SubRegIdx = TRI->getSubRegIndex(LLVMRegNo, Loc.Reg);
if (SubRegIdx)
Offset = TRI->getSubRegIdxOffset(SubRegIdx);
}
}
else {
assert(Loc.LocType != Location::Register &&
"Missing location register");
}
DEBUG(
dbgs() << WSMP << " Loc " << operIdx << ": ";
switch (Loc.LocType) {
case Location::Unprocessed:
dbgs() << "<Unprocessed operand>";
break;
case Location::Register:
dbgs() << "Register " << TRI->getName(Loc.Reg);
break;
case Location::Direct:
dbgs() << "Direct " << TRI->getName(Loc.Reg);
if (Loc.Offset)
dbgs() << " + " << Loc.Offset;
break;
case Location::Indirect:
dbgs() << "Indirect " << TRI->getName(Loc.Reg)
<< " + " << Loc.Offset;
break;
case Location::Constant:
dbgs() << "Constant " << Loc.Offset;
break;
case Location::ConstantIndex:
dbgs() << "Constant Index " << Loc.Offset;
break;
}
dbgs() << " [encoding: .byte " << Loc.LocType
<< ", .byte " << Loc.Size
<< ", .short " << RegNo
<< ", .int " << Offset << "]\n";
);
AP.OutStreamer.EmitIntValue(Loc.LocType, 1);
AP.OutStreamer.EmitIntValue(Loc.Size, 1);
AP.OutStreamer.EmitIntValue(RegNo, 2);
AP.OutStreamer.EmitIntValue(Offset, 4);
}
DEBUG(dbgs() << WSMP << " has " << LiveOuts.size()
<< " live-out registers\n");
// Num live-out registers and padding to align to 4 byte.
AP.OutStreamer.EmitIntValue(0, 2);
AP.OutStreamer.EmitIntValue(LiveOuts.size(), 2);
operIdx = 0;
for (LiveOutVec::const_iterator LI = LiveOuts.begin(), LE = LiveOuts.end();
LI != LE; ++LI, ++operIdx) {
DEBUG(dbgs() << WSMP << " LO " << operIdx << ": "
<< TRI->getName(LI->Reg)
<< " [encoding: .short " << LI->RegNo
<< ", .byte 0, .byte " << LI->Size << "]\n");
AP.OutStreamer.EmitIntValue(LI->RegNo, 2);
AP.OutStreamer.EmitIntValue(0, 1);
AP.OutStreamer.EmitIntValue(LI->Size, 1);
}
// Emit alignment to 8 byte.
AP.OutStreamer.EmitValueToAlignment(8);
}
AP.OutStreamer.AddBlankLine();
CSInfos.clear();
}
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