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//===-- llvm/CodeGen/GlobalISel/Legalizer.cpp -----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// \file This file implements the LegalizerHelper class to legalize individual
/// instructions and the LegalizePass wrapper pass for the primary
/// legalization.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/Legalizer.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/CodeGen/GlobalISel/LegalizerCombiner.h"
#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <iterator>
#define DEBUG_TYPE "legalizer"
using namespace llvm;
char Legalizer::ID = 0;
INITIALIZE_PASS_BEGIN(Legalizer, DEBUG_TYPE,
"Legalize the Machine IR a function's Machine IR", false,
false)
INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
INITIALIZE_PASS_END(Legalizer, DEBUG_TYPE,
"Legalize the Machine IR a function's Machine IR", false,
false)
Legalizer::Legalizer() : MachineFunctionPass(ID) {
initializeLegalizerPass(*PassRegistry::getPassRegistry());
}
void Legalizer::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetPassConfig>();
MachineFunctionPass::getAnalysisUsage(AU);
}
void Legalizer::init(MachineFunction &MF) {
}
bool Legalizer::runOnMachineFunction(MachineFunction &MF) {
// If the ISel pipeline failed, do not bother running that pass.
if (MF.getProperties().hasProperty(
MachineFunctionProperties::Property::FailedISel))
return false;
DEBUG(dbgs() << "Legalize Machine IR for: " << MF.getName() << '\n');
init(MF);
const TargetPassConfig &TPC = getAnalysis<TargetPassConfig>();
MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
LegalizerHelper Helper(MF);
// FIXME: an instruction may need more than one pass before it is legal. For
// example on most architectures <3 x i3> is doubly-illegal. It would
// typically proceed along a path like: <3 x i3> -> <3 x i8> -> <8 x i8>. We
// probably want a worklist of instructions rather than naive iterate until
// convergence for performance reasons.
bool Changed = false;
MachineBasicBlock::iterator NextMI;
using VecType = SmallSetVector<MachineInstr *, 8>;
VecType WorkList;
VecType CombineList;
for (auto &MBB : MF) {
for (auto MI = MBB.begin(); MI != MBB.end(); MI = NextMI) {
// Get the next Instruction before we try to legalize, because there's a
// good chance MI will be deleted.
NextMI = std::next(MI);
// Only legalize pre-isel generic instructions: others don't have types
// and are assumed to be legal.
if (!isPreISelGenericOpcode(MI->getOpcode()))
continue;
unsigned NumNewInsns = 0;
WorkList.clear();
CombineList.clear();
Helper.MIRBuilder.recordInsertions([&](MachineInstr *MI) {
// Only legalize pre-isel generic instructions.
// Legalization process could generate Target specific pseudo
// instructions with generic types. Don't record them
if (isPreISelGenericOpcode(MI->getOpcode())) {
++NumNewInsns;
WorkList.insert(MI);
CombineList.insert(MI);
}
});
WorkList.insert(&*MI);
LegalizerCombiner C(Helper.MIRBuilder, MF.getRegInfo(),
Helper.getLegalizerInfo());
bool Changed = false;
LegalizerHelper::LegalizeResult Res;
do {
assert(!WorkList.empty() && "Expecting illegal ops");
while (!WorkList.empty()) {
NumNewInsns = 0;
MachineInstr *CurrInst = WorkList.pop_back_val();
Res = Helper.legalizeInstrStep(*CurrInst);
// Error out if we couldn't legalize this instruction. We may want to
// fall back to DAG ISel instead in the future.
if (Res == LegalizerHelper::UnableToLegalize) {
Helper.MIRBuilder.stopRecordingInsertions();
if (Res == LegalizerHelper::UnableToLegalize) {
reportGISelFailure(MF, TPC, MORE, "gisel-legalize",
"unable to legalize instruction", *CurrInst);
return false;
}
}
Changed |= Res == LegalizerHelper::Legalized;
// If CurrInst was legalized, there's a good chance that it might have
// been erased. So remove it from the Combine List.
if (Res == LegalizerHelper::Legalized)
CombineList.remove(CurrInst);
#ifndef NDEBUG
if (NumNewInsns)
for (unsigned I = WorkList.size() - NumNewInsns,
E = WorkList.size();
I != E; ++I)
DEBUG(dbgs() << ".. .. New MI: " << *WorkList[I];);
#endif
}
// Do the combines.
while (!CombineList.empty()) {
NumNewInsns = 0;
MachineInstr *CurrInst = CombineList.pop_back_val();
SmallVector<MachineInstr *, 4> DeadInstructions;
Changed |= C.tryCombineInstruction(*CurrInst, DeadInstructions);
for (auto *DeadMI : DeadInstructions) {
DEBUG(dbgs() << ".. Erasing Dead Instruction " << *DeadMI);
CombineList.remove(DeadMI);
WorkList.remove(DeadMI);
DeadMI->eraseFromParent();
}
#ifndef NDEBUG
if (NumNewInsns)
for (unsigned I = CombineList.size() - NumNewInsns,
E = CombineList.size();
I != E; ++I)
DEBUG(dbgs() << ".. .. Combine New MI: " << *CombineList[I];);
#endif
}
} while (!WorkList.empty());
Helper.MIRBuilder.stopRecordingInsertions();
}
}
MachineRegisterInfo &MRI = MF.getRegInfo();
MachineIRBuilder MIRBuilder(MF);
LegalizerCombiner C(MIRBuilder, MRI, Helper.getLegalizerInfo());
for (auto &MBB : MF) {
for (auto MI = MBB.begin(); MI != MBB.end(); MI = NextMI) {
// Get the next Instruction before we try to legalize, because there's a
// good chance MI will be deleted.
// TOOD: Perhaps move this to a combiner pass later?.
NextMI = std::next(MI);
SmallVector<MachineInstr *, 4> DeadInsts;
Changed |= C.tryCombineMerges(*MI, DeadInsts);
for (auto *DeadMI : DeadInsts)
DeadMI->eraseFromParent();
}
}
return Changed;
}
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