llvm-project/llvm/lib/CodeGen/GlobalISel/Combiner.cpp

82 lines
2.7 KiB
C++

//===-- lib/CodeGen/GlobalISel/GICombiner.cpp -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file constains common code to combine machine functions at generic
// level.
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/Combiner.h"
#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
#include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "gi-combiner"
using namespace llvm;
Combiner::Combiner(CombinerInfo &Info, const TargetPassConfig *TPC)
: CInfo(Info), TPC(TPC) {
(void)this->TPC; // FIXME: Remove when used.
}
bool Combiner::combineMachineInstrs(MachineFunction &MF) {
// If the ISel pipeline failed, do not bother running this pass.
// FIXME: Should this be here or in individual combiner passes.
if (MF.getProperties().hasProperty(
MachineFunctionProperties::Property::FailedISel))
return false;
MRI = &MF.getRegInfo();
Builder.setMF(MF);
LLVM_DEBUG(dbgs() << "Generic MI Combiner for: " << MF.getName() << '\n');
MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
bool MFChanged = false;
bool Changed;
do {
// Collect all instructions. Do a post order traversal for basic blocks and
// insert with list bottom up, so while we pop_back_val, we'll traverse top
// down RPOT.
Changed = false;
GISelWorkList<512> WorkList;
for (MachineBasicBlock *MBB : post_order(&MF)) {
if (MBB->empty())
continue;
for (auto MII = MBB->rbegin(), MIE = MBB->rend(); MII != MIE;) {
MachineInstr *CurMI = &*MII;
++MII;
// Erase dead insts before even adding to the list.
if (isTriviallyDead(*CurMI, *MRI)) {
LLVM_DEBUG(dbgs() << *CurMI << "Is dead; erasing.\n");
CurMI->eraseFromParentAndMarkDBGValuesForRemoval();
continue;
}
WorkList.insert(CurMI);
}
}
// Main Loop. Process the instructions here.
while (!WorkList.empty()) {
MachineInstr *CurrInst = WorkList.pop_back_val();
LLVM_DEBUG(dbgs() << "Try combining " << *CurrInst << "\n";);
Changed |= CInfo.combine(*CurrInst, Builder);
}
MFChanged |= Changed;
} while (Changed);
return MFChanged;
}