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Factor out LiveIntervalAnalysis' code to determine whether an instruction

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is trivially rematerializable and integrate it into
TargetInstrInfo::isTriviallyReMaterializable. This way, all places that
need to know whether an instruction is rematerializable will get the
same answer.

This enables the useful parts of the aggressive-remat option by
default -- using AliasAnalysis to determine whether a memory location
is invariant, and removes the questionable parts -- rematting operations
with virtual register inputs that may not be live everywhere.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83687 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-10-09 23:27:56 +00:00
parent ac1ceb3dd3
commit a70dca156f
14 changed files with 161 additions and 130 deletions
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8
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -34,6 +34,7 @@
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
@ -62,6 +63,7 @@ namespace {
const TargetRegisterInfo *TRI;
MachineRegisterInfo *MRI;
LiveVariables *LV;
AliasAnalysis *AA;
// DistanceMap - Keep track the distance of a MI from the start of the
// current basic block.
@ -130,6 +132,7 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
@ -160,7 +163,7 @@ bool TwoAddressInstructionPass::Sink3AddrInstruction(MachineBasicBlock *MBB,
MachineBasicBlock::iterator OldPos) {
// Check if it's safe to move this instruction.
bool SeenStore = true; // Be conservative.
if (!MI->isSafeToMove(TII, SeenStore))
if (!MI->isSafeToMove(TII, SeenStore, AA))
return false;
unsigned DefReg = 0;
@ -903,6 +906,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
TII = TM.getInstrInfo();
TRI = TM.getRegisterInfo();
LV = getAnalysisIfAvailable<LiveVariables>();
AA = &getAnalysis<AliasAnalysis>();
bool MadeChange = false;
@ -1027,7 +1031,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
// copying it.
if (DefMI &&
DefMI->getDesc().isAsCheapAsAMove() &&
DefMI->isSafeToReMat(TII, regB) &&
DefMI->isSafeToReMat(TII, regB, AA) &&
isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist)){
DEBUG(errs() << "2addr: REMATTING : " << *DefMI << "\n");
unsigned regASubIdx = mi->getOperand(DstIdx).getSubReg();