X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FTwoAddressInstructionPass.cpp;h=c52e6756c750adbe0b4d40fa2daedc17e6b32e2d;hb=e5830c4e2603ab36f08911ff6bb117638ae529c7;hp=aca85b2aa17daefc081eb31fa2fdd15d4cb5067e;hpb=b4bd022731b28a80f59818870cc7df5d4771d793;p=oota-llvm.git diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp index aca85b2aa17..c52e6756c75 100644 --- a/lib/CodeGen/TwoAddressInstructionPass.cpp +++ b/lib/CodeGen/TwoAddressInstructionPass.cpp @@ -43,11 +43,11 @@ #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/IR/Function.h" #include "llvm/MC/MCInstrItineraries.h" +#include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetOptions.h" #include "llvm/Target/TargetRegisterInfo.h" using namespace llvm; @@ -59,6 +59,12 @@ STATISTIC(Num3AddrSunk, "Number of 3-address instructions sunk"); STATISTIC(NumReSchedUps, "Number of instructions re-scheduled up"); STATISTIC(NumReSchedDowns, "Number of instructions re-scheduled down"); +// Temporary flag to disable rescheduling. +static cl::opt +EnableRescheduling("twoaddr-reschedule", + cl::desc("Coalesce copies by rescheduling (default=true)"), + cl::init(true), cl::Hidden); + namespace { class TwoAddressInstructionPass : public MachineFunctionPass { MachineFunction *MF; @@ -120,7 +126,7 @@ class TwoAddressInstructionPass : public MachineFunctionPass { bool tryInstructionTransform(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, unsigned SrcIdx, unsigned DstIdx, - unsigned Dist); + unsigned Dist, bool shouldOnlyCommute); void scanUses(unsigned DstReg); @@ -427,10 +433,7 @@ static bool isKilled(MachineInstr &MI, unsigned Reg, /// isTwoAddrUse - Return true if the specified MI uses the specified register /// as a two-address use. If so, return the destination register by reference. static bool isTwoAddrUse(MachineInstr &MI, unsigned Reg, unsigned &DstReg) { - const MCInstrDesc &MCID = MI.getDesc(); - unsigned NumOps = MI.isInlineAsm() - ? MI.getNumOperands() : MCID.getNumOperands(); - for (unsigned i = 0; i != NumOps; ++i) { + for (unsigned i = 0, NumOps = MI.getNumOperands(); i != NumOps; ++i) { const MachineOperand &MO = MI.getOperand(i); if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg) continue; @@ -581,19 +584,9 @@ commuteInstruction(MachineBasicBlock::iterator &mi, } DEBUG(dbgs() << "2addr: COMMUTED TO: " << *NewMI); - // If the instruction changed to commute it, update livevar. - if (NewMI != MI) { - if (LV) - // Update live variables - LV->replaceKillInstruction(RegC, MI, NewMI); - if (LIS) - LIS->ReplaceMachineInstrInMaps(MI, NewMI); - - MBB->insert(mi, NewMI); // Insert the new inst - MBB->erase(mi); // Nuke the old inst. - mi = NewMI; - DistanceMap.insert(std::make_pair(NewMI, Dist)); - } + assert(NewMI == MI && + "TargetInstrInfo::commuteInstruction() should not return a new " + "instruction unless it was requested."); // Update source register map. unsigned FromRegC = getMappedReg(RegC, SrcRegMap); @@ -1095,11 +1088,13 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, /// either eliminate the tied operands or improve the opportunities for /// coalescing away the register copy. Returns true if no copy needs to be /// inserted to untie mi's operands (either because they were untied, or -/// because mi was rescheduled, and will be visited again later). +/// because mi was rescheduled, and will be visited again later). If the +/// shouldOnlyCommute flag is true, only instruction commutation is attempted. bool TwoAddressInstructionPass:: tryInstructionTransform(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, - unsigned SrcIdx, unsigned DstIdx, unsigned Dist) { + unsigned SrcIdx, unsigned DstIdx, + unsigned Dist, bool shouldOnlyCommute) { if (OptLevel == CodeGenOpt::None) return false; @@ -1148,9 +1143,12 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, return false; } + if (shouldOnlyCommute) + return false; + // If there is one more use of regB later in the same MBB, consider // re-schedule this MI below it. - if (rescheduleMIBelowKill(mi, nmi, regB)) { + if (EnableRescheduling && rescheduleMIBelowKill(mi, nmi, regB)) { ++NumReSchedDowns; return true; } @@ -1169,7 +1167,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, // If there is one more use of regB later in the same MBB, consider // re-schedule it before this MI if it's legal. - if (rescheduleKillAboveMI(mi, nmi, regB)) { + if (EnableRescheduling && rescheduleKillAboveMI(mi, nmi, regB)) { ++NumReSchedUps; return true; } @@ -1223,10 +1221,12 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, unsigned NewDstIdx = NewMIs[1]->findRegisterDefOperandIdx(regA); unsigned NewSrcIdx = NewMIs[1]->findRegisterUseOperandIdx(regB); MachineBasicBlock::iterator NewMI = NewMIs[1]; - bool TransformSuccess = - tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist); - if (TransformSuccess || - NewMIs[1]->getOperand(NewSrcIdx).isKill()) { + bool TransformResult = + tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist, true); + (void)TransformResult; + assert(!TransformResult && + "tryInstructionTransform() should return false."); + if (NewMIs[1]->getOperand(NewSrcIdx).isKill()) { // Success, or at least we made an improvement. Keep the unfolded // instructions and discard the original. if (LV) { @@ -1277,8 +1277,6 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, } mi = NewMIs[1]; - if (TransformSuccess) - return true; } else { // Transforming didn't eliminate the tie and didn't lead to an // improvement. Clean up the unfolded instructions and keep the @@ -1541,7 +1539,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { // transformations that may either eliminate the tied operands or // improve the opportunities for coalescing away the register copy. if (TiedOperands.size() == 1) { - SmallVector, 4> &TiedPairs + SmallVectorImpl > &TiedPairs = TiedOperands.begin()->second; if (TiedPairs.size() == 1) { unsigned SrcIdx = TiedPairs[0].first; @@ -1549,7 +1547,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { unsigned SrcReg = mi->getOperand(SrcIdx).getReg(); unsigned DstReg = mi->getOperand(DstIdx).getReg(); if (SrcReg != DstReg && - tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist)) { + tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist, false)) { // The tied operands have been eliminated or shifted further down the // block to ease elimination. Continue processing with 'nmi'. TiedOperands.clear();