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Enable two-address remat by default.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52701 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2008-06-25 01:16:38 +00:00
parent e4f6ee590b
commit 601ca4b434
4 changed files with 102 additions and 37 deletions
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68
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -53,10 +53,6 @@ STATISTIC(NumConvertedTo3Addr, "Number of instructions promoted to 3-address");
STATISTIC(Num3AddrSunk, "Number of 3-address instructions sunk");
STATISTIC(NumReMats, "Number of instructions re-materialized");
static cl::opt<bool>
EnableReMat("two-addr-remat", cl::init(false), cl::Hidden,
cl::desc("Two-addr conversion should remat when possible."));
namespace {
class VISIBILITY_HIDDEN TwoAddressInstructionPass
: public MachineFunctionPass {
@ -71,8 +67,8 @@ namespace {
bool isSafeToReMat(unsigned DstReg, MachineInstr *MI);
bool isProfitableToReMat(unsigned Reg, const TargetRegisterClass *RC,
MachineInstr *MI, unsigned Loc,
MachineInstr *DefMI, MachineBasicBlock *MBB,
MachineInstr *MI, MachineInstr *DefMI,
MachineBasicBlock *MBB, unsigned Loc,
DenseMap<MachineInstr*, unsigned> &DistanceMap);
public:
static char ID; // Pass identification, replacement for typeid
@ -248,12 +244,9 @@ static bool isTwoAddrUse(MachineInstr *UseMI, unsigned Reg) {
bool
TwoAddressInstructionPass::isProfitableToReMat(unsigned Reg,
const TargetRegisterClass *RC,
MachineInstr *MI, unsigned Loc,
MachineInstr *DefMI, MachineBasicBlock *MBB,
DenseMap<MachineInstr*, unsigned> &DistanceMap) {
if (DefMI->getParent() != MBB)
return true;
// If earlier uses in MBB are not two-address uses, then don't remat.
MachineInstr *MI, MachineInstr *DefMI,
MachineBasicBlock *MBB, unsigned Loc,
DenseMap<MachineInstr*, unsigned> &DistanceMap){
bool OtherUse = false;
for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
UE = MRI->use_end(); UI != UE; ++UI) {
@ -261,18 +254,26 @@ TwoAddressInstructionPass::isProfitableToReMat(unsigned Reg,
if (!UseMO.isUse())
continue;
MachineInstr *UseMI = UseMO.getParent();
if (UseMI->getParent() != MBB)
continue;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
if (DI != DistanceMap.end() && DI->second == Loc)
continue; // Current use.
OtherUse = true;
// There is at least one other use in the MBB that will clobber the
// register.
if (isTwoAddrUse(UseMI, Reg))
return true;
MachineBasicBlock *UseMBB = UseMI->getParent();
if (UseMBB == MBB) {
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
if (DI != DistanceMap.end() && DI->second == Loc)
continue; // Current use.
OtherUse = true;
// There is at least one other use in the MBB that will clobber the
// register.
if (isTwoAddrUse(UseMI, Reg))
return true;
}
}
return !OtherUse;
// If other uses in MBB are not two-address uses, then don't remat.
if (OtherUse)
return false;
// No other uses in the same block, remat if it's defined in the same
// block so it does not unnecessarily extend the live range.
return MBB == DefMI->getParent();
}
/// runOnMachineFunction - Reduce two-address instructions to two operands.
@ -428,9 +429,9 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
MachineInstr *DefMI = MRI->getVRegDef(regB);
// If it's safe and profitable, remat the definition instead of
// copying it.
if (EnableReMat && DefMI &&
if (DefMI &&
isSafeToReMat(regB, DefMI) &&
isProfitableToReMat(regB, rc, mi, Dist, DefMI, mbbi,DistanceMap)){
isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist,DistanceMap)){
DEBUG(cerr << "2addr: REMATTING : " << *DefMI << "\n");
TII->reMaterialize(*mbbi, mi, regA, DefMI);
ReMatRegs.set(regB);
@ -473,17 +474,14 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
}
}
if (EnableReMat) {
// Some remat'ed instructions are dead.
int VReg = ReMatRegs.find_first();
while (VReg != -1) {
if (MRI->use_empty(VReg)) {
MachineInstr *DefMI = MRI->getVRegDef(VReg);
DefMI->eraseFromParent();
}
VReg = ReMatRegs.find_next(VReg);
// Some remat'ed instructions are dead.
int VReg = ReMatRegs.find_first();
while (VReg != -1) {
if (MRI->use_empty(VReg)) {
MachineInstr *DefMI = MRI->getVRegDef(VReg);
DefMI->eraseFromParent();
}
VReg = ReMatRegs.find_next(VReg);
}
return MadeChange;