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Rearrange code to eliminate redundancy and avoid gotos.

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llvm-svn: 80798
This commit is contained in:
Bob Wilson 2009-09-02 16:35:35 +00:00
parent fb0a20c04b
commit 02cbc5bd86
1 changed files with 39 additions and 63 deletions
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102
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -895,51 +895,56 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
mi->getOperand(i).getReg() != regA);
#endif
// If this instruction is not the killing user of B, see if we can
// rearrange the code to make it so. Making it the killing user will
// allow us to coalesce A and B together, eliminating the copy we are
// about to insert.
if (!isKilled(*mi, regB, MRI, TII)) {
// If regA is dead and the instruction can be deleted, just delete
// it so it doesn't clobber regB.
bool regBKilled = isKilled(*mi, regB, MRI, TII);
if (!regBKilled && mi->getOperand(ti).isDead() &&
DeleteUnusedInstr(mi, nmi, mbbi, regB, si, Dist)) {
++NumDeletes;
break; // Done with this instruction.
}
// If regA is dead and the instruction can be deleted, just delete
// it so it doesn't clobber regB.
if (mi->getOperand(ti).isDead() &&
DeleteUnusedInstr(mi, nmi, mbbi, regB, si, Dist)) {
++NumDeletes;
break; // Done with this instruction.
}
// Check if it is profitable to commute the operands.
unsigned SrcOp1, SrcOp2;
unsigned regC = 0;
bool TryCommute = false;
bool AggressiveCommute = false;
if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
if (si == SrcOp1)
regC = mi->getOperand(SrcOp2).getReg();
else if (si == SrcOp2)
regC = mi->getOperand(SrcOp1).getReg();
// If this instruction is commutative, check to see if C dies. If
// so, swap the B and C operands. This makes the live ranges of A
// and C joinable.
// FIXME: This code also works for A := B op C instructions.
unsigned SrcOp1, SrcOp2;
if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
unsigned regC = 0;
if (si == SrcOp1)
regC = mi->getOperand(SrcOp2).getReg();
else if (si == SrcOp2)
regC = mi->getOperand(SrcOp1).getReg();
if (isKilled(*mi, regC, MRI, TII)) {
if (CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
++NumCommuted;
regB = regC;
goto InstructionRearranged;
}
if (regC) {
if (!regBKilled && isKilled(*mi, regC, MRI, TII))
// If C dies but B does not, swap the B and C operands.
// This makes the live ranges of A and C joinable.
TryCommute = true;
else if (isProfitableToCommute(regB, regC, mi, mbbi, Dist)) {
TryCommute = true;
AggressiveCommute = true;
}
}
}
// If this instruction is potentially convertible to a true
// three-address instruction,
if (TID.isConvertibleTo3Addr()) {
// If it's profitable to commute, try to do so.
if (TryCommute && CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
++NumCommuted;
if (AggressiveCommute)
++NumAggrCommuted;
regB = regC;
} else if (TID.isConvertibleTo3Addr()) {
// This instruction is potentially convertible to a true
// three-address instruction. Check if it is profitable.
if (!regBKilled || isProfitableToConv3Addr(regA)) {
// FIXME: This assumes there are no more operands which are tied
// to another register.
#ifndef NDEBUG
for (unsigned i = si + 1, e = TID.getNumOperands(); i < e; ++i)
assert(TID.getOperandConstraint(i, TOI::TIED_TO) == -1);
#endif
// Try to convert it.
if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
++NumConvertedTo3Addr;
break; // Done with this instruction.
@ -947,35 +952,6 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
}
}
// If it's profitable to commute the instruction, do so.
unsigned SrcOp1, SrcOp2;
if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
unsigned regC = 0;
if (si == SrcOp1)
regC = mi->getOperand(SrcOp2).getReg();
else if (si == SrcOp2)
regC = mi->getOperand(SrcOp1).getReg();
if (regC && isProfitableToCommute(regB, regC, mi, mbbi, Dist))
if (CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
++NumAggrCommuted;
++NumCommuted;
regB = regC;
goto InstructionRearranged;
}
}
// If it's profitable to convert the 2-address instruction to a
// 3-address one, do so.
if (TID.isConvertibleTo3Addr() && isProfitableToConv3Addr(regA)) {
if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
++NumConvertedTo3Addr;
break; // Done with this instruction.
}
}
InstructionRearranged:
const TargetRegisterClass* rc = MRI->getRegClass(regB);
MachineInstr *DefMI = MRI->getVRegDef(regB);
// If it's safe and profitable, remat the definition instead of