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Erase dead copies that are clobbered by a call.

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This does make a difference, at least when using RABasic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150118 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2012-02-09 00:19:08 +00:00
parent 450b3850ce
commit f56ce53124
1 changed files with 17 additions and 5 deletions
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22
lib/CodeGen/MachineCopyPropagation.cpp
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@ -191,11 +191,11 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
// Not a copy. // Not a copy.
SmallVector<unsigned, 2> Defs; SmallVector<unsigned, 2> Defs;
bool HasRegMask = false; int RegMaskOpNum = -1;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i); MachineOperand &MO = MI->getOperand(i);
if (MO.isRegMask()) if (MO.isRegMask())
HasRegMask = true; RegMaskOpNum = i;
if (!MO.isReg()) if (!MO.isReg())
continue; continue;
unsigned Reg = MO.getReg(); unsigned Reg = MO.getReg();
@ -227,9 +227,21 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
// a large set of registers. It is possible to use the register mask to // a large set of registers. It is possible to use the register mask to
// prune the available copies, but treat it like a basic block boundary for // prune the available copies, but treat it like a basic block boundary for
// now. // now.
if (HasRegMask) { if (RegMaskOpNum >= 0) {
// FIXME: We could possibly erase some MaybeDeadCopies if their registers // Erase any MaybeDeadCopies whose destination register is clobbered.
// are clobbered by the mask. const MachineOperand &MaskMO = MI->getOperand(RegMaskOpNum);
for (SmallSetVector<MachineInstr*, 8>::iterator
DI = MaybeDeadCopies.begin(), DE = MaybeDeadCopies.end();
DI != DE; ++DI) {
unsigned Reg = (*DI)->getOperand(0).getReg();
if (ReservedRegs.test(Reg) || !MaskMO.clobbersPhysReg(Reg))
continue;
(*DI)->eraseFromParent();
Changed = true;
++NumDeletes;
}
// Clear all data structures as if we were beginning a new basic block.
MaybeDeadCopies.clear(); MaybeDeadCopies.clear();
AvailCopyMap.clear(); AvailCopyMap.clear();
CopyMap.clear(); CopyMap.clear();