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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.

llvm-svn: 150118
This commit is contained in:
Jakob Stoklund Olesen 2012-02-09 00:19:08 +00:00
parent 27f005d12d
commit 8a5e7e5027
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.
SmallVector<unsigned, 2> Defs;
bool HasRegMask = false;
int RegMaskOpNum = -1;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isRegMask())
HasRegMask = true;
RegMaskOpNum = i;
if (!MO.isReg())
continue;
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
// prune the available copies, but treat it like a basic block boundary for
// now.
if (HasRegMask) {
// FIXME: We could possibly erase some MaybeDeadCopies if their registers
// are clobbered by the mask.
if (RegMaskOpNum >= 0) {
// Erase any MaybeDeadCopies whose destination register is clobbered.
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();
AvailCopyMap.clear();
CopyMap.clear();