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VirtRegRewriter checks for early clobbers before it reuses an available stack

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slot.

Teach it to also check for early clobbered aliases, and early clobber operands
following the current operand.

This fixes the miscompilation in PR8044 where EC registers eax and ecx were
being used for inputs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112988 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-09-03 18:36:56 +00:00
parent 82de2e1a24
commit 1e3aeefc08
1 changed files with 7 additions and 5 deletions
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12
lib/CodeGen/VirtRegRewriter.cpp
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@ -2027,14 +2027,16 @@ LocalRewriter::RewriteMBB(LiveIntervals *LIs,
CanReuse = !ReusedOperands.isClobbered(PhysReg) &&
Spills.canClobberPhysReg(PhysReg);
}
// If this is an asm, and PhysReg is used elsewhere as an earlyclobber
// operand, we can't also use it as an input. (Outputs always come
// before inputs, so we can stop looking at i.)
// If this is an asm, and a PhysReg alias is used elsewhere as an
// earlyclobber operand, we can't also use it as an input.
if (MI.isInlineAsm()) {
for (unsigned k=0; k<i; ++k) {
for (unsigned k = 0, e = MI.getNumOperands(); k != e; ++k) {
MachineOperand &MOk = MI.getOperand(k);
if (MOk.isReg() && MOk.getReg()==PhysReg && MOk.isEarlyClobber()) {
if (MOk.isReg() && MOk.isEarlyClobber() &&
TRI->regsOverlap(MOk.getReg(), PhysReg)) {
CanReuse = false;
DEBUG(dbgs() << "Not reusing physreg " << TRI->getName(PhysReg)
<< " for vreg" << VirtReg << ": " << MOk << '\n');
break;
}
}