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[CodeGen] Fix peephole optimizer bug introduced in r205481. Fixes PR19318.

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I should have read that comment a little more carefully. ;)

Regression test in the works, committing in the mean time to un-break people.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205511 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames 2014-04-03 05:03:20 +00:00
parent 46aa8c8dae
commit 5a64ab6e03
1 changed files with 11 additions and 9 deletions
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20
lib/CodeGen/PeepholeOptimizer.cpp
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@ -630,20 +630,22 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
// earlier load into MI.
if (!isLoadFoldable(MI, FoldAsLoadDefCandidates) &&
!FoldAsLoadDefCandidates.empty()) {
// We need to fold load after optimizeCmpInstr, since optimizeCmpInstr
// can enable folding by converting SUB to CMP.
// Save FoldAsLoadDefReg because optimizeLoadInstr() resets it and we
// need it for markUsesInDebugValueAsUndef().
const MCInstrDesc &MIDesc = MI->getDesc();
for (unsigned i = MIDesc.getNumDefs(); i != MIDesc.getNumOperands();
++i) {
const MachineOperand &MOp = MI->getOperand(i);
if (!MOp.isReg())
continue;
unsigned TryFoldReg = MOp.getReg();
if (FoldAsLoadDefCandidates.count(TryFoldReg)) {
unsigned FoldAsLoadDefReg = MOp.getReg();
if (FoldAsLoadDefCandidates.count(FoldAsLoadDefReg)) {
// We need to fold load after optimizeCmpInstr, since
// optimizeCmpInstr can enable folding by converting SUB to CMP.
// Save FoldAsLoadDefReg because optimizeLoadInstr() resets it and
// we need it for markUsesInDebugValueAsUndef().
unsigned FoldedReg = FoldAsLoadDefReg;
MachineInstr *DefMI = 0;
MachineInstr *FoldMI = TII->optimizeLoadInstr(MI, MRI, TryFoldReg,
MachineInstr *FoldMI = TII->optimizeLoadInstr(MI, MRI,
FoldAsLoadDefReg,
DefMI);
if (FoldMI) {
// Update LocalMIs since we replaced MI with FoldMI and deleted
@ -655,8 +657,8 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
LocalMIs.insert(FoldMI);
MI->eraseFromParent();
DefMI->eraseFromParent();
MRI->markUsesInDebugValueAsUndef(TryFoldReg);
FoldAsLoadDefCandidates.erase(TryFoldReg);
MRI->markUsesInDebugValueAsUndef(FoldedReg);
FoldAsLoadDefCandidates.erase(FoldedReg);
++NumLoadFold;
// MI is replaced with FoldMI.
Changed = true;