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ConstProp: fix LSHR constant prop

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Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
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Alyssa Rosenzweig committed 2024-06-26 12:06:47 -04:00
1 parent 5da205d91a
commit e2d73014f1
1 file changed
+6 -2
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FEXCore/Source/Interface/IR/Passes/ConstProp.cpp
+6 -2
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@@ -298,8 +298,12 @@ void ConstProp::ConstantPropagation(IREmitter* IREmit, const IRListView& Current
if (IREmit->IsValueConstant(IROp->Args[0], &Constant1) && IREmit->IsValueConstant(IROp->Args[1], &Constant2)) {
// Shifts mask the shift amount by 63 or 31 depending on operating size;
uint64_t ShiftMask = IROp->Size == 8 ? 63 : 31;
uint64_t NewConstant = (Constant1 >> (Constant2 & ShiftMask)) & getMask(IROp);
// The source is masked, which will produce a correctly masked
// destination. Masking the destination without the source instead will
// right-shift garbage into the upper bits instead of zeroes.
Constant1 &= getMask(IROp);
Constant2 &= (IROp->Size == 8 ? 63 : 31);
uint64_t NewConstant = (Constant1 >> Constant2);
IREmit->ReplaceWithConstant(CodeNode, NewConstant);
} else if (IREmit->IsValueConstant(IROp->Args[1], &Constant2) && Constant2 == 0) {
IREmit->SetWriteCursor(CodeNode);