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OpcodeDispatcher: eliminate constants in RCR

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Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
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Alyssa Rosenzweig committed 2024-01-30 22:22:57 -04:00
1 parent 0a164428fa
commit d3f1397325
1 file changed
+5 -5
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FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
+5 -5
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@@ -2481,9 +2481,10 @@ void OpDispatchBuilder::RCROp(OpcodeArgs) {
// Res |= (SrcMasked << (Size - Shift + 1));
// Expressed as Res | ((SrcMasked << (Size - Shift)) << 1) to get correct
// behaviour for Shift without clobbering NZCV.
OrderedNode *SrcMaskedShl = _Sub(OpSize, _Constant(Size, Size), SrcMasked);
Res = _Orlshl(OpSize, Res, _Lshl(OpSize, Dest, SrcMaskedShl), 1);
// behaviour for Shift without clobbering NZCV. Then observe that modulo
// Size, Size - Shift = -Shift so we can use a simple Neg.
OrderedNode *NegSrc = _Neg(OpSize, SrcMasked);
Res = _Orlshl(OpSize, Res, _Lshl(OpSize, Dest, NegSrc), 1);
// Our new CF will be bit (Shift - 1) of the source. this is hoisted up to
// avoid the need to copy the source.
@@ -2491,8 +2492,7 @@ void OpDispatchBuilder::RCROp(OpcodeArgs) {
SetRFLAG<FEXCore::X86State::RFLAG_CF_RAW_LOC>(NewCF, 0, true);
// Since shift != 0 we can inject the CF
OrderedNode *CFShl = _Sub(OpSize, _Constant(Size, Size), SrcMasked);
Res = _Or(OpSize, Res, _Lshl(OpSize::i64Bit, CF, CFShl));
Res = _Or(OpSize, Res, _Lshl(OpSize, CF, NegSrc));
// OF is the top two MSBs XOR'd together
// Only when Shift == 1, it is undefined otherwise