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OpcodeDispatcher: eliminate select in RCR

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the nzcv clobber I actually came ofr

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
This commit is contained in:
Alyssa Rosenzweig 2024-01-25 18:10:04 -04:00
parent 7496175100
commit 0a164428fa
1 changed files with 4 additions and 6 deletions
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10
FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
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@ -2477,15 +2477,13 @@ void OpDispatchBuilder::RCROp(OpcodeArgs) {
OrderedNode *SrcMasked = _And(OpSize, Src, _Constant(Size, Mask));
CalculateFlags_ShiftVariable(SrcMasked, [this, CF, Op, Size, OpSize, SrcMasked, Dest, &Res](){
auto Zero = _Constant(Size, 0);
auto One = _Constant(Size, 1);
// Res |= (SrcMasked << (Size - Shift + 1));
OrderedNode *SrcMaskedShl = _Sub(OpSize, _Constant(Size, Size + 1), SrcMasked);
auto TmpHigher = _Lshl(OpSize, Dest, SrcMaskedShl);
auto CompareResult = _Select(FEXCore::IR::COND_UGT, SrcMasked, One, TmpHigher, Zero);
Res = _Or(OpSize, Res, CompareResult);
// 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);
// Our new CF will be bit (Shift - 1) of the source. this is hoisted up to
// avoid the need to copy the source.