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FEXCore: Fixup ARPL implementation

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Some subtle details were wrong in the implementation, and some minor
changes to be more optimal.
This commit is contained in:
Ryan Houdek committed 2026-02-10 14:29:32 -08:00
1 parent 9bf9c00474
commit cf3c41acc7
2 files changed
+6 -7
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FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
+5 -6
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@@ -1052,19 +1052,18 @@ void OpDispatchBuilder::ARPLOp(OpcodeArgs) {
Ref Src = LoadSourceGPR_WithOpSize(Op, Op->Src[0], Size, Op->Flags, {.AllowUpperGarbage = true});
// RPL is the low two bits of the selector.
Ref DestRPL = _And(Size, Dest, Constant(0x3));
Ref SrcRPL = _And(Size, Src, Constant(0x3));
Ref DestRPL = _Bfe(OpSize::i32Bit, 2, 0, Dest);
Ref SrcRPL = _Bfe(OpSize::i32Bit, 2, 0, Src);
// NeedUpdate is 1 when DestRPL < SrcRPL, else 0.
Ref NeedUpdate = _Select(OpSize::i32Bit, Size, CondClass::ULT, DestRPL, SrcRPL, Constant(1), Constant(0));
Ref NeedUpdate = _Select(OpSize::i32Bit, OpSize::i32Bit, CondClass::ULT, DestRPL, SrcRPL, Constant(1), Constant(0));
SetRFLAG<FEXCore::X86State::RFLAG_ZF_RAW_LOC>(NeedUpdate);
// Compute adjusted destination selector: (Dest & ~3) | SrcRPL.
Ref Cleared = _And(Size, Dest, Constant(0xFFFC));
Ref NewDest = _Or(Size, Cleared, SrcRPL);
auto NewDest = _Bfxil(OpSize::i32Bit, 2, 0, Dest, SrcRPL);
// Conditionally select updated selector based on NeedUpdate.
Ref FinalDest = _Select(Size, OpSize::i32Bit, CondClass::NEQ, NeedUpdate, Constant(0), NewDest, Dest);
Ref FinalDest = _Select(OpSize::i32Bit, OpSize::i32Bit, CondClass::NEQ, NeedUpdate, Constant(0), NewDest, Dest);
StoreResultGPR_WithOpSize(Op, Op->Dest, FinalDest, Size);
}