From 0f25a960eea5c281ca50828dcf71ed74c8b8f7bb Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Date: Mon, 13 Nov 2023 07:56:43 -0400
Subject: [PATCH] OpcodeDispatcher: remove bfe for small shl imm

We allow the garbage in flags calculation, it's ignored.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
---
 FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp       | 4 ----
 FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp | 8 ++++----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp b/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
index 8350dac8c..4f1480b6e 100644
--- a/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
+++ b/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
@@ -1679,10 +1679,6 @@ void OpDispatchBuilder::SHLImmediateOp(OpcodeArgs) {
 
   StoreResult(GPRClass, Op, Result, -1);
 
-  if (Size < 32) {
-    Result = _Bfe(OpSize::i32Bit, Size, 0, Result);
-  }
-
   GenerateFlags_ShiftLeftImmediate(Op, Result, Dest, Shift);
 }
 
diff --git a/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp b/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
index b2d260692..17be9f163 100644
--- a/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
+++ b/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
@@ -806,13 +806,13 @@ void OpDispatchBuilder::CalculateFlags_SignShiftRight(uint8_t SrcSize, OrderedNo
   PossiblySetNZCVBits |= OldSetNZCVBits;
 }
 
-void OpDispatchBuilder::CalculateFlags_ShiftLeftImmediate(uint8_t SrcSize, OrderedNode *Res, OrderedNode *Src1, uint64_t Shift) {
+void OpDispatchBuilder::CalculateFlags_ShiftLeftImmediate(uint8_t SrcSize, OrderedNode *UnmaskedRes, OrderedNode *Src1, uint64_t Shift) {
   // No flags changed if shift is zero
   if (Shift == 0) return;
 
   auto OpSize = SrcSize == 8 ? OpSize::i64Bit : OpSize::i32Bit;
 
-  SetNZ_ZeroCV(SrcSize, Res);
+  SetNZ_ZeroCV(SrcSize, UnmaskedRes);
 
   // CF
   {
@@ -824,7 +824,7 @@ void OpDispatchBuilder::CalculateFlags_ShiftLeftImmediate(uint8_t SrcSize, Order
     SetRFLAG<FEXCore::X86State::RFLAG_CF_RAW_LOC>(Src1, SrcSizeBits - Shift, true);
   }
 
-  CalculatePF(Res);
+  CalculatePF(UnmaskedRes);
 
   // AF
   // Undefined
@@ -833,7 +833,7 @@ void OpDispatchBuilder::CalculateFlags_ShiftLeftImmediate(uint8_t SrcSize, Order
   // OF
   // In the case of left shift. OF is only set from the result of <Top Source Bit> XOR <Top Result Bit>
   if (Shift == 1) {
-    auto Xor = _Xor(OpSize, Res, Src1);
+    auto Xor = _Xor(OpSize, UnmaskedRes, Src1);
     SetRFLAG<FEXCore::X86State::RFLAG_OF_RAW_LOC>(Xor, SrcSize * 8 - 1, true);
   } else {
     // Undefined, we choose to zero as part of SetNZ_ZeroCV