From 0ef8aaebeb291189d9d79399eab3a5cb3bdb1c42 Mon Sep 17 00:00:00 2001
From: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Date: Fri, 9 Aug 2024 17:22:51 -0400
Subject: [PATCH] OpcodeDispatcher: optimize BZHI

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
---
 FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp       | 7 +++++--
 FEXCore/Source/Interface/Core/OpcodeDispatcher.h         | 1 -
 FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp | 6 ------
 3 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp b/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
index 842295699..6743ae2ee 100644
--- a/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
+++ b/FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp
@@ -1877,8 +1877,11 @@ void OpDispatchBuilder::BZHI(OpcodeArgs) {
 
   auto Zero = _Constant(0);
   auto One = _Constant(1);
-  auto CF = _NZCVSelect(OpSize::i32Bit, {COND_NEQ}, One, Zero);
-  CalculateFlags_BZHI(Size, Result, CF);
+  auto CFInv = _NZCVSelect(OpSize::i32Bit, {COND_EQ}, One, Zero);
+
+  InvalidatePF_AF();
+  SetNZ_ZeroCV(Size, Result);
+  SetCFInverted(CFInv);
 }
 
 void OpDispatchBuilder::RORX(OpcodeArgs) {
diff --git a/FEXCore/Source/Interface/Core/OpcodeDispatcher.h b/FEXCore/Source/Interface/Core/OpcodeDispatcher.h
index 0515a632a..3c502940a 100644
--- a/FEXCore/Source/Interface/Core/OpcodeDispatcher.h
+++ b/FEXCore/Source/Interface/Core/OpcodeDispatcher.h
@@ -2306,7 +2306,6 @@ private:
   void CalculateFlags_BLSMSK(uint8_t SrcSize, Ref Res, Ref Src);
   void CalculateFlags_BLSR(uint8_t SrcSize, Ref Res, Ref Src);
   void CalculateFlags_POPCOUNT(Ref Src);
-  void CalculateFlags_BZHI(uint8_t SrcSize, Ref Result, Ref Src);
   void CalculateFlags_ZCNT(uint8_t SrcSize, Ref Result);
   void CalculateFlags_RDRAND(Ref Src);
   /**  @} */
diff --git a/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp b/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
index 116bc17bd..2e382cab2 100644
--- a/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
+++ b/FEXCore/Source/Interface/Core/OpcodeDispatcher/Flags.cpp
@@ -603,12 +603,6 @@ void OpDispatchBuilder::CalculateFlags_POPCOUNT(Ref Result) {
   ZeroPF_AF();
 }
 
-void OpDispatchBuilder::CalculateFlags_BZHI(uint8_t SrcSize, Ref Result, Ref Src) {
-  InvalidatePF_AF();
-  SetNZ_ZeroCV(SrcSize, Result);
-  SetCFDirect(Src);
-}
-
 void OpDispatchBuilder::CalculateFlags_ZCNT(uint8_t SrcSize, Ref Result) {
   // OF, SF, AF, PF all undefined
   // Test ZF of result, SF is undefined so this is ok.