From 5d37d5db1ae8a7e4a36964df5180fa9bbff68a9a Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Mon, 25 Dec 2023 04:58:15 -0800
Subject: [PATCH] FEXCore: Optimize HostFeatures and CPUID feature calculation

Need #3348 merged first.

As I was casually thinking, this code made me realize that it was quite
branch heavy and could likely be optimized to logic.

The previous code generated some fairly nasty branch heavy code. This
can be optimized to be branchless and take roughly five instructions
per flag. Using a bitfield for each feature would turn each calculation
in to 3-4 instructions but that seems overkill.

Very minor thing.
---
 FEXCore/Source/Interface/Core/CPUID.cpp       |  18 +--
 .../Source/Interface/Core/HostFeatures.cpp    | 135 ++++--------------
 2 files changed, 37 insertions(+), 116 deletions(-)

diff --git a/FEXCore/Source/Interface/Core/CPUID.cpp b/FEXCore/Source/Interface/Core/CPUID.cpp
index c04cff637..5215822dc 100644
--- a/FEXCore/Source/Interface/Core/CPUID.cpp
+++ b/FEXCore/Source/Interface/Core/CPUID.cpp
@@ -372,18 +372,18 @@ void CPUIDEmu::SetupFeatures() {
     return;
   }
 
-#define ENABLE_DISABLE_OPTION(name, enum_name) \
+#define ENABLE_DISABLE_OPTION(FeatureName, name, enum_name) \
+    do { \
     const bool Disable##name = (CPUIDFeatures() & FEXCore::Config::CPUID::DISABLE##enum_name) != 0; \
     const bool Enable##name = (CPUIDFeatures() & FEXCore::Config::CPUID::ENABLE##enum_name) != 0;   \
-    LogMan::Throw::AFmt(!(Disable##name && Enable##name), "Disabling and Enabling CPUID feature (" #name ") is mutually exclusive");
+      LogMan::Throw::AFmt(!(Disable##name && Enable##name), "Disabling and Enabling CPU feature (" #name ") is mutually exclusive"); \
+      const bool AlreadyEnabled = Features.FeatureName; \
+      const bool Result = (AlreadyEnabled | Enable##name) & !Disable##name; \
+      Features.FeatureName = Result; \
+    } while (0)
 
-  ENABLE_DISABLE_OPTION(SHA, SHA);
-  if (EnableSHA) {
-    Features.SHA = true;
-  }
-  else if (DisableSHA) {
-    Features.SHA = false;
-  }
+  ENABLE_DISABLE_OPTION(SHA, SHA, SHA);
+#undef ENABLE_DISABLE_OPTION
 }
 
 FEXCore::CPUID::FunctionResults CPUIDEmu::Function_0h(uint32_t Leaf) const {
diff --git a/FEXCore/Source/Interface/Core/HostFeatures.cpp b/FEXCore/Source/Interface/Core/HostFeatures.cpp
index e423255df..165e49a3b 100644
--- a/FEXCore/Source/Interface/Core/HostFeatures.cpp
+++ b/FEXCore/Source/Interface/Core/HostFeatures.cpp
@@ -69,114 +69,41 @@ static void OverrideFeatures(HostFeatures *Features) {
     return;
   }
 
-#define ENABLE_DISABLE_OPTION(name, enum_name) \
+#define ENABLE_DISABLE_OPTION(FeatureName, name, enum_name) \
+    do { \
+      const bool Disable##name = (HostFeatures() & FEXCore::Config::HostFeatures::DISABLE##enum_name) != 0; \
+      const bool Enable##name = (HostFeatures() & FEXCore::Config::HostFeatures::ENABLE##enum_name) != 0;   \
+      LogMan::Throw::AFmt(!(Disable##name && Enable##name), "Disabling and Enabling CPU feature (" #name ") is mutually exclusive"); \
+      const bool AlreadyEnabled = Features->FeatureName; \
+      const bool Result = (AlreadyEnabled | Enable##name) & !Disable##name; \
+      Features->FeatureName = Result; \
+    } while (0)
+
+#define GET_SINGLE_OPTION(name, enum_name) \
     const bool Disable##name = (HostFeatures() & FEXCore::Config::HostFeatures::DISABLE##enum_name) != 0; \
     const bool Enable##name = (HostFeatures() & FEXCore::Config::HostFeatures::ENABLE##enum_name) != 0;   \
     LogMan::Throw::AFmt(!(Disable##name && Enable##name), "Disabling and Enabling CPU feature (" #name ") is mutually exclusive");
 
-  ENABLE_DISABLE_OPTION(AVX, AVX);
-  ENABLE_DISABLE_OPTION(AVX2, AVX2);
-  ENABLE_DISABLE_OPTION(SVE, SVE);
-  ENABLE_DISABLE_OPTION(AFP, AFP);
-  ENABLE_DISABLE_OPTION(LRCPC, LRCPC);
-  ENABLE_DISABLE_OPTION(LRCPC2, LRCPC2);
-  ENABLE_DISABLE_OPTION(CSSC, CSSC);
-  ENABLE_DISABLE_OPTION(PMULL128, PMULL128);
-  ENABLE_DISABLE_OPTION(RNG, RNG);
-  ENABLE_DISABLE_OPTION(CLZERO, CLZERO);
-  ENABLE_DISABLE_OPTION(Atomics, ATOMICS);
-  ENABLE_DISABLE_OPTION(FCMA, FCMA);
-  ENABLE_DISABLE_OPTION(FlagM, FLAGM);
-  ENABLE_DISABLE_OPTION(FlagM2, FLAGM2);
-  ENABLE_DISABLE_OPTION(Crypto, CRYPTO);
-  ENABLE_DISABLE_OPTION(RPRES, RPRES);
+  ENABLE_DISABLE_OPTION(SupportsAVX, AVX, AVX);
+  ENABLE_DISABLE_OPTION(SupportsAVX2, AVX2, AVX2);
+  ENABLE_DISABLE_OPTION(SupportsSVE, SVE, SVE);
+  ENABLE_DISABLE_OPTION(SupportsAFP, AFP, AFP);
+  ENABLE_DISABLE_OPTION(SupportsRCPC, LRCPC, LRCPC);
+  ENABLE_DISABLE_OPTION(SupportsTSOImm9, LRCPC2, LRCPC2);
+  ENABLE_DISABLE_OPTION(SupportsCSSC, CSSC, CSSC);
+  ENABLE_DISABLE_OPTION(SupportsPMULL_128Bit, PMULL128, PMULL128);
+  ENABLE_DISABLE_OPTION(SupportsRAND, RNG, RNG);
+  ENABLE_DISABLE_OPTION(SupportsCLZERO, CLZERO, CLZERO);
+  ENABLE_DISABLE_OPTION(SupportsAtomics, Atomics, ATOMICS);
+  ENABLE_DISABLE_OPTION(SupportsFCMA, FCMA, FCMA);
+  ENABLE_DISABLE_OPTION(SupportsFlagM, FlagM, FLAGM);
+  ENABLE_DISABLE_OPTION(SupportsFlagM2, FlagM2, FLAGM2);
+  ENABLE_DISABLE_OPTION(SupportsRPRES, RPRES, RPRES);
+  GET_SINGLE_OPTION(Crypto, CRYPTO);
 
 #undef ENABLE_DISABLE_OPTION
+#undef GET_SINGLE_OPTION
 
-  if (EnableAVX) {
-    Features->SupportsAVX = true;
-  }
-  else if (DisableAVX) {
-    Features->SupportsAVX = false;
-  }
-  if (EnableAVX2) {
-    Features->SupportsAVX2 = true;
-  }
-  else if (DisableAVX2) {
-    Features->SupportsAVX2 = false;
-  }
-  if (EnableSVE) {
-    Features->SupportsSVE = true;
-  }
-  else if (DisableSVE) {
-    Features->SupportsSVE = false;
-  }
-  if (EnableAFP) {
-    Features->SupportsAFP = true;
-  }
-  else if (DisableAFP) {
-    Features->SupportsAFP = false;
-  }
-  if (EnableLRCPC) {
-    Features->SupportsRCPC = true;
-  }
-  else if (DisableLRCPC) {
-    Features->SupportsRCPC = false;
-  }
-  if (EnableLRCPC2) {
-    Features->SupportsTSOImm9 = true;
-  }
-  else if (DisableLRCPC2) {
-    Features->SupportsTSOImm9 = false;
-  }
-  if (EnableCSSC) {
-    Features->SupportsCSSC = true;
-  }
-  else if (DisableCSSC) {
-    Features->SupportsCSSC = false;
-  }
-  if (EnablePMULL128) {
-    Features->SupportsPMULL_128Bit = true;
-  }
-  else if (DisablePMULL128) {
-    Features->SupportsPMULL_128Bit = false;
-  }
-  if (EnableRNG) {
-    Features->SupportsRAND = true;
-  }
-  else if (DisableRNG) {
-    Features->SupportsRAND = false;
-  }
-  if (EnableCLZERO) {
-    Features->SupportsCLZERO = true;
-  }
-  else if (DisableCLZERO) {
-    Features->SupportsCLZERO = false;
-  }
-  if (EnableAtomics) {
-    Features->SupportsAtomics = true;
-  }
-  else if (DisableAtomics) {
-    Features->SupportsAtomics = false;
-  }
-  if (EnableFCMA) {
-    Features->SupportsFCMA = true;
-  }
-  else if (DisableFCMA) {
-    Features->SupportsFCMA = false;
-  }
-  if (EnableFlagM) {
-    Features->SupportsFlagM = true;
-  }
-  else if (DisableFlagM) {
-    Features->SupportsFlagM = false;
-  }
-  if (EnableFlagM2) {
-    Features->SupportsFlagM2 = true;
-  }
-  else if (DisableFlagM2) {
-    Features->SupportsFlagM2 = false;
-  }
   if (EnableCrypto) {
     Features->SupportsAES = true;
     Features->SupportsCRC = true;
@@ -189,12 +116,6 @@ static void OverrideFeatures(HostFeatures *Features) {
     Features->SupportsSHA = false;
     Features->SupportsPMULL_128Bit = false;
   }
-  if (EnableRPRES) {
-    Features->SupportsRPRES = true;
-  }
-  else if (DisableRPRES) {
-    Features->SupportsRPRES = false;
-  }
 }
 
 HostFeatures::HostFeatures() {