Initialize new FastMathConstantHandling pass

This pass solves the issues where the fast math flags on the instruction do not match the immediate constants on that instruction. If we don't match this we can get wrong behavior later in instcombine

Author: paigeale

IGC/AdaptorCommon/FastMathConstantHandling.cpp

@@ -0,0 +1,103 @@
+/*========================== begin_copyright_notice ============================
+
+Copyright (C) 2023 Intel Corporation
+
+SPDX-License-Identifier: MIT
+
+============================= end_copyright_notice ===========================*/
+
+#include "common/LLVMWarningsPush.hpp"
+#include <llvm/IR/Instructions.h>
+#include <llvm/IR/InstVisitor.h>
+#include <llvm/IR/Operator.h>
+#include "common/LLVMWarningsPop.hpp"
+#include "FastMathConstantHandling.h"
+#include "Compiler/IGCPassSupport.h"
+#include "common/igc_regkeys.hpp"
+
+using namespace llvm;
+namespace IGC
+{
+
+class FastMathConstantHandling : public FunctionPass, public InstVisitor<FastMathConstantHandling>
+{
+public:
+    FastMathConstantHandling();
+    ~FastMathConstantHandling() {}
+    static char ID;
+    bool runOnFunction(Function& F) override;
+    void visitInstruction(Instruction& I);
+    virtual llvm::StringRef getPassName() const override { return "Fast Math Constant Handling"; }
+
+    void getAnalysisUsage(AnalysisUsage& AU) const override
+    {
+        AU.setPreservesCFG();
+    }
+};
+
+#define PASS_FLAG     "FastMathConstantHandling"
+#define PASS_DESC     "Fast Math Constant Handling"
+#define PASS_CFG_ONLY false
+#define PASS_ANALYSIS false
+IGC_INITIALIZE_PASS_BEGIN(FastMathConstantHandling, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
+IGC_INITIALIZE_PASS_END(FastMathConstantHandling, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
+
+char FastMathConstantHandling::ID = 0;
+
+FastMathConstantHandling::FastMathConstantHandling()
+    :FunctionPass(ID)
+{
+    initializeFastMathConstantHandlingPass(*PassRegistry::getPassRegistry());
+}
+
+// This purpose of this pass is to catch bad fast flag management where we are seeing
+// constants that are not matching the fast flags that are set on the instructions
+
+void FastMathConstantHandling::visitInstruction(Instruction& I)
+{
+    if (isa<FPMathOperator>(I))
+    {
+        struct BoolSpecialConstants {
+            bool hasInf = false;
+            bool hasNan = false;
+            bool hasNegZero = false;
+        } BSC;
+
+        for (auto &Op : I.operands())
+        {
+            if (auto* fp_val = dyn_cast<llvm::ConstantFP>(Op))
+            {
+                auto APF = fp_val->getValueAPF();
+                BSC.hasInf |= APF.isInfinity();
+                BSC.hasNan |= APF.isNaN();
+                BSC.hasNegZero |= APF.isNegZero();
+            }
+        }
+
+        if (BSC.hasInf)
+            I.setHasNoInfs(false);
+
+        if (BSC.hasNan)
+            I.setHasNoNaNs(false);
+
+        if (BSC.hasNegZero)
+            I.setHasNoSignedZeros(false);
+    }
+}
+
+bool FastMathConstantHandling::runOnFunction(Function& F)
+{
+    if (IGC_IS_FLAG_DISABLED(DisableFastMathConstantHandling))
+    {
+        visit(F);
+    }
+    return true;
+}
+
+
+FunctionPass* createFastMathConstantHandling()
+{
+    return new FastMathConstantHandling();
+}
+
+}//namespace IGC

IGC/AdaptorCommon/FastMathConstantHandling.h

@@ -0,0 +1,19 @@
+/*========================== begin_copyright_notice ============================
+
+Copyright (C) 2023 Intel Corporation
+
+SPDX-License-Identifier: MIT
+
+============================= end_copyright_notice ===========================*/
+
+#pragma once
+
+#include "common/LLVMWarningsPush.hpp"
+#include "llvm/Pass.h"
+#include "common/LLVMWarningsPop.hpp"
+
+namespace IGC
+{
+    void initializeFastMathConstantHandlingPass(llvm::PassRegistry&);
+    llvm::FunctionPass* createFastMathConstantHandling();
+}

IGC/DriverInterface/CMakeLists.txt

@@ -20,6 +20,7 @@ set(IGC_BUILD__SRC__DriverInterface
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/TypesLegalizationPass.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/LegalizeFunctionSignatures.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/DivergentBarrierPass.cpp"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/FastMathConstantHandling.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/LoadBuffer.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/Patch/patch_parser.cpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/Platform/cmd_media_caps_g8.cpp"
@@ -83,6 +84,7 @@ endif(IGC_BUILD__SPIRV_ENABLED)
 set(IGC_BUILD__HDR__DriverInterface
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/customApi.hpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/DivergentBarrierPass.h"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorCommon/FastMathConstantHandling.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/KernelAnnotations.hpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/CommandStream/SamplerTypes.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/../AdaptorOCL/OCL/CommandStream/SurfaceTypes.h"

IGC/common/igc_flags.h

@@ -759,6 +759,7 @@ DECLARE_IGC_REGKEY(bool, OverrideCsTileLayout,       0,     "Override compute wa
 DECLARE_IGC_REGKEY(DWORD, MemCpyLoweringUnrollThreshold, 12, "Min number of mem instructions that require non-unrolled loop when lowering memcpy", false)
 DECLARE_IGC_REGKEY(bool, EnableSOAPromotionDisablingHeuristic, false, "Enable heuristic to disable SOA promotion when it may be not beneficial", false)
 DECLARE_IGC_REGKEY(bool, EnableCSContentCheck, false, "Enable CS content check to force SIMD32", true)
+DECLARE_IGC_REGKEY(bool, DisableFastMathConstantHandling, false, "Disable Fast Math Constant Handling", true)
 
 DECLARE_IGC_GROUP("Generating precompiled headers")
 DECLARE_IGC_REGKEY(bool, ApplyConservativeRastWAHeader, true, "Apply WaConservativeRasterization for the platforms enabled", false)