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/*========================== 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);
void visitFNeg(Instruction &I);
void visitFDiv(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);
}
}
#if LLVM_VERSION_MAJOR >= 10
void FastMathConstantHandling::visitFNeg(Instruction &I) {
auto *fp_val = dyn_cast<llvm::ConstantFP>(I.getOperand(0));
if (fp_val && fp_val->getValueAPF().isZero()) {
for (auto *UI : I.users()) {
if (isa<FPMathOperator>(UI))
cast<Instruction>(UI)->setHasNoSignedZeros(false);
}
}
}
#endif
void FastMathConstantHandling::visitFDiv(Instruction &I) {
if (auto *fp_val = dyn_cast<llvm::ConstantFP>(I.getOperand(1)); fp_val && fp_val->getValueAPF().isZero()) {
I.setHasNoInfs(false);
}
}
bool FastMathConstantHandling::runOnFunction(Function &F) {
if (IGC_IS_FLAG_DISABLED(DisableFastMathConstantHandling)) {
visit(F);
}
return true;
}
FunctionPass *createFastMathConstantHandling() { return new FastMathConstantHandling(); }
} // namespace IGC
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