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/*========================== begin_copyright_notice ============================
Copyright (C) 2017-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#define DEBUG_TYPE "predefined-constant-resolver"
#include "Compiler/CISACodeGen/ResolvePredefinedConstant.h"
#include "Compiler/IGCPassSupport.h"
#include "common/LLVMWarningsPush.hpp"
#include <llvm/IR/Module.h>
#include <llvm/IR/Instructions.h>
#include <llvm/Pass.h>
#include "common/LLVMWarningsPop.hpp"
using namespace llvm;
using namespace IGC;
namespace {
class PredefinedConstantResolving : public ModulePass {
public:
static char ID;
PredefinedConstantResolving() : ModulePass(ID) {
initializePredefinedConstantResolvingPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module&) override;
void getAnalysisUsage(AnalysisUsage& AU) const override {
AU.setPreservesCFG();
}
};
} // End anonymous namespace
ModulePass* IGC::createResolvePredefinedConstantPass() {
return new PredefinedConstantResolving();
}
char PredefinedConstantResolving::ID = 0;
#define PASS_FLAG "igc-predefined-constant-resolve"
#define PASS_DESC "Resolve compiler predefeind constants"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
namespace IGC {
IGC_INITIALIZE_PASS_BEGIN(PredefinedConstantResolving, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_END(PredefinedConstantResolving, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
}
bool PredefinedConstantResolving::runOnModule(Module& M) {
bool Changed = false;
for (auto& GV : M.globals()) {
if (!GV.isConstant())
continue;
if (!GV.hasUniqueInitializer())
continue;
// We don't use fancy data structure to reduce the lookup overhead due to
// the current limited size of compiler pre-defined constants.
Constant* C = GV.getInitializer();
for (auto I = GV.user_begin(); I != GV.user_end(); /* empty */) {
// Ensure we understand how the predefined constant is used.
LoadInst* LI = dyn_cast<LoadInst>(*I++);
if (!LI)
continue;
LI->replaceAllUsesWith(C);
LI->eraseFromParent();
Changed = true;
}
}
return Changed;
}
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