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markinivanmarkinivan
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Маркин Иван. Лабораторная работа 2: LLVM. Вариант 3. (#158)
Пасс, который объединяет инструкции fadd и fmul, в fmuladd, для ускорения, повышения точности и уменьшения количества инструкций.
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‎llvm/compiler-course/llvm-ir/markin_i_fmuladd/CMakeLists.txt

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set(Title "FmuladdMergePass")
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set(Student "MarkinIvan")
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set(Group "FIIT2")
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set(TARGET_NAME "${Title}_${Student}_${Group}_LLVM_IR")
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if (NOT WIN32 AND NOT CYGWIN)
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file(GLOB_RECURSE SOURCES *.cpp *.h *.hpp)
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add_llvm_pass_plugin(${TARGET_NAME} ${SOURCES}
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DEPENDS
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intrinsics_gen
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BUILDTREE_ONLY
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)
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set(LLVM_TEST_DEPENDS ${TARGET_NAME} ${LLVM_TEST_DEPENDS} PARENT_SCOPE)
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endif()

‎llvm/compiler-course/llvm-ir/markin_i_fmuladd/MergePass.cpp

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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/Passes/PassBuilder.h"
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#include "llvm/Passes/PassPlugin.h"
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#include "llvm/Support/raw_ostream.h"
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namespace {
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struct FmulFaddMergePass final : llvm::PassInfoMixin<FmulFaddMergePass> {
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llvm::PreservedAnalyses run(llvm::Function &F,
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llvm::FunctionAnalysisManager &FAM) {
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bool codeChanged = false;
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struct ReplaceCandidate {
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llvm::BinaryOperator *faddInst;
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llvm::BinaryOperator *fmulInst;
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llvm::Value *otherOperand;
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};
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for (llvm::BasicBlock &block : F) {
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std::vector<ReplaceCandidate> candidates;
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auto isFMulOperand = [](llvm::Value *op,
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llvm::Value *other) -> llvm::BinaryOperator * {
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if (auto *fmul = llvm::dyn_cast<llvm::BinaryOperator>(op)) {
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if (fmul->getOpcode() == llvm::Instruction::FMul) {
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return fmul;
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}
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}
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return nullptr;
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};
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// Collect potential replacements
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for (llvm::Instruction &inst : block) {
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if (auto *fadd = llvm::dyn_cast<llvm::BinaryOperator>(&inst)) {
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if (fadd->getOpcode() == llvm::Instruction::FAdd) {
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llvm::Value *op0 = fadd->getOperand(0);
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llvm::Value *op1 = fadd->getOperand(1);
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if (auto *fmul = isFMulOperand(op0, op1)) {
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if (fmul->hasAllowContract() && fadd->hasAllowContract()) {
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candidates.push_back({fadd, fmul, op1});
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}
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} else if (auto *fmul = isFMulOperand(op1, op0)) {
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if (fmul->hasAllowContract() && fadd->hasAllowContract()) {
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candidates.push_back({fadd, fmul, op0});
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}
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}
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}
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}
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}
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// Perform replacements
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for (const auto &candidate : candidates) {
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llvm::IRBuilder<> builder(candidate.faddInst);
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llvm::FastMathFlags flags = candidate.faddInst->getFastMathFlags();
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llvm::Value *fmuladd = builder.CreateIntrinsic(
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llvm::Intrinsic::fmuladd, candidate.fmulInst->getType(),
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{candidate.fmulInst->getOperand(0),
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candidate.fmulInst->getOperand(1), candidate.otherOperand});
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if (llvm::isa<llvm::FPMathOperator>(fmuladd)) {
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llvm::FPMathOperator *fmuladdInst =
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llvm::cast<llvm::FPMathOperator>(fmuladd);
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}
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candidate.faddInst->replaceAllUsesWith(fmuladd);
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candidate.faddInst->eraseFromParent();
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if (candidate.fmulInst->use_empty()) {
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candidate.fmulInst->eraseFromParent();
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}
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codeChanged = true;
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}
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}
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return codeChanged ? llvm::PreservedAnalyses::none()
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: llvm::PreservedAnalyses::all();
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}
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static bool isRequired() { return true; }
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};
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} // namespace
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extern "C" LLVM_ATTRIBUTE_WEAK ::llvm::PassPluginLibraryInfo
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llvmGetPassPluginInfo() {
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return {LLVM_PLUGIN_API_VERSION, "FmulFaddMergePass", "0.1",
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[](llvm::PassBuilder &PB) {
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PB.registerPipelineParsingCallback(
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[](llvm::StringRef passName, llvm::FunctionPassManager &FPM,
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llvm::ArrayRef<llvm::PassBuilder::PipelineElement>) -> bool {
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if (passName == "FmulFaddMergePass") {
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FPM.addPass(FmulFaddMergePass{});
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return true;
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}
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return false;
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});
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}};
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}

‎llvm/test/compiler-course/markin_i_fmulladdmerge/test.ll

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; RUN: opt -load-pass-plugin %llvmshlibdir/FmuladdMergePass_MarkinIvan_FIIT2_LLVM_IR%pluginext \
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; RUN: -passes="FmulFaddMergePass" -S %s | FileCheck %s
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; CHECK-LABEL: @fmaDouble
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; CHECK: call double @llvm.fmuladd.f64(double %A, double %B, double %C)
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; CHECK-NOT: fmul
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; CHECK-NOT: fadd
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define dso_local noundef double @fmaDouble(double %A, double %B, double %C) {
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entry:
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%mul = fmul contract double %A, %B
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%add = fadd contract double %mul, %C
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ret double %add
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}
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; CHECK-LABEL: @fmaFloat
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; CHECK: call float @llvm.fmuladd.f32(float %A, float %B, float %C)
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; CHECK-NOT: fmul
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; CHECK-NOT: fadd
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define dso_local noundef float @fmaFloat(float %A, float %B, float %C) {
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entry:
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%mul = fmul contract float %A, %B
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%add = fadd contract float %mul, %C
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ret float %add
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}
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; CHECK-LABEL: @recursiveTest
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; CHECK: call float @llvm.fmuladd.f32(float %add1, float %B, float %add)
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; CHECK-NOT: fmul
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; CHECK-NOT: fadd
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define dso_local noundef float @recursiveTest(float %A, float %B, float %C) {
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entry:
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%add = fadd contract float %B, %C
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%add1 = fadd contract float %A, %B
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%mul = fmul contract float %add1, %B
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%add2 = fadd contract float %add, %mul
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ret float %add2
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}
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; CHECK-LABEL: @foo
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; CHECK: %0 = call float @llvm.fmuladd.f32(float %A, float %B, float %C)
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; CHECK: %1 = call float @llvm.fmuladd.f32(float %A, float %B, float 1.000000e+00)
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; CHECK: %div = fdiv float %0, %1
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; CHECK-NOT: %mul = fmul contract float %A, %B
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; CHECK-NOT: fadd
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define float @foo(float %A, float %B, float %C) {
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entry:
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%mul = fmul contract float %A, %B
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%add = fadd contract float %mul, %C
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%add1 = fadd contract float %mul, 1.000000e+00
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%div = fdiv float %add, %add1
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ret float %div
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}
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; CHECK-LABEL: @noContract
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; CHECK: fmul float %A, %B
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; CHECK: fadd float %mul, %C
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define float @noContract(float %A, float %B, float %C) {
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entry:
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%mul = fmul float %A, %B
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%add = fadd float %mul, %C
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ret float %add
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}
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; CHECK-LABEL: @multipleFMA
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; CHECK: call float @llvm.fmuladd.f32(float %A, float %B, float %C)
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; CHECK: call float @llvm.fmuladd.f32(float %D, float %E, float %F)
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define float @multipleFMA(float %A, float %B, float %C, float %D, float %E, float %F) {
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entry:
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%mul1 = fmul contract float %A, %B
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%add1 = fadd contract float %mul1, %C
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%mul2 = fmul contract float %D, %E
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%add2 = fadd contract float %mul2, %F
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ret float %add2
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}
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; CHECK-LABEL: @differentArduments
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; CHECK: fmul contract float %A, %B
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; CHECK: fadd contract float %B, %D
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define float @differentArduments(float %A, float %B, float %D) {
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entry:
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%mul = fmul contract float %A, %B
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%add = fadd contract float %B, %D
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ret float %add
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}
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; CHECK-LABEL: @differentInstructions
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; CHECK: fadd contract float %A, %B
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; CHECK: fadd contract float %add1, %D
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define float @differentInstructions(float %A, float %B, float %D) {
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entry:
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%add1 = fadd contract float %A, %B
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%add = fadd contract float %add1, %D
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ret float %add
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}

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