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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ReduceOperands.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Type.h"
using namespace llvm;
using namespace PatternMatch;
static void
extractOperandsFromModule(Oracle &O, ReducerWorkItem &WorkItem,
function_ref<Value *(Use &)> ReduceValue) {
Module &Program = WorkItem.getModule();
for (auto &F : Program.functions()) {
for (auto &I : instructions(&F)) {
if (PHINode *Phi = dyn_cast<PHINode>(&I)) {
for (auto &Op : Phi->incoming_values()) {
if (!O.shouldKeep()) {
if (Value *Reduced = ReduceValue(Op))
Phi->setIncomingValueForBlock(Phi->getIncomingBlock(Op), Reduced);
}
}
continue;
}
for (auto &Op : I.operands()) {
if (Value *Reduced = ReduceValue(Op)) {
if (!O.shouldKeep())
Op.set(Reduced);
}
}
}
}
}
static bool isOne(Use &Op) {
auto *C = dyn_cast<Constant>(Op);
return C && C->isOneValue();
}
static bool isZero(Use &Op) {
auto *C = dyn_cast<Constant>(Op);
return C && C->isNullValue();
}
static bool isZeroOrOneFP(Value *Op) {
const APFloat *C;
return match(Op, m_APFloat(C)) &&
((C->isZero() && !C->isNegative()) || C->isExactlyValue(1.0));
}
static bool shouldReduceOperand(Use &Op) {
Type *Ty = Op->getType();
if (Ty->isLabelTy() || Ty->isMetadataTy())
return false;
// TODO: be more precise about which GEP operands we can reduce (e.g. array
// indexes)
if (isa<GEPOperator>(Op.getUser()))
return false;
if (auto *CB = dyn_cast<CallBase>(Op.getUser())) {
if (&CB->getCalledOperandUse() == &Op)
return false;
}
return true;
}
static bool switchCaseExists(Use &Op, ConstantInt *CI) {
SwitchInst *SI = dyn_cast<SwitchInst>(Op.getUser());
if (!SI)
return false;
return SI->findCaseValue(CI) != SI->case_default();
}
void llvm::reduceOperandsOneDeltaPass(TestRunner &Test) {
auto ReduceValue = [](Use &Op) -> Value * {
if (!shouldReduceOperand(Op))
return nullptr;
Type *Ty = Op->getType();
if (auto *IntTy = dyn_cast<IntegerType>(Ty)) {
// Don't duplicate an existing switch case.
if (switchCaseExists(Op, ConstantInt::get(IntTy, 1)))
return nullptr;
// Don't replace existing ones and zeroes.
return (isOne(Op) || isZero(Op)) ? nullptr : ConstantInt::get(IntTy, 1);
}
if (Ty->isFloatingPointTy())
return isZeroOrOneFP(Op) ? nullptr : ConstantFP::get(Ty, 1.0);
if (VectorType *VT = dyn_cast<VectorType>(Ty)) {
if (isOne(Op) || isZero(Op) || isZeroOrOneFP(Op))
return nullptr;
Type *ElementType = VT->getElementType();
Constant *C;
if (ElementType->isFloatingPointTy()) {
C = ConstantFP::get(ElementType, 1.0);
} else if (IntegerType *IntTy = dyn_cast<IntegerType>(ElementType)) {
C = ConstantInt::get(IntTy, 1);
} else {
return nullptr;
}
return ConstantVector::getSplat(VT->getElementCount(), C);
}
return nullptr;
};
runDeltaPass(
Test,
[ReduceValue](Oracle &O, ReducerWorkItem &WorkItem) {
extractOperandsFromModule(O, WorkItem, ReduceValue);
},
"Reducing Operands to one");
}
void llvm::reduceOperandsZeroDeltaPass(TestRunner &Test) {
auto ReduceValue = [](Use &Op) -> Value * {
if (!shouldReduceOperand(Op))
return nullptr;
// Don't duplicate an existing switch case.
if (auto *IntTy = dyn_cast<IntegerType>(Op->getType()))
if (switchCaseExists(Op, ConstantInt::get(IntTy, 0)))
return nullptr;
// Don't replace existing zeroes.
return isZero(Op) ? nullptr : Constant::getNullValue(Op->getType());
};
runDeltaPass(
Test,
[ReduceValue](Oracle &O, ReducerWorkItem &Program) {
extractOperandsFromModule(O, Program, ReduceValue);
},
"Reducing Operands to zero");
}
void llvm::reduceOperandsNaNDeltaPass(TestRunner &Test) {
auto ReduceValue = [](Use &Op) -> Value * {
Type *Ty = Op->getType();
if (!Ty->isFPOrFPVectorTy())
return nullptr;
// Prefer 0.0 or 1.0 over NaN.
//
// TODO: Preferring NaN may make more sense because FP operations are more
// universally foldable.
if (match(Op.get(), m_NaN()) || isZeroOrOneFP(Op.get()))
return nullptr;
if (VectorType *VT = dyn_cast<VectorType>(Ty)) {
return ConstantVector::getSplat(VT->getElementCount(),
ConstantFP::getQNaN(VT->getElementType()));
}
return ConstantFP::getQNaN(Ty);
};
runDeltaPass(
Test,
[ReduceValue](Oracle &O, ReducerWorkItem &Program) {
extractOperandsFromModule(O, Program, ReduceValue);
},
"Reducing Operands to NaN");
}
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