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llvm-mirror/lib/Transforms/Utils/FunctionComparator.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===- FunctionComparator.h - Function Comparator -------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the FunctionComparator and GlobalNumberState classes
// which are used by the MergeFunctions pass for comparing functions.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/FunctionComparator.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "functioncomparator"
int FunctionComparator::cmpNumbers(uint64_t L, uint64_t R) const {
if (L < R) return -1;
if (L > R) return 1;
return 0;
}
int FunctionComparator::cmpOrderings(AtomicOrdering L, AtomicOrdering R) const {
if ((int)L < (int)R) return -1;
if ((int)L > (int)R) return 1;
return 0;
}
int FunctionComparator::cmpAPInts(const APInt &L, const APInt &R) const {
if (int Res = cmpNumbers(L.getBitWidth(), R.getBitWidth()))
return Res;
if (L.ugt(R)) return 1;
if (R.ugt(L)) return -1;
return 0;
}
int FunctionComparator::cmpAPFloats(const APFloat &L, const APFloat &R) const {
// Floats are ordered first by semantics (i.e. float, double, half, etc.),
// then by value interpreted as a bitstring (aka APInt).
const fltSemantics &SL = L.getSemantics(), &SR = R.getSemantics();
if (int Res = cmpNumbers(APFloat::semanticsPrecision(SL),
APFloat::semanticsPrecision(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsMaxExponent(SL),
APFloat::semanticsMaxExponent(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsMinExponent(SL),
APFloat::semanticsMinExponent(SR)))
return Res;
if (int Res = cmpNumbers(APFloat::semanticsSizeInBits(SL),
APFloat::semanticsSizeInBits(SR)))
return Res;
return cmpAPInts(L.bitcastToAPInt(), R.bitcastToAPInt());
}
int FunctionComparator::cmpMem(StringRef L, StringRef R) const {
// Prevent heavy comparison, compare sizes first.
if (int Res = cmpNumbers(L.size(), R.size()))
return Res;
// Compare strings lexicographically only when it is necessary: only when
// strings are equal in size.
return L.compare(R);
}
int FunctionComparator::cmpAttrs(const AttributeList L,
const AttributeList R) const {
if (int Res = cmpNumbers(L.getNumAttrSets(), R.getNumAttrSets()))
return Res;
for (unsigned i = L.index_begin(), e = L.index_end(); i != e; ++i) {
AttributeSet LAS = L.getAttributes(i);
AttributeSet RAS = R.getAttributes(i);
AttributeSet::iterator LI = LAS.begin(), LE = LAS.end();
AttributeSet::iterator RI = RAS.begin(), RE = RAS.end();
for (; LI != LE && RI != RE; ++LI, ++RI) {
Attribute LA = *LI;
Attribute RA = *RI;
if (LA < RA)
return -1;
if (RA < LA)
return 1;
}
if (LI != LE)
return 1;
if (RI != RE)
return -1;
}
return 0;
}
int FunctionComparator::cmpRangeMetadata(const MDNode *L,
const MDNode *R) const {
if (L == R)
return 0;
if (!L)
return -1;
if (!R)
return 1;
// Range metadata is a sequence of numbers. Make sure they are the same
// sequence.
// TODO: Note that as this is metadata, it is possible to drop and/or merge
// this data when considering functions to merge. Thus this comparison would
// return 0 (i.e. equivalent), but merging would become more complicated
// because the ranges would need to be unioned. It is not likely that
// functions differ ONLY in this metadata if they are actually the same
// function semantically.
if (int Res = cmpNumbers(L->getNumOperands(), R->getNumOperands()))
return Res;
for (size_t I = 0; I < L->getNumOperands(); ++I) {
ConstantInt *LLow = mdconst::extract<ConstantInt>(L->getOperand(I));
ConstantInt *RLow = mdconst::extract<ConstantInt>(R->getOperand(I));
if (int Res = cmpAPInts(LLow->getValue(), RLow->getValue()))
return Res;
}
return 0;
}
int FunctionComparator::cmpOperandBundlesSchema(const Instruction *L,
const Instruction *R) const {
ImmutableCallSite LCS(L);
ImmutableCallSite RCS(R);
assert(LCS && RCS && "Must be calls or invokes!");
assert(LCS.isCall() == RCS.isCall() && "Can't compare otherwise!");
if (int Res =
cmpNumbers(LCS.getNumOperandBundles(), RCS.getNumOperandBundles()))
return Res;
for (unsigned i = 0, e = LCS.getNumOperandBundles(); i != e; ++i) {
auto OBL = LCS.getOperandBundleAt(i);
auto OBR = RCS.getOperandBundleAt(i);
if (int Res = OBL.getTagName().compare(OBR.getTagName()))
return Res;
if (int Res = cmpNumbers(OBL.Inputs.size(), OBR.Inputs.size()))
return Res;
}
return 0;
}
/// Constants comparison:
/// 1. Check whether type of L constant could be losslessly bitcasted to R
/// type.
/// 2. Compare constant contents.
/// For more details see declaration comments.
int FunctionComparator::cmpConstants(const Constant *L,
const Constant *R) const {
Type *TyL = L->getType();
Type *TyR = R->getType();
// Check whether types are bitcastable. This part is just re-factored
// Type::canLosslesslyBitCastTo method, but instead of returning true/false,
// we also pack into result which type is "less" for us.
int TypesRes = cmpTypes(TyL, TyR);
if (TypesRes != 0) {
// Types are different, but check whether we can bitcast them.
if (!TyL->isFirstClassType()) {
if (TyR->isFirstClassType())
return -1;
// Neither TyL nor TyR are values of first class type. Return the result
// of comparing the types
return TypesRes;
}
if (!TyR->isFirstClassType()) {
if (TyL->isFirstClassType())
return 1;
return TypesRes;
}
// Vector -> Vector conversions are always lossless if the two vector types
// have the same size, otherwise not.
unsigned TyLWidth = 0;
unsigned TyRWidth = 0;
if (auto *VecTyL = dyn_cast<VectorType>(TyL))
TyLWidth = VecTyL->getBitWidth();
if (auto *VecTyR = dyn_cast<VectorType>(TyR))
TyRWidth = VecTyR->getBitWidth();
if (TyLWidth != TyRWidth)
return cmpNumbers(TyLWidth, TyRWidth);
// Zero bit-width means neither TyL nor TyR are vectors.
if (!TyLWidth) {
PointerType *PTyL = dyn_cast<PointerType>(TyL);
PointerType *PTyR = dyn_cast<PointerType>(TyR);
if (PTyL && PTyR) {
unsigned AddrSpaceL = PTyL->getAddressSpace();
unsigned AddrSpaceR = PTyR->getAddressSpace();
if (int Res = cmpNumbers(AddrSpaceL, AddrSpaceR))
return Res;
}
if (PTyL)
return 1;
if (PTyR)
return -1;
// TyL and TyR aren't vectors, nor pointers. We don't know how to
// bitcast them.
return TypesRes;
}
}
// OK, types are bitcastable, now check constant contents.
if (L->isNullValue() && R->isNullValue())
return TypesRes;
if (L->isNullValue() && !R->isNullValue())
return 1;
if (!L->isNullValue() && R->isNullValue())
return -1;
auto GlobalValueL = const_cast<GlobalValue *>(dyn_cast<GlobalValue>(L));
auto GlobalValueR = const_cast<GlobalValue *>(dyn_cast<GlobalValue>(R));
if (GlobalValueL && GlobalValueR) {
return cmpGlobalValues(GlobalValueL, GlobalValueR);
}
if (int Res = cmpNumbers(L->getValueID(), R->getValueID()))
return Res;
if (const auto *SeqL = dyn_cast<ConstantDataSequential>(L)) {
const auto *SeqR = cast<ConstantDataSequential>(R);
// This handles ConstantDataArray and ConstantDataVector. Note that we
// compare the two raw data arrays, which might differ depending on the host
// endianness. This isn't a problem though, because the endiness of a module
// will affect the order of the constants, but this order is the same
// for a given input module and host platform.
return cmpMem(SeqL->getRawDataValues(), SeqR->getRawDataValues());
}
switch (L->getValueID()) {
case Value::UndefValueVal:
case Value::ConstantTokenNoneVal:
return TypesRes;
case Value::ConstantIntVal: {
const APInt &LInt = cast<ConstantInt>(L)->getValue();
const APInt &RInt = cast<ConstantInt>(R)->getValue();
return cmpAPInts(LInt, RInt);
}
case Value::ConstantFPVal: {
const APFloat &LAPF = cast<ConstantFP>(L)->getValueAPF();
const APFloat &RAPF = cast<ConstantFP>(R)->getValueAPF();
return cmpAPFloats(LAPF, RAPF);
}
case Value::ConstantArrayVal: {
const ConstantArray *LA = cast<ConstantArray>(L);
const ConstantArray *RA = cast<ConstantArray>(R);
uint64_t NumElementsL = cast<ArrayType>(TyL)->getNumElements();
uint64_t NumElementsR = cast<ArrayType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (uint64_t i = 0; i < NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LA->getOperand(i)),
cast<Constant>(RA->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantStructVal: {
const ConstantStruct *LS = cast<ConstantStruct>(L);
const ConstantStruct *RS = cast<ConstantStruct>(R);
unsigned NumElementsL = cast<StructType>(TyL)->getNumElements();
unsigned NumElementsR = cast<StructType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (unsigned i = 0; i != NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LS->getOperand(i)),
cast<Constant>(RS->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantVectorVal: {
const ConstantVector *LV = cast<ConstantVector>(L);
const ConstantVector *RV = cast<ConstantVector>(R);
unsigned NumElementsL = cast<VectorType>(TyL)->getNumElements();
unsigned NumElementsR = cast<VectorType>(TyR)->getNumElements();
if (int Res = cmpNumbers(NumElementsL, NumElementsR))
return Res;
for (uint64_t i = 0; i < NumElementsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LV->getOperand(i)),
cast<Constant>(RV->getOperand(i))))
return Res;
}
return 0;
}
case Value::ConstantExprVal: {
const ConstantExpr *LE = cast<ConstantExpr>(L);
const ConstantExpr *RE = cast<ConstantExpr>(R);
unsigned NumOperandsL = LE->getNumOperands();
unsigned NumOperandsR = RE->getNumOperands();
if (int Res = cmpNumbers(NumOperandsL, NumOperandsR))
return Res;
for (unsigned i = 0; i < NumOperandsL; ++i) {
if (int Res = cmpConstants(cast<Constant>(LE->getOperand(i)),
cast<Constant>(RE->getOperand(i))))
return Res;
}
return 0;
}
case Value::BlockAddressVal: {
const BlockAddress *LBA = cast<BlockAddress>(L);
const BlockAddress *RBA = cast<BlockAddress>(R);
if (int Res = cmpValues(LBA->getFunction(), RBA->getFunction()))
return Res;
if (LBA->getFunction() == RBA->getFunction()) {
// They are BBs in the same function. Order by which comes first in the
// BB order of the function. This order is deterministic.
Function* F = LBA->getFunction();
BasicBlock *LBB = LBA->getBasicBlock();
BasicBlock *RBB = RBA->getBasicBlock();
if (LBB == RBB)
return 0;
for(BasicBlock &BB : F->getBasicBlockList()) {
if (&BB == LBB) {
assert(&BB != RBB);
return -1;
}
if (&BB == RBB)
return 1;
}
llvm_unreachable("Basic Block Address does not point to a basic block in "
"its function.");
return -1;
} else {
// cmpValues said the functions are the same. So because they aren't
// literally the same pointer, they must respectively be the left and
// right functions.
assert(LBA->getFunction() == FnL && RBA->getFunction() == FnR);
// cmpValues will tell us if these are equivalent BasicBlocks, in the
// context of their respective functions.
return cmpValues(LBA->getBasicBlock(), RBA->getBasicBlock());
}
}
default: // Unknown constant, abort.
LLVM_DEBUG(dbgs() << "Looking at valueID " << L->getValueID() << "\n");
llvm_unreachable("Constant ValueID not recognized.");
return -1;
}
}
int FunctionComparator::cmpGlobalValues(GlobalValue *L, GlobalValue *R) const {
uint64_t LNumber = GlobalNumbers->getNumber(L);
uint64_t RNumber = GlobalNumbers->getNumber(R);
return cmpNumbers(LNumber, RNumber);
}
/// cmpType - compares two types,
/// defines total ordering among the types set.
/// See method declaration comments for more details.
int FunctionComparator::cmpTypes(Type *TyL, Type *TyR) const {
PointerType *PTyL = dyn_cast<PointerType>(TyL);
PointerType *PTyR = dyn_cast<PointerType>(TyR);
const DataLayout &DL = FnL->getParent()->getDataLayout();
if (PTyL && PTyL->getAddressSpace() == 0)
TyL = DL.getIntPtrType(TyL);
if (PTyR && PTyR->getAddressSpace() == 0)
TyR = DL.getIntPtrType(TyR);
if (TyL == TyR)
return 0;
if (int Res = cmpNumbers(TyL->getTypeID(), TyR->getTypeID()))
return Res;
switch (TyL->getTypeID()) {
default:
llvm_unreachable("Unknown type!");
case Type::IntegerTyID:
return cmpNumbers(cast<IntegerType>(TyL)->getBitWidth(),
cast<IntegerType>(TyR)->getBitWidth());
// TyL == TyR would have returned true earlier, because types are uniqued.
case Type::VoidTyID:
case Type::FloatTyID:
case Type::DoubleTyID:
case Type::X86_FP80TyID:
case Type::FP128TyID:
case Type::PPC_FP128TyID:
case Type::LabelTyID:
case Type::MetadataTyID:
case Type::TokenTyID:
return 0;
case Type::PointerTyID:
assert(PTyL && PTyR && "Both types must be pointers here.");
return cmpNumbers(PTyL->getAddressSpace(), PTyR->getAddressSpace());
case Type::StructTyID: {
StructType *STyL = cast<StructType>(TyL);
StructType *STyR = cast<StructType>(TyR);
if (STyL->getNumElements() != STyR->getNumElements())
return cmpNumbers(STyL->getNumElements(), STyR->getNumElements());
if (STyL->isPacked() != STyR->isPacked())
return cmpNumbers(STyL->isPacked(), STyR->isPacked());
for (unsigned i = 0, e = STyL->getNumElements(); i != e; ++i) {
if (int Res = cmpTypes(STyL->getElementType(i), STyR->getElementType(i)))
return Res;
}
return 0;
}
case Type::FunctionTyID: {
FunctionType *FTyL = cast<FunctionType>(TyL);
FunctionType *FTyR = cast<FunctionType>(TyR);
if (FTyL->getNumParams() != FTyR->getNumParams())
return cmpNumbers(FTyL->getNumParams(), FTyR->getNumParams());
if (FTyL->isVarArg() != FTyR->isVarArg())
return cmpNumbers(FTyL->isVarArg(), FTyR->isVarArg());
if (int Res = cmpTypes(FTyL->getReturnType(), FTyR->getReturnType()))
return Res;
for (unsigned i = 0, e = FTyL->getNumParams(); i != e; ++i) {
if (int Res = cmpTypes(FTyL->getParamType(i), FTyR->getParamType(i)))
return Res;
}
return 0;
}
case Type::ArrayTyID:
case Type::VectorTyID: {
auto *STyL = cast<SequentialType>(TyL);
auto *STyR = cast<SequentialType>(TyR);
if (STyL->getNumElements() != STyR->getNumElements())
return cmpNumbers(STyL->getNumElements(), STyR->getNumElements());
return cmpTypes(STyL->getElementType(), STyR->getElementType());
}
}
}
// Determine whether the two operations are the same except that pointer-to-A
// and pointer-to-B are equivalent. This should be kept in sync with
// Instruction::isSameOperationAs.
// Read method declaration comments for more details.
int FunctionComparator::cmpOperations(const Instruction *L,
const Instruction *R,
bool &needToCmpOperands) const {
needToCmpOperands = true;
if (int Res = cmpValues(L, R))
return Res;
// Differences from Instruction::isSameOperationAs:
// * replace type comparison with calls to cmpTypes.
// * we test for I->getRawSubclassOptionalData (nuw/nsw/tail) at the top.
// * because of the above, we don't test for the tail bit on calls later on.
if (int Res = cmpNumbers(L->getOpcode(), R->getOpcode()))
return Res;
if (const GetElementPtrInst *GEPL = dyn_cast<GetElementPtrInst>(L)) {
needToCmpOperands = false;
const GetElementPtrInst *GEPR = cast<GetElementPtrInst>(R);
if (int Res =
cmpValues(GEPL->getPointerOperand(), GEPR->getPointerOperand()))
return Res;
return cmpGEPs(GEPL, GEPR);
}
if (int Res = cmpNumbers(L->getNumOperands(), R->getNumOperands()))
return Res;
if (int Res = cmpTypes(L->getType(), R->getType()))
return Res;
if (int Res = cmpNumbers(L->getRawSubclassOptionalData(),
R->getRawSubclassOptionalData()))
return Res;
// We have two instructions of identical opcode and #operands. Check to see
// if all operands are the same type
for (unsigned i = 0, e = L->getNumOperands(); i != e; ++i) {
if (int Res =
cmpTypes(L->getOperand(i)->getType(), R->getOperand(i)->getType()))
return Res;
}
// Check special state that is a part of some instructions.
if (const AllocaInst *AI = dyn_cast<AllocaInst>(L)) {
if (int Res = cmpTypes(AI->getAllocatedType(),
cast<AllocaInst>(R)->getAllocatedType()))
return Res;
return cmpNumbers(AI->getAlignment(), cast<AllocaInst>(R)->getAlignment());
}
if (const LoadInst *LI = dyn_cast<LoadInst>(L)) {
if (int Res = cmpNumbers(LI->isVolatile(), cast<LoadInst>(R)->isVolatile()))
return Res;
if (int Res =
cmpNumbers(LI->getAlignment(), cast<LoadInst>(R)->getAlignment()))
return Res;
if (int Res =
cmpOrderings(LI->getOrdering(), cast<LoadInst>(R)->getOrdering()))
return Res;
if (int Res = cmpNumbers(LI->getSyncScopeID(),
cast<LoadInst>(R)->getSyncScopeID()))
return Res;
return cmpRangeMetadata(LI->getMetadata(LLVMContext::MD_range),
cast<LoadInst>(R)->getMetadata(LLVMContext::MD_range));
}
if (const StoreInst *SI = dyn_cast<StoreInst>(L)) {
if (int Res =
cmpNumbers(SI->isVolatile(), cast<StoreInst>(R)->isVolatile()))
return Res;
if (int Res =
cmpNumbers(SI->getAlignment(), cast<StoreInst>(R)->getAlignment()))
return Res;
if (int Res =
cmpOrderings(SI->getOrdering(), cast<StoreInst>(R)->getOrdering()))
return Res;
return cmpNumbers(SI->getSyncScopeID(),
cast<StoreInst>(R)->getSyncScopeID());
}
if (const CmpInst *CI = dyn_cast<CmpInst>(L))
return cmpNumbers(CI->getPredicate(), cast<CmpInst>(R)->getPredicate());
if (auto CSL = CallSite(const_cast<Instruction *>(L))) {
auto CSR = CallSite(const_cast<Instruction *>(R));
if (int Res = cmpNumbers(CSL.getCallingConv(), CSR.getCallingConv()))
return Res;
if (int Res = cmpAttrs(CSL.getAttributes(), CSR.getAttributes()))
return Res;
if (int Res = cmpOperandBundlesSchema(L, R))
return Res;
if (const CallInst *CI = dyn_cast<CallInst>(L))
if (int Res = cmpNumbers(CI->getTailCallKind(),
cast<CallInst>(R)->getTailCallKind()))
return Res;
return cmpRangeMetadata(L->getMetadata(LLVMContext::MD_range),
R->getMetadata(LLVMContext::MD_range));
}
if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(L)) {
ArrayRef<unsigned> LIndices = IVI->getIndices();
ArrayRef<unsigned> RIndices = cast<InsertValueInst>(R)->getIndices();
if (int Res = cmpNumbers(LIndices.size(), RIndices.size()))
return Res;
for (size_t i = 0, e = LIndices.size(); i != e; ++i) {
if (int Res = cmpNumbers(LIndices[i], RIndices[i]))
return Res;
}
return 0;
}
if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(L)) {
ArrayRef<unsigned> LIndices = EVI->getIndices();
ArrayRef<unsigned> RIndices = cast<ExtractValueInst>(R)->getIndices();
if (int Res = cmpNumbers(LIndices.size(), RIndices.size()))
return Res;
for (size_t i = 0, e = LIndices.size(); i != e; ++i) {
if (int Res = cmpNumbers(LIndices[i], RIndices[i]))
return Res;
}
}
if (const FenceInst *FI = dyn_cast<FenceInst>(L)) {
if (int Res =
cmpOrderings(FI->getOrdering(), cast<FenceInst>(R)->getOrdering()))
return Res;
return cmpNumbers(FI->getSyncScopeID(),
cast<FenceInst>(R)->getSyncScopeID());
}
if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(L)) {
if (int Res = cmpNumbers(CXI->isVolatile(),
cast<AtomicCmpXchgInst>(R)->isVolatile()))
return Res;
if (int Res = cmpNumbers(CXI->isWeak(),
cast<AtomicCmpXchgInst>(R)->isWeak()))
return Res;
if (int Res =
cmpOrderings(CXI->getSuccessOrdering(),
cast<AtomicCmpXchgInst>(R)->getSuccessOrdering()))
return Res;
if (int Res =
cmpOrderings(CXI->getFailureOrdering(),
cast<AtomicCmpXchgInst>(R)->getFailureOrdering()))
return Res;
return cmpNumbers(CXI->getSyncScopeID(),
cast<AtomicCmpXchgInst>(R)->getSyncScopeID());
}
if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(L)) {
if (int Res = cmpNumbers(RMWI->getOperation(),
cast<AtomicRMWInst>(R)->getOperation()))
return Res;
if (int Res = cmpNumbers(RMWI->isVolatile(),
cast<AtomicRMWInst>(R)->isVolatile()))
return Res;
if (int Res = cmpOrderings(RMWI->getOrdering(),
cast<AtomicRMWInst>(R)->getOrdering()))
return Res;
return cmpNumbers(RMWI->getSyncScopeID(),
cast<AtomicRMWInst>(R)->getSyncScopeID());
}
if (const PHINode *PNL = dyn_cast<PHINode>(L)) {
const PHINode *PNR = cast<PHINode>(R);
// Ensure that in addition to the incoming values being identical
// (checked by the caller of this function), the incoming blocks
// are also identical.
for (unsigned i = 0, e = PNL->getNumIncomingValues(); i != e; ++i) {
if (int Res =
cmpValues(PNL->getIncomingBlock(i), PNR->getIncomingBlock(i)))
return Res;
}
}
return 0;
}
// Determine whether two GEP operations perform the same underlying arithmetic.
// Read method declaration comments for more details.
int FunctionComparator::cmpGEPs(const GEPOperator *GEPL,
const GEPOperator *GEPR) const {
unsigned int ASL = GEPL->getPointerAddressSpace();
unsigned int ASR = GEPR->getPointerAddressSpace();
if (int Res = cmpNumbers(ASL, ASR))
return Res;
// When we have target data, we can reduce the GEP down to the value in bytes
// added to the address.
const DataLayout &DL = FnL->getParent()->getDataLayout();
unsigned BitWidth = DL.getPointerSizeInBits(ASL);
APInt OffsetL(BitWidth, 0), OffsetR(BitWidth, 0);
if (GEPL->accumulateConstantOffset(DL, OffsetL) &&
GEPR->accumulateConstantOffset(DL, OffsetR))
return cmpAPInts(OffsetL, OffsetR);
if (int Res = cmpTypes(GEPL->getSourceElementType(),
GEPR->getSourceElementType()))
return Res;
if (int Res = cmpNumbers(GEPL->getNumOperands(), GEPR->getNumOperands()))
return Res;
for (unsigned i = 0, e = GEPL->getNumOperands(); i != e; ++i) {
if (int Res = cmpValues(GEPL->getOperand(i), GEPR->getOperand(i)))
return Res;
}
return 0;
}
int FunctionComparator::cmpInlineAsm(const InlineAsm *L,
const InlineAsm *R) const {
// InlineAsm's are uniqued. If they are the same pointer, obviously they are
// the same, otherwise compare the fields.
if (L == R)
return 0;
if (int Res = cmpTypes(L->getFunctionType(), R->getFunctionType()))
return Res;
if (int Res = cmpMem(L->getAsmString(), R->getAsmString()))
return Res;
if (int Res = cmpMem(L->getConstraintString(), R->getConstraintString()))
return Res;
if (int Res = cmpNumbers(L->hasSideEffects(), R->hasSideEffects()))
return Res;
if (int Res = cmpNumbers(L->isAlignStack(), R->isAlignStack()))
return Res;
if (int Res = cmpNumbers(L->getDialect(), R->getDialect()))
return Res;
assert(L->getFunctionType() != R->getFunctionType());
return 0;
}
/// Compare two values used by the two functions under pair-wise comparison. If
/// this is the first time the values are seen, they're added to the mapping so
/// that we will detect mismatches on next use.
/// See comments in declaration for more details.
int FunctionComparator::cmpValues(const Value *L, const Value *R) const {
// Catch self-reference case.
if (L == FnL) {
if (R == FnR)
return 0;
return -1;
}
if (R == FnR) {
if (L == FnL)
return 0;
return 1;
}
const Constant *ConstL = dyn_cast<Constant>(L);
const Constant *ConstR = dyn_cast<Constant>(R);
if (ConstL && ConstR) {
if (L == R)
return 0;
return cmpConstants(ConstL, ConstR);
}
if (ConstL)
return 1;
if (ConstR)
return -1;
const InlineAsm *InlineAsmL = dyn_cast<InlineAsm>(L);
const InlineAsm *InlineAsmR = dyn_cast<InlineAsm>(R);
if (InlineAsmL && InlineAsmR)
return cmpInlineAsm(InlineAsmL, InlineAsmR);
if (InlineAsmL)
return 1;
if (InlineAsmR)
return -1;
auto LeftSN = sn_mapL.insert(std::make_pair(L, sn_mapL.size())),
RightSN = sn_mapR.insert(std::make_pair(R, sn_mapR.size()));
return cmpNumbers(LeftSN.first->second, RightSN.first->second);
}
// Test whether two basic blocks have equivalent behaviour.
int FunctionComparator::cmpBasicBlocks(const BasicBlock *BBL,
const BasicBlock *BBR) const {
BasicBlock::const_iterator InstL = BBL->begin(), InstLE = BBL->end();
BasicBlock::const_iterator InstR = BBR->begin(), InstRE = BBR->end();
do {
bool needToCmpOperands = true;
if (int Res = cmpOperations(&*InstL, &*InstR, needToCmpOperands))
return Res;
if (needToCmpOperands) {
assert(InstL->getNumOperands() == InstR->getNumOperands());
for (unsigned i = 0, e = InstL->getNumOperands(); i != e; ++i) {
Value *OpL = InstL->getOperand(i);
Value *OpR = InstR->getOperand(i);
if (int Res = cmpValues(OpL, OpR))
return Res;
// cmpValues should ensure this is true.
assert(cmpTypes(OpL->getType(), OpR->getType()) == 0);
}
}
++InstL;
++InstR;
} while (InstL != InstLE && InstR != InstRE);
if (InstL != InstLE && InstR == InstRE)
return 1;
if (InstL == InstLE && InstR != InstRE)
return -1;
return 0;
}
int FunctionComparator::compareSignature() const {
if (int Res = cmpAttrs(FnL->getAttributes(), FnR->getAttributes()))
return Res;
if (int Res = cmpNumbers(FnL->hasGC(), FnR->hasGC()))
return Res;
if (FnL->hasGC()) {
if (int Res = cmpMem(FnL->getGC(), FnR->getGC()))
return Res;
}
if (int Res = cmpNumbers(FnL->hasSection(), FnR->hasSection()))
return Res;
if (FnL->hasSection()) {
if (int Res = cmpMem(FnL->getSection(), FnR->getSection()))
return Res;
}
if (int Res = cmpNumbers(FnL->isVarArg(), FnR->isVarArg()))
return Res;
// TODO: if it's internal and only used in direct calls, we could handle this
// case too.
if (int Res = cmpNumbers(FnL->getCallingConv(), FnR->getCallingConv()))
return Res;
if (int Res = cmpTypes(FnL->getFunctionType(), FnR->getFunctionType()))
return Res;
assert(FnL->arg_size() == FnR->arg_size() &&
"Identically typed functions have different numbers of args!");
// Visit the arguments so that they get enumerated in the order they're
// passed in.
for (Function::const_arg_iterator ArgLI = FnL->arg_begin(),
ArgRI = FnR->arg_begin(),
ArgLE = FnL->arg_end();
ArgLI != ArgLE; ++ArgLI, ++ArgRI) {
if (cmpValues(&*ArgLI, &*ArgRI) != 0)
llvm_unreachable("Arguments repeat!");
}
return 0;
}
// Test whether the two functions have equivalent behaviour.
int FunctionComparator::compare() {
beginCompare();
if (int Res = compareSignature())
return Res;
// We do a CFG-ordered walk since the actual ordering of the blocks in the
// linked list is immaterial. Our walk starts at the entry block for both
// functions, then takes each block from each terminator in order. As an
// artifact, this also means that unreachable blocks are ignored.
SmallVector<const BasicBlock *, 8> FnLBBs, FnRBBs;
SmallPtrSet<const BasicBlock *, 32> VisitedBBs; // in terms of F1.
FnLBBs.push_back(&FnL->getEntryBlock());
FnRBBs.push_back(&FnR->getEntryBlock());
VisitedBBs.insert(FnLBBs[0]);
while (!FnLBBs.empty()) {
const BasicBlock *BBL = FnLBBs.pop_back_val();
const BasicBlock *BBR = FnRBBs.pop_back_val();
if (int Res = cmpValues(BBL, BBR))
return Res;
if (int Res = cmpBasicBlocks(BBL, BBR))
return Res;
const Instruction *TermL = BBL->getTerminator();
const Instruction *TermR = BBR->getTerminator();
assert(TermL->getNumSuccessors() == TermR->getNumSuccessors());
for (unsigned i = 0, e = TermL->getNumSuccessors(); i != e; ++i) {
if (!VisitedBBs.insert(TermL->getSuccessor(i)).second)
continue;
FnLBBs.push_back(TermL->getSuccessor(i));
FnRBBs.push_back(TermR->getSuccessor(i));
}
}
return 0;
}
namespace {
// Accumulate the hash of a sequence of 64-bit integers. This is similar to a
// hash of a sequence of 64bit ints, but the entire input does not need to be
// available at once. This interface is necessary for functionHash because it
// needs to accumulate the hash as the structure of the function is traversed
// without saving these values to an intermediate buffer. This form of hashing
// is not often needed, as usually the object to hash is just read from a
// buffer.
class HashAccumulator64 {
uint64_t Hash;
public:
// Initialize to random constant, so the state isn't zero.
HashAccumulator64() { Hash = 0x6acaa36bef8325c5ULL; }
void add(uint64_t V) {
Hash = hashing::detail::hash_16_bytes(Hash, V);
}
// No finishing is required, because the entire hash value is used.
uint64_t getHash() { return Hash; }
};
} // end anonymous namespace
// A function hash is calculated by considering only the number of arguments and
// whether a function is varargs, the order of basic blocks (given by the
// successors of each basic block in depth first order), and the order of
// opcodes of each instruction within each of these basic blocks. This mirrors
// the strategy compare() uses to compare functions by walking the BBs in depth
// first order and comparing each instruction in sequence. Because this hash
// does not look at the operands, it is insensitive to things such as the
// target of calls and the constants used in the function, which makes it useful
// when possibly merging functions which are the same modulo constants and call
// targets.
FunctionComparator::FunctionHash FunctionComparator::functionHash(Function &F) {
HashAccumulator64 H;
H.add(F.isVarArg());
H.add(F.arg_size());
SmallVector<const BasicBlock *, 8> BBs;
SmallPtrSet<const BasicBlock *, 16> VisitedBBs;
// Walk the blocks in the same order as FunctionComparator::cmpBasicBlocks(),
// accumulating the hash of the function "structure." (BB and opcode sequence)
BBs.push_back(&F.getEntryBlock());
VisitedBBs.insert(BBs[0]);
while (!BBs.empty()) {
const BasicBlock *BB = BBs.pop_back_val();
// This random value acts as a block header, as otherwise the partition of
// opcodes into BBs wouldn't affect the hash, only the order of the opcodes
H.add(45798);
for (auto &Inst : *BB) {
H.add(Inst.getOpcode());
}
const Instruction *Term = BB->getTerminator();
for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
if (!VisitedBBs.insert(Term->getSuccessor(i)).second)
continue;
BBs.push_back(Term->getSuccessor(i));
}
}
return H.getHash();
}
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