forked from OSchip/llvm-project
917 lines
34 KiB
C++
917 lines
34 KiB
C++
//==- AliasAnalysis.cpp - Generic Alias Analysis Interface Implementation --==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the generic AliasAnalysis interface which is used as the
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// common interface used by all clients and implementations of alias analysis.
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//
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// This file also implements the default version of the AliasAnalysis interface
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// that is to be used when no other implementation is specified. This does some
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// simple tests that detect obvious cases: two different global pointers cannot
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// alias, a global cannot alias a malloc, two different mallocs cannot alias,
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// etc.
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//
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// This alias analysis implementation really isn't very good for anything, but
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// it is very fast, and makes a nice clean default implementation. Because it
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// handles lots of little corner cases, other, more complex, alias analysis
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// implementations may choose to rely on this pass to resolve these simple and
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// easy cases.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/BasicAliasAnalysis.h"
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#include "llvm/Analysis/CFLAndersAliasAnalysis.h"
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#include "llvm/Analysis/CFLSteensAliasAnalysis.h"
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#include "llvm/Analysis/CaptureTracking.h"
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#include "llvm/Analysis/GlobalsModRef.h"
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#include "llvm/Analysis/MemoryLocation.h"
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#include "llvm/Analysis/ObjCARCAliasAnalysis.h"
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#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
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#include "llvm/Analysis/ScopedNoAliasAA.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Analysis/TypeBasedAliasAnalysis.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/Argument.h"
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#include "llvm/IR/Attributes.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/Value.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/AtomicOrdering.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/CommandLine.h"
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#include <algorithm>
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#include <cassert>
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#include <functional>
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#include <iterator>
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using namespace llvm;
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/// Allow disabling BasicAA from the AA results. This is particularly useful
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/// when testing to isolate a single AA implementation.
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cl::opt<bool> DisableBasicAA("disable-basic-aa", cl::Hidden, cl::init(false));
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AAResults::AAResults(AAResults &&Arg)
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: TLI(Arg.TLI), AAs(std::move(Arg.AAs)), AADeps(std::move(Arg.AADeps)) {
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for (auto &AA : AAs)
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AA->setAAResults(this);
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}
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AAResults::~AAResults() {
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// FIXME; It would be nice to at least clear out the pointers back to this
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// aggregation here, but we end up with non-nesting lifetimes in the legacy
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// pass manager that prevent this from working. In the legacy pass manager
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// we'll end up with dangling references here in some cases.
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#if 0
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for (auto &AA : AAs)
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AA->setAAResults(nullptr);
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#endif
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}
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bool AAResults::invalidate(Function &F, const PreservedAnalyses &PA,
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FunctionAnalysisManager::Invalidator &Inv) {
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// AAResults preserves the AAManager by default, due to the stateless nature
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// of AliasAnalysis. There is no need to check whether it has been preserved
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// explicitly. Check if any module dependency was invalidated and caused the
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// AAManager to be invalidated. Invalidate ourselves in that case.
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auto PAC = PA.getChecker<AAManager>();
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if (!PAC.preservedWhenStateless())
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return true;
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// Check if any of the function dependencies were invalidated, and invalidate
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// ourselves in that case.
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for (AnalysisKey *ID : AADeps)
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if (Inv.invalidate(ID, F, PA))
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return true;
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// Everything we depend on is still fine, so are we. Nothing to invalidate.
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return false;
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}
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//===----------------------------------------------------------------------===//
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// Default chaining methods
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//===----------------------------------------------------------------------===//
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AliasResult AAResults::alias(const MemoryLocation &LocA,
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const MemoryLocation &LocB) {
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AAQueryInfo AAQIP;
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return alias(LocA, LocB, AAQIP);
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}
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AliasResult AAResults::alias(const MemoryLocation &LocA,
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const MemoryLocation &LocB, AAQueryInfo &AAQI) {
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for (const auto &AA : AAs) {
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auto Result = AA->alias(LocA, LocB, AAQI);
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if (Result != MayAlias)
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return Result;
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}
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return MayAlias;
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}
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bool AAResults::pointsToConstantMemory(const MemoryLocation &Loc,
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bool OrLocal) {
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AAQueryInfo AAQIP;
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return pointsToConstantMemory(Loc, AAQIP, OrLocal);
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}
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bool AAResults::pointsToConstantMemory(const MemoryLocation &Loc,
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AAQueryInfo &AAQI, bool OrLocal) {
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for (const auto &AA : AAs)
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if (AA->pointsToConstantMemory(Loc, AAQI, OrLocal))
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return true;
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return false;
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}
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ModRefInfo AAResults::getArgModRefInfo(const CallBase *Call, unsigned ArgIdx) {
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ModRefInfo Result = ModRefInfo::ModRef;
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for (const auto &AA : AAs) {
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Result = intersectModRef(Result, AA->getArgModRefInfo(Call, ArgIdx));
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// Early-exit the moment we reach the bottom of the lattice.
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if (isNoModRef(Result))
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return ModRefInfo::NoModRef;
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}
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return Result;
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}
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ModRefInfo AAResults::getModRefInfo(Instruction *I, const CallBase *Call2) {
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AAQueryInfo AAQIP;
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return getModRefInfo(I, Call2, AAQIP);
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}
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ModRefInfo AAResults::getModRefInfo(Instruction *I, const CallBase *Call2,
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AAQueryInfo &AAQI) {
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// We may have two calls.
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if (const auto *Call1 = dyn_cast<CallBase>(I)) {
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// Check if the two calls modify the same memory.
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return getModRefInfo(Call1, Call2, AAQI);
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} else if (I->isFenceLike()) {
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// If this is a fence, just return ModRef.
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return ModRefInfo::ModRef;
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} else {
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// Otherwise, check if the call modifies or references the
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// location this memory access defines. The best we can say
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// is that if the call references what this instruction
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// defines, it must be clobbered by this location.
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const MemoryLocation DefLoc = MemoryLocation::get(I);
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ModRefInfo MR = getModRefInfo(Call2, DefLoc, AAQI);
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if (isModOrRefSet(MR))
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return setModAndRef(MR);
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}
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return ModRefInfo::NoModRef;
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}
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ModRefInfo AAResults::getModRefInfo(const CallBase *Call,
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const MemoryLocation &Loc) {
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AAQueryInfo AAQIP;
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return getModRefInfo(Call, Loc, AAQIP);
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}
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ModRefInfo AAResults::getModRefInfo(const CallBase *Call,
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const MemoryLocation &Loc,
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AAQueryInfo &AAQI) {
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ModRefInfo Result = ModRefInfo::ModRef;
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for (const auto &AA : AAs) {
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Result = intersectModRef(Result, AA->getModRefInfo(Call, Loc, AAQI));
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// Early-exit the moment we reach the bottom of the lattice.
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if (isNoModRef(Result))
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return ModRefInfo::NoModRef;
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}
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// Try to refine the mod-ref info further using other API entry points to the
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// aggregate set of AA results.
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auto MRB = getModRefBehavior(Call);
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if (onlyAccessesInaccessibleMem(MRB))
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return ModRefInfo::NoModRef;
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if (onlyReadsMemory(MRB))
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Result = clearMod(Result);
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else if (doesNotReadMemory(MRB))
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Result = clearRef(Result);
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if (onlyAccessesArgPointees(MRB) || onlyAccessesInaccessibleOrArgMem(MRB)) {
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bool IsMustAlias = true;
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ModRefInfo AllArgsMask = ModRefInfo::NoModRef;
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if (doesAccessArgPointees(MRB)) {
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for (auto AI = Call->arg_begin(), AE = Call->arg_end(); AI != AE; ++AI) {
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const Value *Arg = *AI;
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if (!Arg->getType()->isPointerTy())
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continue;
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unsigned ArgIdx = std::distance(Call->arg_begin(), AI);
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MemoryLocation ArgLoc =
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MemoryLocation::getForArgument(Call, ArgIdx, TLI);
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AliasResult ArgAlias = alias(ArgLoc, Loc, AAQI);
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if (ArgAlias != NoAlias) {
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ModRefInfo ArgMask = getArgModRefInfo(Call, ArgIdx);
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AllArgsMask = unionModRef(AllArgsMask, ArgMask);
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}
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// Conservatively clear IsMustAlias unless only MustAlias is found.
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IsMustAlias &= (ArgAlias == MustAlias);
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}
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}
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// Return NoModRef if no alias found with any argument.
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if (isNoModRef(AllArgsMask))
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return ModRefInfo::NoModRef;
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// Logical & between other AA analyses and argument analysis.
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Result = intersectModRef(Result, AllArgsMask);
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// If only MustAlias found above, set Must bit.
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Result = IsMustAlias ? setMust(Result) : clearMust(Result);
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}
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// If Loc is a constant memory location, the call definitely could not
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// modify the memory location.
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if (isModSet(Result) && pointsToConstantMemory(Loc, AAQI, /*OrLocal*/ false))
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Result = clearMod(Result);
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return Result;
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}
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ModRefInfo AAResults::getModRefInfo(const CallBase *Call1,
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const CallBase *Call2) {
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AAQueryInfo AAQIP;
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return getModRefInfo(Call1, Call2, AAQIP);
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}
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ModRefInfo AAResults::getModRefInfo(const CallBase *Call1,
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const CallBase *Call2, AAQueryInfo &AAQI) {
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ModRefInfo Result = ModRefInfo::ModRef;
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for (const auto &AA : AAs) {
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Result = intersectModRef(Result, AA->getModRefInfo(Call1, Call2, AAQI));
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// Early-exit the moment we reach the bottom of the lattice.
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if (isNoModRef(Result))
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return ModRefInfo::NoModRef;
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}
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// Try to refine the mod-ref info further using other API entry points to the
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// aggregate set of AA results.
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// If Call1 or Call2 are readnone, they don't interact.
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auto Call1B = getModRefBehavior(Call1);
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if (Call1B == FMRB_DoesNotAccessMemory)
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return ModRefInfo::NoModRef;
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auto Call2B = getModRefBehavior(Call2);
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if (Call2B == FMRB_DoesNotAccessMemory)
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return ModRefInfo::NoModRef;
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// If they both only read from memory, there is no dependence.
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if (onlyReadsMemory(Call1B) && onlyReadsMemory(Call2B))
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return ModRefInfo::NoModRef;
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// If Call1 only reads memory, the only dependence on Call2 can be
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// from Call1 reading memory written by Call2.
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if (onlyReadsMemory(Call1B))
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Result = clearMod(Result);
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else if (doesNotReadMemory(Call1B))
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Result = clearRef(Result);
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// If Call2 only access memory through arguments, accumulate the mod/ref
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// information from Call1's references to the memory referenced by
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// Call2's arguments.
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if (onlyAccessesArgPointees(Call2B)) {
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if (!doesAccessArgPointees(Call2B))
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return ModRefInfo::NoModRef;
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ModRefInfo R = ModRefInfo::NoModRef;
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bool IsMustAlias = true;
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for (auto I = Call2->arg_begin(), E = Call2->arg_end(); I != E; ++I) {
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const Value *Arg = *I;
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if (!Arg->getType()->isPointerTy())
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continue;
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unsigned Call2ArgIdx = std::distance(Call2->arg_begin(), I);
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auto Call2ArgLoc =
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MemoryLocation::getForArgument(Call2, Call2ArgIdx, TLI);
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// ArgModRefC2 indicates what Call2 might do to Call2ArgLoc, and the
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// dependence of Call1 on that location is the inverse:
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// - If Call2 modifies location, dependence exists if Call1 reads or
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// writes.
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// - If Call2 only reads location, dependence exists if Call1 writes.
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ModRefInfo ArgModRefC2 = getArgModRefInfo(Call2, Call2ArgIdx);
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ModRefInfo ArgMask = ModRefInfo::NoModRef;
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if (isModSet(ArgModRefC2))
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ArgMask = ModRefInfo::ModRef;
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else if (isRefSet(ArgModRefC2))
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ArgMask = ModRefInfo::Mod;
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// ModRefC1 indicates what Call1 might do to Call2ArgLoc, and we use
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// above ArgMask to update dependence info.
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ModRefInfo ModRefC1 = getModRefInfo(Call1, Call2ArgLoc, AAQI);
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ArgMask = intersectModRef(ArgMask, ModRefC1);
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// Conservatively clear IsMustAlias unless only MustAlias is found.
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IsMustAlias &= isMustSet(ModRefC1);
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R = intersectModRef(unionModRef(R, ArgMask), Result);
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if (R == Result) {
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// On early exit, not all args were checked, cannot set Must.
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if (I + 1 != E)
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IsMustAlias = false;
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break;
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}
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}
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if (isNoModRef(R))
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return ModRefInfo::NoModRef;
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// If MustAlias found above, set Must bit.
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return IsMustAlias ? setMust(R) : clearMust(R);
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}
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// If Call1 only accesses memory through arguments, check if Call2 references
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// any of the memory referenced by Call1's arguments. If not, return NoModRef.
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if (onlyAccessesArgPointees(Call1B)) {
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if (!doesAccessArgPointees(Call1B))
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return ModRefInfo::NoModRef;
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ModRefInfo R = ModRefInfo::NoModRef;
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bool IsMustAlias = true;
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for (auto I = Call1->arg_begin(), E = Call1->arg_end(); I != E; ++I) {
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const Value *Arg = *I;
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if (!Arg->getType()->isPointerTy())
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continue;
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unsigned Call1ArgIdx = std::distance(Call1->arg_begin(), I);
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auto Call1ArgLoc =
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MemoryLocation::getForArgument(Call1, Call1ArgIdx, TLI);
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// ArgModRefC1 indicates what Call1 might do to Call1ArgLoc; if Call1
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// might Mod Call1ArgLoc, then we care about either a Mod or a Ref by
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// Call2. If Call1 might Ref, then we care only about a Mod by Call2.
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ModRefInfo ArgModRefC1 = getArgModRefInfo(Call1, Call1ArgIdx);
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ModRefInfo ModRefC2 = getModRefInfo(Call2, Call1ArgLoc, AAQI);
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if ((isModSet(ArgModRefC1) && isModOrRefSet(ModRefC2)) ||
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(isRefSet(ArgModRefC1) && isModSet(ModRefC2)))
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R = intersectModRef(unionModRef(R, ArgModRefC1), Result);
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// Conservatively clear IsMustAlias unless only MustAlias is found.
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IsMustAlias &= isMustSet(ModRefC2);
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if (R == Result) {
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// On early exit, not all args were checked, cannot set Must.
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if (I + 1 != E)
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IsMustAlias = false;
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break;
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}
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}
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if (isNoModRef(R))
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return ModRefInfo::NoModRef;
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// If MustAlias found above, set Must bit.
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return IsMustAlias ? setMust(R) : clearMust(R);
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}
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return Result;
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}
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FunctionModRefBehavior AAResults::getModRefBehavior(const CallBase *Call) {
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FunctionModRefBehavior Result = FMRB_UnknownModRefBehavior;
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for (const auto &AA : AAs) {
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Result = FunctionModRefBehavior(Result & AA->getModRefBehavior(Call));
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// Early-exit the moment we reach the bottom of the lattice.
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if (Result == FMRB_DoesNotAccessMemory)
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return Result;
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}
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return Result;
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}
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FunctionModRefBehavior AAResults::getModRefBehavior(const Function *F) {
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FunctionModRefBehavior Result = FMRB_UnknownModRefBehavior;
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for (const auto &AA : AAs) {
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Result = FunctionModRefBehavior(Result & AA->getModRefBehavior(F));
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// Early-exit the moment we reach the bottom of the lattice.
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if (Result == FMRB_DoesNotAccessMemory)
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return Result;
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}
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return Result;
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}
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raw_ostream &llvm::operator<<(raw_ostream &OS, AliasResult AR) {
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switch (AR) {
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case NoAlias:
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OS << "NoAlias";
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break;
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case MustAlias:
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OS << "MustAlias";
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break;
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case MayAlias:
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OS << "MayAlias";
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break;
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case PartialAlias:
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OS << "PartialAlias";
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break;
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}
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return OS;
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}
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//===----------------------------------------------------------------------===//
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// Helper method implementation
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//===----------------------------------------------------------------------===//
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ModRefInfo AAResults::getModRefInfo(const LoadInst *L,
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const MemoryLocation &Loc) {
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AAQueryInfo AAQIP;
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return getModRefInfo(L, Loc, AAQIP);
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}
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ModRefInfo AAResults::getModRefInfo(const LoadInst *L,
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const MemoryLocation &Loc,
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AAQueryInfo &AAQI) {
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// Be conservative in the face of atomic.
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if (isStrongerThan(L->getOrdering(), AtomicOrdering::Unordered))
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return ModRefInfo::ModRef;
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// If the load address doesn't alias the given address, it doesn't read
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// or write the specified memory.
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if (Loc.Ptr) {
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AliasResult AR = alias(MemoryLocation::get(L), Loc, AAQI);
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if (AR == NoAlias)
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return ModRefInfo::NoModRef;
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if (AR == MustAlias)
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return ModRefInfo::MustRef;
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}
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// Otherwise, a load just reads.
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return ModRefInfo::Ref;
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}
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ModRefInfo AAResults::getModRefInfo(const StoreInst *S,
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const MemoryLocation &Loc) {
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AAQueryInfo AAQIP;
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return getModRefInfo(S, Loc, AAQIP);
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}
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ModRefInfo AAResults::getModRefInfo(const StoreInst *S,
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const MemoryLocation &Loc,
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AAQueryInfo &AAQI) {
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// Be conservative in the face of atomic.
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if (isStrongerThan(S->getOrdering(), AtomicOrdering::Unordered))
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return ModRefInfo::ModRef;
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if (Loc.Ptr) {
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AliasResult AR = alias(MemoryLocation::get(S), Loc, AAQI);
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// If the store address cannot alias the pointer in question, then the
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// specified memory cannot be modified by the store.
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if (AR == NoAlias)
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return ModRefInfo::NoModRef;
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// If the pointer is a pointer to constant memory, then it could not have
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// been modified by this store.
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if (pointsToConstantMemory(Loc, AAQI))
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return ModRefInfo::NoModRef;
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// If the store address aliases the pointer as must alias, set Must.
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if (AR == MustAlias)
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return ModRefInfo::MustMod;
|
|
}
|
|
|
|
// Otherwise, a store just writes.
|
|
return ModRefInfo::Mod;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const FenceInst *S, const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(S, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const FenceInst *S,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
// If we know that the location is a constant memory location, the fence
|
|
// cannot modify this location.
|
|
if (Loc.Ptr && pointsToConstantMemory(Loc, AAQI))
|
|
return ModRefInfo::Ref;
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const VAArgInst *V,
|
|
const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(V, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const VAArgInst *V,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
if (Loc.Ptr) {
|
|
AliasResult AR = alias(MemoryLocation::get(V), Loc, AAQI);
|
|
// If the va_arg address cannot alias the pointer in question, then the
|
|
// specified memory cannot be accessed by the va_arg.
|
|
if (AR == NoAlias)
|
|
return ModRefInfo::NoModRef;
|
|
|
|
// If the pointer is a pointer to constant memory, then it could not have
|
|
// been modified by this va_arg.
|
|
if (pointsToConstantMemory(Loc, AAQI))
|
|
return ModRefInfo::NoModRef;
|
|
|
|
// If the va_arg aliases the pointer as must alias, set Must.
|
|
if (AR == MustAlias)
|
|
return ModRefInfo::MustModRef;
|
|
}
|
|
|
|
// Otherwise, a va_arg reads and writes.
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const CatchPadInst *CatchPad,
|
|
const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(CatchPad, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const CatchPadInst *CatchPad,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
if (Loc.Ptr) {
|
|
// If the pointer is a pointer to constant memory,
|
|
// then it could not have been modified by this catchpad.
|
|
if (pointsToConstantMemory(Loc, AAQI))
|
|
return ModRefInfo::NoModRef;
|
|
}
|
|
|
|
// Otherwise, a catchpad reads and writes.
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const CatchReturnInst *CatchRet,
|
|
const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(CatchRet, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const CatchReturnInst *CatchRet,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
if (Loc.Ptr) {
|
|
// If the pointer is a pointer to constant memory,
|
|
// then it could not have been modified by this catchpad.
|
|
if (pointsToConstantMemory(Loc, AAQI))
|
|
return ModRefInfo::NoModRef;
|
|
}
|
|
|
|
// Otherwise, a catchret reads and writes.
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const AtomicCmpXchgInst *CX,
|
|
const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(CX, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const AtomicCmpXchgInst *CX,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
// Acquire/Release cmpxchg has properties that matter for arbitrary addresses.
|
|
if (isStrongerThanMonotonic(CX->getSuccessOrdering()))
|
|
return ModRefInfo::ModRef;
|
|
|
|
if (Loc.Ptr) {
|
|
AliasResult AR = alias(MemoryLocation::get(CX), Loc, AAQI);
|
|
// If the cmpxchg address does not alias the location, it does not access
|
|
// it.
|
|
if (AR == NoAlias)
|
|
return ModRefInfo::NoModRef;
|
|
|
|
// If the cmpxchg address aliases the pointer as must alias, set Must.
|
|
if (AR == MustAlias)
|
|
return ModRefInfo::MustModRef;
|
|
}
|
|
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const AtomicRMWInst *RMW,
|
|
const MemoryLocation &Loc) {
|
|
AAQueryInfo AAQIP;
|
|
return getModRefInfo(RMW, Loc, AAQIP);
|
|
}
|
|
|
|
ModRefInfo AAResults::getModRefInfo(const AtomicRMWInst *RMW,
|
|
const MemoryLocation &Loc,
|
|
AAQueryInfo &AAQI) {
|
|
// Acquire/Release atomicrmw has properties that matter for arbitrary addresses.
|
|
if (isStrongerThanMonotonic(RMW->getOrdering()))
|
|
return ModRefInfo::ModRef;
|
|
|
|
if (Loc.Ptr) {
|
|
AliasResult AR = alias(MemoryLocation::get(RMW), Loc, AAQI);
|
|
// If the atomicrmw address does not alias the location, it does not access
|
|
// it.
|
|
if (AR == NoAlias)
|
|
return ModRefInfo::NoModRef;
|
|
|
|
// If the atomicrmw address aliases the pointer as must alias, set Must.
|
|
if (AR == MustAlias)
|
|
return ModRefInfo::MustModRef;
|
|
}
|
|
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
/// Return information about whether a particular call site modifies
|
|
/// or reads the specified memory location \p MemLoc before instruction \p I
|
|
/// in a BasicBlock.
|
|
/// FIXME: this is really just shoring-up a deficiency in alias analysis.
|
|
/// BasicAA isn't willing to spend linear time determining whether an alloca
|
|
/// was captured before or after this particular call, while we are. However,
|
|
/// with a smarter AA in place, this test is just wasting compile time.
|
|
ModRefInfo AAResults::callCapturesBefore(const Instruction *I,
|
|
const MemoryLocation &MemLoc,
|
|
DominatorTree *DT) {
|
|
if (!DT)
|
|
return ModRefInfo::ModRef;
|
|
|
|
const Value *Object = getUnderlyingObject(MemLoc.Ptr);
|
|
if (!isIdentifiedObject(Object) || isa<GlobalValue>(Object) ||
|
|
isa<Constant>(Object))
|
|
return ModRefInfo::ModRef;
|
|
|
|
const auto *Call = dyn_cast<CallBase>(I);
|
|
if (!Call || Call == Object)
|
|
return ModRefInfo::ModRef;
|
|
|
|
if (PointerMayBeCapturedBefore(Object, /* ReturnCaptures */ true,
|
|
/* StoreCaptures */ true, I, DT,
|
|
/* include Object */ true))
|
|
return ModRefInfo::ModRef;
|
|
|
|
unsigned ArgNo = 0;
|
|
ModRefInfo R = ModRefInfo::NoModRef;
|
|
bool IsMustAlias = true;
|
|
// Set flag only if no May found and all operands processed.
|
|
for (auto CI = Call->data_operands_begin(), CE = Call->data_operands_end();
|
|
CI != CE; ++CI, ++ArgNo) {
|
|
// Only look at the no-capture or byval pointer arguments. If this
|
|
// pointer were passed to arguments that were neither of these, then it
|
|
// couldn't be no-capture.
|
|
if (!(*CI)->getType()->isPointerTy() ||
|
|
(!Call->doesNotCapture(ArgNo) && ArgNo < Call->getNumArgOperands() &&
|
|
!Call->isByValArgument(ArgNo)))
|
|
continue;
|
|
|
|
AliasResult AR = alias(*CI, Object);
|
|
// If this is a no-capture pointer argument, see if we can tell that it
|
|
// is impossible to alias the pointer we're checking. If not, we have to
|
|
// assume that the call could touch the pointer, even though it doesn't
|
|
// escape.
|
|
if (AR != MustAlias)
|
|
IsMustAlias = false;
|
|
if (AR == NoAlias)
|
|
continue;
|
|
if (Call->doesNotAccessMemory(ArgNo))
|
|
continue;
|
|
if (Call->onlyReadsMemory(ArgNo)) {
|
|
R = ModRefInfo::Ref;
|
|
continue;
|
|
}
|
|
// Not returning MustModRef since we have not seen all the arguments.
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
return IsMustAlias ? setMust(R) : clearMust(R);
|
|
}
|
|
|
|
/// canBasicBlockModify - Return true if it is possible for execution of the
|
|
/// specified basic block to modify the location Loc.
|
|
///
|
|
bool AAResults::canBasicBlockModify(const BasicBlock &BB,
|
|
const MemoryLocation &Loc) {
|
|
return canInstructionRangeModRef(BB.front(), BB.back(), Loc, ModRefInfo::Mod);
|
|
}
|
|
|
|
/// canInstructionRangeModRef - Return true if it is possible for the
|
|
/// execution of the specified instructions to mod\ref (according to the
|
|
/// mode) the location Loc. The instructions to consider are all
|
|
/// of the instructions in the range of [I1,I2] INCLUSIVE.
|
|
/// I1 and I2 must be in the same basic block.
|
|
bool AAResults::canInstructionRangeModRef(const Instruction &I1,
|
|
const Instruction &I2,
|
|
const MemoryLocation &Loc,
|
|
const ModRefInfo Mode) {
|
|
assert(I1.getParent() == I2.getParent() &&
|
|
"Instructions not in same basic block!");
|
|
BasicBlock::const_iterator I = I1.getIterator();
|
|
BasicBlock::const_iterator E = I2.getIterator();
|
|
++E; // Convert from inclusive to exclusive range.
|
|
|
|
for (; I != E; ++I) // Check every instruction in range
|
|
if (isModOrRefSet(intersectModRef(getModRefInfo(&*I, Loc), Mode)))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
// Provide a definition for the root virtual destructor.
|
|
AAResults::Concept::~Concept() = default;
|
|
|
|
// Provide a definition for the static object used to identify passes.
|
|
AnalysisKey AAManager::Key;
|
|
|
|
namespace {
|
|
|
|
|
|
} // end anonymous namespace
|
|
|
|
ExternalAAWrapperPass::ExternalAAWrapperPass() : ImmutablePass(ID) {
|
|
initializeExternalAAWrapperPassPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
ExternalAAWrapperPass::ExternalAAWrapperPass(CallbackT CB)
|
|
: ImmutablePass(ID), CB(std::move(CB)) {
|
|
initializeExternalAAWrapperPassPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
char ExternalAAWrapperPass::ID = 0;
|
|
|
|
INITIALIZE_PASS(ExternalAAWrapperPass, "external-aa", "External Alias Analysis",
|
|
false, true)
|
|
|
|
ImmutablePass *
|
|
llvm::createExternalAAWrapperPass(ExternalAAWrapperPass::CallbackT Callback) {
|
|
return new ExternalAAWrapperPass(std::move(Callback));
|
|
}
|
|
|
|
AAResultsWrapperPass::AAResultsWrapperPass() : FunctionPass(ID) {
|
|
initializeAAResultsWrapperPassPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
char AAResultsWrapperPass::ID = 0;
|
|
|
|
INITIALIZE_PASS_BEGIN(AAResultsWrapperPass, "aa",
|
|
"Function Alias Analysis Results", false, true)
|
|
INITIALIZE_PASS_DEPENDENCY(BasicAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(CFLAndersAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(CFLSteensAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(ExternalAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(ObjCARCAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(ScopedNoAliasAAWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(TypeBasedAAWrapperPass)
|
|
INITIALIZE_PASS_END(AAResultsWrapperPass, "aa",
|
|
"Function Alias Analysis Results", false, true)
|
|
|
|
FunctionPass *llvm::createAAResultsWrapperPass() {
|
|
return new AAResultsWrapperPass();
|
|
}
|
|
|
|
/// Run the wrapper pass to rebuild an aggregation over known AA passes.
|
|
///
|
|
/// This is the legacy pass manager's interface to the new-style AA results
|
|
/// aggregation object. Because this is somewhat shoe-horned into the legacy
|
|
/// pass manager, we hard code all the specific alias analyses available into
|
|
/// it. While the particular set enabled is configured via commandline flags,
|
|
/// adding a new alias analysis to LLVM will require adding support for it to
|
|
/// this list.
|
|
bool AAResultsWrapperPass::runOnFunction(Function &F) {
|
|
// NB! This *must* be reset before adding new AA results to the new
|
|
// AAResults object because in the legacy pass manager, each instance
|
|
// of these will refer to the *same* immutable analyses, registering and
|
|
// unregistering themselves with them. We need to carefully tear down the
|
|
// previous object first, in this case replacing it with an empty one, before
|
|
// registering new results.
|
|
AAR.reset(
|
|
new AAResults(getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F)));
|
|
|
|
// BasicAA is always available for function analyses. Also, we add it first
|
|
// so that it can trump TBAA results when it proves MustAlias.
|
|
// FIXME: TBAA should have an explicit mode to support this and then we
|
|
// should reconsider the ordering here.
|
|
if (!DisableBasicAA)
|
|
AAR->addAAResult(getAnalysis<BasicAAWrapperPass>().getResult());
|
|
|
|
// Populate the results with the currently available AAs.
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<ScopedNoAliasAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<TypeBasedAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass =
|
|
getAnalysisIfAvailable<objcarc::ObjCARCAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<GlobalsAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<SCEVAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<CFLAndersAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<CFLSteensAAWrapperPass>())
|
|
AAR->addAAResult(WrapperPass->getResult());
|
|
|
|
// If available, run an external AA providing callback over the results as
|
|
// well.
|
|
if (auto *WrapperPass = getAnalysisIfAvailable<ExternalAAWrapperPass>())
|
|
if (WrapperPass->CB)
|
|
WrapperPass->CB(*this, F, *AAR);
|
|
|
|
// Analyses don't mutate the IR, so return false.
|
|
return false;
|
|
}
|
|
|
|
void AAResultsWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesAll();
|
|
AU.addRequired<BasicAAWrapperPass>();
|
|
AU.addRequired<TargetLibraryInfoWrapperPass>();
|
|
|
|
// We also need to mark all the alias analysis passes we will potentially
|
|
// probe in runOnFunction as used here to ensure the legacy pass manager
|
|
// preserves them. This hard coding of lists of alias analyses is specific to
|
|
// the legacy pass manager.
|
|
AU.addUsedIfAvailable<ScopedNoAliasAAWrapperPass>();
|
|
AU.addUsedIfAvailable<TypeBasedAAWrapperPass>();
|
|
AU.addUsedIfAvailable<objcarc::ObjCARCAAWrapperPass>();
|
|
AU.addUsedIfAvailable<GlobalsAAWrapperPass>();
|
|
AU.addUsedIfAvailable<SCEVAAWrapperPass>();
|
|
AU.addUsedIfAvailable<CFLAndersAAWrapperPass>();
|
|
AU.addUsedIfAvailable<CFLSteensAAWrapperPass>();
|
|
AU.addUsedIfAvailable<ExternalAAWrapperPass>();
|
|
}
|
|
|
|
AAResults llvm::createLegacyPMAAResults(Pass &P, Function &F,
|
|
BasicAAResult &BAR) {
|
|
AAResults AAR(P.getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F));
|
|
|
|
// Add in our explicitly constructed BasicAA results.
|
|
if (!DisableBasicAA)
|
|
AAR.addAAResult(BAR);
|
|
|
|
// Populate the results with the other currently available AAs.
|
|
if (auto *WrapperPass =
|
|
P.getAnalysisIfAvailable<ScopedNoAliasAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = P.getAnalysisIfAvailable<TypeBasedAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass =
|
|
P.getAnalysisIfAvailable<objcarc::ObjCARCAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = P.getAnalysisIfAvailable<GlobalsAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = P.getAnalysisIfAvailable<CFLAndersAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = P.getAnalysisIfAvailable<CFLSteensAAWrapperPass>())
|
|
AAR.addAAResult(WrapperPass->getResult());
|
|
if (auto *WrapperPass = P.getAnalysisIfAvailable<ExternalAAWrapperPass>())
|
|
if (WrapperPass->CB)
|
|
WrapperPass->CB(P, F, AAR);
|
|
|
|
return AAR;
|
|
}
|
|
|
|
bool llvm::isNoAliasCall(const Value *V) {
|
|
if (const auto *Call = dyn_cast<CallBase>(V))
|
|
return Call->hasRetAttr(Attribute::NoAlias);
|
|
return false;
|
|
}
|
|
|
|
bool llvm::isNoAliasArgument(const Value *V) {
|
|
if (const Argument *A = dyn_cast<Argument>(V))
|
|
return A->hasNoAliasAttr();
|
|
return false;
|
|
}
|
|
|
|
bool llvm::isIdentifiedObject(const Value *V) {
|
|
if (isa<AllocaInst>(V))
|
|
return true;
|
|
if (isa<GlobalValue>(V) && !isa<GlobalAlias>(V))
|
|
return true;
|
|
if (isNoAliasCall(V))
|
|
return true;
|
|
if (const Argument *A = dyn_cast<Argument>(V))
|
|
return A->hasNoAliasAttr() || A->hasByValAttr();
|
|
return false;
|
|
}
|
|
|
|
bool llvm::isIdentifiedFunctionLocal(const Value *V) {
|
|
return isa<AllocaInst>(V) || isNoAliasCall(V) || isNoAliasArgument(V);
|
|
}
|
|
|
|
void llvm::getAAResultsAnalysisUsage(AnalysisUsage &AU) {
|
|
// This function needs to be in sync with llvm::createLegacyPMAAResults -- if
|
|
// more alias analyses are added to llvm::createLegacyPMAAResults, they need
|
|
// to be added here also.
|
|
AU.addRequired<TargetLibraryInfoWrapperPass>();
|
|
AU.addUsedIfAvailable<ScopedNoAliasAAWrapperPass>();
|
|
AU.addUsedIfAvailable<TypeBasedAAWrapperPass>();
|
|
AU.addUsedIfAvailable<objcarc::ObjCARCAAWrapperPass>();
|
|
AU.addUsedIfAvailable<GlobalsAAWrapperPass>();
|
|
AU.addUsedIfAvailable<CFLAndersAAWrapperPass>();
|
|
AU.addUsedIfAvailable<CFLSteensAAWrapperPass>();
|
|
AU.addUsedIfAvailable<ExternalAAWrapperPass>();
|
|
}
|