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Attributor.cpp
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Attributor.cpp
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//===- Attributor.cpp - Module-wide attribute deduction -------------------===//
//
// 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 an interprocedural pass that deduces and/or propagates
// attributes. This is done in an abstract interpretation style fixpoint
// iteration. See the Attributor.h file comment and the class descriptions in
// that file for more information.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/Attributor.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/MustExecute.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
#include <string>
using namespace llvm;
#define DEBUG_TYPE "attributor"
STATISTIC(NumFnDeleted, "Number of function deleted");
STATISTIC(NumFnWithExactDefinition,
"Number of functions with exact definitions");
STATISTIC(NumFnWithoutExactDefinition,
"Number of functions without exact definitions");
STATISTIC(NumFnShallowWrapperCreated, "Number of shallow wrappers created");
STATISTIC(NumAttributesTimedOut,
"Number of abstract attributes timed out before fixpoint");
STATISTIC(NumAttributesValidFixpoint,
"Number of abstract attributes in a valid fixpoint state");
STATISTIC(NumAttributesManifested,
"Number of abstract attributes manifested in IR");
STATISTIC(NumAttributesFixedDueToRequiredDependences,
"Number of abstract attributes fixed due to required dependences");
// TODO: Determine a good default value.
//
// In the LLVM-TS and SPEC2006, 32 seems to not induce compile time overheads
// (when run with the first 5 abstract attributes). The results also indicate
// that we never reach 32 iterations but always find a fixpoint sooner.
//
// This will become more evolved once we perform two interleaved fixpoint
// iterations: bottom-up and top-down.
static cl::opt<unsigned>
MaxFixpointIterations("attributor-max-iterations", cl::Hidden,
cl::desc("Maximal number of fixpoint iterations."),
cl::init(32));
static cl::opt<unsigned, true> MaxInitializationChainLengthX(
"attributor-max-initialization-chain-length", cl::Hidden,
cl::desc(
"Maximal number of chained initializations (to avoid stack overflows)"),
cl::location(MaxInitializationChainLength), cl::init(1024));
unsigned llvm::MaxInitializationChainLength;
static cl::opt<bool> VerifyMaxFixpointIterations(
"attributor-max-iterations-verify", cl::Hidden,
cl::desc("Verify that max-iterations is a tight bound for a fixpoint"),
cl::init(false));
static cl::opt<bool> AnnotateDeclarationCallSites(
"attributor-annotate-decl-cs", cl::Hidden,
cl::desc("Annotate call sites of function declarations."), cl::init(false));
static cl::opt<bool> EnableHeapToStack("enable-heap-to-stack-conversion",
cl::init(true), cl::Hidden);
static cl::opt<bool>
AllowShallowWrappers("attributor-allow-shallow-wrappers", cl::Hidden,
cl::desc("Allow the Attributor to create shallow "
"wrappers for non-exact definitions."),
cl::init(false));
static cl::opt<bool>
AllowDeepWrapper("attributor-allow-deep-wrappers", cl::Hidden,
cl::desc("Allow the Attributor to use IP information "
"derived from non-exact functions via cloning"),
cl::init(false));
// These options can only used for debug builds.
#ifndef NDEBUG
static cl::list<std::string>
SeedAllowList("attributor-seed-allow-list", cl::Hidden,
cl::desc("Comma seperated list of attribute names that are "
"allowed to be seeded."),
cl::ZeroOrMore, cl::CommaSeparated);
static cl::list<std::string> FunctionSeedAllowList(
"attributor-function-seed-allow-list", cl::Hidden,
cl::desc("Comma seperated list of function names that are "
"allowed to be seeded."),
cl::ZeroOrMore, cl::CommaSeparated);
#endif
static cl::opt<bool>
DumpDepGraph("attributor-dump-dep-graph", cl::Hidden,
cl::desc("Dump the dependency graph to dot files."),
cl::init(false));
static cl::opt<std::string> DepGraphDotFileNamePrefix(
"attributor-depgraph-dot-filename-prefix", cl::Hidden,
cl::desc("The prefix used for the CallGraph dot file names."));
static cl::opt<bool> ViewDepGraph("attributor-view-dep-graph", cl::Hidden,
cl::desc("View the dependency graph."),
cl::init(false));
static cl::opt<bool> PrintDependencies("attributor-print-dep", cl::Hidden,
cl::desc("Print attribute dependencies"),
cl::init(false));
/// Logic operators for the change status enum class.
///
///{
ChangeStatus llvm::operator|(ChangeStatus L, ChangeStatus R) {
return L == ChangeStatus::CHANGED ? L : R;
}
ChangeStatus llvm::operator&(ChangeStatus L, ChangeStatus R) {
return L == ChangeStatus::UNCHANGED ? L : R;
}
///}
/// Return true if \p New is equal or worse than \p Old.
static bool isEqualOrWorse(const Attribute &New, const Attribute &Old) {
if (!Old.isIntAttribute())
return true;
return Old.getValueAsInt() >= New.getValueAsInt();
}
/// Return true if the information provided by \p Attr was added to the
/// attribute list \p Attrs. This is only the case if it was not already present
/// in \p Attrs at the position describe by \p PK and \p AttrIdx.
static bool addIfNotExistent(LLVMContext &Ctx, const Attribute &Attr,
AttributeList &Attrs, int AttrIdx) {
if (Attr.isEnumAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isStringAttribute()) {
StringRef Kind = Attr.getKindAsString();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isIntAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.removeAttribute(Ctx, AttrIdx, Kind);
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
llvm_unreachable("Expected enum or string attribute!");
}
Argument *IRPosition::getAssociatedArgument() const {
if (getPositionKind() == IRP_ARGUMENT)
return cast<Argument>(&getAnchorValue());
// Not an Argument and no argument number means this is not a call site
// argument, thus we cannot find a callback argument to return.
int ArgNo = getArgNo();
if (ArgNo < 0)
return nullptr;
// Use abstract call sites to make the connection between the call site
// values and the ones in callbacks. If a callback was found that makes use
// of the underlying call site operand, we want the corresponding callback
// callee argument and not the direct callee argument.
Optional<Argument *> CBCandidateArg;
SmallVector<const Use *, 4> CallbackUses;
const auto &CB = cast<CallBase>(getAnchorValue());
AbstractCallSite::getCallbackUses(CB, CallbackUses);
for (const Use *U : CallbackUses) {
AbstractCallSite ACS(U);
assert(ACS && ACS.isCallbackCall());
if (!ACS.getCalledFunction())
continue;
for (unsigned u = 0, e = ACS.getNumArgOperands(); u < e; u++) {
// Test if the underlying call site operand is argument number u of the
// callback callee.
if (ACS.getCallArgOperandNo(u) != ArgNo)
continue;
assert(ACS.getCalledFunction()->arg_size() > u &&
"ACS mapped into var-args arguments!");
if (CBCandidateArg.hasValue()) {
CBCandidateArg = nullptr;
break;
}
CBCandidateArg = ACS.getCalledFunction()->getArg(u);
}
}
// If we found a unique callback candidate argument, return it.
if (CBCandidateArg.hasValue() && CBCandidateArg.getValue())
return CBCandidateArg.getValue();
// If no callbacks were found, or none used the underlying call site operand
// exclusively, use the direct callee argument if available.
const Function *Callee = CB.getCalledFunction();
if (Callee && Callee->arg_size() > unsigned(ArgNo))
return Callee->getArg(ArgNo);
return nullptr;
}
ChangeStatus AbstractAttribute::update(Attributor &A) {
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
if (getState().isAtFixpoint())
return HasChanged;
LLVM_DEBUG(dbgs() << "[Attributor] Update: " << *this << "\n");
HasChanged = updateImpl(A);
LLVM_DEBUG(dbgs() << "[Attributor] Update " << HasChanged << " " << *this
<< "\n");
return HasChanged;
}
ChangeStatus
IRAttributeManifest::manifestAttrs(Attributor &A, const IRPosition &IRP,
const ArrayRef<Attribute> &DeducedAttrs) {
Function *ScopeFn = IRP.getAnchorScope();
IRPosition::Kind PK = IRP.getPositionKind();
// In the following some generic code that will manifest attributes in
// DeducedAttrs if they improve the current IR. Due to the different
// annotation positions we use the underlying AttributeList interface.
AttributeList Attrs;
switch (PK) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
return ChangeStatus::UNCHANGED;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
Attrs = ScopeFn->getAttributes();
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
Attrs = cast<CallBase>(IRP.getAnchorValue()).getAttributes();
break;
}
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
LLVMContext &Ctx = IRP.getAnchorValue().getContext();
for (const Attribute &Attr : DeducedAttrs) {
if (!addIfNotExistent(Ctx, Attr, Attrs, IRP.getAttrIdx()))
continue;
HasChanged = ChangeStatus::CHANGED;
}
if (HasChanged == ChangeStatus::UNCHANGED)
return HasChanged;
switch (PK) {
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
ScopeFn->setAttributes(Attrs);
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
cast<CallBase>(IRP.getAnchorValue()).setAttributes(Attrs);
break;
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
break;
}
return HasChanged;
}
const IRPosition IRPosition::EmptyKey(DenseMapInfo<void *>::getEmptyKey());
const IRPosition
IRPosition::TombstoneKey(DenseMapInfo<void *>::getTombstoneKey());
SubsumingPositionIterator::SubsumingPositionIterator(const IRPosition &IRP) {
IRPositions.emplace_back(IRP);
const auto *CB = dyn_cast<CallBase>(&IRP.getAnchorValue());
switch (IRP.getPositionKind()) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
case IRPosition::IRP_FUNCTION:
return;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_RETURNED:
IRPositions.emplace_back(IRPosition::function(*IRP.getAnchorScope()));
return;
case IRPosition::IRP_CALL_SITE:
assert(CB && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles())
if (const Function *Callee = CB->getCalledFunction())
IRPositions.emplace_back(IRPosition::function(*Callee));
return;
case IRPosition::IRP_CALL_SITE_RETURNED:
assert(CB && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles()) {
if (const Function *Callee = CB->getCalledFunction()) {
IRPositions.emplace_back(IRPosition::returned(*Callee));
IRPositions.emplace_back(IRPosition::function(*Callee));
for (const Argument &Arg : Callee->args())
if (Arg.hasReturnedAttr()) {
IRPositions.emplace_back(
IRPosition::callsite_argument(*CB, Arg.getArgNo()));
IRPositions.emplace_back(
IRPosition::value(*CB->getArgOperand(Arg.getArgNo())));
IRPositions.emplace_back(IRPosition::argument(Arg));
}
}
}
IRPositions.emplace_back(IRPosition::callsite_function(*CB));
return;
case IRPosition::IRP_CALL_SITE_ARGUMENT: {
int ArgNo = IRP.getArgNo();
assert(CB && ArgNo >= 0 && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!CB->hasOperandBundles()) {
const Function *Callee = CB->getCalledFunction();
if (Callee && Callee->arg_size() > unsigned(ArgNo))
IRPositions.emplace_back(IRPosition::argument(*Callee->getArg(ArgNo)));
if (Callee)
IRPositions.emplace_back(IRPosition::function(*Callee));
}
IRPositions.emplace_back(IRPosition::value(IRP.getAssociatedValue()));
return;
}
}
}
bool IRPosition::hasAttr(ArrayRef<Attribute::AttrKind> AKs,
bool IgnoreSubsumingPositions, Attributor *A) const {
SmallVector<Attribute, 4> Attrs;
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs)
if (EquivIRP.getAttrsFromIRAttr(AK, Attrs))
return true;
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
if (A)
for (Attribute::AttrKind AK : AKs)
if (getAttrsFromAssumes(AK, Attrs, *A))
return true;
return false;
}
void IRPosition::getAttrs(ArrayRef<Attribute::AttrKind> AKs,
SmallVectorImpl<Attribute> &Attrs,
bool IgnoreSubsumingPositions, Attributor *A) const {
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs)
EquivIRP.getAttrsFromIRAttr(AK, Attrs);
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
if (A)
for (Attribute::AttrKind AK : AKs)
getAttrsFromAssumes(AK, Attrs, *A);
}
bool IRPosition::getAttrsFromIRAttr(Attribute::AttrKind AK,
SmallVectorImpl<Attribute> &Attrs) const {
if (getPositionKind() == IRP_INVALID || getPositionKind() == IRP_FLOAT)
return false;
AttributeList AttrList;
if (const auto *CB = dyn_cast<CallBase>(&getAnchorValue()))
AttrList = CB->getAttributes();
else
AttrList = getAssociatedFunction()->getAttributes();
bool HasAttr = AttrList.hasAttribute(getAttrIdx(), AK);
if (HasAttr)
Attrs.push_back(AttrList.getAttribute(getAttrIdx(), AK));
return HasAttr;
}
bool IRPosition::getAttrsFromAssumes(Attribute::AttrKind AK,
SmallVectorImpl<Attribute> &Attrs,
Attributor &A) const {
assert(getPositionKind() != IRP_INVALID && "Did expect a valid position!");
Value &AssociatedValue = getAssociatedValue();
const Assume2KnowledgeMap &A2K =
A.getInfoCache().getKnowledgeMap().lookup({&AssociatedValue, AK});
// Check if we found any potential assume use, if not we don't need to create
// explorer iterators.
if (A2K.empty())
return false;
LLVMContext &Ctx = AssociatedValue.getContext();
unsigned AttrsSize = Attrs.size();
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
auto EIt = Explorer.begin(getCtxI()), EEnd = Explorer.end(getCtxI());
for (auto &It : A2K)
if (Explorer.findInContextOf(It.first, EIt, EEnd))
Attrs.push_back(Attribute::get(Ctx, AK, It.second.Max));
return AttrsSize != Attrs.size();
}
void IRPosition::verify() {
#ifdef EXPENSIVE_CHECKS
switch (getPositionKind()) {
case IRP_INVALID:
assert(!Enc.getOpaqueValue() &&
"Expected a nullptr for an invalid position!");
return;
case IRP_FLOAT:
assert((!isa<CallBase>(&getAssociatedValue()) &&
!isa<Argument>(&getAssociatedValue())) &&
"Expected specialized kind for call base and argument values!");
return;
case IRP_RETURNED:
assert(isa<Function>(getAsValuePtr()) &&
"Expected function for a 'returned' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE_RETURNED:
assert((isa<CallBase>(getAsValuePtr())) &&
"Expected call base for 'call site returned' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE:
assert((isa<CallBase>(getAsValuePtr())) &&
"Expected call base for 'call site function' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_FUNCTION:
assert(isa<Function>(getAsValuePtr()) &&
"Expected function for a 'function' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_ARGUMENT:
assert(isa<Argument>(getAsValuePtr()) &&
"Expected argument for a 'argument' position!");
assert(getAsValuePtr() == &getAssociatedValue() &&
"Associated value mismatch!");
return;
case IRP_CALL_SITE_ARGUMENT: {
Use *U = getAsUsePtr();
assert(U && "Expected use for a 'call site argument' position!");
assert(isa<CallBase>(U->getUser()) &&
"Expected call base user for a 'call site argument' position!");
assert(cast<CallBase>(U->getUser())->isArgOperand(U) &&
"Expected call base argument operand for a 'call site argument' "
"position");
assert(cast<CallBase>(U->getUser())->getArgOperandNo(U) ==
unsigned(getArgNo()) &&
"Argument number mismatch!");
assert(U->get() == &getAssociatedValue() && "Associated value mismatch!");
return;
}
}
#endif
}
Optional<Constant *>
Attributor::getAssumedConstant(const Value &V, const AbstractAttribute &AA,
bool &UsedAssumedInformation) {
const auto &ValueSimplifyAA = getAAFor<AAValueSimplify>(
AA, IRPosition::value(V), /* TrackDependence */ false);
Optional<Value *> SimplifiedV =
ValueSimplifyAA.getAssumedSimplifiedValue(*this);
bool IsKnown = ValueSimplifyAA.isKnown();
UsedAssumedInformation |= !IsKnown;
if (!SimplifiedV.hasValue()) {
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return llvm::None;
}
if (isa_and_nonnull<UndefValue>(SimplifiedV.getValue())) {
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return llvm::None;
}
Constant *CI = dyn_cast_or_null<Constant>(SimplifiedV.getValue());
if (CI && CI->getType() != V.getType()) {
// TODO: Check for a save conversion.
return nullptr;
}
if (CI)
recordDependence(ValueSimplifyAA, AA, DepClassTy::OPTIONAL);
return CI;
}
Attributor::~Attributor() {
// The abstract attributes are allocated via the BumpPtrAllocator Allocator,
// thus we cannot delete them. We can, and want to, destruct them though.
for (auto &DepAA : DG.SyntheticRoot.Deps) {
AbstractAttribute *AA = cast<AbstractAttribute>(DepAA.getPointer());
AA->~AbstractAttribute();
}
}
bool Attributor::isAssumedDead(const AbstractAttribute &AA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
const IRPosition &IRP = AA.getIRPosition();
if (!Functions.count(IRP.getAnchorScope()))
return false;
return isAssumedDead(IRP, &AA, FnLivenessAA, CheckBBLivenessOnly, DepClass);
}
bool Attributor::isAssumedDead(const Use &U,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
Instruction *UserI = dyn_cast<Instruction>(U.getUser());
if (!UserI)
return isAssumedDead(IRPosition::value(*U.get()), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
if (auto *CB = dyn_cast<CallBase>(UserI)) {
// For call site argument uses we can check if the argument is
// unused/dead.
if (CB->isArgOperand(&U)) {
const IRPosition &CSArgPos =
IRPosition::callsite_argument(*CB, CB->getArgOperandNo(&U));
return isAssumedDead(CSArgPos, QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(UserI)) {
const IRPosition &RetPos = IRPosition::returned(*RI->getFunction());
return isAssumedDead(RetPos, QueryingAA, FnLivenessAA, CheckBBLivenessOnly,
DepClass);
} else if (PHINode *PHI = dyn_cast<PHINode>(UserI)) {
BasicBlock *IncomingBB = PHI->getIncomingBlock(U);
return isAssumedDead(*IncomingBB->getTerminator(), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
return isAssumedDead(IRPosition::value(*UserI), QueryingAA, FnLivenessAA,
CheckBBLivenessOnly, DepClass);
}
bool Attributor::isAssumedDead(const Instruction &I,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
if (!FnLivenessAA)
FnLivenessAA = lookupAAFor<AAIsDead>(IRPosition::function(*I.getFunction()),
QueryingAA,
/* TrackDependence */ false);
// If we have a context instruction and a liveness AA we use it.
if (FnLivenessAA &&
FnLivenessAA->getIRPosition().getAnchorScope() == I.getFunction() &&
FnLivenessAA->isAssumedDead(&I)) {
if (QueryingAA)
recordDependence(*FnLivenessAA, *QueryingAA, DepClass);
return true;
}
if (CheckBBLivenessOnly)
return false;
const AAIsDead &IsDeadAA = getOrCreateAAFor<AAIsDead>(
IRPosition::value(I), QueryingAA, /* TrackDependence */ false);
// Don't check liveness for AAIsDead.
if (QueryingAA == &IsDeadAA)
return false;
if (IsDeadAA.isAssumedDead()) {
if (QueryingAA)
recordDependence(IsDeadAA, *QueryingAA, DepClass);
return true;
}
return false;
}
bool Attributor::isAssumedDead(const IRPosition &IRP,
const AbstractAttribute *QueryingAA,
const AAIsDead *FnLivenessAA,
bool CheckBBLivenessOnly, DepClassTy DepClass) {
Instruction *CtxI = IRP.getCtxI();
if (CtxI &&
isAssumedDead(*CtxI, QueryingAA, FnLivenessAA,
/* CheckBBLivenessOnly */ true,
CheckBBLivenessOnly ? DepClass : DepClassTy::OPTIONAL))
return true;
if (CheckBBLivenessOnly)
return false;
// If we haven't succeeded we query the specific liveness info for the IRP.
const AAIsDead *IsDeadAA;
if (IRP.getPositionKind() == IRPosition::IRP_CALL_SITE)
IsDeadAA = &getOrCreateAAFor<AAIsDead>(
IRPosition::callsite_returned(cast<CallBase>(IRP.getAssociatedValue())),
QueryingAA, /* TrackDependence */ false);
else
IsDeadAA = &getOrCreateAAFor<AAIsDead>(IRP, QueryingAA,
/* TrackDependence */ false);
// Don't check liveness for AAIsDead.
if (QueryingAA == IsDeadAA)
return false;
if (IsDeadAA->isAssumedDead()) {
if (QueryingAA)
recordDependence(*IsDeadAA, *QueryingAA, DepClass);
return true;
}
return false;
}
bool Attributor::checkForAllUses(function_ref<bool(const Use &, bool &)> Pred,
const AbstractAttribute &QueryingAA,
const Value &V, DepClassTy LivenessDepClass) {
// Check the trivial case first as it catches void values.
if (V.use_empty())
return true;
// If the value is replaced by another one, for now a constant, we do not have
// uses. Note that this requires users of `checkForAllUses` to not recurse but
// instead use the `follow` callback argument to look at transitive users,
// however, that should be clear from the presence of the argument.
bool UsedAssumedInformation = false;
Optional<Constant *> C =
getAssumedConstant(V, QueryingAA, UsedAssumedInformation);
if (C.hasValue() && C.getValue()) {
LLVM_DEBUG(dbgs() << "[Attributor] Value is simplified, uses skipped: " << V
<< " -> " << *C.getValue() << "\n");
return true;
}
const IRPosition &IRP = QueryingAA.getIRPosition();
SmallVector<const Use *, 16> Worklist;
SmallPtrSet<const Use *, 16> Visited;
for (const Use &U : V.uses())
Worklist.push_back(&U);
LLVM_DEBUG(dbgs() << "[Attributor] Got " << Worklist.size()
<< " initial uses to check\n");
const Function *ScopeFn = IRP.getAnchorScope();
const auto *LivenessAA =
ScopeFn ? &getAAFor<AAIsDead>(QueryingAA, IRPosition::function(*ScopeFn),
/* TrackDependence */ false)
: nullptr;
while (!Worklist.empty()) {
const Use *U = Worklist.pop_back_val();
if (!Visited.insert(U).second)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Check use: " << **U << " in "
<< *U->getUser() << "\n");
if (isAssumedDead(*U, &QueryingAA, LivenessAA,
/* CheckBBLivenessOnly */ false, LivenessDepClass)) {
LLVM_DEBUG(dbgs() << "[Attributor] Dead use, skip!\n");
continue;
}
if (U->getUser()->isDroppable()) {
LLVM_DEBUG(dbgs() << "[Attributor] Droppable user, skip!\n");
continue;
}
bool Follow = false;
if (!Pred(*U, Follow))
return false;
if (!Follow)
continue;
for (const Use &UU : U->getUser()->uses())
Worklist.push_back(&UU);
}
return true;
}
bool Attributor::checkForAllCallSites(function_ref<bool(AbstractCallSite)> Pred,
const AbstractAttribute &QueryingAA,
bool RequireAllCallSites,
bool &AllCallSitesKnown) {
// We can try to determine information from
// the call sites. However, this is only possible all call sites are known,
// hence the function has internal linkage.
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction) {
LLVM_DEBUG(dbgs() << "[Attributor] No function associated with " << IRP
<< "\n");
AllCallSitesKnown = false;
return false;
}
return checkForAllCallSites(Pred, *AssociatedFunction, RequireAllCallSites,
&QueryingAA, AllCallSitesKnown);
}
bool Attributor::checkForAllCallSites(function_ref<bool(AbstractCallSite)> Pred,
const Function &Fn,
bool RequireAllCallSites,
const AbstractAttribute *QueryingAA,
bool &AllCallSitesKnown) {
if (RequireAllCallSites && !Fn.hasLocalLinkage()) {
LLVM_DEBUG(
dbgs()
<< "[Attributor] Function " << Fn.getName()
<< " has no internal linkage, hence not all call sites are known\n");
AllCallSitesKnown = false;
return false;
}
// If we do not require all call sites we might not see all.
AllCallSitesKnown = RequireAllCallSites;
SmallVector<const Use *, 8> Uses(make_pointer_range(Fn.uses()));
for (unsigned u = 0; u < Uses.size(); ++u) {
const Use &U = *Uses[u];
LLVM_DEBUG(dbgs() << "[Attributor] Check use: " << *U << " in "
<< *U.getUser() << "\n");
if (isAssumedDead(U, QueryingAA, nullptr, /* CheckBBLivenessOnly */ true)) {
LLVM_DEBUG(dbgs() << "[Attributor] Dead use, skip!\n");
continue;
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U.getUser())) {
if (CE->isCast() && CE->getType()->isPointerTy() &&
CE->getType()->getPointerElementType()->isFunctionTy()) {
for (const Use &CEU : CE->uses())
Uses.push_back(&CEU);
continue;
}
}
AbstractCallSite ACS(&U);
if (!ACS) {
LLVM_DEBUG(dbgs() << "[Attributor] Function " << Fn.getName()
<< " has non call site use " << *U.get() << " in "
<< *U.getUser() << "\n");
// BlockAddress users are allowed.
if (isa<BlockAddress>(U.getUser()))
continue;
return false;
}
const Use *EffectiveUse =
ACS.isCallbackCall() ? &ACS.getCalleeUseForCallback() : &U;
if (!ACS.isCallee(EffectiveUse)) {
if (!RequireAllCallSites)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] User " << EffectiveUse->getUser()
<< " is an invalid use of " << Fn.getName() << "\n");
return false;
}
// Make sure the arguments that can be matched between the call site and the
// callee argee on their type. It is unlikely they do not and it doesn't
// make sense for all attributes to know/care about this.
assert(&Fn == ACS.getCalledFunction() && "Expected known callee");
unsigned MinArgsParams =
std::min(size_t(ACS.getNumArgOperands()), Fn.arg_size());
for (unsigned u = 0; u < MinArgsParams; ++u) {
Value *CSArgOp = ACS.getCallArgOperand(u);
if (CSArgOp && Fn.getArg(u)->getType() != CSArgOp->getType()) {
LLVM_DEBUG(
dbgs() << "[Attributor] Call site / callee argument type mismatch ["
<< u << "@" << Fn.getName() << ": "
<< *Fn.getArg(u)->getType() << " vs. "
<< *ACS.getCallArgOperand(u)->getType() << "\n");
return false;
}
}
if (Pred(ACS))
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Call site callback failed for "
<< *ACS.getInstruction() << "\n");
return false;
}
return true;
}
bool Attributor::checkForAllReturnedValuesAndReturnInsts(
function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)> Pred,
const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide return instructions we have to have an exact
// definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// If this is a call site query we use the call site specific return values
// and liveness information.
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal = getAAFor<AAReturnedValues>(QueryingAA, QueryIRP);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(Pred);
}
bool Attributor::checkForAllReturnedValues(
function_ref<bool(Value &)> Pred, const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal = getAAFor<AAReturnedValues>(QueryingAA, QueryIRP);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(
[&](Value &RV, const SmallSetVector<ReturnInst *, 4> &) {
return Pred(RV);
});
}
static bool checkForAllInstructionsImpl(
Attributor *A, InformationCache::OpcodeInstMapTy &OpcodeInstMap,
function_ref<bool(Instruction &)> Pred, const AbstractAttribute *QueryingAA,
const AAIsDead *LivenessAA, const ArrayRef<unsigned> &Opcodes,
bool CheckBBLivenessOnly = false) {
for (unsigned Opcode : Opcodes) {
// Check if we have instructions with this opcode at all first.
auto *Insts = OpcodeInstMap.lookup(Opcode);
if (!Insts)
continue;
for (Instruction *I : *Insts) {
// Skip dead instructions.
if (A && A->isAssumedDead(IRPosition::value(*I), QueryingAA, LivenessAA,
CheckBBLivenessOnly))
continue;
if (!Pred(*I))
return false;
}
}
return true;
}
bool Attributor::checkForAllInstructions(function_ref<bool(Instruction &)> Pred,
const AbstractAttribute &QueryingAA,
const ArrayRef<unsigned> &Opcodes,
bool CheckBBLivenessOnly) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide instructions we have to have an exact definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto *LivenessAA =
CheckBBLivenessOnly ? nullptr
: &(getAAFor<AAIsDead>(QueryingAA, QueryIRP,
/* TrackDependence */ false));
auto &OpcodeInstMap =
InfoCache.getOpcodeInstMapForFunction(*AssociatedFunction);
if (!checkForAllInstructionsImpl(this, OpcodeInstMap, Pred, &QueryingAA,
LivenessAA, Opcodes, CheckBBLivenessOnly))
return false;
return true;
}
bool Attributor::checkForAllReadWriteInstructions(
function_ref<bool(Instruction &)> Pred, AbstractAttribute &QueryingAA) {
const Function *AssociatedFunction =
QueryingAA.getIRPosition().getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &LivenessAA =
getAAFor<AAIsDead>(QueryingAA, QueryIRP, /* TrackDependence */ false);
for (Instruction *I :
InfoCache.getReadOrWriteInstsForFunction(*AssociatedFunction)) {
// Skip dead instructions.
if (isAssumedDead(IRPosition::value(*I), &QueryingAA, &LivenessAA))
continue;
if (!Pred(*I))
return false;
}
return true;
}
void Attributor::runTillFixpoint() {
TimeTraceScope TimeScope("Attributor::runTillFixpoint");
LLVM_DEBUG(dbgs() << "[Attributor] Identified and initialized "
<< DG.SyntheticRoot.Deps.size()
<< " abstract attributes.\n");
// Now that all abstract attributes are collected and initialized we start
// the abstract analysis.
unsigned IterationCounter = 1;
SmallVector<AbstractAttribute *, 32> ChangedAAs;
SetVector<AbstractAttribute *> Worklist, InvalidAAs;
Worklist.insert(DG.SyntheticRoot.begin(), DG.SyntheticRoot.end());
do {
// Remember the size to determine new attributes.
size_t NumAAs = DG.SyntheticRoot.Deps.size();
LLVM_DEBUG(dbgs() << "\n\n[Attributor] #Iteration: " << IterationCounter
<< ", Worklist size: " << Worklist.size() << "\n");
// For invalid AAs we can fix dependent AAs that have a required dependence,
// thereby folding long dependence chains in a single step without the need
// to run updates.
for (unsigned u = 0; u < InvalidAAs.size(); ++u) {
AbstractAttribute *InvalidAA = InvalidAAs[u];
// Check the dependences to fast track invalidation.
LLVM_DEBUG(dbgs() << "[Attributor] InvalidAA: " << *InvalidAA << " has "
<< InvalidAA->Deps.size()
<< " required & optional dependences\n");
while (!InvalidAA->Deps.empty()) {
const auto &Dep = InvalidAA->Deps.back();
InvalidAA->Deps.pop_back();
AbstractAttribute *DepAA = cast<AbstractAttribute>(Dep.getPointer());
if (Dep.getInt() == unsigned(DepClassTy::OPTIONAL)) {
Worklist.insert(DepAA);
continue;
}
DepAA->getState().indicatePessimisticFixpoint();