forked from OSchip/llvm-project
Fixing build error from commit 95cbc3d
[Attributor] Liveness analysis. Liveness analysis abstract attribute used to indicate which BasicBlocks are dead and can therefore be ignored. Right now we are only looking at noreturn calls. Reviewers: jdoerfert, uenoku Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D64162 llvm-svn: 366769
This commit is contained in:
Stefan Stipanovic
parent
b2a9cf7764
commit
6058b86373
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@ -805,6 +805,46 @@ struct AANoAlias : public AbstractAttribute {
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static constexpr Attribute::AttrKind ID = Attribute::NoAlias;
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};
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/// An AbstractAttribute for noreturn.
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struct AANoReturn : public AbstractAttribute {
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/// See AbstractAttribute::AbstractAttribute(...).
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AANoReturn(Value &V, InformationCache &InfoCache)
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: AbstractAttribute(V, InfoCache) {}
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/// Return true if the underlying object is known to never return.
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virtual bool isKnownNoReturn() const = 0;
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/// Return true if the underlying object is assumed to never return.
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virtual bool isAssumedNoReturn() const = 0;
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/// See AbstractAttribute::getAttrKind()
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Attribute::AttrKind getAttrKind() const override { return ID; }
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/// The identifier used by the Attributor for this class of attributes.
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static constexpr Attribute::AttrKind ID = Attribute::NoReturn;
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};
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/// An abstract interface for liveness abstract attribute.
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struct AAIsDead : public AbstractAttribute {
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/// See AbstractAttribute::AbstractAttribute(...).
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AAIsDead(Value &V, InformationCache &InfoCache)
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: AbstractAttribute(V, InfoCache) {}
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/// See AbstractAttribute::getAttrKind()
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Attribute::AttrKind getAttrKind() const override { return ID; }
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static constexpr Attribute::AttrKind ID =
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Attribute::AttrKind(Attribute::EndAttrKinds + 1);
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/// Returns true if \p BB is assumed dead.
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virtual bool isAssumedDead(BasicBlock *BB) const = 0;
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/// Returns true if \p BB is known dead.
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virtual bool isKnownDead(BasicBlock *BB) const = 0;
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
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@ -271,6 +271,9 @@ inline unsigned getKnownAlignment(Value *V, const DataLayout &DL,
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return getOrEnforceKnownAlignment(V, 0, DL, CxtI, AC, DT);
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}
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/// This function converts the specified invoek into a normall call.
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void changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr);
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///===---------------------------------------------------------------------===//
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/// Dbg Intrinsic utilities
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///
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@ -16,6 +16,7 @@
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#include "llvm/Transforms/IPO/Attributor.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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@ -31,6 +32,9 @@
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include <cassert>
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using namespace llvm;
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@ -1411,6 +1415,173 @@ ChangeStatus AANoAliasReturned::updateImpl(Attributor &A) {
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return ChangeStatus::UNCHANGED;
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}
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/// -------------------AAIsDead Function Attribute-----------------------
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struct AAIsDeadFunction : AAIsDead, BooleanState {
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AAIsDeadFunction(Function &F, InformationCache &InfoCache)
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: AAIsDead(F, InfoCache) {}
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/// See AbstractAttribute::getState()
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/// {
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AbstractState &getState() override { return *this; }
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const AbstractState &getState() const override { return *this; }
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/// }
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/// See AbstractAttribute::getManifestPosition().
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ManifestPosition getManifestPosition() const override { return MP_FUNCTION; }
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void initialize(Attributor &A) override {
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Function &F = getAnchorScope();
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ToBeExploredPaths.insert(&(F.getEntryBlock().front()));
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AssumedLiveBlocks.insert(&(F.getEntryBlock()));
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for (size_t i = 0; i < ToBeExploredPaths.size(); ++i)
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explorePath(A, ToBeExploredPaths[i]);
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}
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/// Explores new instructions starting from \p I. If instruction is dead, stop
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/// and return true if it discovered a new instruction.
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bool explorePath(Attributor &A, Instruction *I);
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const std::string getAsStr() const override {
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return "LiveBBs(" + std::to_string(AssumedLiveBlocks.size()) + "/" +
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std::to_string(getAnchorScope().size()) + ")";
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}
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/// See AbstractAttribute::manifest(...).
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ChangeStatus manifest(Attributor &A) override {
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assert(getState().isValidState() &&
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"Attempted to manifest an invalid state!");
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ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
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for (Instruction *I : NoReturnCalls) {
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BasicBlock *BB = I->getParent();
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/// Invoke is replaced with a call and unreachable is placed after it.
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if (auto *II = dyn_cast<InvokeInst>(I)) {
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changeToCall(II);
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changeToUnreachable(BB->getTerminator(), /* UseLLVMTrap */ false);
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LLVM_DEBUG(dbgs() << "[AAIsDead] Replaced invoke with call inst\n");
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continue;
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}
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SplitBlock(BB, I->getNextNode());
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changeToUnreachable(BB->getTerminator(), /* UseLLVMTrap */ false);
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HasChanged = ChangeStatus::CHANGED;
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}
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return HasChanged;
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}
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/// See AbstractAttribute::updateImpl(...).
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ChangeStatus updateImpl(Attributor &A) override;
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/// See AAIsDead::isAssumedDead().
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bool isAssumedDead(BasicBlock *BB) const override {
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if (!getAssumed())
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return false;
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return !AssumedLiveBlocks.count(BB);
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}
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/// See AAIsDead::isKnownDead().
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bool isKnownDead(BasicBlock *BB) const override {
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if (!getKnown())
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return false;
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return !AssumedLiveBlocks.count(BB);
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}
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/// Collection of to be explored paths.
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SmallSetVector<Instruction *, 8> ToBeExploredPaths;
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/// Collection of all assumed live BasicBlocks.
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DenseSet<BasicBlock *> AssumedLiveBlocks;
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/// Collection of calls with noreturn attribute, assumed or knwon.
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SmallSetVector<Instruction *, 4> NoReturnCalls;
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};
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bool AAIsDeadFunction::explorePath(Attributor &A, Instruction *I) {
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BasicBlock *BB = I->getParent();
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while (I) {
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ImmutableCallSite ICS(I);
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if (ICS) {
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auto *NoReturnAA = A.getAAFor<AANoReturn>(*this, *I);
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if (NoReturnAA && NoReturnAA->isAssumedNoReturn()) {
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if (!NoReturnCalls.insert(I))
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// If I is already in the NoReturnCalls set, then it stayed noreturn
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// and we didn't discover any new instructions.
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return false;
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// Discovered new noreturn call, return true to indicate that I is not
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// noreturn anymore and should be deleted from NoReturnCalls.
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return true;
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}
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if (ICS.hasFnAttr(Attribute::NoReturn)) {
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if(!NoReturnCalls.insert(I))
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return false;
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return true;
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}
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}
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I = I->getNextNode();
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}
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// get new paths (reachable blocks).
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for (BasicBlock *SuccBB : successors(BB)) {
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Instruction *Inst = &(SuccBB->front());
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AssumedLiveBlocks.insert(SuccBB);
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ToBeExploredPaths.insert(Inst);
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}
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return true;
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}
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ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
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Function &F = getAnchorScope();
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// Temporary collection to iterate over existing noreturn instructions. This
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// will alow easier modification of NoReturnCalls collection
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SmallVector<Instruction *, 8> NoReturnChanged;
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ChangeStatus Status = ChangeStatus::UNCHANGED;
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for (Instruction *I : NoReturnCalls)
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NoReturnChanged.push_back(I);
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for (Instruction *I : NoReturnChanged) {
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size_t Size = ToBeExploredPaths.size();
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// Still noreturn.
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if (!explorePath(A, I))
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continue;
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NoReturnCalls.remove(I);
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// No new paths.
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if (Size == ToBeExploredPaths.size())
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continue;
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// At least one new path.
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Status = ChangeStatus::CHANGED;
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// explore new paths.
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while (Size != ToBeExploredPaths.size())
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explorePath(A, ToBeExploredPaths[Size++]);
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}
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LLVM_DEBUG(dbgs() << "[AAIsDead] AssumedLiveBlocks: "
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<< AssumedLiveBlocks.size()
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<< "Total number of blocks: " << F.size() << "\n");
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return Status;
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}
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/// ----------------------------------------------------------------------------
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/// Attributor
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/// ----------------------------------------------------------------------------
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@ -1627,6 +1798,9 @@ void Attributor::identifyDefaultAbstractAttributes(
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// Every function might be "will-return".
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registerAA(*new AAWillReturnFunction(F, InfoCache));
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// Check for dead BasicBlocks in every function.
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registerAA(*new AAIsDeadFunction(F, InfoCache));
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// Walk all instructions to find more attribute opportunities and also
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// interesting instructions that might be queried by abstract attributes
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// during their initialization or update.
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@ -1964,7 +1964,7 @@ unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap,
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}
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/// changeToCall - Convert the specified invoke into a normal call.
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static void changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr) {
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void llvm::changeToCall(InvokeInst *II, DomTreeUpdater *DTU) {
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SmallVector<Value*, 8> Args(II->arg_begin(), II->arg_end());
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SmallVector<OperandBundleDef, 1> OpBundles;
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II->getOperandBundlesAsDefs(OpBundles);
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@ -0,0 +1,250 @@
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; RUN: opt -attributor --attributor-disable=false -S < %s | FileCheck %s
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declare void @no_return_call() noreturn
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declare void @normal_call()
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declare i32 @foo()
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declare i32 @foo_noreturn() noreturn
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declare i32 @bar()
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; TEST 1: cond.true is dead, but cond.end is not, since cond.false is live
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; This is just an example. For example we can put a sync call in a
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; dead block and check if it is deduced.
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define i32 @dead_block_present(i32 %a) #0 {
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entry:
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%cmp = icmp eq i32 %a, 0
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br i1 %cmp, label %cond.true, label %cond.false
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cond.true: ; preds = %entry
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call void @no_return_call()
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; CHECK: call void @no_return_call()
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; CHECK-NEXT: unreachable
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%call = call i32 @foo()
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br label %cond.end
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cond.false: ; preds = %entry
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call void @normal_call()
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%call1 = call i32 @bar()
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br label %cond.end
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cond.end: ; preds = %cond.false, %cond.true
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%cond = phi i32 [ %call, %cond.true ], [ %call1, %cond.false ]
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ret i32 %cond
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}
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; TEST 2: both cond.true and cond.false are dead, therfore cond.end is dead as well.
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define i32 @all_dead(i32 %a) #0 {
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entry:
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%cmp = icmp eq i32 %a, 0
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br i1 %cmp, label %cond.true, label %cond.false
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cond.true: ; preds = %entry
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call void @no_return_call()
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; CHECK: call void @no_return_call()
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; CHECK-NEXT: unreachable
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%call = call i32 @foo()
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br label %cond.end
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cond.false: ; preds = %entry
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call void @no_return_call()
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; CHECK: call void @no_return_call()
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; CHECK-NEXT: unreachable
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%call1 = call i32 @bar()
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br label %cond.end
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cond.end: ; preds = %cond.false, %cond.true
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%cond = phi i32 [ %call, %cond.true ], [ %call1, %cond.false ]
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ret i32 %cond
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}
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declare i32 @__gxx_personality_v0(...)
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; TEST 3: All blocks are live.
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; CHECK: define i32 @all_live(i32 %a)
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define i32 @all_live(i32 %a) #0 {
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entry:
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%cmp = icmp eq i32 %a, 0
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br i1 %cmp, label %cond.true, label %cond.false
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cond.true: ; preds = %entry
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call void @normal_call()
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%call = call i32 @foo_noreturn()
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br label %cond.end
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cond.false: ; preds = %entry
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call void @normal_call()
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%call1 = call i32 @bar()
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br label %cond.end
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cond.end: ; preds = %cond.false, %cond.true
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%cond = phi i32 [ %call, %cond.true ], [ %call1, %cond.false ]
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ret i32 %cond
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}
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; TEST 4 noreturn invoke instruction replaced by a call and an unreachable instruction
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; put after it.
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; CHECK: define i32 @invoke_noreturn(i32 %a)
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define i32 @invoke_noreturn(i32 %a) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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entry:
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%cmp = icmp eq i32 %a, 0
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br i1 %cmp, label %cond.true, label %cond.false
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cond.true: ; preds = %entry
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call void @normal_call()
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%call = invoke i32 @foo_noreturn() to label %continue
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unwind label %cleanup
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; CHECK: call i32 @foo_noreturn()
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; CHECK-NEXT unreachable
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cond.false: ; preds = %entry
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call void @normal_call()
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%call1 = call i32 @bar()
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br label %cond.end
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cond.end: ; preds = %cond.false, %continue
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%cond = phi i32 [ %call, %continue ], [ %call1, %cond.false ]
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ret i32 %cond
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continue:
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br label %cond.end
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cleanup:
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%res = landingpad { i8*, i32 }
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catch i8* null
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ret i32 0
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}
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; TEST 5: Undefined behvior, taken from LangRef.
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; FIXME: Should be able to detect undefined behavior.
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; CHECK define @ub(i32)
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define void @ub(i32* ) {
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%poison = sub nuw i32 0, 1 ; Results in a poison value.
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%still_poison = and i32 %poison, 0 ; 0, but also poison.
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%poison_yet_again = getelementptr i32, i32* %0, i32 %still_poison
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store i32 0, i32* %poison_yet_again ; Undefined behavior due to store to poison.
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ret void
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}
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define void @inf_loop() #0 {
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entry:
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br label %while.body
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while.body: ; preds = %entry, %while.body
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br label %while.body
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}
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; TEST 6: Infinite loop.
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; FIXME: Detect infloops, and mark affected blocks dead.
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define i32 @test5(i32, i32) #0 {
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%3 = icmp sgt i32 %0, %1
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br i1 %3, label %cond.if, label %cond.elseif
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cond.if: ; preds = %2
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%4 = tail call i32 @bar()
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br label %cond.end
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cond.elseif: ; preds = %2
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call void @inf_loop()
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%5 = icmp slt i32 %0, %1
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br i1 %5, label %cond.end, label %cond.else
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cond.else: ; preds = %cond.elseif
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%6 = tail call i32 @foo()
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br label %cond.end
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cond.end: ; preds = %cond.if, %cond.else, %cond.elseif
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%7 = phi i32 [ %1, %cond.elseif ], [ 0, %cond.else ], [ 0, %cond.if ]
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ret i32 %7
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}
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define void @rec() #0 {
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entry:
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call void @rec()
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ret void
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}
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; TEST 7: Recursion
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; FIXME: everything after first block should be marked dead
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; and unreachable should be put after call to @rec().
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define i32 @test6(i32, i32) #0 {
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call void @rec()
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%3 = icmp sgt i32 %0, %1
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br i1 %3, label %cond.if, label %cond.elseif
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cond.if: ; preds = %2
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%4 = tail call i32 @bar()
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br label %cond.end
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cond.elseif: ; preds = %2
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call void @rec()
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%5 = icmp slt i32 %0, %1
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br i1 %5, label %cond.end, label %cond.else
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cond.else: ; preds = %cond.elseif
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%6 = tail call i32 @foo()
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br label %cond.end
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cond.end: ; preds = %cond.if, %cond.else, %cond.elseif
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%7 = phi i32 [ %1, %cond.elseif ], [ 0, %cond.else ], [ 0, %cond.if ]
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ret i32 %7
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}
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; TEST 8: Recursion
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; FIXME: contains recursive call to itself in cond.elseif block
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||||
|
||||
define i32 @test7(i32, i32) #0 {
|
||||
%3 = icmp sgt i32 %0, %1
|
||||
br i1 %3, label %cond.if, label %cond.elseif
|
||||
|
||||
cond.if: ; preds = %2
|
||||
%4 = tail call i32 @bar()
|
||||
br label %cond.end
|
||||
|
||||
cond.elseif: ; preds = %2
|
||||
%5 = tail call i32 @test7(i32 %0, i32 %1)
|
||||
%6 = icmp slt i32 %0, %1
|
||||
br i1 %6, label %cond.end, label %cond.else
|
||||
|
||||
cond.else: ; preds = %cond.elseif
|
||||
%7 = tail call i32 @foo()
|
||||
br label %cond.end
|
||||
|
||||
cond.end: ; preds = %cond.if, %cond.else, %cond.elseif
|
||||
%8 = phi i32 [ %1, %cond.elseif ], [ 0, %cond.else ], [ 0, %cond.if ]
|
||||
ret i32 %8
|
||||
}
|
||||
|
||||
; TEST 9: Only first block is live.
|
||||
|
||||
define i32 @first_block_no_return(i32 %a) #0 {
|
||||
entry:
|
||||
call void @no_return_call()
|
||||
; CHECK: call void @no_return_call()
|
||||
; CHECK-NEXT: unreachable
|
||||
%cmp = icmp eq i32 %a, 0
|
||||
br i1 %cmp, label %cond.true, label %cond.false
|
||||
|
||||
cond.true: ; preds = %entry
|
||||
call void @normal_call()
|
||||
%call = call i32 @foo()
|
||||
br label %cond.end
|
||||
|
||||
cond.false: ; preds = %entry
|
||||
call void @normal_call()
|
||||
%call1 = call i32 @bar()
|
||||
br label %cond.end
|
||||
|
||||
cond.end: ; preds = %cond.false, %cond.true
|
||||
%cond = phi i32 [ %call, %cond.true ], [ %call1, %cond.false ]
|
||||
ret i32 %cond
|
||||
}
|
||||
Loading…
Reference in New Issue