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Reverting [JumpThreading] Preservation of DT and LVI across the pass 

Stage 2 bootstrap failed:
http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules-2/builds/14434

llvm-svn: 320641
This commit is contained in:
Brian M. Rzycki 2017-12-13 22:01:17 +00:00
parent 3c7a35de7f
commit 580bc3c8fa
12 changed files with 99 additions and 893 deletions
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190
llvm/include/llvm/IR/DeferredDominance.h
View File

@ -1,190 +0,0 @@
//===- DeferredDominance.h - Deferred Dominators ----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the DeferredDominance class, which provides deferred
// updates to Dominators.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_DEFERREDDOMINANCE_H
#define LLVM_IR_DEFERREDDOMINANCE_H
#include "llvm/ADT/SmallSet.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
namespace llvm {
/// \brief Class to defer updates to a DominatorTree.
///
/// Definition: Applying updates to every edge insertion and deletion is
/// expensive and not necessary. When one needs the DominatorTree for analysis
/// they can request a flush() to perform a larger batch update. This has the
/// advantage of the DominatorTree inspecting the set of updates to find
/// duplicates or unnecessary subtree updates.
///
/// The scope of DeferredDominance operates at a Function level.
///
/// It is not necessary for the user to scrub the updates for duplicates or
/// updates that point to the same block (Delete, BB_A, BB_A). Performance
/// can be gained if the caller attempts to batch updates before submitting
/// to applyUpdates(ArrayRef) in cases where duplicate edge requests will
/// occur.
///
/// It is required for the state of the LLVM IR to be applied *before*
/// submitting updates. The update routines must analyze the current state
/// between a pair of (From, To) basic blocks to determine if the update
/// needs to be queued.
/// Example (good):
/// TerminatorInstructionBB->removeFromParent();
/// DDT->deleteEdge(BB, Successor);
/// Example (bad):
/// DDT->deleteEdge(BB, Successor);
/// TerminatorInstructionBB->removeFromParent();
class DeferredDominance {
public:
DeferredDominance(DominatorTree &DT_) : DT(DT_) {}
/// \brief Queues multiple updates and discards duplicates.
void applyUpdates(ArrayRef<DominatorTree::UpdateType> Updates) {
SmallVector<DominatorTree::UpdateType, 8> Seen;
for (auto U : Updates)
// Avoid duplicates to applyUpdate() to save on analysis.
if (std::none_of(Seen.begin(), Seen.end(),
[U](DominatorTree::UpdateType S) { return S == U; })) {
Seen.push_back(U);
applyUpdate(U.getKind(), U.getFrom(), U.getTo());
}
}
void insertEdge(BasicBlock *From, BasicBlock *To) {
applyUpdate(DominatorTree::Insert, From, To);
}
void deleteEdge(BasicBlock *From, BasicBlock *To) {
applyUpdate(DominatorTree::Delete, From, To);
}
/// \brief Delays the deletion of a basic block until a flush() event.
void deleteBB(BasicBlock *DelBB) {
assert(DelBB && "Invalid push_back of nullptr DelBB.");
assert(pred_empty(DelBB) && "DelBB has one or more predecessors.");
// DelBB is unreachable and all its instructions are dead.
while (!DelBB->empty()) {
Instruction &I = DelBB->back();
// Replace used instructions with an arbitrary value (undef).
if (!I.use_empty())
I.replaceAllUsesWith(llvm::UndefValue::get(I.getType()));
DelBB->getInstList().pop_back();
}
// Make sure DelBB has a valid terminator instruction. As long as DelBB is
// a Child of Function F it must contain valid IR.
new UnreachableInst(DelBB->getContext(), DelBB);
DeletedBBs.insert(DelBB);
}
/// \brief Returns true if DelBB is awaiting deletion at a flush() event.
bool pendingDeletedBB(BasicBlock *DelBB) {
if (DeletedBBs.empty())
return false;
return DeletedBBs.count(DelBB) != 0;
}
/// \brief Flushes all pending updates and block deletions. Returns a
/// correct DominatorTree reference to be used by the caller for analysis.
DominatorTree &flush() {
// Updates to DT must happen before blocks are deleted below. Otherwise the
// DT traversal will encounter badref blocks and assert.
if (!PendUpdates.empty()) {
DT.applyUpdates(PendUpdates);
PendUpdates.clear();
}
flushDelBB();
return DT;
}
/// \brief Drops all internal state and forces a (slow) recalculation of the
/// DominatorTree based on the current state of the LLVM IR in F. This should
/// only be used in corner cases such as the Entry block of F being deleted.
void recalculate(Function &F) {
// flushDelBB must be flushed before the recalculation. The state of the IR
// must be consistent before the DT traversal algorithm determines the
// actual DT.
if (flushDelBB() || !PendUpdates.empty()) {
DT.recalculate(F);
PendUpdates.clear();
}
}
/// \brief Debug method to help view the state of pending updates.
LLVM_DUMP_METHOD void dump() const;
private:
DominatorTree &DT;
SmallVector<DominatorTree::UpdateType, 16> PendUpdates;
SmallPtrSet<BasicBlock *, 8> DeletedBBs;
/// Apply an update (Kind, From, To) to the internal queued updates. The
/// update is only added when determined to be necessary. Checks for
/// self-domination, unnecessary updates, duplicate requests, and balanced
/// pairs of requests are all performed. Returns true if the update is
/// queued and false if it is discarded.
bool applyUpdate(DominatorTree::UpdateKind Kind, BasicBlock *From,
BasicBlock *To) {
if (From == To)
return false; // Cannot dominate self; discard update.
// Discard updates by inspecting the current state of successors of From.
// Since applyUpdate() must be called *after* the Terminator of From is
// altered we can determine if the update is unnecessary.
bool HasEdge = std::any_of(succ_begin(From), succ_end(From),
[To](BasicBlock *B) { return B == To; });
if (Kind == DominatorTree::Insert && !HasEdge)
return false; // Unnecessary Insert: edge does not exist in IR.
if (Kind == DominatorTree::Delete && HasEdge)
return false; // Unnecessary Delete: edge still exists in IR.
// Analyze pending updates to determine if the update is unnecessary.
DominatorTree::UpdateType Update = {Kind, From, To};
DominatorTree::UpdateType Invert = {Kind != DominatorTree::Insert
? DominatorTree::Insert
: DominatorTree::Delete,
From, To};
for (auto I = PendUpdates.begin(), E = PendUpdates.end(); I != E; ++I) {
if (Update == *I)
return false; // Discard duplicate updates.
if (Invert == *I) {
// Update and Invert are both valid (equivalent to a no-op). Remove
// Invert from PendUpdates and discard the Update.
PendUpdates.erase(I);
return false;
}
}
PendUpdates.push_back(Update); // Save the valid update.
return true;
}
/// Performs all pending basic block deletions. We have to defer the deletion
/// of these blocks until after the DominatorTree updates are applied. The
/// internal workings of the DominatorTree code expect every update's From
/// and To blocks to exist and to be a member of the same Function.
bool flushDelBB() {
if (DeletedBBs.empty())
return false;
for (auto *BB : DeletedBBs)
BB->eraseFromParent();
DeletedBBs.clear();
return true;
}
};
} // end namespace llvm
#endif // LLVM_IR_DEFERREDDOMINANCE_H

6
llvm/include/llvm/Transforms/Scalar/JumpThreading.h
View File

@ -34,7 +34,6 @@ class BinaryOperator;
class BranchInst;
class CmpInst;
class Constant;
class DeferredDominance;
class Function;
class Instruction;
class IntrinsicInst;
@ -78,7 +77,6 @@ class JumpThreadingPass : public PassInfoMixin<JumpThreadingPass> {
TargetLibraryInfo *TLI;
LazyValueInfo *LVI;
AliasAnalysis *AA;
DeferredDominance *DDT;
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
bool HasProfileData = false;
@ -109,8 +107,8 @@ public:
// Glue for old PM.
bool runImpl(Function &F, TargetLibraryInfo *TLI_, LazyValueInfo *LVI_,
AliasAnalysis *AA_, DeferredDominance *DDT_,
bool HasProfileData_, std::unique_ptr<BlockFrequencyInfo> BFI_,
AliasAnalysis *AA_, bool HasProfileData_,
std::unique_ptr<BlockFrequencyInfo> BFI_,
std::unique_ptr<BranchProbabilityInfo> BPI_);
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);

3
llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
View File

@ -27,7 +27,6 @@ namespace llvm {
class BlockFrequencyInfo;
class BranchProbabilityInfo;
class DeferredDominance;
class DominatorTree;
class Function;
class Instruction;
@ -39,7 +38,7 @@ class TargetLibraryInfo;
class Value;
/// Delete the specified block, which must have no predecessors.
void DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT = nullptr);
void DeleteDeadBlock(BasicBlock *BB);
/// We know that BB has one predecessor. If there are any single-entry PHI nodes
/// in it, fold them away. This handles the case when all entries to the PHI

21
llvm/include/llvm/Transforms/Utils/Local.h
View File

@ -24,7 +24,6 @@
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DeferredDominance.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/Operator.h"
@ -110,8 +109,7 @@ struct SimplifyCFGOptions {
/// conditions and indirectbr addresses this might make dead if
/// DeleteDeadConditions is true.
bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false,
const TargetLibraryInfo *TLI = nullptr,
DeferredDominance *DDT = nullptr);
const TargetLibraryInfo *TLI = nullptr);
//===----------------------------------------------------------------------===//
// Local dead code elimination.
@ -165,21 +163,18 @@ bool SimplifyInstructionsInBlock(BasicBlock *BB,
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the 'and' to 0.
void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
DeferredDominance *DDT = nullptr);
void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred);
/// BB is a block with one predecessor and its predecessor is known to have one
/// successor (BB!). Eliminate the edge between them, moving the instructions in
/// the predecessor into BB. This deletes the predecessor block.
void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, DominatorTree *DT = nullptr,
DeferredDominance *DDT = nullptr);
void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, DominatorTree *DT = nullptr);
/// BB is known to contain an unconditional branch, and contains no instructions
/// other than PHI nodes, potential debug intrinsics and the branch. If
/// possible, eliminate BB by rewriting all the predecessors to branch to the
/// successor block and return true. If we can't transform, return false.
bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
DeferredDominance *DDT = nullptr);
bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB);
/// Check for and eliminate duplicate PHI nodes in this block. This doesn't try
/// to be clever about PHI nodes which differ only in the order of the incoming
@ -379,8 +374,7 @@ unsigned removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB);
/// Insert an unreachable instruction before the specified
/// instruction, making it and the rest of the code in the block dead.
unsigned changeToUnreachable(Instruction *I, bool UseLLVMTrap,
bool PreserveLCSSA = false,
DeferredDominance *DDT = nullptr);
bool PreserveLCSSA = false);
/// Convert the CallInst to InvokeInst with the specified unwind edge basic
/// block. This also splits the basic block where CI is located, because
@ -395,13 +389,12 @@ BasicBlock *changeToInvokeAndSplitBasicBlock(CallInst *CI,
///
/// \param BB Block whose terminator will be replaced. Its terminator must
/// have an unwind successor.
void removeUnwindEdge(BasicBlock *BB, DeferredDominance *DDT = nullptr);
void removeUnwindEdge(BasicBlock *BB);
/// Remove all blocks that can not be reached from the function's entry.
///
/// Returns true if any basic block was removed.
bool removeUnreachableBlocks(Function &F, LazyValueInfo *LVI = nullptr,
DeferredDominance *DDT = nullptr);
bool removeUnreachableBlocks(Function &F, LazyValueInfo *LVI = nullptr);
/// Combine the metadata of two instructions so that K can replace J
///

54
llvm/lib/IR/Dominators.cpp
View File

@ -18,7 +18,6 @@
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DeferredDominance.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Support/CommandLine.h"
@ -390,56 +389,3 @@ void DominatorTreeWrapperPass::print(raw_ostream &OS, const Module *) const {
DT.print(OS);
}
//===----------------------------------------------------------------------===//
// DeferredDominance Implementation
//===----------------------------------------------------------------------===//
//
// The implementation details of the DeferredDominance class which allows
// one to queue updates to a DominatorTree.
//
//===----------------------------------------------------------------------===//
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void DeferredDominance::dump() const {
raw_ostream &OS = llvm::dbgs();
OS << "PendUpdates:\n";
int I = 0;
for (auto U : PendUpdates) {
OS << " " << I << " : ";
++I;
if (U.getKind() == DominatorTree::Insert)
OS << "Insert, ";
else
OS << "Delete, ";
BasicBlock *From = U.getFrom();
if (From) {
auto S = From->getName();
if (!From->hasName())
S = "(no name)";
OS << S << "(" << From << "), ";
} else {
OS << "(badref), ";
}
BasicBlock *To = U.getTo();
if (To) {
auto S = To->getName();
if (!To->hasName())
S = "(no_name)";
OS << S << "(" << To << ")\n";
} else {
OS << "(badref)\n";
}
}
OS << "DeletedBBs:\n";
I = 0;
for (auto BB : DeletedBBs) {
OS << " " << I << " : ";
++I;
if (BB->hasName())
OS << BB->getName() << "(";
else
OS << "(no_name)(";
OS << BB << ")\n";
}
}
#endif

2
llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
View File

@ -77,7 +77,6 @@ namespace {
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LazyValueInfoWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
}
@ -89,7 +88,6 @@ char CorrelatedValuePropagation::ID = 0;
INITIALIZE_PASS_BEGIN(CorrelatedValuePropagation, "correlated-propagation",
"Value Propagation", false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)
INITIALIZE_PASS_END(CorrelatedValuePropagation, "correlated-propagation",
"Value Propagation", false, false)

175
llvm/lib/Transforms/Scalar/JumpThreading.cpp
View File

@ -37,7 +37,6 @@
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DeferredDominance.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstrTypes.h"
@ -132,11 +131,10 @@ namespace {
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
AU.addPreserved<DominatorTreeWrapperPass>();
if (PrintLVIAfterJumpThreading)
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<AAResultsWrapperPass>();
AU.addRequired<LazyValueInfoWrapperPass>();
AU.addPreserved<LazyValueInfoWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
@ -150,7 +148,6 @@ char JumpThreading::ID = 0;
INITIALIZE_PASS_BEGIN(JumpThreading, "jump-threading",
"Jump Threading", false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
@ -281,12 +278,8 @@ bool JumpThreading::runOnFunction(Function &F) {
if (skipFunction(F))
return false;
auto TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
// Get DT analysis before LVI. When LVI is initialized it conditionally adds
// DT if it's available.
auto DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto LVI = &getAnalysis<LazyValueInfoWrapperPass>().getLVI();
auto AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
DeferredDominance DDT(*DT);
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
bool HasProfileData = F.getEntryCount().hasValue();
@ -296,11 +289,12 @@ bool JumpThreading::runOnFunction(Function &F) {
BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
}
bool Changed = Impl.runImpl(F, TLI, LVI, AA, &DDT, HasProfileData,
std::move(BFI), std::move(BPI));
bool Changed = Impl.runImpl(F, TLI, LVI, AA, HasProfileData, std::move(BFI),
std::move(BPI));
if (PrintLVIAfterJumpThreading) {
dbgs() << "LVI for function '" << F.getName() << "':\n";
LVI->printLVI(F, *DT, dbgs());
LVI->printLVI(F, getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
dbgs());
}
return Changed;
}
@ -308,12 +302,8 @@ bool JumpThreading::runOnFunction(Function &F) {
PreservedAnalyses JumpThreadingPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
// Get DT analysis before LVI. When LVI is initialized it conditionally adds
// DT if it's available.
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &LVI = AM.getResult<LazyValueAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
DeferredDominance DDT(DT);
std::unique_ptr<BlockFrequencyInfo> BFI;
std::unique_ptr<BranchProbabilityInfo> BPI;
@ -324,28 +314,25 @@ PreservedAnalyses JumpThreadingPass::run(Function &F,
BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
}
bool Changed = runImpl(F, &TLI, &LVI, &AA, &DDT, HasProfileData,
std::move(BFI), std::move(BPI));
bool Changed = runImpl(F, &TLI, &LVI, &AA, HasProfileData, std::move(BFI),
std::move(BPI));
if (!Changed)
return PreservedAnalyses::all();
PreservedAnalyses PA;
PA.preserve<GlobalsAA>();
PA.preserve<DominatorTreeAnalysis>();
PA.preserve<LazyValueAnalysis>();
return PA;
}
bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
LazyValueInfo *LVI_, AliasAnalysis *AA_,
DeferredDominance *DDT_, bool HasProfileData_,
bool HasProfileData_,
std::unique_ptr<BlockFrequencyInfo> BFI_,
std::unique_ptr<BranchProbabilityInfo> BPI_) {
DEBUG(dbgs() << "Jump threading on function '" << F.getName() << "'\n");
TLI = TLI_;
LVI = LVI_;
AA = AA_;
DDT = DDT_;
BFI.reset();
BPI.reset();
// When profile data is available, we need to update edge weights after
@ -367,7 +354,7 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
// back edges. This works for normal cases but not for unreachable blocks as
// they may have cycle with no back edge.
bool EverChanged = false;
EverChanged |= removeUnreachableBlocks(F, LVI, DDT);
EverChanged |= removeUnreachableBlocks(F, LVI);
FindLoopHeaders(F);
@ -382,10 +369,6 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
++I;
// Don't thread branches over a block that's slated for deletion.
if (DDT->pendingDeletedBB(BB))
continue;
// If the block is trivially dead, zap it. This eliminates the successor
// edges which simplifies the CFG.
if (pred_empty(BB) &&
@ -394,7 +377,7 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
<< "' with terminator: " << *BB->getTerminator() << '\n');
LoopHeaders.erase(BB);
LVI->eraseBlock(BB);
DeleteDeadBlock(BB, DDT);
DeleteDeadBlock(BB);
Changed = true;
continue;
}
@ -418,7 +401,7 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
// awesome, but it allows us to use AssertingVH to prevent nasty
// dangling pointer issues within LazyValueInfo.
LVI->eraseBlock(BB);
if (TryToSimplifyUncondBranchFromEmptyBlock(BB, DDT))
if (TryToSimplifyUncondBranchFromEmptyBlock(BB))
Changed = true;
}
}
@ -426,7 +409,6 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_,
} while (Changed);
LoopHeaders.clear();
DDT->flush();
return EverChanged;
}
@ -950,8 +932,8 @@ static bool hasAddressTakenAndUsed(BasicBlock *BB) {
bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
// If the block is trivially dead, just return and let the caller nuke it.
// This simplifies other transformations.
if (DDT->pendingDeletedBB(BB) ||
(pred_empty(BB) && BB != &BB->getParent()->getEntryBlock()))
if (pred_empty(BB) &&
BB != &BB->getParent()->getEntryBlock())
return false;
// If this block has a single predecessor, and if that pred has a single
@ -967,7 +949,7 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
LoopHeaders.insert(BB);
LVI->eraseBlock(SinglePred);
MergeBasicBlockIntoOnlyPred(BB, nullptr, DDT);
MergeBasicBlockIntoOnlyPred(BB);
// Now that BB is merged into SinglePred (i.e. SinglePred Code followed by
// BB code within one basic block `BB`), we need to invalidate the LVI
@ -1050,23 +1032,18 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
// successors to branch to. Let GetBestDestForJumpOnUndef decide.
if (isa<UndefValue>(Condition)) {
unsigned BestSucc = GetBestDestForJumpOnUndef(BB);
std::vector<DominatorTree::UpdateType> Updates;
// Fold the branch/switch.
TerminatorInst *BBTerm = BB->getTerminator();
Updates.reserve(BBTerm->getNumSuccessors());
for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) {
if (i == BestSucc) continue;
BasicBlock *Succ = BBTerm->getSuccessor(i);
Succ->removePredecessor(BB, true);
Updates.push_back({DominatorTree::Delete, BB, Succ});
BBTerm->getSuccessor(i)->removePredecessor(BB, true);
}
DEBUG(dbgs() << " In block '" << BB->getName()
<< "' folding undef terminator: " << *BBTerm << '\n');
BranchInst::Create(BBTerm->getSuccessor(BestSucc), BBTerm);
BBTerm->eraseFromParent();
DDT->applyUpdates(Updates);
return true;
}
@ -1077,7 +1054,7 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
DEBUG(dbgs() << " In block '" << BB->getName()
<< "' folding terminator: " << *BB->getTerminator() << '\n');
++NumFolds;
ConstantFoldTerminator(BB, true, nullptr, DDT);
ConstantFoldTerminator(BB, true);
return true;
}
@ -1110,8 +1087,7 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
if (Ret != LazyValueInfo::Unknown) {
unsigned ToRemove = Ret == LazyValueInfo::True ? 1 : 0;
unsigned ToKeep = Ret == LazyValueInfo::True ? 0 : 1;
BasicBlock *ToRemoveSucc = CondBr->getSuccessor(ToRemove);
ToRemoveSucc->removePredecessor(BB, true);
CondBr->getSuccessor(ToRemove)->removePredecessor(BB, true);
BranchInst::Create(CondBr->getSuccessor(ToKeep), CondBr);
CondBr->eraseFromParent();
if (CondCmp->use_empty())
@ -1129,7 +1105,6 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
ConstantInt::getFalse(CondCmp->getType());
ReplaceFoldableUses(CondCmp, CI);
}
DDT->deleteEdge(BB, ToRemoveSucc);
return true;
}
@ -1208,12 +1183,9 @@ bool JumpThreadingPass::ProcessImpliedCondition(BasicBlock *BB) {
Optional<bool> Implication =
isImpliedCondition(PBI->getCondition(), Cond, DL, CondIsTrue);
if (Implication) {
BasicBlock *KeepSucc = BI->getSuccessor(*Implication ? 0 : 1);
BasicBlock *RemoveSucc = BI->getSuccessor(*Implication ? 1 : 0);
RemoveSucc->removePredecessor(BB);
BranchInst::Create(KeepSucc, BI);
BI->getSuccessor(*Implication ? 1 : 0)->removePredecessor(BB);
BranchInst::Create(BI->getSuccessor(*Implication ? 0 : 1), BI);
BI->eraseFromParent();
DDT->deleteEdge(BB, RemoveSucc);
return true;
}
CurrentBB = CurrentPred;
@ -1606,22 +1578,17 @@ bool JumpThreadingPass::ProcessThreadableEdges(Value *Cond, BasicBlock *BB,
if (PredWithKnownDest ==
(size_t)std::distance(pred_begin(BB), pred_end(BB))) {
bool SeenFirstBranchToOnlyDest = false;
std::vector <DominatorTree::UpdateType> Updates;
Updates.reserve(BB->getTerminator()->getNumSuccessors() - 1);
for (BasicBlock *SuccBB : successors(BB)) {
if (SuccBB == OnlyDest && !SeenFirstBranchToOnlyDest) {
if (SuccBB == OnlyDest && !SeenFirstBranchToOnlyDest)
SeenFirstBranchToOnlyDest = true; // Don't modify the first branch.
} else {
else
SuccBB->removePredecessor(BB, true); // This is unreachable successor.
Updates.push_back({DominatorTree::Delete, BB, SuccBB});
}
}
// Finally update the terminator.
TerminatorInst *Term = BB->getTerminator();
BranchInst::Create(OnlyDest, Term);
Term->eraseFromParent();
DDT->applyUpdates(Updates);
// If the condition is now dead due to the removal of the old terminator,
// erase it.
@ -1985,10 +1952,6 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
PredTerm->setSuccessor(i, NewBB);
}
DDT->applyUpdates({{DominatorTree::Insert, NewBB, SuccBB},
{DominatorTree::Insert, PredBB, NewBB},
{DominatorTree::Delete, PredBB, BB}});
// At this point, the IR is fully up to date and consistent. Do a quick scan
// over the new instructions and zap any that are constants or dead. This
// frequently happens because of phi translation.
@ -2008,42 +1971,20 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
BasicBlock *JumpThreadingPass::SplitBlockPreds(BasicBlock *BB,
ArrayRef<BasicBlock *> Preds,
const char *Suffix) {
SmallVector<BasicBlock *, 2> NewBBs;
// Collect the frequencies of all predecessors of BB, which will be used to
// update the edge weight of the result of splitting predecessors.
DenseMap<BasicBlock *, BlockFrequency> FreqMap;
// update the edge weight on BB->SuccBB.
BlockFrequency PredBBFreq(0);
if (HasProfileData)
for (auto Pred : Preds)
FreqMap.insert(std::make_pair(
Pred, BFI->getBlockFreq(Pred) * BPI->getEdgeProbability(Pred, BB)));
PredBBFreq += BFI->getBlockFreq(Pred) * BPI->getEdgeProbability(Pred, BB);
// In the case when BB is a LandingPad block we create 2 new predecessors
// instead of just one.
if (BB->isLandingPad()) {
std::string NewName = std::string(Suffix) + ".split-lp";
SplitLandingPadPredecessors(BB, Preds, Suffix, NewName.c_str(), NewBBs);
} else {
NewBBs.push_back(SplitBlockPredecessors(BB, Preds, Suffix));
}
BasicBlock *PredBB = SplitBlockPredecessors(BB, Preds, Suffix);
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve((2 * Preds.size()) + NewBBs.size());
for (auto NewBB : NewBBs) {
BlockFrequency NewBBFreq(0);
Updates.push_back({DominatorTree::Insert, NewBB, BB});
for (auto Pred : predecessors(NewBB)) {
Updates.push_back({DominatorTree::Delete, Pred, BB});
Updates.push_back({DominatorTree::Insert, Pred, NewBB});
if (HasProfileData) // Update frequencies between Pred -> NewBB.
NewBBFreq += FreqMap.lookup(Pred);
}
if (HasProfileData) // Apply the summed frequency to NewBB.
BFI->setBlockFreq(NewBB, NewBBFreq.getFrequency());
}
DDT->applyUpdates(Updates);
return NewBBs[0];
// Set the block frequency of the newly created PredBB, which is the sum of
// frequencies of Preds.
if (HasProfileData)
BFI->setBlockFreq(PredBB, PredBBFreq.getFrequency());
return PredBB;
}
bool JumpThreadingPass::doesBlockHaveProfileData(BasicBlock *BB) {
@ -2187,7 +2128,6 @@ bool JumpThreadingPass::DuplicateCondBranchOnPHIIntoPred(
}
// And finally, do it! Start by factoring the predecessors if needed.
std::vector<DominatorTree::UpdateType> Updates;
BasicBlock *PredBB;
if (PredBBs.size() == 1)
PredBB = PredBBs[0];
@ -2196,7 +2136,6 @@ bool JumpThreadingPass::DuplicateCondBranchOnPHIIntoPred(
<< " common predecessors.\n");
PredBB = SplitBlockPreds(BB, PredBBs, ".thr_comm");
}
Updates.push_back({DominatorTree::Delete, PredBB, BB});
// Okay, we decided to do this! Clone all the instructions in BB onto the end
// of PredBB.
@ -2209,11 +2148,7 @@ bool JumpThreadingPass::DuplicateCondBranchOnPHIIntoPred(
BranchInst *OldPredBranch = dyn_cast<BranchInst>(PredBB->getTerminator());
if (!OldPredBranch || !OldPredBranch->isUnconditional()) {
BasicBlock *OldPredBB = PredBB;
PredBB = SplitEdge(OldPredBB, BB);
Updates.push_back({DominatorTree::Insert, OldPredBB, PredBB});
Updates.push_back({DominatorTree::Insert, PredBB, BB});
Updates.push_back({DominatorTree::Delete, OldPredBB, BB});
PredBB = SplitEdge(PredBB, BB);
OldPredBranch = cast<BranchInst>(PredBB->getTerminator());
}
@ -2255,10 +2190,6 @@ bool JumpThreadingPass::DuplicateCondBranchOnPHIIntoPred(
// Otherwise, insert the new instruction into the block.
New->setName(BI->getName());
PredBB->getInstList().insert(OldPredBranch->getIterator(), New);
// Update Dominance from simplified New instruction operands.
for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
if (BasicBlock *SuccBB = dyn_cast<BasicBlock>(New->getOperand(i)))
Updates.push_back({DominatorTree::Insert, PredBB, SuccBB});
}
}
@ -2314,7 +2245,6 @@ bool JumpThreadingPass::DuplicateCondBranchOnPHIIntoPred(
// Remove the unconditional branch at the end of the PredBB block.
OldPredBranch->eraseFromParent();
DDT->applyUpdates(Updates);
++NumDupes;
return true;
@ -2387,8 +2317,6 @@ bool JumpThreadingPass::TryToUnfoldSelect(CmpInst *CondCmp, BasicBlock *BB) {
// The select is now dead.
SI->eraseFromParent();
DDT->applyUpdates({{DominatorTree::Insert, NewBB, BB},
{DominatorTree::Insert, Pred, NewBB}});
// Update any other PHI nodes in BB.
for (BasicBlock::iterator BI = BB->begin();
PHINode *Phi = dyn_cast<PHINode>(BI); ++BI)
@ -2467,25 +2395,11 @@ bool JumpThreadingPass::TryToUnfoldSelectInCurrBB(BasicBlock *BB) {
// Expand the select.
TerminatorInst *Term =
SplitBlockAndInsertIfThen(SI->getCondition(), SI, false);
BasicBlock *SplitBB = SI->getParent();
BasicBlock *NewBB = Term->getParent();
PHINode *NewPN = PHINode::Create(SI->getType(), 2, "", SI);
NewPN->addIncoming(SI->getTrueValue(), Term->getParent());
NewPN->addIncoming(SI->getFalseValue(), BB);
SI->replaceAllUsesWith(NewPN);
SI->eraseFromParent();
// NewBB and SplitBB are newly created blocks which require insertion.
std::vector<DominatorTree::UpdateType> Updates;
Updates.reserve((2 * SplitBB->getTerminator()->getNumSuccessors()) + 3);
Updates.push_back({DominatorTree::Insert, BB, SplitBB});
Updates.push_back({DominatorTree::Insert, BB, NewBB});
Updates.push_back({DominatorTree::Insert, NewBB, SplitBB});
// BB's successors were moved to SplitBB, update DDT accordingly.
for (auto *Succ : successors(SplitBB)) {
Updates.push_back({DominatorTree::Delete, BB, Succ});
Updates.push_back({DominatorTree::Insert, SplitBB, Succ});
}
DDT->applyUpdates(Updates);
return true;
}
return false;
@ -2572,8 +2486,8 @@ bool JumpThreadingPass::ThreadGuard(BasicBlock *BB, IntrinsicInst *Guard,
if (!TrueDestIsSafe && !FalseDestIsSafe)
return false;
BasicBlock *PredUnguardedBlock = TrueDestIsSafe ? TrueDest : FalseDest;
BasicBlock *PredGuardedBlock = FalseDestIsSafe ? TrueDest : FalseDest;
BasicBlock *UnguardedBlock = TrueDestIsSafe ? TrueDest : FalseDest;
BasicBlock *GuardedBlock = FalseDestIsSafe ? TrueDest : FalseDest;
ValueToValueMapTy UnguardedMapping, GuardedMapping;
Instruction *AfterGuard = Guard->getNextNode();
@ -2582,29 +2496,18 @@ bool JumpThreadingPass::ThreadGuard(BasicBlock *BB, IntrinsicInst *Guard,
return false;
// Duplicate all instructions before the guard and the guard itself to the
// branch where implication is not proved.
BasicBlock *GuardedBlock = DuplicateInstructionsInSplitBetween(
BB, PredGuardedBlock, AfterGuard, GuardedMapping);
GuardedBlock = DuplicateInstructionsInSplitBetween(
BB, GuardedBlock, AfterGuard, GuardedMapping);
assert(GuardedBlock && "Could not create the guarded block?");
// Duplicate all instructions before the guard in the unguarded branch.
// Since we have successfully duplicated the guarded block and this block
// has fewer instructions, we expect it to succeed.
BasicBlock *UnguardedBlock = DuplicateInstructionsInSplitBetween(
BB, PredUnguardedBlock, Guard, UnguardedMapping);
UnguardedBlock = DuplicateInstructionsInSplitBetween(BB, UnguardedBlock,
Guard, UnguardedMapping);
assert(UnguardedBlock && "Could not create the unguarded block?");
DEBUG(dbgs() << "Moved guard " << *Guard << " to block "
<< GuardedBlock->getName() << "\n");
// DuplicateInstructionsInSplitBetween inserts a new block "BB.split" between
// PredBB and BB. We need to perform two inserts and one delete for each of
// the above calls to update Dominators.
DDT->applyUpdates(
{// Guarded block split.
{DominatorTree::Delete, PredGuardedBlock, BB},
{DominatorTree::Insert, PredGuardedBlock, GuardedBlock},
{DominatorTree::Insert, GuardedBlock, BB},
// Unguarded block split.
{DominatorTree::Delete, PredUnguardedBlock, BB},
{DominatorTree::Insert, PredUnguardedBlock, UnguardedBlock},
{DominatorTree::Insert, UnguardedBlock, BB}});
// Some instructions before the guard may still have uses. For them, we need
// to create Phi nodes merging their copies in both guarded and unguarded
// branches. Those instructions that have no uses can be just removed.

18
llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
View File

@ -45,22 +45,16 @@
using namespace llvm;
void llvm::DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT) {
void llvm::DeleteDeadBlock(BasicBlock *BB) {
assert((pred_begin(BB) == pred_end(BB) ||
// Can delete self loop.
BB->getSinglePredecessor() == BB) && "Block is not dead!");
TerminatorInst *BBTerm = BB->getTerminator();
std::vector<DominatorTree::UpdateType> Updates;
// Loop through all of our successors and make sure they know that one
// of their predecessors is going away.
if (DDT)
Updates.reserve(BBTerm->getNumSuccessors());
for (BasicBlock *Succ : BBTerm->successors()) {
for (BasicBlock *Succ : BBTerm->successors())
Succ->removePredecessor(BB);
if (DDT)
Updates.push_back({DominatorTree::Delete, BB, Succ});
}
// Zap all the instructions in the block.
while (!BB->empty()) {
@ -75,12 +69,8 @@ void llvm::DeleteDeadBlock(BasicBlock *BB, DeferredDominance *DDT) {
BB->getInstList().pop_back();
}
if (DDT) {
DDT->applyUpdates(Updates);
DDT->deleteBB(BB); // Deferred deletion of BB.
} else {
BB->eraseFromParent(); // Zap the block!
}
// Zap the block!
BB->eraseFromParent();
}
void llvm::FoldSingleEntryPHINodes(BasicBlock *BB,

205
llvm/lib/Transforms/Utils/Local.cpp
View File

@ -100,8 +100,7 @@ STATISTIC(NumRemoved, "Number of unreachable basic blocks removed");
/// conditions and indirectbr addresses this might make dead if
/// DeleteDeadConditions is true.
bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
const TargetLibraryInfo *TLI,
DeferredDominance *DDT) {
const TargetLibraryInfo *TLI) {
TerminatorInst *T = BB->getTerminator();
IRBuilder<> Builder(T);
@ -128,8 +127,6 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
// Replace the conditional branch with an unconditional one.
Builder.CreateBr(Destination);
BI->eraseFromParent();
if (DDT)
DDT->deleteEdge(BB, OldDest);
return true;
}
@ -200,12 +197,9 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
createBranchWeights(Weights));
}
// Remove this entry.
BasicBlock *ParentBB = SI->getParent();
DefaultDest->removePredecessor(ParentBB);
DefaultDest->removePredecessor(SI->getParent());
i = SI->removeCase(i);
e = SI->case_end();
if (DDT)
DDT->deleteEdge(ParentBB, DefaultDest);
continue;
}
@ -231,20 +225,14 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
// Insert the new branch.
Builder.CreateBr(TheOnlyDest);
BasicBlock *BB = SI->getParent();
std::vector <DominatorTree::UpdateType> Updates;
if (DDT)
Updates.reserve(SI->getNumSuccessors() - 1);
// Remove entries from PHI nodes which we no longer branch to...
for (BasicBlock *Succ : SI->successors()) {
// Found case matching a constant operand?
if (Succ == TheOnlyDest) {
if (Succ == TheOnlyDest)
TheOnlyDest = nullptr; // Don't modify the first branch to TheOnlyDest
} else {
else
Succ->removePredecessor(BB);
if (DDT)
Updates.push_back({DominatorTree::Delete, BB, Succ});
}
}
// Delete the old switch.
@ -252,8 +240,6 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
SI->eraseFromParent();
if (DeleteDeadConditions)
RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
if (DDT)
DDT->applyUpdates(Updates);
return true;
}
@ -299,23 +285,14 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
if (BlockAddress *BA =
dyn_cast<BlockAddress>(IBI->getAddress()->stripPointerCasts())) {
BasicBlock *TheOnlyDest = BA->getBasicBlock();
std::vector <DominatorTree::UpdateType> Updates;
if (DDT)
Updates.reserve(IBI->getNumDestinations() - 1);
// Insert the new branch.
Builder.CreateBr(TheOnlyDest);
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
if (IBI->getDestination(i) == TheOnlyDest) {
if (IBI->getDestination(i) == TheOnlyDest)
TheOnlyDest = nullptr;
} else {
BasicBlock *ParentBB = IBI->getParent();
BasicBlock *DestBB = IBI->getDestination(i);
DestBB->removePredecessor(ParentBB);
if (DDT)
Updates.push_back({DominatorTree::Delete, ParentBB, DestBB});
}
else
IBI->getDestination(i)->removePredecessor(IBI->getParent());
}
Value *Address = IBI->getAddress();
IBI->eraseFromParent();
@ -330,8 +307,6 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
new UnreachableInst(BB->getContext(), BB);
}
if (DDT)
DDT->applyUpdates(Updates);
return true;
}
}
@ -608,8 +583,7 @@ bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB,
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the and to 0.
void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
DeferredDominance *DDT) {
void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred) {
// This only adjusts blocks with PHI nodes.
if (!isa<PHINode>(BB->begin()))
return;
@ -632,18 +606,13 @@ void llvm::RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
// of the block.
if (PhiIt != OldPhiIt) PhiIt = &BB->front();
}
if (DDT)
DDT->deleteEdge(Pred, BB);
}
/// MergeBasicBlockIntoOnlyPred - DestBB is a block with one predecessor and its
/// predecessor is known to have one successor (DestBB!). Eliminate the edge
/// between them, moving the instructions in the predecessor into DestBB and
/// deleting the predecessor block.
void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT,
DeferredDominance *DDT) {
assert(!(DT && DDT) && "Cannot call with both DT and DDT.");
void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT) {
// If BB has single-entry PHI nodes, fold them.
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
Value *NewVal = PN->getIncomingValue(0);
@ -656,23 +625,6 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT,
BasicBlock *PredBB = DestBB->getSinglePredecessor();
assert(PredBB && "Block doesn't have a single predecessor!");
bool ReplaceEntryBB = false;
if (PredBB == &DestBB->getParent()->getEntryBlock())
ReplaceEntryBB = true;
// Deferred DT update: Collect all the edges that enter PredBB. These
// dominator edges will be redirected to DestBB.
std::vector <DominatorTree::UpdateType> Updates;
if (DDT && !ReplaceEntryBB) {
Updates.reserve((2 * std::distance(pred_begin(PredBB), pred_end(PredBB))) +
1);
Updates.push_back({DominatorTree::Delete, PredBB, DestBB});
for (auto I = pred_begin(PredBB), E = pred_end(PredBB); I != E; ++I) {
Updates.push_back({DominatorTree::Delete, *I, PredBB});
Updates.push_back({DominatorTree::Insert, *I, DestBB});
}
}
// Zap anything that took the address of DestBB. Not doing this will give the
// address an invalid value.
if (DestBB->hasAddressTaken()) {
@ -693,7 +645,7 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT,
// If the PredBB is the entry block of the function, move DestBB up to
// become the entry block after we erase PredBB.
if (ReplaceEntryBB)
if (PredBB == &DestBB->getParent()->getEntryBlock())
DestBB->moveAfter(PredBB);
if (DT) {
@ -705,19 +657,8 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT,
DT->eraseNode(PredBB);
}
}
if (DDT) {
DDT->deleteBB(PredBB); // Deferred deletion of BB.
if (ReplaceEntryBB)
// The entry block was removed and there is no external interface for the
// dominator tree to be notified of this change. In this corner-case we
// recalculate the entire tree.
DDT->recalculate(*(DestBB->getParent()));
else
DDT->applyUpdates(Updates);
} else {
PredBB->eraseFromParent(); // Nuke BB.
}
// Nuke BB.
PredBB->eraseFromParent();
}
/// CanMergeValues - Return true if we can choose one of these values to use
@ -924,8 +865,7 @@ static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
/// potential side-effect free intrinsics and the branch. If possible,
/// eliminate BB by rewriting all the predecessors to branch to the successor
/// block and return true. If we can't transform, return false.
bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
DeferredDominance *DDT) {
bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB) {
assert(BB != &BB->getParent()->getEntryBlock() &&
"TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
@ -966,17 +906,6 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
std::vector<DominatorTree::UpdateType> Updates;
if (DDT) {
Updates.reserve((2 * std::distance(pred_begin(BB), pred_end(BB))) + 1);
Updates.push_back({DominatorTree::Delete, BB, Succ});
// All predecessors of BB will be moved to Succ.
for (auto I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
Updates.push_back({DominatorTree::Delete, *I, BB});
Updates.push_back({DominatorTree::Insert, *I, Succ});
}
}
if (isa<PHINode>(Succ->begin())) {
// If there is more than one pred of succ, and there are PHI nodes in
// the successor, then we need to add incoming edges for the PHI nodes
@ -1021,13 +950,7 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
// Everything that jumped to BB now goes to Succ.
BB->replaceAllUsesWith(Succ);
if (!Succ->hasName()) Succ->takeName(BB);
if (DDT) {
DDT->deleteBB(BB); // Deferred deletion of the old basic block.
DDT->applyUpdates(Updates);
} else {
BB->eraseFromParent(); // Delete the old basic block.
}
BB->eraseFromParent(); // Delete the old basic block.
return true;
}
@ -1529,19 +1452,13 @@ unsigned llvm::removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB) {
}
unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap,
bool PreserveLCSSA, DeferredDominance *DDT) {
bool PreserveLCSSA) {
BasicBlock *BB = I->getParent();
std::vector <DominatorTree::UpdateType> Updates;
// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
if (DDT)
Updates.reserve(BB->getTerminator()->getNumSuccessors());
for (BasicBlock *Successor : successors(BB)) {
for (BasicBlock *Successor : successors(BB))
Successor->removePredecessor(BB, PreserveLCSSA);
if (DDT)
Updates.push_back({DominatorTree::Delete, BB, Successor});
}
// Insert a call to llvm.trap right before this. This turns the undefined
// behavior into a hard fail instead of falling through into random code.
if (UseLLVMTrap) {
@ -1561,13 +1478,11 @@ unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap,
BB->getInstList().erase(BBI++);
++NumInstrsRemoved;
}
if (DDT)
DDT->applyUpdates(Updates);
return NumInstrsRemoved;
}
/// changeToCall - Convert the specified invoke into a normal call.
static void changeToCall(InvokeInst *II, DeferredDominance *DDT = nullptr) {
static void changeToCall(InvokeInst *II) {
SmallVector<Value*, 8> Args(II->arg_begin(), II->arg_end());
SmallVector<OperandBundleDef, 1> OpBundles;
II->getOperandBundlesAsDefs(OpBundles);
@ -1580,16 +1495,11 @@ static void changeToCall(InvokeInst *II, DeferredDominance *DDT = nullptr) {
II->replaceAllUsesWith(NewCall);
// Follow the call by a branch to the normal destination.
BasicBlock *NormalDestBB = II->getNormalDest();
BranchInst::Create(NormalDestBB, II);
BranchInst::Create(II->getNormalDest(), II);
// Update PHI nodes in the unwind destination
BasicBlock *BB = II->getParent();
BasicBlock *UnwindDestBB = II->getUnwindDest();
UnwindDestBB->removePredecessor(BB);
II->getUnwindDest()->removePredecessor(II->getParent());
II->eraseFromParent();
if (DDT)
DDT->deleteEdge(BB, UnwindDestBB);
}
BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
@ -1630,8 +1540,7 @@ BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
}
static bool markAliveBlocks(Function &F,
SmallPtrSetImpl<BasicBlock*> &Reachable,
DeferredDominance *DDT = nullptr) {
SmallPtrSetImpl<BasicBlock*> &Reachable) {
SmallVector<BasicBlock*, 128> Worklist;
BasicBlock *BB = &F.front();
Worklist.push_back(BB);
@ -1651,7 +1560,7 @@ static bool markAliveBlocks(Function &F,
if (II->getIntrinsicID() == Intrinsic::assume) {
if (match(II->getArgOperand(0), m_CombineOr(m_Zero(), m_Undef()))) {
// Don't insert a call to llvm.trap right before the unreachable.
changeToUnreachable(II, false, false, DDT);
changeToUnreachable(II, false);
Changed = true;
break;
}
@ -1668,8 +1577,7 @@ static bool markAliveBlocks(Function &F,
// still be useful for widening.
if (match(II->getArgOperand(0), m_Zero()))
if (!isa<UnreachableInst>(II->getNextNode())) {
changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/false,
false, DDT);
changeToUnreachable(II->getNextNode(), /*UseLLVMTrap=*/ false);
Changed = true;
break;
}
@ -1679,7 +1587,7 @@ static bool markAliveBlocks(Function &F,
if (auto *CI = dyn_cast<CallInst>(&I)) {
Value *Callee = CI->getCalledValue();
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
changeToUnreachable(CI, /*UseLLVMTrap=*/false, false, DDT);
changeToUnreachable(CI, /*UseLLVMTrap=*/false);
Changed = true;
break;
}
@ -1689,7 +1597,7 @@ static bool markAliveBlocks(Function &F,
// though.
if (!isa<UnreachableInst>(CI->getNextNode())) {
// Don't insert a call to llvm.trap right before the unreachable.
changeToUnreachable(CI->getNextNode(), false, false, DDT);
changeToUnreachable(CI->getNextNode(), false);
Changed = true;
}
break;
@ -1708,7 +1616,7 @@ static bool markAliveBlocks(Function &F,
if (isa<UndefValue>(Ptr) ||
(isa<ConstantPointerNull>(Ptr) &&
SI->getPointerAddressSpace() == 0)) {
changeToUnreachable(SI, true, false, DDT);
changeToUnreachable(SI, true);
Changed = true;
break;
}
@ -1720,20 +1628,16 @@ static bool markAliveBlocks(Function &F,
// Turn invokes that call 'nounwind' functions into ordinary calls.
Value *Callee = II->getCalledValue();
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
changeToUnreachable(II, true, false, DDT);
changeToUnreachable(II, true);
Changed = true;
} else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
if (II->use_empty() && II->onlyReadsMemory()) {
// jump to the normal destination branch.
BasicBlock *NormalDestBB = II->getNormalDest();
BasicBlock *UnwindDestBB = II->getUnwindDest();
BranchInst::Create(NormalDestBB, II);
UnwindDestBB->removePredecessor(II->getParent());
BranchInst::Create(II->getNormalDest(), II);
II->getUnwindDest()->removePredecessor(II->getParent());
II->eraseFromParent();
if (DDT)
DDT->deleteEdge(BB, UnwindDestBB);
} else
changeToCall(II, DDT);
changeToCall(II);
Changed = true;
}
} else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Terminator)) {
@ -1779,7 +1683,7 @@ static bool markAliveBlocks(Function &F,
}
}
Changed |= ConstantFoldTerminator(BB, true, nullptr, DDT);
Changed |= ConstantFoldTerminator(BB, true);
for (BasicBlock *Successor : successors(BB))
if (Reachable.insert(Successor).second)
Worklist.push_back(Successor);
@ -1787,11 +1691,11 @@ static bool markAliveBlocks(Function &F,
return Changed;
}
void llvm::removeUnwindEdge(BasicBlock *BB, DeferredDominance *DDT) {
void llvm::removeUnwindEdge(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (auto *II = dyn_cast<InvokeInst>(TI)) {
changeToCall(II, DDT);
changeToCall(II);
return;
}
@ -1819,18 +1723,15 @@ void llvm::removeUnwindEdge(BasicBlock *BB, DeferredDominance *DDT) {
UnwindDest->removePredecessor(BB);
TI->replaceAllUsesWith(NewTI);
TI->eraseFromParent();
if (DDT)
DDT->deleteEdge(BB, UnwindDest);
}
/// removeUnreachableBlocks - Remove blocks that are not reachable, even
/// if they are in a dead cycle. Return true if a change was made, false
/// otherwise. If `LVI` is passed, this function preserves LazyValueInfo
/// after modifying the CFG.
bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI,
DeferredDominance *DDT) {
bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI) {
SmallPtrSet<BasicBlock*, 16> Reachable;
bool Changed = markAliveBlocks(F, Reachable, DDT);
bool Changed = markAliveBlocks(F, Reachable);
// If there are unreachable blocks in the CFG...
if (Reachable.size() == F.size())
@ -1840,39 +1741,25 @@ bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI,
NumRemoved += F.size()-Reachable.size();
// Loop over all of the basic blocks that are not reachable, dropping all of
// their internal references. Update DDT and LVI if available.
std::vector <DominatorTree::UpdateType> Updates;
for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ++I) {
auto *BB = &*I;
if (Reachable.count(BB))
// their internal references...
for (Function::iterator BB = ++F.begin(), E = F.end(); BB != E; ++BB) {
if (Reachable.count(&*BB))
continue;
for (BasicBlock *Successor : successors(BB)) {
for (BasicBlock *Successor : successors(&*BB))
if (Reachable.count(Successor))
Successor->removePredecessor(BB);
if (DDT)
Updates.push_back({DominatorTree::Delete, BB, Successor});
}
Successor->removePredecessor(&*BB);
if (LVI)
LVI->eraseBlock(BB);
LVI->eraseBlock(&*BB);
BB->dropAllReferences();
}
for (Function::iterator I = ++F.begin(); I != F.end();) {
auto *BB = &*I;
if (Reachable.count(BB)) {
++I;
continue;
}
if (DDT) {
DDT->deleteBB(BB); // deferred deletion of BB.
++I;
} else {
for (Function::iterator I = ++F.begin(); I != F.end();)
if (!Reachable.count(&*I))
I = F.getBasicBlockList().erase(I);
}
}
else
++I;
if (DDT)
DDT->applyUpdates(Updates);
return true;
}

3
llvm/test/Analysis/LazyValueAnalysis/lvi-after-jumpthreading.ll
View File

@ -19,13 +19,10 @@ entry:
; CHECK-NEXT: ; LatticeVal for: 'i32 %a' is: overdefined
; CHECK-NEXT: ; LatticeVal for: 'i32 %length' is: overdefined
; CHECK-NEXT: ; LatticeVal for: ' %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]' in BB: '%backedge' is: constantrange<0, 400>
; CHECK-NEXT: ; LatticeVal for: ' %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]' in BB: '%exit' is: constantrange<399, 400>
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
; CHECK-NEXT: ; LatticeVal for: ' %iv.next = add nsw i32 %iv, 1' in BB: '%backedge' is: constantrange<1, 401>
; CHECK-NEXT: ; LatticeVal for: ' %iv.next = add nsw i32 %iv, 1' in BB: '%exit' is: constantrange<400, 401>
; CHECK-NEXT: %iv.next = add nsw i32 %iv, 1
; CHECK-NEXT: ; LatticeVal for: ' %cont = icmp slt i32 %iv.next, 400' in BB: '%backedge' is: overdefined
; CHECK-NEXT: ; LatticeVal for: ' %cont = icmp slt i32 %iv.next, 400' in BB: '%exit' is: constantrange<0, -1>
; CHECK-NEXT: %cont = icmp slt i32 %iv.next, 400
; CHECK-NOT: loop
loop:

265
llvm/test/Transforms/JumpThreading/ddt-crash.ll
View File

@ -1,265 +0,0 @@
; RUN: opt < %s -jump-threading -disable-output
%struct.ham = type { i8, i8, i16, i32 }
%struct.zot = type { i32 (...)** }
%struct.quux.0 = type { %struct.wombat }
%struct.wombat = type { %struct.zot }
@global = external global %struct.ham*, align 8
@global.1 = external constant i8*
declare i32 @wombat.2()
define void @blam() {
bb:
%tmp = load i32, i32* undef
%tmp1 = icmp eq i32 %tmp, 0
br i1 %tmp1, label %bb11, label %bb2
bb2:
%tmp3 = tail call i32 @wombat.2()
switch i32 %tmp3, label %bb4 [
i32 0, label %bb5
i32 1, label %bb7
i32 2, label %bb7
i32 3, label %bb11
]
bb4:
br label %bb7
bb5:
%tmp6 = tail call i32 @wombat.2()
br label %bb7
bb7:
%tmp8 = phi i32 [ 0, %bb5 ], [ 1, %bb4 ], [ 2, %bb2 ], [ 2, %bb2 ]
%tmp9 = icmp eq i32 %tmp8, 0
br i1 %tmp9, label %bb11, label %bb10
bb10:
ret void
bb11:
ret void
}
define void @spam(%struct.ham* %arg) {
bb:
%tmp = load i8, i8* undef, align 8
switch i8 %tmp, label %bb11 [
i8 1, label %bb11
i8 2, label %bb11
i8 3, label %bb1
i8 4, label %bb1
]
bb1:
br label %bb2
bb2:
%tmp3 = phi i32 [ 0, %bb1 ], [ %tmp3, %bb8 ]
br label %bb4
bb4:
%tmp5 = load i8, i8* undef, align 8
switch i8 %tmp5, label %bb11 [
i8 0, label %bb11
i8 1, label %bb10
i8 2, label %bb10
i8 3, label %bb6
i8 4, label %bb6
]
bb6:
br label %bb7
bb7:
br i1 undef, label %bb8, label %bb10
bb8:
%tmp9 = icmp eq %struct.ham* undef, %arg
br i1 %tmp9, label %bb10, label %bb2
bb10:
switch i32 %tmp3, label %bb4 [
i32 0, label %bb14
i32 1, label %bb11
i32 2, label %bb12
]
bb11:
unreachable
bb12:
%tmp13 = load %struct.ham*, %struct.ham** undef
br label %bb14
bb14:
%tmp15 = phi %struct.ham* [ %tmp13, %bb12 ], [ null, %bb10 ]
br label %bb16
bb16:
%tmp17 = load i8, i8* undef, align 8
switch i8 %tmp17, label %bb11 [
i8 0, label %bb11
i8 11, label %bb18
i8 12, label %bb18
]
bb18:
br label %bb19
bb19:
br label %bb20
bb20:
%tmp21 = load %struct.ham*, %struct.ham** undef
switch i8 undef, label %bb22 [
i8 0, label %bb4
i8 11, label %bb10
i8 12, label %bb10
]
bb22:
br label %bb23
bb23:
%tmp24 = icmp eq %struct.ham* %tmp21, null
br i1 %tmp24, label %bb35, label %bb25
bb25:
%tmp26 = icmp eq %struct.ham* %tmp15, null
br i1 %tmp26, label %bb34, label %bb27
bb27:
%tmp28 = load %struct.ham*, %struct.ham** undef
%tmp29 = icmp eq %struct.ham* %tmp28, %tmp21
br i1 %tmp29, label %bb35, label %bb30
bb30:
br label %bb31
bb31:
%tmp32 = load i8, i8* undef, align 8
%tmp33 = icmp eq i8 %tmp32, 0
br i1 %tmp33, label %bb31, label %bb34
bb34:
br label %bb35
bb35:
%tmp36 = phi i1 [ true, %bb34 ], [ false, %bb23 ], [ true, %bb27 ]
br label %bb37
bb37:
%tmp38 = icmp eq %struct.ham* %tmp15, null
br i1 %tmp38, label %bb39, label %bb41
bb39:
%tmp40 = load %struct.ham*, %struct.ham** @global
br label %bb41
bb41:
%tmp42 = select i1 %tmp36, %struct.ham* undef, %struct.ham* undef
ret void
}
declare i32 @foo(...)
define void @zot() align 2 personality i8* bitcast (i32 (...)* @foo to i8*) {
bb:
invoke void @bar()
to label %bb1 unwind label %bb3
bb1:
invoke void @bar()
to label %bb2 unwind label %bb4
bb2:
invoke void @bar()
to label %bb6 unwind label %bb17
bb3:
%tmp = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb4:
%tmp5 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb6:
invoke void @bar()
to label %bb7 unwind label %bb19
bb7:
invoke void @bar()
to label %bb10 unwind label %bb8
bb8:
%tmp9 = landingpad { i8*, i32 }
cleanup
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb10:
%tmp11 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
%tmp12 = invoke i32 %tmp11(%struct.zot* nonnull undef)
to label %bb13 unwind label %bb21
bb13:
invoke void @bar()
to label %bb14 unwind label %bb23
bb14:
%tmp15 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
%tmp16 = invoke i32 %tmp15(%struct.zot* nonnull undef)
to label %bb26 unwind label %bb23
bb17:
%tmp18 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb19:
%tmp20 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb21:
%tmp22 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
unreachable
bb23:
%tmp24 = phi %struct.quux.0* [ null, %bb26 ], [ null, %bb14 ], [ undef, %bb13 ]
%tmp25 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @global.1 to i8*)
catch i8* null
br label %bb30
bb26:
%tmp27 = load i32 (%struct.zot*)*, i32 (%struct.zot*)** undef, align 8
%tmp28 = invoke i32 %tmp27(%struct.zot* nonnull undef)
to label %bb29 unwind label %bb23
bb29:
unreachable
bb30:
%tmp31 = icmp eq %struct.quux.0* %tmp24, null
br i1 %tmp31, label %bb32, label %bb29
bb32:
unreachable
}
declare void @bar()

50
llvm/test/Transforms/JumpThreading/lvi-tristate.ll
View File

@ -1,50 +0,0 @@
; RUN: opt -jump-threading -simplifycfg -S < %s | FileCheck %s
; CHECK-NOT: bb6:
; CHECK-NOT: bb7:
; CHECK-NOT: bb8:
; CHECK-NOT: bb11:
; CHECK-NOT: bb12:
; CHECK: bb:
; CHECK: bb2:
; CHECK: bb4:
; CHECK: bb10:
; CHECK: bb13:
declare void @ham()
define void @hoge() {
bb:
%tmp = and i32 undef, 1073741823
%tmp1 = icmp eq i32 %tmp, 2
br i1 %tmp1, label %bb12, label %bb2
bb2:
%tmp3 = icmp eq i32 %tmp, 3
br i1 %tmp3, label %bb13, label %bb4
bb4:
%tmp5 = icmp eq i32 %tmp, 5
br i1 %tmp5, label %bb6, label %bb7
bb6:
tail call void @ham()
br label %bb7
bb7:
br i1 %tmp3, label %bb13, label %bb8
bb8:
%tmp9 = icmp eq i32 %tmp, 4
br i1 %tmp9, label %bb13, label %bb10
bb10:
br i1 %tmp9, label %bb11, label %bb13
bb11:
br label %bb13
bb12:
br label %bb2
bb13:
ret void
}