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Re-submit r272891 "Prevent dangling pointer problems in BranchProbabilityInfo"

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Most possibly problem was caused by the same reason as PR28400. This change
bypasses it by using CallbackVH instead of AssertingVH.

Differential Revision: https://reviews.llvm.org/D20957

llvm-svn: 275563
This commit is contained in:
Igor Laevsky 2016-07-15 14:31:16 +00:00
parent c30e5f441e
commit 5c0a8c41b7
2 changed files with 30 additions and 0 deletions
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21
include/llvm/Analysis/BranchProbabilityInfo.h
View File

@ -15,9 +15,11 @@
#define LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/BranchProbability.h"
@ -116,10 +118,29 @@ public:
void calculate(const Function &F, const LoopInfo &LI);
/// Forget analysis results for the given basic block.
void eraseBlock(const BasicBlock *BB);
private:
void operator=(const BranchProbabilityInfo &) = delete;
BranchProbabilityInfo(const BranchProbabilityInfo &) = delete;
// We need to store CallbackVH's in order to correctly handle basic block
// removal.
class BasicBlockCallbackVH final : public CallbackVH {
BranchProbabilityInfo *BPI;
void deleted() override {
assert(BPI != nullptr);
BPI->eraseBlock(cast<BasicBlock>(getValPtr()));
BPI->Handles.erase(*this);
}
public:
BasicBlockCallbackVH(const Value *V, BranchProbabilityInfo *BPI=nullptr)
: CallbackVH(const_cast<Value *>(V)), BPI(BPI) {}
};
DenseSet<BasicBlockCallbackVH, DenseMapInfo<Value*>> Handles;
// Since we allow duplicate edges from one basic block to another, we use
// a pair (PredBlock and an index in the successors) to specify an edge.
typedef std::pair<const BasicBlock *, unsigned> Edge;

9
lib/Analysis/BranchProbabilityInfo.cpp
View File

@ -624,6 +624,7 @@ void BranchProbabilityInfo::setEdgeProbability(const BasicBlock *Src,
unsigned IndexInSuccessors,
BranchProbability Prob) {
Probs[std::make_pair(Src, IndexInSuccessors)] = Prob;
Handles.insert(BasicBlockCallbackVH(Src, this));
DEBUG(dbgs() << "set edge " << Src->getName() << " -> " << IndexInSuccessors
<< " successor probability to " << Prob << "\n");
}
@ -641,6 +642,14 @@ BranchProbabilityInfo::printEdgeProbability(raw_ostream &OS,
return OS;
}
void BranchProbabilityInfo::eraseBlock(const BasicBlock *BB) {
for (auto I = Probs.begin(), E = Probs.end(); I != E; ++I) {
auto Key = I->first;
if (Key.first == BB)
Probs.erase(Key);
}
}
void BranchProbabilityInfo::calculate(const Function &F, const LoopInfo &LI) {
DEBUG(dbgs() << "---- Branch Probability Info : " << F.getName()
<< " ----\n\n");