[llvm] r272891 - [JumpThreading] Prevent dangling pointer problems in BranchProbabilityInfo
Igor Laevsky via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 16 06:28:25 PDT 2016
Author: igor.laevsky
Date: Thu Jun 16 08:28:25 2016
New Revision: 272891
URL: http://llvm.org/viewvc/llvm-project?rev=272891&view=rev
Log:
[JumpThreading] Prevent dangling pointer problems in BranchProbabilityInfo
We should update results of the BranchProbabilityInfo after removing block in JumpThreading. Otherwise
we will get dangling pointer inside BranchProbabilityInfo cache.
Differential Revision: http://reviews.llvm.org/D20957
Added:
llvm/trunk/test/Transforms/JumpThreading/dangling-pointers-in-bpi.ll
Modified:
llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h
llvm/trunk/include/llvm/Transforms/Utils/Local.h
llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
llvm/trunk/lib/Transforms/Utils/Local.cpp
llvm/trunk/unittests/Analysis/BlockFrequencyInfoTest.cpp
Modified: llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h Thu Jun 16 08:28:25 2016
@@ -18,6 +18,7 @@
#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"
@@ -116,13 +117,16 @@ 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;
// 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;
+ typedef std::pair<AssertingVH<const BasicBlock>, unsigned> Edge;
// Default weight value. Used when we don't have information about the edge.
// TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
Modified: llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h (original)
+++ llvm/trunk/include/llvm/Transforms/Scalar/JumpThreading.h Thu Jun 16 08:28:25 2016
@@ -134,6 +134,8 @@ private:
const char *Suffix);
void UpdateBlockFreqAndEdgeWeight(BasicBlock *PredBB, BasicBlock *BB,
BasicBlock *NewBB, BasicBlock *SuccBB);
+
+ void dropBlockAnalysisResults(BasicBlock *BB);
};
} // end namespace llvm
Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Thu Jun 16 08:28:25 2016
@@ -44,6 +44,7 @@ class TargetTransformInfo;
class DIBuilder;
class DominatorTree;
class LazyValueInfo;
+class BranchProbabilityInfo;
template<typename T> class SmallVectorImpl;
@@ -300,7 +301,11 @@ 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);
+/// \param F Target function
+/// \param LVI Will update this analysis if non null
+/// \param BPI Will update this analysis if non null
+bool removeUnreachableBlocks(Function &F, LazyValueInfo *LVI = nullptr,
+ BranchProbabilityInfo *BPI = nullptr);
/// Combine the metadata of two instructions so that K can replace J
///
Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Thu Jun 16 08:28:25 2016
@@ -639,6 +639,14 @@ BranchProbabilityInfo::printEdgeProbabil
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");
Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Thu Jun 16 08:28:25 2016
@@ -182,7 +182,7 @@ bool JumpThreadingPass::runImpl(Function
// 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);
+ EverChanged |= removeUnreachableBlocks(F, LVI, BPI.get());
FindLoopHeaders(F);
@@ -204,7 +204,7 @@ bool JumpThreadingPass::runImpl(Function
DEBUG(dbgs() << " JT: Deleting dead block '" << BB->getName()
<< "' with terminator: " << *BB->getTerminator() << '\n');
LoopHeaders.erase(BB);
- LVI->eraseBlock(BB);
+ dropBlockAnalysisResults(BB);
DeleteDeadBlock(BB);
Changed = true;
continue;
@@ -232,7 +232,7 @@ bool JumpThreadingPass::runImpl(Function
// for a block even if it doesn't get erased. This isn't totally
// awesome, but it allows us to use AssertingVH to prevent nasty
// dangling pointer issues within LazyValueInfo.
- LVI->eraseBlock(BB);
+ dropBlockAnalysisResults(BB);
if (TryToSimplifyUncondBranchFromEmptyBlock(BB)) {
Changed = true;
// If we deleted BB and BB was the header of a loop, then the
@@ -715,7 +715,7 @@ bool JumpThreadingPass::ProcessBlock(Bas
if (LoopHeaders.erase(SinglePred))
LoopHeaders.insert(BB);
- LVI->eraseBlock(SinglePred);
+ dropBlockAnalysisResults(SinglePred);
MergeBasicBlockIntoOnlyPred(BB);
return true;
@@ -1949,3 +1949,11 @@ bool JumpThreadingPass::TryToUnfoldSelec
return false;
}
+
+/// dropBlockAnalysisResults - Inform relevant analyzes that BB is going to
+/// be removed. This is important in order to prevent dangling pointer problems.
+void JumpThreadingPass::dropBlockAnalysisResults(BasicBlock *BB) {
+ LVI->eraseBlock(BB);
+ if (BPI)
+ BPI->eraseBlock(BB);
+}
Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Thu Jun 16 08:28:25 2016
@@ -20,6 +20,7 @@
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemoryBuiltins.h"
@@ -1486,7 +1487,8 @@ void llvm::removeUnwindEdge(BasicBlock *
/// removeUnreachableBlocksFromFn - Remove blocks that are not reachable, even
/// if they are in a dead cycle. Return true if a change was made, false
/// otherwise.
-bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI) {
+bool llvm::removeUnreachableBlocks(Function &F, LazyValueInfo *LVI,
+ BranchProbabilityInfo *BPI) {
SmallPtrSet<BasicBlock*, 16> Reachable;
bool Changed = markAliveBlocks(F, Reachable);
@@ -1509,6 +1511,8 @@ bool llvm::removeUnreachableBlocks(Funct
(*SI)->removePredecessor(&*BB);
if (LVI)
LVI->eraseBlock(&*BB);
+ if (BPI)
+ BPI->eraseBlock(&*BB);
BB->dropAllReferences();
}
Added: llvm/trunk/test/Transforms/JumpThreading/dangling-pointers-in-bpi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/JumpThreading/dangling-pointers-in-bpi.ll?rev=272891&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/JumpThreading/dangling-pointers-in-bpi.ll (added)
+++ llvm/trunk/test/Transforms/JumpThreading/dangling-pointers-in-bpi.ll Thu Jun 16 08:28:25 2016
@@ -0,0 +1,19 @@
+; RUN: opt -S -jump-threading %s 2>&1 | FileCheck %s
+
+; Test that after removing basic block we had also removed it from BPI. If we
+; didn't there will be dangling pointer inside BPI. It can lead to a
+; miscalculation in the edge weight and possibly other problems.
+; Checks that we are not failing assertion inside AssettingVH
+
+; CHECK-NOT: An asserting value handle still pointed to this value
+
+define void @foo(i32 %n, i1 %cond) !prof !0 {
+; Record this block into BPI cache
+single-pred:
+ br i1 %cond, label %entry, label %entry, !prof !{!"branch_weights", i32 1, i32 1}
+
+entry:
+ ret void
+}
+
+!0 = !{!"function_entry_count", i64 1}
Modified: llvm/trunk/unittests/Analysis/BlockFrequencyInfoTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Analysis/BlockFrequencyInfoTest.cpp?rev=272891&r1=272890&r2=272891&view=diff
==============================================================================
--- llvm/trunk/unittests/Analysis/BlockFrequencyInfoTest.cpp (original)
+++ llvm/trunk/unittests/Analysis/BlockFrequencyInfoTest.cpp Thu Jun 16 08:28:25 2016
@@ -54,6 +54,11 @@ protected:
SMDiagnostic Err;
return parseAssemblyString(ModuleStrig, Err, C);
}
+
+ void destroyBFI() {
+ // Prevent AssertingVH from failing.
+ BPI->releaseMemory();
+ }
};
TEST_F(BlockFrequencyInfoTest, Basic) {
@@ -80,6 +85,8 @@ TEST_F(BlockFrequencyInfoTest, Basic) {
EXPECT_EQ(BFI.getBlockProfileCount(BB3).getValue(), UINT64_C(100));
EXPECT_EQ(BFI.getBlockProfileCount(BB1).getValue(), 100 * BB1Freq / BB0Freq);
EXPECT_EQ(BFI.getBlockProfileCount(BB2).getValue(), 100 * BB2Freq / BB0Freq);
+
+ destroyBFI();
}
} // end anonymous namespace
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