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Pull in r292133 from upstream llvm trunk (by Hal Finkel):

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Fix use-after-free bug in AffectedValueCallbackVH::allUsesReplacedWith

  When transferring affected values in the cache from an old value,
  identified by the value of the current callback, to the specified new
  value we might need to insert a new entry into the DenseMap which
  constitutes the cache. Doing so might delete the current callback
  object. Move the copying logic into a new function, a member of the
  assumption cache itself, so that we don't run into UB should the
  callback handle itself be removed mid-copy.

  Differential Revision: https://reviews.llvm.org/D28749

This should fix crashes when building lld (as part of the llvmXY ports).

Reported by:	jbeich
PR:		216117
This commit is contained in:
Dimitry Andric 2017-01-16 19:53:18 +00:00
parent 2714e44c8b
commit 9b1870035a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/clang400-import/; revision=312308
2 changed files with 21 additions and 11 deletions
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5
contrib/llvm/include/llvm/Analysis/AssumptionCache.h
View File

@ -68,7 +68,10 @@ class AssumptionCache {
AffectedValuesMap AffectedValues;
/// Get the vector of assumptions which affect a value from the cache.
SmallVector<WeakVH, 1> &getAffectedValues(Value *V);
SmallVector<WeakVH, 1> &getOrInsertAffectedValues(Value *V);
/// Copy affected values in the cache for OV to be affected values for NV.
void copyAffectedValuesInCache(Value *OV, Value *NV);
/// \brief Flag tracking whether we have scanned the function yet.
///

27
contrib/llvm/lib/Analysis/AssumptionCache.cpp
View File

@ -24,7 +24,7 @@
using namespace llvm;
using namespace llvm::PatternMatch;
SmallVector<WeakVH, 1> &AssumptionCache::getAffectedValues(Value *V) {
SmallVector<WeakVH, 1> &AssumptionCache::getOrInsertAffectedValues(Value *V) {
// Try using find_as first to avoid creating extra value handles just for the
// purpose of doing the lookup.
auto AVI = AffectedValues.find_as(V);
@ -98,7 +98,7 @@ void AssumptionCache::updateAffectedValues(CallInst *CI) {
}
for (auto &AV : Affected) {
auto &AVV = getAffectedValues(AV);
auto &AVV = getOrInsertAffectedValues(AV);
if (std::find(AVV.begin(), AVV.end(), CI) == AVV.end())
AVV.push_back(CI);
}
@ -111,20 +111,27 @@ void AssumptionCache::AffectedValueCallbackVH::deleted() {
// 'this' now dangles!
}
void AssumptionCache::copyAffectedValuesInCache(Value *OV, Value *NV) {
auto &NAVV = getOrInsertAffectedValues(NV);
auto AVI = AffectedValues.find(OV);
if (AVI == AffectedValues.end())
return;
for (auto &A : AVI->second)
if (std::find(NAVV.begin(), NAVV.end(), A) == NAVV.end())
NAVV.push_back(A);
}
void AssumptionCache::AffectedValueCallbackVH::allUsesReplacedWith(Value *NV) {
if (!isa<Instruction>(NV) && !isa<Argument>(NV))
return;
// Any assumptions that affected this value now affect the new value.
auto &NAVV = AC->getAffectedValues(NV);
auto AVI = AC->AffectedValues.find(getValPtr());
if (AVI == AC->AffectedValues.end())
return;
for (auto &A : AVI->second)
if (std::find(NAVV.begin(), NAVV.end(), A) == NAVV.end())
NAVV.push_back(A);
AC->copyAffectedValuesInCache(getValPtr(), NV);
// 'this' now might dangle! If the AffectedValues map was resized to add an
// entry for NV then this object might have been destroyed in favor of some
// copy in the grown map.
}
void AssumptionCache::scanFunction() {