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Fix an obscure read-after-free bug that Duncan found. 

llvm-svn: 46738
This commit is contained in:
Owen Anderson 2008-02-05 04:34:03 +00:00
parent 6c037da51c
commit 1de5997119
1 changed files with 20 additions and 10 deletions
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30
llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -463,15 +463,17 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction* rem) {
reverseDep[depGraphLocal[rem].first].erase(rem); reverseDep[depGraphLocal[rem].first].erase(rem);
if (depGraphEntry->second.first != NonLocal && if (depGraphEntry->second.first != NonLocal &&
depGraphEntry->second.first != None &&
depGraphEntry->second.second) { depGraphEntry->second.second) {
// If we have dep info for rem, set them to it // If we have dep info for rem, set them to it
BasicBlock::iterator RI = depGraphEntry->second.first; BasicBlock::iterator RI = depGraphEntry->second.first;
RI++; RI++;
newDep = RI; newDep = RI;
} else if (depGraphEntry->second.first == NonLocal && } else if ( (depGraphEntry->second.first == NonLocal ||
depGraphEntry->second.first == None ) &&
depGraphEntry->second.second ) { depGraphEntry->second.second ) {
// If we have a confirmed non-local flag, use it // If we have a confirmed non-local flag, use it
newDep = NonLocal; newDep = depGraphEntry->second.first;
} else { } else {
// Otherwise, use the immediate successor of rem // Otherwise, use the immediate successor of rem
// NOTE: This is because, when getDependence is called, it will first // NOTE: This is because, when getDependence is called, it will first
@ -480,14 +482,22 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction* rem) {
RI++; RI++;
newDep = RI; newDep = RI;
} }
} else {
SmallPtrSet<Instruction*, 4>& set = reverseDep[rem]; // Otherwise, use the immediate successor of rem
for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end(); // NOTE: This is because, when getDependence is called, it will first
I != E; ++I) { // check the immediate predecessor of what is in the cache.
// Insert the new dependencies BasicBlock::iterator RI = rem;
// Mark it as unconfirmed as long as it is not the non-local flag RI++;
depGraphLocal[*I] = std::make_pair(newDep, !newDep); newDep = RI;
} }
SmallPtrSet<Instruction*, 4>& set = reverseDep[rem];
for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
I != E; ++I) {
// Insert the new dependencies
// Mark it as unconfirmed as long as it is not the non-local flag
depGraphLocal[*I] = std::make_pair(newDep, (newDep == NonLocal ||
newDep == None));
} }
depGraphLocal.erase(rem); depGraphLocal.erase(rem);