maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Fix a PassManager pointer use-after-free bug. 

The bug can be triggered when we require LoopInfo analysis ahead of DominatorTree construction in a Module Pass. The cause is that the LoopInfo analysis itself also invokes DominatorTree construction, therefore, when PassManager schedules LoopInfo, it will add DominatorTree first. Then after that, when the PassManger turns to schedule DominatorTree invoked by the above ModulePass, it finds there is already a DominatorTree, so it delete the redundant one. However, somehow it still try to access that pass pointer after free as code pasted below, which results in segment fault.

llvm-svn: 168581
This commit is contained in:
Zhou Sheng 2012-11-26 05:45:53 +00:00
parent 604937d1cc
commit c1cf629e41
1 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
llvm/lib/VMCore/PassManager.cpp
View File

@ -1654,6 +1654,18 @@ void MPPassManager::addLowerLevelRequiredPass(Pass *P, Pass *RequiredPass) {
OnTheFlyManagers[P] = FPP;
}
// If RequiredPass is an analysis pass and it is available then do not
// generate the analysis again. Stale analysis info should not be
// available at this point.
const PassInfo *PI =
PassRegistry::getPassRegistry()->getPassInfo(RequiredPass->getPassID());
if (PI && PI->isAnalysis() &&
FPP->getTopLevelManager()->findAnalysisPass(RequiredPass->getPassID())) {
delete RequiredPass;
return;
}
FPP->add(RequiredPass);
// Register P as the last user of RequiredPass.