[LLVMdev] 2.9 segfault when requesting for both LoopInfo and DominatorTree analyses.
Ralf Karrenberg
Chareos at gmx.de
Wed May 4 13:59:29 PDT 2011
Hi Michael,
thanks a lot. It seems like I missed quite some things when porting to
LLVM 2.9. After the changes you suggested, the code works as expected. :)
However, I think a segfault is not what should happen there.
Best,
Ralf
Am 04.05.2011 21:58, schrieb Michael Ilseman:
> Your constructor is not calling initializeTestMPPass(), and you're
> using RegisterPass which I think was deprecated in favor of
> INITIALIZE_PASS. You can look at, for example,
> lib/Transforms/Scalar/IndVarSimplify.cpp for examples of how to
> initialize, e.g. having "INITIALIZE_PASS_DEPENDENCY(LoopInfo)"
> sandwiched between BEGIN and END. Note that you'll want a forward
> declaration of initializeTestMPPass(), as it won't have a declaration
> in include/llvm/InitializePasses.h. These are all the changes I think
> I had to make to port my passes to 2.9 from 2.8.
>
> On Wed, May 4, 2011 at 12:48 PM, Ralf Karrenberg<Chareos at gmx.de> wrote:
>> Hi Michael, hi Duncan,
>>
>> yesterday I stumbled over something that might be related.
>> At least I could also just be doing some initialization wrong or something
>> in this direction...
>>
>> In my case, I hit a segfault in PassInfo::isAnalysisGroup() after
>> PassManager.add(myModulePass) is called.
>> My setup seems fairly simple, the attached code should reproduce the error.
>>
>> Compile with
>> g++ test.cpp `llvm-config --cxxflags --ldflags --libs all` -o test
>>
>> gdb --args ./test
>> prints the following stack trace:
>>
>> #0 0x00000000004e35ba in llvm::PassInfo::isAnalysisGroup (this=0x0) at
>> llvm/include/llvm/PassSupport.h:91
>> #1 0x00000000004e2ffa in llvm::PassInfo::createPass (this=0x0) at
>> llvm/lib/VMCore/Pass.cpp:196
>> #2 0x00000000004e522e in llvm::PMTopLevelManager::schedulePass
>> (this=0x85eb60, P=0x85ef10) at llvm/lib/VMCore/PassManager.cpp:617
>> #3 0x00000000004ebcce in llvm::PassManagerImpl::add (this=0x85e9b0,
>> P=0x85ef10) at llvm/lib/VMCore/PassManager.cpp:396
>> #4 0x00000000004e9735 in llvm::PassManager::addImpl (this=0x7fffffffdd90,
>> P=0x85ef10) at llvm/lib/VMCore/PassManager.cpp:1659
>> #5 0x00000000004e9884 in llvm::PassManager::add (this=0x7fffffffdd90,
>> P=0x85ef10) at llvm/lib/VMCoree/PassManager.cpp:1672
>> #6 0x000000000040b9be in main () at test.cpp:32
>>
>>
>> Best,
>> Ralf
>>
>>
>> Am 04.05.2011 18:15, schrieb Michael Ilseman:
>>>
>>> Thanks for the response. I do have assertions enabled, and none of
>>> them are getting hit. I did do a search of the mailing list for the
>>> past year (approximately) before writing my email, and what I found
>>> was that you should be allowed to use LoopInfo and other analysis
>>> function passes from a module pass, with the only difference being
>>> that getAnalysis is passed the function. The example code I posted
>>> conforms to all of the suggestions from the mailing list. Also, the
>>> same code (with modifications w.r.t. 2.8 initialization) works just
>>> fine in 2.8, and works fine in 2.9 with the rearranging I mentioned in
>>> my email.
>>>
>>> My concern is that having certain rearrangements segfault (even with
>>> assertions enabled), while others succeed may be due to a
>>> misunderstanding on my part of how initialization is done properly in
>>> 2.9. I have tried to model my code (and the example code given) after
>>> how the passes in lib/Transforms/Scalar are modeled.
>>>
>>> On Wed, May 4, 2011 at 12:59 AM, Duncan Sands<baldrick at free.fr> wrote:
>>>>
>>>> Hi Michael,
>>>>
>>>>> When migrating my project to 2.9, I've encountered a strange segfault
>>>>> where if a ModulePass's getAnalysisUsage adds LoopInfo and
>>>>> DominatorTree, then llvm::PMTopLevelManager::findAnalysisUsage will
>>>>> segfault.
>>>>
>>>> I suggest you build LLVM with assertions enabled - then you should get a
>>>> helpful error message rather than a segfault. I think you are not
>>>> allowed
>>>> to use LoopInfo from a ModulePass, but I don't recall the details. This
>>>> came up several times already on the mailing list, so I suggest you
>>>> search
>>>> the archives.
>>>>
>>>> Ciao, Duncan.
>>>>
>>>> What's odd is that if I rearrange this (add required for
>>>>>
>>>>> DominatorTree before LoopInfo), it does not segfault. I realize that
>>>>> LoopInfo requires and preserves DominatorTree, but this behavior is
>>>>> strange. All my other passes migrated fine (after adding in code to do
>>>>> the initializations), but perhaps I'm still not initializing
>>>>> everything properly?. Below is an example program and it's stack trace
>>>>> and debug info.
>>>>>
>>>>> #include "llvm/Pass.h"
>>>>> #include "llvm/PassManager.h"
>>>>> #include "llvm/Analysis/Dominators.h"
>>>>> #include "llvm/Analysis/LoopInfo.h"
>>>>>
>>>>> using namespace llvm;
>>>>>
>>>>> // Forward decl
>>>>> namespace llvm {
>>>>> void initializeFooPass(PassRegistry&);
>>>>> } // end namespace llvm
>>>>>
>>>>> namespace {
>>>>> class Foo : public ModulePass {
>>>>> public:
>>>>> Foo() : ModulePass(ID) {
>>>>> initializeFooPass(*PassRegistry::getPassRegistry());
>>>>> }
>>>>>
>>>>> ~Foo() { }
>>>>>
>>>>> static char ID;
>>>>> bool runOnModule(Module&);
>>>>> void print(std::ostream&, const Module*) const;
>>>>> void getAnalysisUsage(AnalysisUsage&) const;
>>>>> };
>>>>> } // end namespace
>>>>>
>>>>> bool Foo::runOnModule(Module&M) {
>>>>> return false;
>>>>> }
>>>>>
>>>>> void Foo::getAnalysisUsage(AnalysisUsage&AU) const {
>>>>> AU.addRequired<LoopInfo>();
>>>>> AU.addRequired<DominatorTree>();
>>>>> }
>>>>>
>>>>> void Foo::print(std::ostream&, const Module*) const { }
>>>>>
>>>>> char Foo::ID = 0;
>>>>> INITIALIZE_PASS_BEGIN(Foo, "foo", "foo bar", true, true)
>>>>> INITIALIZE_PASS_DEPENDENCY(LoopInfo)
>>>>> INITIALIZE_PASS_DEPENDENCY(DominatorTree)
>>>>> INITIALIZE_PASS_END(Foo, "foo", "foo bar", true, true)
>>>>>
>>>>> Foo *createFooPass() {
>>>>> return new Foo();
>>>>> }
>>>>>
>>>>> void runFooPass(Module&M)
>>>>> {
>>>>> PassManager PM;
>>>>> PM.add(createFooPass());
>>>>> PM.run(M);
>>>>> }
>>>>>
>>>>>
>>>>> Program received signal SIGSEGV, Segmentation fault.
>>>>>
>>>>> #0 0x0832312f in llvm::PMTopLevelManager::findAnalysisUsage
>>>>> (this=0x86f798c, P=0x892bfc0) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:577
>>>>> #1 0x08322cfb in llvm::PMTopLevelManager::setLastUser
>>>>> (this=0x86f798c, AnalysisPasses=..., P=0x892d2e0) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:516
>>>>> #2 0x083275f5 in llvm::MPPassManager::addLowerLevelRequiredPass
>>>>> (this=0x885cc60, P=0x892d2e0, RequiredPass=0x892bfc0) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:1608
>>>>> #3 0x08324cef in llvm::PMDataManager::add (this=0x885cc70,
>>>>> P=0x892d2e0, ProcessAnalysis=true) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:989
>>>>> #4 0x08327f11 in llvm::ModulePass::assignPassManager (this=0x892d2e0,
>>>>> PMS=..., PreferredType=llvm::PMT_ModulePassManager) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:1768
>>>>> #5 0x08329b11 in llvm::PassManagerImpl::addTopLevelPass
>>>>> (this=0x885cab8, P=0x892d2e0) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:423
>>>>> #6 0x0832339f in llvm::PMTopLevelManager::schedulePass
>>>>> (this=0x885cb8c, P=0x892d2e0) at
>>>>> <...>/llvm-2.9/lib/VMCore/PassManager.cpp:639
>>>>> #7 0x083299dc in llvm::PassManagerImpl::add (this=0x885cab8,
>>>>> P=0x892d2e0) at<...>/llvm-2.9/lib/VMCore/PassManager.cpp:396
>>>>> #8 0x083279e5 in llvm::PassManager::addImpl (this=0xbffe9578,
>>>>> P=0x892d2e0) at<...>/llvm-2.9/lib/VMCore/PassManager.cpp:1659
>>>>> #9 0x08327b0a in llvm::PassManager::add (this=0xbffe9578,
>>>>> P=0x892d2e0) at<...>/llvm-2.9/lib/VMCore/PassManager.cpp:1672
>>>>> #10 0x08089480 in runFooPass (M=...) at<...>/Hello.h:56
>>>>> ...
>>>>>
>>>>> At that point, the variable "P" is
>>>>>
>>>>> $9 = {_vptr.Pass = 0x0, Resolver = 0x0, PassID = 0x8533e00, Kind =
>>>>> llvm::PT_Function}
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>
>
More information about the llvm-dev
mailing list