[LLVMdev] Metadata/Value split has landed
Duncan P. N. Exon Smith
dexonsmith at apple.com
Thu Dec 11 13:56:02 PST 2014
I committed:
r224058 = 966942da9e68b59c31ce770e7f94c55a63482c6b
r224060 = da75f7277e3a129aed8ef8aa4e0d84de40b76fd4
r224061 = f88e4c8e9171045454b2c8e05054c2af8da3fe4f
Let me know if somehow you're still hitting the problem.
r224061 removes leak detection entirely from `MachineInstr`. There aren't
any leaks to be had there, since they're allocated in a custom allocator.
They're just dropped away once `MachineFunction` is deleted.
@Zalman, thanks again for your help digging into this.
> On 2014 Dec 11, at 09:05, Tom Stellard <tom at stellard.net> wrote:
>
> On Thu, Dec 11, 2014 at 11:52:34AM -0500, Tom Stellard wrote:
>> On Wed, Dec 10, 2014 at 05:27:45PM -0800, Duncan P. N. Exon Smith wrote:
>>> +zalman at google.com
>>>
>>
>> Hi Duncan,
>>
>> This patch plus another small change fixes the assertion failure for
>> me. With the patch alone, the void* overload of addGarbageObject()
>> was being used by MDNode::getTemporary(), so I had to cast the object as
>> an MDNode*:
>>
>> diff --git a/lib/IR/Metadata.cpp b/lib/IR/Metadata.cpp
>> index cd5edd2..916d216 100644
>> --- a/lib/IR/Metadata.cpp
>> +++ b/lib/IR/Metadata.cpp
>> @@ -564,7 +564,7 @@ MDNode *MDNode::getMDNode(LLVMContext &Context,
>> ArrayRef<Metadata *> MDs,
>> MDNodeFwdDecl *MDNode::getTemporary(LLVMContext &Context,
>> ArrayRef<Metadata *> MDs) {
>> MDNodeFwdDecl *N = new (MDs.size()) MDNodeFwdDecl(Context, MDs);
>> - LeakDetector::addGarbageObject(N);
>> + LeakDetector::addGarbageObject((MDNode*)N);
>> return N;
>> }
>
> Sorry, after more extensive testing, this doesn't work. It looks like
> you need to add const MDNode * overloads to addGarbageObject() adding
> them for addGarbageObjectImpl() doesn't seem to work:
>
> diff --git a/include/llvm/IR/LeakDetector.h
> b/include/llvm/IR/LeakDetector.h
> index e0b131e..b272eaf 100644
> --- a/include/llvm/IR/LeakDetector.h
> +++ b/include/llvm/IR/LeakDetector.h
> @@ -79,6 +79,17 @@ struct LeakDetector {
> #endif
> }
>
> + static void addGarbageObject(const MDNode *Object) {
> +#ifndef NDEBUG
> + addGarbageObjectImpl(Object);
> +#endif
> + }
> + static void removeGarbageObject(const MDNode *Object) {
> +#ifndef NDEBUG
> + removeGarbageObjectImpl(Object);
> +#endif
> + }
> +
> private:
> // If we are debugging, the actual implementations will be called...
> static void addGarbageObjectImpl(const Value *Object);
>>
>>
>> I'm in favor of committing this.
>>
>> -Tom
>>
>>
>>>> On 2014 Dec 10, at 15:57, Duncan P. N. Exon Smith <dexonsmith at apple.com> wrote:
>>>>
>>>>>
>>>>> On 2014 Dec 10, at 14:08, Tom Stellard <tom at stellard.net> wrote:
>>>>>
>>>>> On Wed, Dec 10, 2014 at 11:21:08AM -0800, Duncan P. N. Exon Smith wrote:
>>>>>>
>>>>>>> On 2014 Dec 10, at 08:40, Tom Stellard <tom at stellard.net> wrote:
>>>>>>>
>>>>>>> On Tue, Dec 09, 2014 at 09:22:16PM -0800, Duncan P. N. Exon Smith wrote:
>>>>>>>> The `Metadata`/`Value` split (PR21532) landed in r223802 -- at least, the
>>>>>>>> C++ side of it. This was a rocky day, but I suppose that's what I get
>>>>>>>> for failing to stage the change in smaller pieces.
>>>>>>>>
>>>>>>>> As of r223916 (lldb), I'm not aware of any remaining (in-tree) breakage,
>>>>>>>> so if I've missed some problem in the sea of buildbot errors, please
>>>>>>>> flag me down.
>>>>>>>>
>>>>>>>> I'll follow up soon with bitcode and assembly changes!
>>>>>>>
>>>>>>> Hi Duncan,
>>>>>>>
>>>>>>> I started getting random assertion failures in some tests yesterday, and I think
>>>>>>> it may be related to this change. Here is the stack trace:
>>>>>>>
>>>>>>> #0 0x00007ffff59f4c39 in raise () from /lib64/libc.so.6
>>>>>>> #1 0x00007ffff59f6348 in abort () from /lib64/libc.so.6
>>>>>>> #2 0x00007ffff59edb96 in __assert_fail_base () from /lib64/libc.so.6
>>>>>>> #3 0x00007ffff59edc42 in __assert_fail () from /lib64/libc.so.6
>>>>>>> #4 0x00007ffff3a30e92 in llvm::LeakDetectorImpl<void>::addGarbage(void const*) [clone .part.19] () from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #5 0x00007ffff3a30fd3 in llvm::LeakDetector::addGarbageObjectImpl(void*) () from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #6 0x00007ffff3a40eed in llvm::MDNode::getTemporary(llvm::LLVMContext&, llvm::ArrayRef<llvm::Metadata*>) () from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #7 0x00007ffff3426b3f in MapValueImpl(llvm::Metadata const*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #8 0x00007ffff3426bd6 in MapValueImpl(llvm::Metadata const*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #9 0x00007ffff3426bd6 in MapValueImpl(llvm::Metadata const*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #10 0x00007ffff3426eed in llvm::MapValue(llvm::Metadata const*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #11 0x00007ffff3426f39 in llvm::MapValue(llvm::MDNode const*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #12 0x00007ffff3427174 in llvm::RemapInstruction(llvm::Instruction*, llvm::ValueMap<llvm::Value const*, llvm::WeakVH, llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false> > >&, llvm::RemapFlags, llvm::ValueMapTypeRemapper*, llvm::ValueMaterializer*) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #13 0x00007ffff3755786 in (anonymous namespace)::ModuleLinker::linkGlobalValueBody(llvm::GlobalValue&) () from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #14 0x00007ffff375767f in llvm::Linker::linkInModule(llvm::Module*) () from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #15 0x00007ffff3758cfb in llvm::Linker::LinkModules(llvm::Module*, llvm::Module*, std::function<void (llvm::DiagnosticInfo const&)>) ()
>>>>>>> from /opt/buildbot/lib/libLLVM-3.6svn.so
>>>>>>> #16 0x00007ffff6c9d8cf in clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) () from /opt/buildbot/lib/libOpenCL.so.1
>>>>>>> #17 0x00007ffff6e61f23 in clang::ParseAST(clang::Sema&, bool, bool) () from /opt/buildbot/lib/libOpenCL.so.1
>>>>>>> #18 0x00007ffff6c9e6bb in clang::CodeGenAction::ExecuteAction() () from /opt/buildbot/lib/libOpenCL.so.1
>>>>>>> #19 0x00007ffff6b7ead6 in clang::FrontendAction::Execute() () from /opt/buildbot/lib/libOpenCL.so.1
>>>>>>> #20 0x00007ffff6b5d179 in clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) () from /opt/buildbot/lib/libOpenCL.so.1
>>>>>>> #21 0x00007ffff6b1282c in (anonymous namespace)::compile_llvm (llvm_ctx=...,
>>>>>>> source="\n__kernel void test_fn(__local float *sSharedStorage, __global float *srcValues, __global uint *offsets, __global float *destBuffer, uint alignmentOffset )\n{\n int tid = get_global_id( 0 );\n sSha"..., headers=..., name="input.cl", triple="r600--", processor="verde", opts="",
>>>>>>> address_spaces=..., optimization_level=@0x7fffffff21cc: 2, r_log=...) at llvm/invocation.cpp:255
>>>>>>> #22 0x00007ffff6b140c8 in clover::compile_program_llvm (source=..., headers=..., ir=ir at entry=PIPE_SHADER_IR_NATIVE, target=..., opts=..., r_log=...)
>>>>>>> at llvm/invocation.cpp:710
>>>>>>> #23 0x00007ffff6b0a371 in clover::program::build (this=this at entry=0x23a0530, devs=..., opts=opts at entry=0x7ffff793dc0d "", headers=...)
>>>>>>> at core/program.cpp:63
>>>>>>> #24 0x00007ffff6af31c4 in clBuildProgram (d_prog=0x23a0538, num_devs=0, d_devs=0x0, p_opts=<optimized out>, pfn_notify=0x0, user_data=0x0)
>>>>>>> at api/program.cpp:182
>>>>>>>
>>>>>>> Does this look related? If so, let me know what other information you need to
>>>>>>> try to debug this issue.
>>>>>>
>>>>>> This could be related; I'm not sure.
>>>>>>
>>>>>
>>>>> I'm pretty sure that this commit is the cause of the regression.
>>>>>
>>>>> r223801 works and r223810 does not, and I don't think any of the other
>>>>> commits in that range could cause this.
>>>>>
>>>>>> It looks like a leak detection assertion, and I didn't need to change
>>>>>> that logic at all. `ValueMap` calls `MDNode::getTemporary()` and
>>>>>> `MDNode::deleteTemporary()` in the same ways it used to (and I didn't
>>>>>> touch the implementation of those).
>>>>>>
>>>>>> Can you reproduce this with `llvm-link`? If so, that sounds like the
>>>>>> best place to start.
>>>>>
>>>>> I can't reproduce this using llvm-link unfortunately. Any other ideas?
>>>>
>>>> (Continuing via email, since Tom stepped away IRC.)
>>>>
>>>> Tom, from the trace [1], it the problematic pointer (0x27e4c80) only shows
>>>> up once.
>>>>
>>>> [1]: http://people.freedesktop.org/~tstellar/md-crash.out
>>>>
>>>> That means that something *else* -- other than `MDNode::getTemporary()`
>>>> -- must be adding that address to garbage and failing to remove it.
>>>>
>>>> I just dug into `LeakDetector::addGarbageObject()` and it stores *all*
>>>> calls to `addGarbage()` in the same place. There are a fair number of
>>>> these in the IR:
>>>>
>>>> $ git grep -e addGarbageObject -w -- lib/IR/
>>>> lib/IR/BasicBlock.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/BasicBlock.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Function.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Function.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Function.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Function.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Globals.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Globals.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Globals.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Globals.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Globals.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Instruction.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Instruction.cpp: LeakDetector::addGarbageObject(this);
>>>> lib/IR/Instruction.cpp: if (!P) LeakDetector::addGarbageObject(this);
>>>> lib/IR/Metadata.cpp: LeakDetector::addGarbageObject(N);
>>>>
>>>> I think the next step is to identify who called `addGarbageObject()` with
>>>> the problematic address, and what the stack trace was.
>>>>
>>>> The weird thing is, I also noticed a semantic change I made here
>>>> accidentally. `addGarbageObject()` has two overloads: `void*` and
>>>> `const Value*`. `MDNode::getTemporary()` used to match the latter, but
>>>> now it matches the former.
>>>>
>>>> The weird part: all the other calls to `addGarbageObject()` look like they
>>>> send in a `Value *`.
>>>>
>>>> Do you have any other calls to `addGarbageObject()`? Do they match
>>>> `void *`?
>>>>
>>>> Also, what happens with the attached patch? (If this fixes your problem,
>>>> I think it's just papering over something...)
>>>>
>>>> <0001-IR-Detect-Metadata-leaks-separately-from-generic-obj.patch>
>>>
>>> Zalman also had a reproduction, and he's been able to track it down to
>>> an `addGarbageObject()` call from `MachineBasicBlock`. It looks like
>>> the MBB gets deallocated but `removeGarbageObject()` isn't called yet.
>>>
>>> CC'ing him here so he can join the thread once he's gotten a little
>>> further.
>>>
>>> BTW, if this is blocking anyone, I can commit the patch I attached to
>>> my previous email (or you can apply it locally). I think it's probably
>>> the right thing eventually -- it improves the output when there *is* an
>>> issue -- but I haven't committed it yet since it'll cover up the
>>> problem.
>> _______________________________________________
>> 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