[LLVMdev] Metadata/Value split has landed
Duncan P. N. Exon Smith
dexonsmith at apple.com
Wed Dec 10 15:57:26 PST 2014
> 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...)
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