[llvm-dev] uninitialized values in Attributes.cpp

[regehr via llvm-dev]

Well, it looks like almost all of the problems go away when I build 
using trunk instead of 3.9.  So, that was scary but I'm going to forget 
it ever happened.  >8000 test cases failed under Valgrind!!

John



On 11/20/2016 03:03 AM, Sanjoy Das via llvm-dev wrote:
> Hi John,
>
> This is probably somewhat of a stretch, but since the problem does not
> happen with a Debug build, could it be due to loop unswitching (or
> optimizations like that) kicking in when building LLVM?  That is, due
> to speculating the branch out of loops like
>
>   val = *uninitialized_loc
>   for (; false;) {
>     if (val)
>       foo();
>     else
>       bar();
>   }
>
> ?
>
> What compiler are you building with?
>
> -- Sanjoy
>
> On Sat, Nov 19, 2016 at 9:00 PM, regehr via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I did a RelWithDebInfo + asserts build of LLVM just now and, when running
>> "make check" under Valgrind, am seeing a lot of uses of uninitialized memory
>> like the one below.  Anyone know offhand what's likely to be the root cause?
>> Unfortunately a Debug build doesn't give these errors.  Thanks,
>>
>> John
>>
>>
>> FAIL: LLVM :: Analysis/BasicAA/pr18573.ll (2093 of 18733)
>> ******************** TEST 'LLVM :: Analysis/BasicAA/pr18573.ll' FAILED
>> ********************
>> Script:
>> --
>> /home/regehr/llvm/build-vg/./bin/opt
>> /home/regehr/llvm/test/Analysis/BasicAA/pr18573.ll -O2 -S |
>> /home/regehr/llvm/build-vg/./bin/FileCheck
>> /home/regehr/llvm/test/Analysis/BasicAA/pr18573.ll
>> --
>> Exit Code: 123
>>
>> Command Output (stderr):
>> --
>> ==29299== Conditional jump or move depends on uninitialised value(s)
>> ==29299==    at 0x13FCF12: hasAttribute (Attributes.cpp:421)
>> ==29299==    by 0x13FCF12: hasAttribute (Attributes.cpp:186)
>> ==29299==    by 0x13FCF12: operator() (Attributes.cpp:627)
>> ==29299==    by 0x13FCF12: operator()<const std::pair<unsigned int,
>> llvm::Attribute> *> (predefined_ops.h:234)
>> ==29299==    by 0x13FCF12: __find_if<const std::pair<unsigned int,
>> llvm::Attribute> *, __gnu_cxx::__ops::_Iter_pred<(lambda at
>> ../lib/IR/Attributes.cpp:627:3)> > (stl_algo.h:140)
>> ==29299==    by 0x13FCF12: __find_if<const std::pair<unsigned int,
>> llvm::Attribute> *, __gnu_cxx::__ops::_Iter_pred<(lambda at
>> ../lib/IR/Attributes.cpp:627:3)> > (stl_algo.h:161)
>> ==29299==    by 0x13FCF12: find_if<const std::pair<unsigned int,
>> llvm::Attribute> *, (lambda at ../lib/IR/Attributes.cpp:627:3)>
>> (stl_algo.h:3815)
>> ==29299==    by 0x13FCF12: none_of<const std::pair<unsigned int,
>> llvm::Attribute> *, (lambda at ../lib/IR/Attributes.cpp:627:3)>
>> (stl_algo.h:526)
>> ==29299==    by 0x13FCF12: none_of<llvm::ArrayRef<std::pair<unsigned int,
>> llvm::Attribute> > &, (lambda at ../lib/IR/Attributes.cpp:627:3)>
>> (STLExtras.h:607)
>> ==29299==    by 0x13FCF12: llvm::AttributeSet::get(llvm::LLVMContext&,
>> llvm::ArrayRef<std::pair<unsigned int, llvm::Attribute> >)
>> (Attributes.cpp:627)
>> ==29299==    by 0x13FD62B: llvm::AttributeSet::get(llvm::LLVMContext&,
>> unsigned int, llvm::ArrayRef<llvm::Attribute::AttrKind>)
>> (Attributes.cpp:712)
>> ==29299==    by 0x146F9AC:
>> llvm::Intrinsic::getAttributes(llvm::LLVMContext&, llvm::Intrinsic::ID)
>> (Intrinsics.gen:20104)
>> ==29299==    by 0x146F3A0: llvm::Function::Function(llvm::FunctionType*,
>> llvm::GlobalValue::LinkageTypes, llvm::Twine const&, llvm::Module*)
>> (Function.cpp:277)
>> ==29299==    by 0x1CD2B36: Create (Function.h:106)
>> ==29299==    by 0x1CD2B36:
>> llvm::LLParser::ParseFunctionHeader(llvm::Function*&, bool)
>> (LLParser.cpp:4766)
>> ==29299==    by 0x1CCE2C2: llvm::LLParser::ParseDeclare() (LLParser.cpp:444)
>> ==29299==    by 0x1CCC15A: llvm::LLParser::ParseTopLevelEntities()
>> (LLParser.cpp:276)
>> ==29299==    by 0x1CCBFBF: llvm::LLParser::Run() (LLParser.cpp:74)
>> ==29299==    by 0x1CC59D8: llvm::parseAssemblyInto(llvm::MemoryBufferRef,
>> llvm::Module&, llvm::SMDiagnostic&, llvm::SlotMapping*) (Parser.cpp:31)
>> ==29299==    by 0x1CC5C16: llvm::parseAssembly(llvm::MemoryBufferRef,
>> llvm::SMDiagnostic&, llvm::LLVMContext&, llvm::SlotMapping*) (Parser.cpp:41)
>> ==29299==    by 0x158C59E: llvm::parseIR(llvm::MemoryBufferRef,
>> llvm::SMDiagnostic&, llvm::LLVMContext&) (IRReader.cpp:89)
>> ==29299==    by 0x158CA61: llvm::parseIRFile(llvm::StringRef,
>> llvm::SMDiagnostic&, llvm::LLVMContext&) (IRReader.cpp:102)
>> ==29299==
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