llvm dev - Oct 2010 - [LLVMdev] llvm-dis fails to parse bytecode emitted by clang

Thanks to everyone for the quick replies! I spent some time looking
into the issue. It turns out that llvm-dis crashes on CLANG-generated
bytecode if LLVM is compiled for a 64-bit architecture. The problem
disappears when compiling for a 32-bit architecture. Should I file a
bug report?

Lorenzo

On Tue, Oct 26, 2010 at 3:34 AM, Xinfinity <xinfinity_a at yahoo.com>
wrote:
>
> Hi,
>
> For the first problem, try
> clang -S -emit-llvm test.c -o test.ll
> you should get the llvm IR and you don't need to use llvm-dis. Although
I
> have tried your example with the exact commands and source code you posted
> and it worked just fine for me. I also use clang and LLVM 2.8 compiled from
> sources.
>
> For the second problem, suppress -emit-llvm, since you want the executable,
> not an object file:
> clang test.c -o test.
>
> Hope this helps,
> Alexandra
>
> Lorenzo De Carli-3 wrote:
>>
>> Hi,
>>
>> I am trying to generate LLVM bytecode using CLANG and I ran into the
>> following problem. If I run clang with the -emit-llvm option and then
>> try to get a textual representation of the output using llvm-dis, the
>> latter crashes because of a failed assertion in BitCodeReader.cpp,
>> mentioning a "Type mismatch in value table" (the exact error
message
>> is appended at the end of this email). However, if I generate the
>> bytecode from the same source using llvm-gcc instead of clang,
>> llvm-dis works fine.
>>
>> I am also experiencing another (potentially unrelated problem). If I
>> try to run clang without the "-c" option (i.e. to generate an
>> executable instead of an object file) it crashes emitting the message
>> " clang: error: 'x86_64-unknown-linux-gnu': unable to pass
LLVM
>> bit-code files to linker". Output for this problem is also
attached.
>>
>> Could anyone shed some light on those problem? I am using CLANG/LLVM
>> 2.8 compiled from source. The test program I am trying to compile is
>> simply:
>>
>> int main()
>> {
>>   return 0;
>> }
>>
>>
>> Thanks,
>> Lorenzo De Carli
>>
>> Output for problem #1:
>> $ clang -c -emit-llvm test.c -o test.bc
>> $ llvm-dis test.bc
>> llvm-dis: BitcodeReader.cpp:205: llvm::Value*
>> llvm::BitcodeReaderValueList::getValueFwdRef(unsigned int, const
>> llvm::Type*): Assertion `(Ty == 0 || Ty == V->getType()) &&
"Type
>> mismatch in value table!"' failed.
>> 0   llvm-dis  0x00000000006131c6
>> 1   llvm-dis  0x0000000000613502
>> 2   libc.so.6 0x00000039cf4302d0
>> 3   libc.so.6 0x00000039cf430265 gsignal + 53
>> 4   libc.so.6 0x00000039cf431d10 abort + 272
>> 5   libc.so.6 0x00000039cf4296e6 __assert_fail + 246
>> 6   llvm-dis  0x000000000051005b
>> llvm::BitcodeReaderValueList::getValueFwdRef(unsigned int, llvm::Type
>> const*) + 173
>> 7   llvm-dis  0x000000000052e574
>> llvm::BitcodeReader::getFnValueByID(unsigned int, llvm::Type const*) +
>> 42
>> 8   llvm-dis  0x000000000051482b
>> llvm::BitcodeReader::ParseFunctionBody(llvm::Function*) + 11371
>> 9   llvm-dis  0x000000000051574a
>> llvm::BitcodeReader::materializeFunction(llvm::Function*,
>> std::string*) + 284
>> 10  llvm-dis  0x000000000050ddca
>> llvm::BitcodeReader::materializeModule(std::string*) + 210
>> 11  llvm-dis  0x00000000005171b2
>> llvm::ParseBitcodeFile(llvm::MemoryBuffer*, std::string*) + 74
>> 12  llvm-dis  0x000000000050b894 main + 160
>> 13  libc.so.6 0x00000039cf41d994 __libc_start_main + 244
>> 14  llvm-dis  0x000000000050b569 __gxx_personality_v0 + 625
>> Aborted
>>
>> Output for problem #2:
>> $ clang -emit-llvm -c test.c [WORKS FINE]
>> $ clang -emit-llvm test.c
>> clang: error: 'x86_64-unknown-linux-gnu': unable to pass LLVM
bit-code
>> files to linker
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
> --
> View this message in context:
http://old.nabble.com/llvm-dis-fails-to-parse-bytecode-emitted-by-clang-tp30052324p30055357.html
> Sent from the LLVM - Dev mailing list archive at Nabble.com.
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


-- 
Lorenzo De Carli
lorenzo.decarli at gmail.com
"People want to interact sometimes, and sometimes
they want to do something that isn't inherently social.
I don't see that changing." (Ron Gilbert)

Hi Lorenzo,
> Thanks to everyone for the quick replies! I spent some time looking
> into the issue. It turns out that llvm-dis crashes on CLANG-generated
> bytecode if LLVM is compiled for a 64-bit architecture. The problem
> disappears when compiling for a 32-bit architecture. Should I file a
> bug report?
it still sounds like LLVM is being miscompiled to me.  What compiler
did you use to build LLVM?

Ciao,

Duncan.

Ehm... this is embarassing. I realized that an old version of LLVM was
laying around on my machine and in $PATH, so I was running an old
version of llvm-dis without realizing it. Once I removed it,
everything started working perfectly.

Sorry for the false alarm :-(

Lorenzo


On Tue, Oct 26, 2010 at 2:28 PM, Duncan Sands <baldrick at free.fr>
wrote:
> Hi Lorenzo,
>
>> Thanks to everyone for the quick replies! I spent some time looking
>> into the issue. It turns out that llvm-dis crashes on CLANG-generated
>> bytecode if LLVM is compiled for a 64-bit architecture. The problem
>> disappears when compiling for a 32-bit architecture. Should I file a
>> bug report?
>
> it still sounds like LLVM is being miscompiled to me.  What compiler
> did you use to build LLVM?
>
> Ciao,
>
> Duncan.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>