[cfe-dev] MS style ASM failure and crash

[JB Feldman]

Bug has been filed: http://llvm.org/bugs/show_bug.cgi?id=18994


On Thu, Feb 27, 2014 at 10:52 AM, Reid Kleckner <rnk at google.com> wrote:

> This also happens (just once) in the Chromium build:
>
> http://build.chromium.org/p/chromium.fyi/builders/Chromium%20Win%20Clang/builds/645/steps/compile/logs/stdio
>
> Parsing this involves Clang and
> llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp.  It's really tricky because
> C++ expressions can occur in lots of places, making it harder to parse the
> assembly.
>
> Feel free to file a bug on this.
>
>
> On Thu, Feb 27, 2014 at 7:22 AM, JB Feldman <jb.feldman at kyrus-tech.com>wrote:
>
>> Hi guys,
>>
>> I will file a bug report in a little bit (once I get a minimal test case)
>> but I wanted to ask if anyone understands the problem I'm seeing.
>>
>> Trying to include ntddk.h and compiling with clang-cl, I get the
>> following message:
>>
>> In file included from kbfiltr.c:19:
>> In file included from ./kbfiltr.h:28:
>> C:\WINDDK\3790.1830\inc\ddk\wxp\ntddk.h(7149,29) :  error: unexpected
>> type name
>>       'KPCR': expected expression
>>     __asm {  movzx eax, _PCR KPCR.Number  }
>>                              ^
>> Assertion failed: End.getPointer() <= EndPtr && "frontend claimed part of
>> a token?", file ..\..\..\..\..\lib\Target\X86\AsmParser\X86AsmParser.cpp,
>> line 1481
>> clang-cl.exe: error: clang frontend command failed with exit code 3 (use
>> -v to s
>> ee invocation)
>>
>> The assertion failure obviously results in a crash.
>>
>> So my initial guess was some kind of Lexer issue, maybe because of no
>> semicolon, or... who knows. But then, I rewrote that code to read:
>>
>> int x = FIELD_OFFSET(KPCR, Number);
>> __asm { movzx eax, fs:[x] }
>>
>> Which compiles to the same code, and that actually did work with
>> clang-cl. Can anyone tell me why one works and the other doesn't? (My
>> guess: MS not following standard Intel notation spec)
>>
>> Thanks,
>> JB
>>
>> _______________________________________________
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>> cfe-dev at cs.uiuc.edu
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>>
>>
>
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