[cfe-dev] clang-tidy & SSE with GCC toolchain

[Daniel Evers via cfe-dev]

Hi,

Thanks for the tip. I checked the output and clang++ uses its own includes instead of the GCC headers.
Does the compiler add some pre-defined include paths that the clang-based tools don't have by default?

Clang-tidy at least doesn't complain about -gcc-toolchain ;-) But I'm not sure if it's relevant here.

Thx
Daniel

-----Original Message-----
From: Csaba Raduly [mailto:rcsaba at gmail.com]
Sent: Freitag, 26. Januar 2018 10:08
To: Craig Topper <craig.topper at gmail.com>
Cc: Daniel Evers <Daniel.Evers at utimaco.com>; cfe-dev at lists.llvm.org
Subject: Re: [cfe-dev] clang-tidy & SSE with GCC toolchain

Daniel,
check the original compilation with -H to see which xmmintrin.h got compiled.

Does clang-tidy understand  -gcc-toolchain?


Csaba

On Thu, Jan 25, 2018 at 6:43 PM, Craig Topper via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> The gcc version of xmmintrin.h is not compatible with clang. Clang has
> its own version. Maybe you need to explicitly add the clang include
> directory to your command line?
>
> ~Craig
>
> On Thu, Jan 25, 2018 at 4:25 AM, Daniel Evers via cfe-dev
> <cfe-dev at lists.llvm.org> wrote:
>>
>> Hey!
>>
>>
>>
>> I have a project which is compiled with GCC (7) and Clang (5.0). The
>> clang built uses the GCC tool chain, like this (Red Hat 7 with devtoolset-7):
>>
>>      clang++ -gcc-toolchain /opt/rh/devtoolset-7/root/usr […]
>>
>>
>>
>> The code compiles and runs fine, but running clang-tidy (using the
>> same compiler flags) chokes on the SSE built-ins in GCC’s headers:
>>
>>
>> /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/include/xmmintrin.h:54:3:
>> error: argument to '__builtin_prefetch' must be a constant integer
>> [clang-diagnostic-error]
>>
>>   __builtin_prefetch (__P, (__I & 0x4) >> 2, __I & 0x3);
>>
>>   ^
>>
>>
>> /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/include/xmmintrin.h:130:19:
>> error: use of undeclared identifier '__builtin_ia32_addss'
>> [clang-diagnostic-error]
>>
>>   return (__m128) __builtin_ia32_addss ((__v4sf)__A, (__v4sf)__B);
>>
>>                   ^
>>
>>
>> /opt/rh/devtoolset-7/root/usr/lib/gcc/x86_64-redhat-linux/7/include/xmmintrin.h:136:19:
>> error: use of undeclared identifier '__builtin_ia32_subss'
>> [clang-diagnostic-error]
>>
>>   return (__m128) __builtin_ia32_subss ((__v4sf)__A, (__v4sf)__B);
>>
>>
>>
>> [more errors following…]
>>
>>
>>
>> This happens as soon as I include <xmmintrin.h> (e.g. indirectly via
>> Boost.UUID).
>>
>>
>>
>> I’m wondering that the clang compiler accepts the code, while
>> clang-tidy doesn’t.
>>
>> Any ideas how to fix this? My current workaround is to disable
>> SSE-support in Boost.UUID via macro for clang-tidy, but the problem
>> will re-appear as soon as some other lib tries to use SSE instructions.
>>
>>
>>
>> Cheers,
>>
>> Daniel Evers
>>
>>
>>
>>
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>
>
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