Bug 93454

Hmmm... this comes from

#if defined(PIPE_ARCH_SSSE3)

#include <tmmintrin.h>

Which in turn comes from, hilariously,

#if defined(PIPE_CC_GCC) && (__GNUC__ * 100 + __GNUC_MINOR__) < 409 && !defined(__SSSE3__)
/* #warning SSE3 support requires -msse3 compiler options before GCC 4.9 */
#else
#define PIPE_ARCH_SSSE3
#endif

I'm guessing that was meant to be

#if defined(PIPE_CC_GCC) && (__GNUC__ * 100 + __GNUC_MINOR__) < 409 || !defined(__SSSE3__)

Hmmm... this comes from

#if defined(PIPE_ARCH_SSSE3)

#include <tmmintrin.h>

Which in turn comes from, hilariously,

#if defined(PIPE_CC_GCC) && (__GNUC__ * 100 + __GNUC_MINOR__) < 409 && !defined(__SSSE3__)
/* #warning SSE3 support requires -msse3 compiler options before GCC 4.9 */
#else
#define PIPE_ARCH_SSSE3
#endif

I'm guessing that was meant to be

#if defined(PIPE_CC_GCC) && (__GNUC__ * 100 + __GNUC_MINOR__) < 409 || !defined(__SSSE3__)

Let me try that in src/gallium/include/pipe/p_config.h

This logic was last altered in the change below... My copy of clang 3.5 purports to be gcc 4.2.1. What does clang 3.7 report?

clang -E -dM - < /dev/null | grep GNUC

commit eb643db30e1bdf5171d0a012674016c317925b6e
Author: Jose Fonseca <jfonseca@vmware.com>
Date:   Sun Aug 9 11:21:03 2015 +0100

    gallium: GCC 4.9 allows to include tmmintrin.h without -msse3.
    
    Fixes build with MinGW x86_64 build with GCC 4.9, due to conflicting
    definition _mm_shuffle_epi8 of u_sse.h and system headers.
    
    Trivial.

(In reply to Ilia Mirkin from comment #4)

> clang -E -dM - < /dev/null | grep GNUC

#define __GNUC_MINOR__ 9
#define __GNUC_PATCHLEVEL__ 1
#define __GNUC_STDC_INLINE__ 1
#define __GNUC__4

The issue is simple:

- GCC used to require -msse3 in order to include tmmintrin.h 
- MSVC/ICC does not
- GCC 4.9 finally eliminated that awkward requirement -- it's now possible to use SSE3 instrinsics without giving GCC carte blanch to emit SSSE3 whenever it wants

- it appears Clang claims to be GCC 4.9 but does not in fact support this.


We can workaround by adding   

diff --git a/src/gallium/include/pipe/p_config.h b/src/gallium/include/pipe/p_config.h
index 0b570c7..7d5d7d4 100644
--- a/src/gallium/include/pipe/p_config.h
+++ b/src/gallium/include/pipe/p_config.h
@@ -96,7 +96,7 @@
 #else
 #define PIPE_ARCH_SSE
 #endif
-#if defined(PIPE_CC_GCC) && (__GNUC__ * 100 + __GNUC_MINOR__) < 409 && !defined(__SSSE3__)
+#if defined(PIPE_CC_GCC) && ((__GNUC__ * 100 + __GNUC_MINOR__) < 409 || defined(__clang__)) && !defined(__SSSE3__)
 /* #warning SSE3 support requires -msse3 compiler options before GCC 4.9 */
 #else
 #define PIPE_ARCH_SSSE3


But this is above all a bug in Clang 3.7.  If that strive/claim to be GCC 4.9 then they should handle this too.

Hi, thanks for the workaround
I found this bug report https://llvm.org/bugs/show_bug.cgi?id=24990 and i was paring commits for llvm and clang and i did not found anything that would corresponds to above bug.

(In reply to Tomasz Paweł Gajc from comment #7)
> Hi, thanks for the workaround
> I found this bug report https://llvm.org/bugs/show_bug.cgi?id=24990 and i
> was paring commits for llvm and clang and i did not found anything that
> would corresponds to above bug.

It looks like they had fixed this already before the bug report.

From the git history, the fix is 

  https://github.com/llvm-mirror/clang/commit/41885d36e85ead75a1d18ef7d2f43663f90ed67e

Not sure what clang version got it in the end.

But given this has already been fixed in Clang, I think we shouldn't fix it in Mesa, otherwise we'll need complex logic to detect exactly which clang versions support or not this.

OpenMandriva Cooker made the decision to use LLVM/clang 3.7.0 as default compiler, so they should crossport any fixes necessary to keep light on.