[PATCH] Warn on use of vector initializers in ARM BE mode

[James Molloy]

Hi,

 

The ability to use vector initializer lists is a GNU vector extension and is
unrelated to the NEON intrinsics in arm_neon.h. On little endian machines it
works fine, however on big endian machines it exhibits surprising behaviour:

    

        uint32x2_t x = {42, 64};

        return vget_lane_u32(x, 0); // Will return 64.

    

Because of this, explicitly call out that it is unsupported on big endian
machines.

    

This patch will emit the following warning in big-endian mode:

    

    test.c:3:15: warning: Vector initializers are part of the GNU vector
extensions and are not compatible with NEON intrinsics on big endian ARM
targets [-Wgnu]

   int32x4_t x = {0, 1, 2, 3};

                      ^

    test.c:3:15: note: Consider using vld1q_s32() to initialize a vector
from memory, or vcombine_s32(vcreate_s32(), vcreate_s32()) to initialize
from integer constants

    1 warning generated.

 

It's fairly simple, is it OK to commit?

 

Cheers,

 

James
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