r192143 - Suppress useless -Wshadow warning when using _mm* macros from emmintrin.h
Ted Kremenek
kremenek at apple.com
Mon Oct 7 23:34:03 PDT 2013
Yes I agree. I’ll look into doing something more general.
On Oct 7, 2013, at 10:22 PM, Bob Wilson <bob.wilson at apple.com> wrote:
>
> On Oct 7, 2013, at 5:19 PM, Ted Kremenek <kremenek at apple.com> wrote:
>
>> Interesting. Yes that seems like a reasonably generic heuristic. It does get potentially complicated if a macro uses another macro though… conceptually all from the same “expansion”.
>
> emmintrin.h is just one case. Many of the ARM Neon intrinsics have this same issue. I suppose we could use the same _Pragma approach for those, but a more general solution would be nice.
>
>>
>> On Oct 7, 2013, at 5:11 PM, Richard Smith <richard at metafoo.co.uk> wrote:
>>
>>> Maybe we should teach Clang not to warn on shadowing if the declaration and all its uses come from the same macro expansion?
>>>
>>>
>>> On Mon, Oct 7, 2013 at 4:51 PM, Ted Kremenek <kremenek at apple.com> wrote:
>>> Author: kremenek
>>> Date: Mon Oct 7 18:51:11 2013
>>> New Revision: 192143
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=192143&view=rev
>>> Log:
>>> Suppress useless -Wshadow warning when using _mm* macros from emmintrin.h
>>>
>>> Fixes <rdar://problem/10679282>.
>>>
>>> I'm not completely satisfied with this patch. Sprinkling "diagnostic ignored"
>>> _Pragmas throughout this file is gross, but I couldn't suppress
>>> it for the entire file.
>>>
>>> Modified:
>>> cfe/trunk/lib/Headers/emmintrin.h
>>> cfe/trunk/test/Sema/warn-shadow.c
>>>
>>> Modified: cfe/trunk/lib/Headers/emmintrin.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Headers/emmintrin.h?rev=192143&r1=192142&r2=192143&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Headers/emmintrin.h (original)
>>> +++ cfe/trunk/lib/Headers/emmintrin.h Mon Oct 7 18:51:11 2013
>>> @@ -826,7 +826,9 @@ _mm_xor_si128(__m128i __a, __m128i __b)
>>> }
>>>
>>> #define _mm_slli_si128(a, count) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128i __a = (a); \
>>> + _Pragma("clang diagnostic pop"); \
>>> (__m128i)__builtin_ia32_pslldqi128(__a, (count)*8); })
>>>
>>> static __inline__ __m128i __attribute__((__always_inline__, __nodebug__))
>>> @@ -891,7 +893,9 @@ _mm_sra_epi32(__m128i __a, __m128i __cou
>>>
>>>
>>> #define _mm_srli_si128(a, count) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128i __a = (a); \
>>> + _Pragma("clang diagnostic pop"); \
>>> (__m128i)__builtin_ia32_psrldqi128(__a, (count)*8); })
>>>
>>> static __inline__ __m128i __attribute__((__always_inline__, __nodebug__))
>>> @@ -1280,20 +1284,26 @@ _mm_movemask_epi8(__m128i __a)
>>> }
>>>
>>> #define _mm_shuffle_epi32(a, imm) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128i __a = (a); \
>>> + _Pragma("clang diagnostic pop"); \
>>> (__m128i)__builtin_shufflevector((__v4si)__a, (__v4si) _mm_set1_epi32(0), \
>>> (imm) & 0x3, ((imm) & 0xc) >> 2, \
>>> ((imm) & 0x30) >> 4, ((imm) & 0xc0) >> 6); })
>>>
>>> #define _mm_shufflelo_epi16(a, imm) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128i __a = (a); \
>>> + _Pragma("clang diagnostic pop"); \
>>> (__m128i)__builtin_shufflevector((__v8hi)__a, (__v8hi) _mm_set1_epi16(0), \
>>> (imm) & 0x3, ((imm) & 0xc) >> 2, \
>>> ((imm) & 0x30) >> 4, ((imm) & 0xc0) >> 6, \
>>> 4, 5, 6, 7); })
>>>
>>> #define _mm_shufflehi_epi16(a, imm) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128i __a = (a); \
>>> + _Pragma("clang diagnostic pop"); \
>>> (__m128i)__builtin_shufflevector((__v8hi)__a, (__v8hi) _mm_set1_epi16(0), \
>>> 0, 1, 2, 3, \
>>> 4 + (((imm) & 0x03) >> 0), \
>>> @@ -1386,8 +1396,10 @@ _mm_movemask_pd(__m128d __a)
>>> }
>>>
>>> #define _mm_shuffle_pd(a, b, i) __extension__ ({ \
>>> + _Pragma("clang diagnostic push") _Pragma("clang diagnostic ignored \"-Wshadow\""); \
>>> __m128d __a = (a); \
>>> __m128d __b = (b); \
>>> + _Pragma("clang diagnostic pop"); \
>>> __builtin_shufflevector(__a, __b, (i) & 1, (((i) & 2) >> 1) + 2); })
>>>
>>> static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
>>>
>>> Modified: cfe/trunk/test/Sema/warn-shadow.c
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-shadow.c?rev=192143&r1=192142&r2=192143&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/test/Sema/warn-shadow.c (original)
>>> +++ cfe/trunk/test/Sema/warn-shadow.c Mon Oct 7 18:51:11 2013
>>> @@ -1,5 +1,7 @@
>>> // RUN: %clang_cc1 -verify -fsyntax-only -fblocks -Wshadow %s
>>>
>>> +#include <emmintrin.h>
>>> +
>>> int i; // expected-note 3 {{previous declaration is here}}
>>>
>>> void foo() {
>>> @@ -59,3 +61,11 @@ void rdar8883302() {
>>> void test8() {
>>> int bob; // expected-warning {{declaration shadows a variable in the global scope}}
>>> }
>>> +
>>> +// Test that using two macros from emmintrin do not cause a
>>> +// useless -Wshadow warning.
>>> +void rdar10679282() {
>>> + __m128i qf = _mm_setzero_si128();
>>> + qf = _mm_slli_si128(_mm_add_epi64(qf, _mm_srli_si128(qf, 8)), 8); // no-warning
>>> + (void) qf;
>>> +}
>>>
>>>
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>>
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