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As reported in the PR, there are some -Wuninitialized warnings in
avx512erintrin.h. One can see that by compiling sse-23.c testcase with
-Wuninitialized (or when actually using those intrinsics).
Those 6 spots use an uninitialized variable and pass it as one of the
argument to a builtin with constant mask -1, because there is no unmasked
builtin. It is true that expansion of those builtins into RTL will see
mask is all ones and ignore the unneeded argument, but -Wuninitialized
is diagnosed on GIMPLE and on GIMPLE these builtins are just builtin calls.
avx512fintrin.h and other headers use in these cases the _mm*_undefined_* ()
intrinsics, like:
return (__m512i) __builtin_ia32_psrav8di_mask ((__v8di) __X,
(__v8di) __Y,
(__v8di)
_mm512_undefined_epi32 (),
(__mmask8) -1);
etc. and the following patch does the same for avx512erintrin.h.
With the recent changes in C++ FE and the _mm*_undefined_* intrinsics,
we don't emit -Wuninitialized warnings for those (previously we didn't
just in C due to self-initialization). Of course we could also
just self-initialize these uninitialized vars and add the #pragma GCC
diagnostic dances around it, but using the intrinsics is consistent with
the rest and IMHO cleaner.
2023-01-31 Jakub Jelinek <jakub@redhat.com>
PR c++/105593
* config/i386/avx512erintrin.h (_mm512_exp2a23_round_pd,
_mm512_exp2a23_round_ps, _mm512_rcp28_round_pd, _mm512_rcp28_round_ps,
_mm512_rsqrt28_round_pd, _mm512_rsqrt28_round_ps): Use
_mm512_undefined_pd () or _mm512_undefined_ps () instead of using
uninitialized automatic variable __W.
* gcc.target/i386/sse-23.c: Add -Wuninitialized to dg-options.
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