[gcc r13-5526] i386: Fix up -Wuninitialized warnings in avx512erintrin.h [PR105593]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:41602390456901c14ecdfa2fa64c3cebd5b6ff09

commit r13-5526-g41602390456901c14ecdfa2fa64c3cebd5b6ff09
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Jan 31 09:20:34 2023 +0100

    i386: Fix up -Wuninitialized warnings in avx512erintrin.h [PR105593]
    
    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.

Diff:
---
 gcc/config/i386/avx512erintrin.h       | 18 ++++++------------
 gcc/testsuite/gcc.target/i386/sse-23.c |  2 +-
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/gcc/config/i386/avx512erintrin.h b/gcc/config/i386/avx512erintrin.h
index 7d6aecb70c2..bd83b7fbbc6 100644
--- a/gcc/config/i386/avx512erintrin.h
+++ b/gcc/config/i386/avx512erintrin.h
@@ -51,9 +51,8 @@ extern __inline __m512d
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_exp2a23_round_pd (__m512d __A, int __R)
 {
-  __m512d __W;
   return (__m512d) __builtin_ia32_exp2pd_mask ((__v8df) __A,
-					       (__v8df) __W,
+					       (__v8df) _mm512_undefined_pd (),
 					       (__mmask8) -1, __R);
 }
 
@@ -79,9 +78,8 @@ extern __inline __m512
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_exp2a23_round_ps (__m512 __A, int __R)
 {
-  __m512 __W;
   return (__m512) __builtin_ia32_exp2ps_mask ((__v16sf) __A,
-					      (__v16sf) __W,
+					      (__v16sf) _mm512_undefined_ps (),
 					      (__mmask16) -1, __R);
 }
 
@@ -107,9 +105,8 @@ extern __inline __m512d
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_rcp28_round_pd (__m512d __A, int __R)
 {
-  __m512d __W;
   return (__m512d) __builtin_ia32_rcp28pd_mask ((__v8df) __A,
-						(__v8df) __W,
+						(__v8df) _mm512_undefined_pd (),
 						(__mmask8) -1, __R);
 }
 
@@ -135,9 +132,8 @@ extern __inline __m512
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_rcp28_round_ps (__m512 __A, int __R)
 {
-  __m512 __W;
   return (__m512) __builtin_ia32_rcp28ps_mask ((__v16sf) __A,
-					       (__v16sf) __W,
+					       (__v16sf) _mm512_undefined_ps (),
 					       (__mmask16) -1, __R);
 }
 
@@ -229,9 +225,8 @@ extern __inline __m512d
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_rsqrt28_round_pd (__m512d __A, int __R)
 {
-  __m512d __W;
   return (__m512d) __builtin_ia32_rsqrt28pd_mask ((__v8df) __A,
-						  (__v8df) __W,
+						  (__v8df) _mm512_undefined_pd (),
 						  (__mmask8) -1, __R);
 }
 
@@ -257,9 +252,8 @@ extern __inline __m512
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_rsqrt28_round_ps (__m512 __A, int __R)
 {
-  __m512 __W;
   return (__m512) __builtin_ia32_rsqrt28ps_mask ((__v16sf) __A,
-						 (__v16sf) __W,
+						 (__v16sf) _mm512_undefined_ps (),
 						 (__mmask16) -1, __R);
 }
 
diff --git a/gcc/testsuite/gcc.target/i386/sse-23.c b/gcc/testsuite/gcc.target/i386/sse-23.c
index 0f56e937aeb..37cc2fd50df 100644
--- a/gcc/testsuite/gcc.target/i386/sse-23.c
+++ b/gcc/testsuite/gcc.target/i386/sse-23.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -Werror-implicit-function-declaration -march=k8" } */
+/* { dg-options "-O2 -Werror-implicit-function-declaration -Wuninitialized -march=k8" } */
 /* { dg-add-options bind_pic_locally } */
 
 #include <mm_malloc.h>