x86: Avoid -Wuninitialized warnings on _mm*_undefined_* in C++ [PR105593]

In https://gcc.gnu.org/pipermail/gcc-patches/2023-January/609844.html
I've posted a patch to allow ignoring -Winit-self using GCC diagnostic
pragmas, such that one can mark self-initialization as intentional
disabling of -Wuninitialized warnings.

The following incremental patch uses that in the x86 intrinsic
headers.

2023-01-16  Jakub Jelinek  <jakub@redhat.com>

	PR c++/105593
gcc/
	* config/i386/xmmintrin.h (_mm_undefined_ps): Temporarily
	disable -Winit-self using pragma GCC diagnostic ignored.
	* config/i386/emmintrin.h (_mm_undefined_pd, _mm_undefined_si128):
	Likewise.
	* config/i386/avxintrin.h (_mm256_undefined_pd, _mm256_undefined_ps,
	_mm256_undefined_si256): Likewise.
	* config/i386/avx512fintrin.h (_mm512_undefined_pd,
	_mm512_undefined_ps, _mm512_undefined_epi32): Likewise.
	* config/i386/avx512fp16intrin.h (_mm_undefined_ph,
	_mm256_undefined_ph, _mm512_undefined_ph): Likewise.
gcc/testsuite/
	* g++.target/i386/pr105593.C: New test.

(cherry picked from commit 6b0907b4fc455377e5f8109f427d97da02b6aec9)

6 files changed, 56 insertions, 0 deletions

diff --git a/gcc/config/i386/avx512fintrin.h b/gcc/config/i386/avx512fintrin.h
index 77d6249c2bc..24316c5a495 100644
--- a/gcc/config/i386/avx512fintrin.h
+++ b/gcc/config/i386/avx512fintrin.h
@@ -185,7 +185,10 @@ extern __inline __m512
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_undefined_ps (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m512 __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
@@ -195,7 +198,10 @@ extern __inline __m512d
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_undefined_pd (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m512d __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
@@ -203,7 +209,10 @@ extern __inline __m512i
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_undefined_epi32 (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m512i __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
diff --git a/gcc/config/i386/avx512fp16intrin.h b/gcc/config/i386/avx512fp16intrin.h
index e43acaab12a..b16ccfcb7f1 100644
--- a/gcc/config/i386/avx512fp16intrin.h
+++ b/gcc/config/i386/avx512fp16intrin.h
@@ -204,7 +204,10 @@ extern __inline __m128h
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm_undefined_ph (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m128h __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
@@ -212,7 +215,10 @@ extern __inline __m256h
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm256_undefined_ph (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m256h __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
@@ -220,7 +226,10 @@ extern __inline __m512h
 __attribute__ ((__gnu_inline__, __always_inline__, __artificial__))
 _mm512_undefined_ph (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m512h __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
diff --git a/gcc/config/i386/avxintrin.h b/gcc/config/i386/avxintrin.h
index c76d600ee5c..d5aff7ddcfa 100644
--- a/gcc/config/i386/avxintrin.h
+++ b/gcc/config/i386/avxintrin.h
@@ -1207,21 +1207,30 @@ _mm256_movemask_ps (__m256 __A)
 extern __inline __m256d __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm256_undefined_pd (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m256d __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
 extern __inline __m256 __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm256_undefined_ps (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m256 __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
 extern __inline __m256i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm256_undefined_si256 (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m256i __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
diff --git a/gcc/config/i386/emmintrin.h b/gcc/config/i386/emmintrin.h
index 654a8e8c9ad..069b1a193a2 100644
--- a/gcc/config/i386/emmintrin.h
+++ b/gcc/config/i386/emmintrin.h
@@ -99,7 +99,10 @@ _mm_setr_pd (double __W, double __X)
 extern __inline __m128d __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm_undefined_pd (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m128d __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
@@ -785,7 +788,10 @@ _mm_move_epi64 (__m128i __A)
 extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm_undefined_si128 (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m128i __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
diff --git a/gcc/config/i386/xmmintrin.h b/gcc/config/i386/xmmintrin.h
index 62659080601..f1c704a2d43 100644
--- a/gcc/config/i386/xmmintrin.h
+++ b/gcc/config/i386/xmmintrin.h
@@ -109,7 +109,10 @@ typedef float __v4sf __attribute__ ((__vector_size__ (16)));
 extern __inline __m128 __attribute__((__gnu_inline__, __always_inline__, __artificial__))
 _mm_undefined_ps (void)
 {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winit-self"
   __m128 __Y = __Y;
+#pragma GCC diagnostic pop
   return __Y;
 }
 
diff --git a/gcc/testsuite/g++.target/i386/pr105593.C b/gcc/testsuite/g++.target/i386/pr105593.C
new file mode 100644
index 00000000000..3897f706bb1
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr105593.C
@@ -0,0 +1,20 @@
+// PR c++/105593
+// { dg-do compile { target c++14 } }
+// { dg-options "-mavx512fp16 -W -Wall -O2" }
+
+#include <x86intrin.h>
+
+auto f1 () { return _mm_undefined_pd (); }
+auto f2 () { return _mm_undefined_ps (); }
+auto f3 () { return _mm_undefined_si128 (); }
+auto f4 () { return _mm_undefined_ph (); }
+auto f5 () { return _mm256_undefined_pd (); }
+auto f6 () { return _mm256_undefined_ps (); }
+auto f7 () { return _mm256_undefined_si256 (); }
+auto f8 () { return _mm256_undefined_ph (); }
+auto f9 () { return _mm512_undefined_pd (); }
+auto f10 () { return _mm512_undefined_ps (); }
+auto f11 () { return _mm512_undefined_epi32 (); }
+auto f12 () { return _mm512_undefined_ph (); }
+
+// { dg-bogus "is used uninitialized" "" { target *-*-* } 0 }