[X86][AVX512FP16] Relax limitation to AVX512FP16 intrinsics. NFCI

[pengfei]

Summary

Since we have enabled the support for _Float16 on SSE2, we can relax
the limitation for AVX512FP16 now. This helps for user to use AVX512FP16
mixed with unsupported versions, e.g., multiversioning.

Also fix lit fails due to missing const modifier. Found during this change.

[pengfei]

Don't know why, but check !defined(__SSE2__) leads to compiler_builtins_x86.c fails like below. Move the check into avx512[vl]fp16intrin.h instead.

error: 'error' diagnostics seen but not expected:
  File /export/users/pengfeiw/llvm-project/clang/test/Modules/compiler_builtins_x86.c Line 8: could not build module '_Builtin_intrinsics'
1 error generated.

[craig.topper]

Should the const change be a separate patch? They feel unrelated.

[pengfei]

Rebased on D132372.

Should the const change be a separate patch? They feel unrelated.

Done. The change results in lit test fails.

[RKSimon]

clang/lib/Headers/avx512fp16intrin.h

13

Doesn't this have to be the general case like in other places in the headers?

#if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
    defined(__SSE2__)

[pengfei]

clang/lib/Headers/avx512fp16intrin.h

13

I don't think so. !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) || defined(__AVX512FP16__) has already been checked in immintrin.h

So if we are preprocessing here, the above condition must be true. Since AVX512FP16 implies SSE2, the new condition is constant ture.

[RKSimon]

clang/lib/Headers/avx512fp16intrin.h

13

got it - cheers

[RKSimon]

LGTM

clang/lib/Headers/immintrin.h

223

(style) - other uses in this header put the defined(AVX512VL) after:

(defined(__AVX512FP16__) && defined(__AVX512VL__))

[pengfei]

Thanks @RKSimon

clang/lib/Headers/immintrin.h

223

This was copy+paste from AVX512BF16. Just have a look, puting it ahead seems a little more that the other. So let leave it as is :)

clang/lib/Headers/avx512fp16intrin.h

 /*===----------- avx512fp16intrin.h - AVX512-FP16 intrinsics ---------------===
  *
  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  * See https://llvm.org/LICENSE.txt for license information.
  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  *
  *===-----------------------------------------------------------------------===
  */
 #ifndef __IMMINTRIN_H
 #error "Never use <avx512fp16intrin.h> directly; include <immintrin.h> instead."
 #endif
 
+#ifdef __SSE2__
+
 #ifndef __AVX512FP16INTRIN_H
 #define __AVX512FP16INTRIN_H
 
 /* Define the default attributes for the functions in this file. */
 typedef _Float16 __v32hf __attribute__((__vector_size__(64), __aligned__(64)));
 typedef _Float16 __m512h __attribute__((__vector_size__(64), __aligned__(64)));
 typedef _Float16 __m512h_u __attribute__((__vector_size__(64), __aligned__(1)));
 typedef _Float16 __v8hf __attribute__((__vector_size__(16), __aligned__(16)));

 #define _mm_maskz_cmul_round_sch(U, A, B, R)                                   \
   _mm_maskz_fcmul_round_sch(U, A, B, R)
 
 #undef __DEFAULT_FN_ATTRS128
 #undef __DEFAULT_FN_ATTRS256
 #undef __DEFAULT_FN_ATTRS512
 
 #endif
+#endif

clang/lib/Headers/avx512vlfp16intrin.h

 /*===---------- avx512vlfp16intrin.h - AVX512-FP16 intrinsics --------------===
  *
  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  * See https://llvm.org/LICENSE.txt for license information.
  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  *
  *===-----------------------------------------------------------------------===
  */
 #ifndef __IMMINTRIN_H
 #error                                                                         \
     "Never use <avx512vlfp16intrin.h> directly; include <immintrin.h> instead."
 #endif
 
+#ifdef __SSE2__
+
 #ifndef __AVX512VLFP16INTRIN_H
 #define __AVX512VLFP16INTRIN_H
 
 /* Define the default attributes for the functions in this file. */
 #define __DEFAULT_FN_ATTRS256                                                  \
   __attribute__((__always_inline__, __nodebug__,                               \
                  __target__("avx512fp16, avx512vl"),                           \
                  __min_vector_width__(256)))

 #define _mm256_cmul_pch(A, B) _mm256_fcmul_pch(A, B)
 #define _mm256_mask_cmul_pch(W, U, A, B) _mm256_mask_fcmul_pch(W, U, A, B)
 #define _mm256_maskz_cmul_pch(U, A, B) _mm256_maskz_fcmul_pch(U, A, B)
 
 #undef __DEFAULT_FN_ATTRS128
 #undef __DEFAULT_FN_ATTRS256
 
 #endif
+#endif

clang/lib/Headers/immintrin.h

 #include <avx512vlvbmi2intrin.h>
 #endif
 
 #if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
     defined(__AVX512PF__)
 #include <avx512pfintrin.h>
 #endif
 
-/*
- * FIXME: _Float16 type is legal only when HW support float16 operation.
- * We use __AVX512FP16__ to identify if float16 is supported or not, so
- * when float16 is not supported, the related header is not included.
- *
- */
-#if defined(__AVX512FP16__)
+#if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
+    defined(__AVX512FP16__)
 #include <avx512fp16intrin.h>
 #endif
 
-#if defined(__AVX512FP16__) && defined(__AVX512VL__)
+#if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
+    (defined(__AVX512VL__) && defined(__AVX512FP16__))
 #include <avx512vlfp16intrin.h>
 #endif
 
 #if !(defined(_MSC_VER) || defined(__SCE__)) || __has_feature(modules) ||      \
     defined(__AVX512BF16__)
 #include <avx512bf16intrin.h>
 #endif