x86: Install <sys/platform/x86.h> [BZ #26124]

Install <sys/platform/x86.h> so that programmers can do

 #if __has_include(<sys/platform/x86.h>)
 #include <sys/platform/x86.h>
 #endif
 ...

   if (CPU_FEATURE_USABLE (SSE2))
 ...
   if (CPU_FEATURE_USABLE (AVX2))
 ...

<sys/platform/x86.h> exports only:

enum
{
  COMMON_CPUID_INDEX_1 = 0,
  COMMON_CPUID_INDEX_7,
  COMMON_CPUID_INDEX_80000001,
  COMMON_CPUID_INDEX_D_ECX_1,
  COMMON_CPUID_INDEX_80000007,
  COMMON_CPUID_INDEX_80000008,
  COMMON_CPUID_INDEX_7_ECX_1,
  /* Keep the following line at the end.  */
  COMMON_CPUID_INDEX_MAX
};

struct cpuid_features
{
  struct cpuid_registers cpuid;
  struct cpuid_registers usable;
};

struct cpu_features
{
  struct cpu_features_basic basic;
  struct cpuid_features features[COMMON_CPUID_INDEX_MAX];
};

/* Get a pointer to the CPU features structure.  */
extern const struct cpu_features *__x86_get_cpu_features
  (unsigned int max) __attribute__ ((const));

Since all feature checks are done through macros, programs compiled with
a newer <sys/platform/x86.h> are compatible with the older glibc binaries
as long as the layout of struct cpu_features is identical.  The features
array can be expanded with backward binary compatibility for both .o and
.so files.  When COMMON_CPUID_INDEX_MAX is increased to support new
processor features, __x86_get_cpu_features in the older glibc binaries
returns NULL and HAS_CPU_FEATURE/CPU_FEATURE_USABLE return false on the
new processor feature.  No new symbol version is neeeded.

Both CPU_FEATURE_USABLE and HAS_CPU_FEATURE are provided.  HAS_CPU_FEATURE
can be used to identify processor features.

Note: Although GCC has __builtin_cpu_supports, it only supports a subset
of <sys/platform/x86.h> and it is equivalent to CPU_FEATURE_USABLE.  It
doesn't support HAS_CPU_FEATURE.

1 files changed, 192 insertions, 0 deletions

diff --git a/sysdeps/x86/tst-cpu-features-supports.c b/sysdeps/x86/tst-cpu-features-supports.c
new file mode 100644
index 0000000000..bf881b531f
--- /dev/null
+++ b/sysdeps/x86/tst-cpu-features-supports.c
@@ -0,0 +1,192 @@
+/* Test CPU feature data against __builtin_cpu_supports.
+   This file is part of the GNU C Library.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sys/platform/x86.h>
+#include <stdio.h>
+
+int
+check_supports (int supports, int usable, const char *supports_name,
+		const char *name)
+{
+  printf ("Checking %s:\n", name);
+  printf ("  %s: %d\n", name, usable);
+  printf ("  __builtin_cpu_supports (%s): %d\n",
+	  supports_name, supports);
+
+  if ((supports != 0) != (usable != 0))
+    {
+      printf (" *** failure ***\n");
+      return 1;
+    }
+
+  return 0;
+}
+
+#define CHECK_SUPPORTS(str, name) \
+  check_supports (__builtin_cpu_supports (#str), \
+		  CPU_FEATURE_USABLE (name), \
+		  #str, "HAS_CPU_FEATURE (" #name ")");
+
+static int
+do_test (int argc, char **argv)
+{
+  int fails = 0;
+
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (adx, ADX);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (aes, AES);
+#endif
+#if __GNUC_PREREQ (11, 1)
+  fails += CHECK_SUPPORTS (amx_bf16, AMX_BF16);
+  fails += CHECK_SUPPORTS (amx_int8, AMX_INT8);
+  fails += CHECK_SUPPORTS (amx_tile, AMX_TILE);
+#endif
+  fails += CHECK_SUPPORTS (avx, AVX);
+  fails += CHECK_SUPPORTS (avx2, AVX2);
+#if __GNUC_PREREQ (7, 0)
+  fails += CHECK_SUPPORTS (avx5124fmaps, AVX512_4FMAPS);
+  fails += CHECK_SUPPORTS (avx5124vnniw, AVX512_4VNNIW);
+#endif
+#if __GNUC_PREREQ (10, 0)
+  fails += CHECK_SUPPORTS (avx512bf16, AVX512_BF16);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (avx512bitalg, AVX512_BITALG);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512ifma, AVX512_IFMA);
+  fails += CHECK_SUPPORTS (avx512vbmi, AVX512_VBMI);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (avx512vbmi2, AVX512_VBMI2);
+  fails += CHECK_SUPPORTS (avx512vnni, AVX512_VNNI);
+#endif
+#if __GNUC_PREREQ (10, 0)
+  fails += CHECK_SUPPORTS (avx512vp2intersect, AVX512_VP2INTERSECT);
+#endif
+#if __GNUC_PREREQ (7, 0)
+  fails += CHECK_SUPPORTS (avx512vpopcntdq, AVX512_VPOPCNTDQ);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512bw, AVX512BW);
+  fails += CHECK_SUPPORTS (avx512cd, AVX512CD);
+  fails += CHECK_SUPPORTS (avx512er, AVX512ER);
+  fails += CHECK_SUPPORTS (avx512dq, AVX512DQ);
+#endif
+#if __GNUC_PREREQ (5, 0)
+  fails += CHECK_SUPPORTS (avx512f, AVX512F);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512pf, AVX512PF);
+  fails += CHECK_SUPPORTS (avx512vl, AVX512VL);
+#endif
+#if __GNUC_PREREQ (5, 0)
+  fails += CHECK_SUPPORTS (bmi, BMI1);
+  fails += CHECK_SUPPORTS (bmi2, BMI2);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (cldemote, CLDEMOTE);
+  fails += CHECK_SUPPORTS (clflushopt, CLFLUSHOPT);
+  fails += CHECK_SUPPORTS (clwb, CLWB);
+#endif
+  fails += CHECK_SUPPORTS (cmov, CMOV);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (cmpxchg16b, CMPXCHG16B);
+  fails += CHECK_SUPPORTS (cmpxchg8b, CX8);
+  fails += CHECK_SUPPORTS (enqcmd, ENQCMD);
+  fails += CHECK_SUPPORTS (f16c, F16C);
+#endif
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (fma, FMA);
+  fails += CHECK_SUPPORTS (fma4, FMA4);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (fsgsbase, FSGSBASE);
+  fails += CHECK_SUPPORTS (fxsave, FXSR);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (gfni, GFNI);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (hle, HLE);
+  fails += CHECK_SUPPORTS (ibt, IBT);
+  fails += CHECK_SUPPORTS (lahf_lm, LAHF64_SAHF64);
+  fails += CHECK_SUPPORTS (lm, LM);
+  fails += CHECK_SUPPORTS (lwp, LWP);
+  fails += CHECK_SUPPORTS (lzcnt, LZCNT);
+#endif
+  fails += CHECK_SUPPORTS (mmx, MMX);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (movbe, MOVBE);
+  fails += CHECK_SUPPORTS (movdiri, MOVDIRI);
+  fails += CHECK_SUPPORTS (movdir64b, MOVDIR64B);
+  fails += CHECK_SUPPORTS (osxsave, OSXSAVE);
+  fails += CHECK_SUPPORTS (pconfig, PCONFIG);
+  fails += CHECK_SUPPORTS (pku, PKU);
+#endif
+  fails += CHECK_SUPPORTS (popcnt, POPCNT);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (prefetchwt1, PREFETCHWT1);
+  fails += CHECK_SUPPORTS (rdpid, RDPID);
+  fails += CHECK_SUPPORTS (rdrnd, RDRAND);
+  fails += CHECK_SUPPORTS (rdseed, RDSEED);
+  fails += CHECK_SUPPORTS (rtm, RTM);
+  fails += CHECK_SUPPORTS (serialize, SERIALIZE);
+  fails += CHECK_SUPPORTS (sha, SHA);
+  fails += CHECK_SUPPORTS (shstk, SHSTK);
+#endif
+  fails += CHECK_SUPPORTS (sse, SSE);
+  fails += CHECK_SUPPORTS (sse2, SSE2);
+  fails += CHECK_SUPPORTS (sse3, SSE3);
+  fails += CHECK_SUPPORTS (sse4.1, SSE4_1);
+  fails += CHECK_SUPPORTS (sse4.2, SSE4_2);
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (sse4a, SSE4A);
+#endif
+  fails += CHECK_SUPPORTS (ssse3, SSSE3);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (tbm, TBM);
+  fails += CHECK_SUPPORTS (tsxldtrk, TSXLDTRK);
+  fails += CHECK_SUPPORTS (vaes, VAES);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (vpclmulqdq, VPCLMULQDQ);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (waitpkg, WAITPKG);
+  fails += CHECK_SUPPORTS (wbnoinvd, WBNOINVD);
+#endif
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (xop, XOP);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (xsave, XSAVE);
+  fails += CHECK_SUPPORTS (xsavec, XSAVEC);
+  fails += CHECK_SUPPORTS (xsaveopt, XSAVEOPT);
+  fails += CHECK_SUPPORTS (xsaves, XSAVES);
+#endif
+
+  printf ("%d differences between __builtin_cpu_supports and glibc code.\n",
+	  fails);
+
+  return (fails != 0);
+}
+
+#include "../../../test-skeleton.c"