[PATCH 2.33 COMMITTED] x86: Automate generation of PREFERRED_FEATURE_INDEX_1 bitfield

[PATCH 2.33 COMMITTED] x86: Automate generation of PREFERRED_FEATURE_INDEX_1 bitfield

[Florian Weimer]

Use a .def file to define the bitfield layout, so that it is possible
to iterate over field members using the preprocessor.

(cherry picked from commit e4933c8a92ea08eecdf3ab45e7f76c95dc3d20ac)

---
 .../cpu-features-preferred_feature_index_1.def     | 34 +++++++++++++++
 sysdeps/x86/include/cpu-features.h                 | 51 ++++++++--------------
 2 files changed, 51 insertions(+), 34 deletions(-)

diff --git a/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def
new file mode 100644
index 0000000000..06af1a8dd5
--- /dev/null
+++ b/sysdeps/x86/include/cpu-features-preferred_feature_index_1.def
@@ -0,0 +1,34 @@
+/* Bits in the PREFERRED_FEATURE_INDEX_1 bitfield of <cpu-features.h>.
+   Copyright (C) 2020-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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/>.  */
+
+BIT (Fast_Rep_String)
+BIT (Fast_Copy_Backward)
+BIT (Slow_BSF)
+BIT (Fast_Unaligned_Load)
+BIT (Prefer_PMINUB_for_stringop)
+BIT (Fast_Unaligned_Copy)
+BIT (I586)
+BIT (I686)
+BIT (Slow_SSE4_2)
+BIT (AVX_Fast_Unaligned_Load)
+BIT (Prefer_MAP_32BIT_EXEC)
+BIT (Prefer_No_VZEROUPPER)
+BIT (Prefer_ERMS)
+BIT (Prefer_No_AVX512)
+BIT (MathVec_Prefer_No_AVX512)
+BIT (Prefer_FSRM)
diff --git a/sysdeps/x86/include/cpu-features.h b/sysdeps/x86/include/cpu-features.h
index 624736b40e..e7f314657c 100644
--- a/sysdeps/x86/include/cpu-features.h
+++ b/sysdeps/x86/include/cpu-features.h
@@ -757,40 +757,23 @@ enum
 #define reg_AESKLE		ebx
 #define reg_WIDE_KL		ebx
 
-/* PREFERRED_FEATURE_INDEX_1.  */
-#define bit_arch_I586				(1u << 0)
-#define bit_arch_I686				(1u << 1)
-#define bit_arch_Fast_Rep_String		(1u << 2)
-#define bit_arch_Fast_Copy_Backward		(1u << 3)
-#define bit_arch_Fast_Unaligned_Load		(1u << 4)
-#define bit_arch_Fast_Unaligned_Copy		(1u << 5)
-#define bit_arch_Slow_BSF			(1u << 6)
-#define bit_arch_Slow_SSE4_2			(1u << 7)
-#define bit_arch_AVX_Fast_Unaligned_Load	(1u << 8)
-#define bit_arch_Prefer_MAP_32BIT_EXEC		(1u << 9)
-#define bit_arch_Prefer_PMINUB_for_stringop	(1u << 10)
-#define bit_arch_Prefer_No_VZEROUPPER		(1u << 11)
-#define bit_arch_Prefer_ERMS			(1u << 12)
-#define bit_arch_Prefer_FSRM			(1u << 13)
-#define bit_arch_Prefer_No_AVX512		(1u << 14)
-#define bit_arch_MathVec_Prefer_No_AVX512	(1u << 15)
-
-#define index_arch_Fast_Rep_String		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Copy_Backward		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Slow_BSF			PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Unaligned_Load		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_PMINUB_for_stringop 	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Unaligned_Copy		PREFERRED_FEATURE_INDEX_1
-#define index_arch_I586				PREFERRED_FEATURE_INDEX_1
-#define index_arch_I686				PREFERRED_FEATURE_INDEX_1
-#define index_arch_Slow_SSE4_2			PREFERRED_FEATURE_INDEX_1
-#define index_arch_AVX_Fast_Unaligned_Load	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_MAP_32BIT_EXEC	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_No_VZEROUPPER		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_ERMS			PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_No_AVX512		PREFERRED_FEATURE_INDEX_1
-#define index_arch_MathVec_Prefer_No_AVX512	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_FSRM			PREFERRED_FEATURE_INDEX_1
+/* PREFERRED_FEATURE_INDEX_1.  First define the bitindex values
+   sequentially, then define the bit_arch* and index_arch_* lookup
+   constants.  */
+enum
+  {
+#define BIT(x) _bitindex_arch_##x ,
+#include "cpu-features-preferred_feature_index_1.def"
+#undef BIT
+  };
+enum
+  {
+#define BIT(x)					\
+    bit_arch_##x = 1u << _bitindex_arch_##x ,	\
+    index_arch_##x = PREFERRED_FEATURE_INDEX_1,
+#include "cpu-features-preferred_feature_index_1.def"
+#undef BIT
+  };
 
 /* XCR0 Feature flags.  */
 #define bit_XMM_state		(1u << 1)