[glibc] x86: Properly set x86 minimum ISA level [BZ #31883]

[glibc] x86: Properly set x86 minimum ISA level [BZ #31883]

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=29807a271edca3e47195bda0c69ae45e245551a9

commit 29807a271edca3e47195bda0c69ae45e245551a9
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Jun 11 20:14:56 2024 -0700

    x86: Properly set x86 minimum ISA level [BZ #31883]
    
    Properly set libc_cv_have_x86_isa_level in shell for MINIMUM_X86_ISA_LEVEL
    defined as
    
    (__X86_ISA_V1 + __X86_ISA_V2 + __X86_ISA_V3 + __X86_ISA_V4)
    
    Also set __X86_ISA_V2 to 1 for i386 if __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8
    is defined.  There are no changes in config.h nor in config.make on x86-64.
    On i386, -march=x86-64-v2 with GCC generates
    
     #define MINIMUM_X86_ISA_LEVEL 2
    
    in config.h and
    
    have-x86-isa-level = 2
    
    in config.make.  This fixes BZ #31883.
    
    Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
    Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

Diff:
---
 sysdeps/x86/configure    |  4 +++-
 sysdeps/x86/configure.ac |  4 +++-
 sysdeps/x86/isa-level.h  | 12 +++++++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
index 1e2325d0d7..04c6ba3e6c 100644
--- a/sysdeps/x86/configure
+++ b/sysdeps/x86/configure
@@ -141,8 +141,10 @@ libc_cv_have_x86_isa_level=3
 libc_cv_have_x86_isa_level=2
 #elif defined __x86_64__
 libc_cv_have_x86_isa_level=baseline
+#elif MINIMUM_X86_ISA_LEVEL == 1
+libc_cv_have_x86_isa_level=1
 #else
-libc_cv_have_x86_isa_level=MINIMUM_X86_ISA_LEVEL
+libc_cv_have_x86_isa_level=0
 #endif
 EOF
 		 eval `${CC-cc} $CFLAGS $CPPFLAGS $ISAFLAG -I$srcdir -E conftest.c | grep libc_cv_have_x86_isa_level`
diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
index 0b32fdfd4f..8a259d3971 100644
--- a/sysdeps/x86/configure.ac
+++ b/sysdeps/x86/configure.ac
@@ -98,8 +98,10 @@ libc_cv_have_x86_isa_level=3
 libc_cv_have_x86_isa_level=2
 #elif defined __x86_64__
 libc_cv_have_x86_isa_level=baseline
+#elif MINIMUM_X86_ISA_LEVEL == 1
+libc_cv_have_x86_isa_level=1
 #else
-libc_cv_have_x86_isa_level=MINIMUM_X86_ISA_LEVEL
+libc_cv_have_x86_isa_level=0
 #endif
 EOF
 		 eval `${CC-cc} $CFLAGS $CPPFLAGS $ISAFLAG -I$srcdir -E conftest.c | grep libc_cv_have_x86_isa_level`
diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
index 2c7f74212b..03c1fe2bf5 100644
--- a/sysdeps/x86/isa-level.h
+++ b/sysdeps/x86/isa-level.h
@@ -35,7 +35,17 @@
 # define __X86_ISA_V1 0
 #endif
 
-#if __X86_ISA_V1 && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16               \
+#ifdef __x86_64__
+# ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16
+#  define __GCC_HAVE_SYNC_COMPARE_AND_SWAP
+# endif
+#else
+# ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8
+#  define __GCC_HAVE_SYNC_COMPARE_AND_SWAP
+# endif
+#endif
+
+#if __X86_ISA_V1 && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP		      \
     && defined HAVE_X86_LAHF_SAHF && defined __POPCNT__ && defined __SSE3__   \
     && defined __SSSE3__ && defined __SSE4_1__ && defined __SSE4_2__
 /* NB: ISAs in x86-64 ISA level v2 are used.  */