[PATCH v3 5/5] config: Rename HAVE_BUILTIN_MEMSET macro
Naohiro Tamura
naohirot@fujitsu.com
Thu Aug 5 07:52:07 GMT 2021
This patch renames HAVE_BUILTIN_MEMSET macro to
HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET.
The name "HAVE_BUILTIN_MEMSET" is very confusing.
This macro cannot be removed even though GCC 6.2, that is minimum
requirement to compile glibc, already supports __builtin_memset[1].
It doesn't indicate whether GCC supports __builtin_memset or not.
But it indicates whether GCC supports __builtin_memset which doesn't
expand to a memset libcall or not.
Therefor HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET is more appropriate to
increase code readability.
[1] https://gcc.gnu.org/onlinedocs/gcc-6.2.0/gcc/Other-Builtins.html
---
config.h.in | 4 ++--
configure | 14 +++++++-------
configure.ac | 10 +++++-----
elf/rtld.c | 9 +++++----
4 files changed, 19 insertions(+), 18 deletions(-)
diff --git a/config.h.in b/config.h.in
index 8b45a3a61d77..4700dc9eba9b 100644
--- a/config.h.in
+++ b/config.h.in
@@ -40,8 +40,8 @@
shared between GNU libc and GNU gettext projects. */
#define HAVE_BUILTIN_EXPECT 1
-/* Define if the compiler supports __builtin_memset. */
-#undef HAVE_BUILTIN_MEMSET
+/* Define if the compiler supports non lib expand __builtin_memset. */
+#undef HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET
/* Define if compiler accepts -ftree-loop-distribute-patterns. */
#undef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
diff --git a/configure b/configure
index 9619c10991d0..224c754cf466 100755
--- a/configure
+++ b/configure
@@ -6263,7 +6263,7 @@ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_memset" >&5
$as_echo_n "checking for __builtin_memset... " >&6; }
-if ${libc_cv_gcc_builtin_memset+:} false; then :
+if ${libc_cv_gcc_non_lib_expand_builtin_memset+:} false; then :
$as_echo_n "(cached) " >&6
else
cat > conftest.c <<\EOF
@@ -6279,16 +6279,16 @@ if { ac_try='${CC-cc} -O3 -S conftest.c -o - | grep -F "memset" > /dev/null'
$as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
test $ac_status = 0; }; };
then
- libc_cv_gcc_builtin_memset=no
+ libc_cv_gcc_non_lib_expand_builtin_memset=no
else
- libc_cv_gcc_builtin_memset=yes
+ libc_cv_gcc_non_lib_expand_builtin_memset=yes
fi
rm -f conftest*
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_builtin_memset" >&5
-$as_echo "$libc_cv_gcc_builtin_memset" >&6; }
-if test "$libc_cv_gcc_builtin_memset" = yes ; then
- $as_echo "#define HAVE_BUILTIN_MEMSET 1" >>confdefs.h
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_non_lib_expand_builtin_memset" >&5
+$as_echo "$libc_cv_gcc_non_lib_expand_builtin_memset" >&6; }
+if test "$libc_cv_gcc_non_lib_expand_builtin_memset" = yes ; then
+ $as_echo "#define HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET 1" >>confdefs.h
fi
diff --git a/configure.ac b/configure.ac
index 34ecbba54054..451cea7683e6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1508,7 +1508,7 @@ if test $libc_cv_have_section_quotes = yes; then
AC_DEFINE(HAVE_SECTION_QUOTES)
fi
-AC_CACHE_CHECK(for __builtin_memset, libc_cv_gcc_builtin_memset, [dnl
+AC_CACHE_CHECK(for __builtin_memset, libc_cv_gcc_non_lib_expand_builtin_memset, [dnl
cat > conftest.c <<\EOF
void zero (void *x)
{
@@ -1518,13 +1518,13 @@ EOF
dnl
if AC_TRY_COMMAND([${CC-cc} -O3 -S conftest.c -o - | grep -F "memset" > /dev/null]);
then
- libc_cv_gcc_builtin_memset=no
+ libc_cv_gcc_non_lib_expand_builtin_memset=no
else
- libc_cv_gcc_builtin_memset=yes
+ libc_cv_gcc_non_lib_expand_builtin_memset=yes
fi
rm -f conftest* ])
-if test "$libc_cv_gcc_builtin_memset" = yes ; then
- AC_DEFINE(HAVE_BUILTIN_MEMSET)
+if test "$libc_cv_gcc_non_lib_expand_builtin_memset" = yes ; then
+ AC_DEFINE(HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET)
fi
AC_CACHE_CHECK(for redirection of built-in functions, libc_cv_gcc_builtin_redirection, [dnl
diff --git a/elf/rtld.c b/elf/rtld.c
index d733359eaf80..a18494fcd38e 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -527,11 +527,12 @@ _dl_start (void *arg)
/* Partly clean the `bootstrap_map' structure up. Don't use
`memset' since it might not be built in or inlined and we cannot
make function calls at this point. Use '__builtin_memset' if we
- know it is available. We do not have to clear the memory if we
- do not have to use the temporary bootstrap_map. Global variables
- are initialized to zero by default. */
+ know it is available and does not expand to a memset libcall.
+ We do not have to clear the memory if we do not have to use the
+ temporary bootstrap_map. Global variables are initialized to
+ zero by default. */
#ifndef DONT_USE_BOOTSTRAP_MAP
-# ifdef HAVE_BUILTIN_MEMSET
+# ifdef HAVE_NON_LIB_EXPAND_BUILTIN_MEMSET
__builtin_memset (bootstrap_map.l_info, '\0', sizeof (bootstrap_map.l_info));
# else
for (size_t cnt = 0;
--
2.17.1
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