[PATCH v3 5/5] config: Rename HAVE_BUILTIN_MEMSET macro

[Naohiro Tamura via Libc-alpha <libc-alpha@sourceware.org>]

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