[PATCH] configure: cache result of "sys/sdt.h" header check

[David Seifert via Gcc-patches]

Use AC_CACHE_CHECK to store the result of the header check for
systemtap's "sys/sdt.h", which is similar in spirit to libstdc++'s
AC_CACHE_CHECK(..., glibcxx_cv_sys_sdt_h).

gcc/
        * configure.ac: Add AC_CACHE_CHECK(..., gcc_cv_sys_sdt_h).
        * configure: Regenerate.
---
 gcc/configure    | 20 +++++++++++++++-----
 gcc/configure.ac | 16 +++++++++-------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/gcc/configure b/gcc/configure
index 14b19c8fe0c..1dfc5cc7344 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -31389,15 +31389,25 @@ fi
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking sys/sdt.h in the target C 
library" >&5
 $as_echo_n "checking sys/sdt.h in the target C library... " >&6; }
-have_sys_sdt_h=no
-if test -f $target_header_dir/sys/sdt.h; then
-  have_sys_sdt_h=yes
+if ${gcc_cv_sys_sdt_h+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  gcc_cv_sys_sdt_h=no
+  if test -f $target_header_dir/sys/sdt.h; then
+    gcc_cv_sys_sdt_h=yes
+  fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_sys_sdt_h" >&5
+$as_echo "$gcc_cv_sys_sdt_h" >&6; }
+if test x$gcc_cv_sys_sdt_h = xyes; then :
+
 
 $as_echo "#define HAVE_SYS_SDT_H 1" >>confdefs.h
 
+
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_sys_sdt_h" >&5
-$as_echo "$have_sys_sdt_h" >&6; }
 
 # Check if TFmode long double should be used by default or not.
 # Some glibc targets used DFmode long double, but with glibc 2.4
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 90cad309762..c86ce5e0a9b 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -6904,14 +6904,16 @@ AC_SUBST([enable_default_ssp])
 
 # Test for <sys/sdt.h> on the target.
 GCC_TARGET_TEMPLATE([HAVE_SYS_SDT_H])
-AC_MSG_CHECKING(sys/sdt.h in the target C library)
-have_sys_sdt_h=no
-if test -f $target_header_dir/sys/sdt.h; then
-  have_sys_sdt_h=yes
-  AC_DEFINE(HAVE_SYS_SDT_H, 1,
+AC_CACHE_CHECK([sys/sdt.h in the target C library], [gcc_cv_sys_sdt_h], [
+  gcc_cv_sys_sdt_h=no
+  if test -f $target_header_dir/sys/sdt.h; then
+    gcc_cv_sys_sdt_h=yes
+  fi
+])
+AS_IF([test x$gcc_cv_sys_sdt_h = xyes], [
+  AC_DEFINE([HAVE_SYS_SDT_H], [1],
             [Define if your target C library provides sys/sdt.h])
-fi
-AC_MSG_RESULT($have_sys_sdt_h)
+])
 
 # Check if TFmode long double should be used by default or not.
 # Some glibc targets used DFmode long double, but with glibc 2.4
-- 
2.35.1