From 3d558f4ec7fecbac0dddb4d321a1ec10f14e8e03 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@redhat.com>
Date: Sat, 31 Jul 1999 05:15:48 +0000
Subject: Update.

	* configure.in: Add test for local label subtraction.
	* config.h.in: Ad HAVE_SUBTRACT_LOCAL_LABELS.
	* stdio-common/vfprintf.c (vfprintf): Use subtraction of local
	labels to reduce number of runtime relocations and move jump
	tables in read-only seciton.
---
 configure.in | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

(limited to 'configure.in')

diff --git a/configure.in b/configure.in
index e6b2dacf1d..6203266658 100644
--- a/configure.in
+++ b/configure.in
@@ -1050,6 +1050,36 @@ if test "$libc_cv_gcc_builtin_expect" = yes; then
   AC_DEFINE(HAVE_BUILTIN_EXPECT)
 fi
 
+dnl Check whether the compiler supports subtraction of local labels.
+AC_CACHE_CHECK(for local label subtraction, libc_cv_gcc_subtract_local_labels,
+[cat > conftest.c <<EOF
+changequote(,)dnl
+#line __oline__ "configure"
+int foo (int a)
+{
+  static const int ar[] = { &&l1 - &&l1, &&l2 - &&l1 };
+  void *p = &&l1 + ar[a];
+  goto *p;
+ l1:
+  return 1;
+ l2:
+  return 2;
+}
+changequote([,])dnl
+EOF
+dnl No \ in command here because it ends up inside ''.
+if AC_TRY_COMMAND([${CC-cc} $CFLAGS -nostdlib -nostartfiles
+			    -o conftest conftest.c -lgcc >&AC_FD_CC]); then
+  libc_cv_gcc_subtract_local_labels=yes
+else
+  libc_cv_gcc_subtract_local_labels=no
+fi
+rm -f conftest*])
+if test "$libc_cv_gcc_subtract_local_labels" = yes; then
+  AC_DEFINE(HAVE_SUBTRACT_LOCAL_LABELS)
+fi
+
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
-- 
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