2005-09-06  Stepan Kasal  <address@hidden>

	* lib/autoconf/general.m4 (_AC_COMPUTE_INT_COMPILE): Do not use
	"break" in the parameters to _AC_COMPILE_IFELSE; reorganize the
	code, so that _AC_COMPILE_IFELSE is called only once.

Index: lib/autoconf/general.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/general.m4,v
retrieving revision 1.885
diff -u -r1.885 general.m4
--- lib/autoconf/general.m4	6 Sep 2005 15:39:01 -0000	1.885
+++ lib/autoconf/general.m4	7 Sep 2005 11:21:15 -0000
@@ -2548,37 +2548,46 @@
 # Compute the integer EXPRESSION and store the result in the VARIABLE.
 # Works OK if cross compiling, but assumes twos-complement arithmetic.
 m4_define([_AC_COMPUTE_INT_COMPILE],
-[# Depending upon the size, compute the lo and hi bounds.
-_AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) >= 0])],
- [ac_lo=0 ac_mid=0
-  while :; do
-    _AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) <= $ac_mid])],
-		       [ac_hi=$ac_mid; break],
-		       [ac_lo=`expr $ac_mid + 1`
-			if test $ac_lo -le $ac_mid; then
-			  ac_lo= ac_hi=
-			  break
-			fi
-			ac_mid=`expr 2 '*' $ac_mid + 1`])
-  done],
-[AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) < 0])],
- [ac_hi=-1 ac_mid=-1
-  while :; do
-    _AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) >= $ac_mid])],
-		       [ac_lo=$ac_mid; break],
-		       [ac_hi=`expr '(' $ac_mid ')' - 1`
-			if test $ac_mid -le $ac_hi; then
-			  ac_lo= ac_hi=
-			  break
-			fi
-			ac_mid=`expr 2 '*' $ac_mid`])
-  done],
- [ac_lo= ac_hi=])])
-# Binary search between lo and hi bounds.
-while test "x$ac_lo" != "x$ac_hi"; do
-  ac_mid=`expr '(' $ac_hi - $ac_lo ')' / 2 + $ac_lo`
-  _AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) <= $ac_mid])],
-		     [ac_hi=$ac_mid], [ac_lo=`expr '(' $ac_mid ')' + 1`])
+[# Compute the lo and hi bounds, then do a binary search between them:
+ac_mid=0 ac_lo= ac_hi= ac_pos=
+# Most of the time, ac_sign is <= or >=, but for the very first run, it is different:
+ac_sign=">"
+while :; do
+  _AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([$3], [($1) $ac_sign $ac_mid])],
+    [ac_res=y], [ac_res=n])
+  # Now deduce from the result of the above experiment:
+  # (ac_pos indicates whether the value is positive.)
+  case $ac_pos:$ac_lo:$ac_hi:$ac_res in
+    # If ac_pos is empty, this was the very first run:
+    :::*) ac_pos=$ac_res ac_sign='<=';; # ac_mid remains 0
+    # If both ac_lo and ac_hi are empty, this was the second run:
+    y:::n) ac_lo=1 ac_mid=1;; # ac_sign remains <=
+    n:::y) ac_hi=0 ac_mid=-1 ac_sign='>=';;
+    *:::*) # Contradicting results:
+	break;; # ac_lo is empty
+    # Positive value, ac_sign is <=, ac_hi is empty:
+    y:*::y) ac_hi=$ac_mid;;
+    y:*::n) ac_lo=`expr $ac_mid + 1`
+	AS_IF([test $ac_lo -le $ac_mid], [ac_lo=; break])dnl Overflow.
+	ac_mid=`expr 2 '*' $ac_mid + 1`
+	;;
+    # Negative value (or zero), ac_sign is >=, ac_lo is empty:
+    n::*:y) ac_lo=$ac_mid;;
+    n::*:n) ac_hi=`expr '(' $ac_mid ')' - 1`
+	AS_IF([test $ac_mid -le $ac_hi], [ac_lo=; break])dnl Overflow.
+	ac_mid=`expr 2 '*' $ac_mid`
+	;;
+    # Binary search, ac_sign is <=:
+    ?:*:*:y) ac_hi=$ac_mid;;
+    ?:*:*:n) ac_lo=`expr '(' $ac_mid ')' + 1`;;
+  esac
+  # If both ac_lo and ac_hi are now non-empty, we are performing binary search:
+  case $ac_lo:$ac_hi in
+    :* | *:) ;;
+    *)	test x$ac_lo = x$ac_hi && break
+	ac_mid=`expr '(' $ac_hi - $ac_lo ')' / 2 + $ac_lo`
+	ac_sign='<=' ;;
+  esac
 done
 case $ac_lo in
 ?*) $2=$ac_lo;;