disable maintenance of errno

From-SVN: r26897

gcc/ChangeLog

+Wed May 12 07:27:31 1999  Craig Burley  <craig@jcb-sc.com>
+
+	Allow front end (like g77's) to override maintenance of errno:
+	* expr.c (expand_builtin): Bother with errno only if
+	flag_errno_math.
+	* flags.h: Declare flag_errno_math.
+	* toplev.c: Define flag_errno_math.
+
 Tue May 11 23:55:49 1999  Jeffrey A Law  (law@cygnus.com)
 
 	* fixproto: Change "mkdir" calls to "mkdir -p"

gcc/expr.c

@@ -8757,7 +8757,7 @@ expand_builtin (exp, target, subtarget, mode, ignore)
       /* Check the results by default.  But if flag_fast_math is turned on,
 	 then assume sqrt will always be called with valid arguments.  */
 
-      if (! flag_fast_math)
+      if (flag_errno_math && ! flag_fast_math)
 	{
 	  /* Don't define the builtin FP instructions
 	     if your machine is not IEEE.  */

gcc/f/ChangeLog

+Wed May 12 07:30:05 1999  Craig Burley  <craig@jcb-sc.com>
+
+	* com.c (lang_init_options): Disable back end's maintenance
+	of errno.
+	* news.texi: Document dropping of errno.
+
 1999-05-10 18:21 -0400  Zack Weinberg  <zack@rabi.phys.columbia.edu>
 
 	* lang-specs.h: Pass -$ to the preprocessor.

gcc/f/com.c

@@ -14958,6 +14958,7 @@ lang_init_options ()
   flag_move_all_movables = 1;
   flag_reduce_all_givs = 1;
   flag_argument_noalias = 2;
+  flag_errno_math = 0;
 }
 
 void

gcc/f/news.texi

@@ -9,7 +9,7 @@
 @c in the standalone derivations of this file (e.g. NEWS).
 @set copyrights-news 1995-1999
 
-@set last-update-news 1999-05-10
+@set last-update-news 1999-05-12
 
 @include root.texi
 
@@ -273,6 +273,11 @@ that are not in @code{EQUIVALENCE} areas
 and not @code{SAVE}'d.
 @end ifclear
 
+@item
+@code{g77} no longer generates code to maintain @code{errno},
+a C-language concept,
+when performing operations such as the @code{SqRt} intrinsic.
+
 @ifclear USERVISONLY
 @item
 A substantial portion of the @code{g77} front end's code-generation component

gcc/flags.h

@@ -291,6 +291,11 @@ extern int flag_volatile_static;
 
 extern int flag_fast_math;
 
+/* Nonzero means the front end generally wants `errno' maintained by math
+   operations, like built-in SQRT, unless overridden by flag_fast_math.  */
+
+extern int flag_errno_math;
+
 /* Nonzero means to run loop optimizations twice.  */
 
 extern int flag_rerun_loop_opt;

gcc/toplev.c

@@ -558,6 +558,11 @@ int flag_no_peephole = 0;
 
 int flag_fast_math = 0;
 
+/* Nonzero means the front end generally wants `errno' maintained by math
+   operations, like built-in SQRT, unless overridden by flag_fast_math.  */
+
+int flag_errno_math = 1;
+
 /* Nonzero means all references through pointers are volatile.  */
 
 int flag_volatile;