re PR rtl-optimization/8492 (GCC spins forever compiling loop)

	PR opt/8492
	* gcse.c (one_cprop_pass): Delete unreachable blocks.

Co-Authored-By: Eric Botcazou <ebotcazou@libertysurf.fr>

From-SVN: r61798

gcc/ChangeLog

+Sat Jan 25 21:04:33 CET 2003  Jan Hubicka  <jh@suse.cz>
+			      Eric Botcazou <ebotcazou@libertysurf.fr>
+	PR opt/8492
+	* gcse.c (one_cprop_pass): Delete unreachable blocks.
+
 2003-01-25  Richard Henderson  <rth@redhat.com>
 
 	* config/ia64/ia64.c (ia64_rwreloc_select_rtx_section): Rename

gcc/gcse.c

@@ -4378,6 +4378,7 @@ local_cprop_pass (alter_jumps)
   rtx insn;
   struct reg_use *reg_used;
   rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
+  bool changed = false;
 
   cselib_init ();
   libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
@@ -4409,13 +4410,19 @@ local_cprop_pass (alter_jumps)
 		   reg_used++, reg_use_count--)
 		if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
 		    libcall_sp))
-		  break;
+		  {
+		    changed = true;
+		    break;
+		  }
 	    }
 	  while (reg_use_count);
 	}
       cselib_process_insn (insn);
     }
   cselib_finish ();
+  /* Global analysis may get into infinite loops for unreachable blocks.  */
+  if (changed && alter_jumps)
+    delete_unreachable_blocks ();
 }
 
 /* Forward propagate copies.  This includes copies and constants.  Return
@@ -4506,6 +4513,9 @@ one_cprop_pass (pass, cprop_jumps, bypass_jumps)
       fprintf (gcse_file, "%d const props, %d copy props\n\n",
 	       const_prop_count, copy_prop_count);
     }
+  /* Global analysis may get into infinite loops for unreachable blocks.  */
+  if (changed && cprop_jumps)
+    delete_unreachable_blocks ();
 
   return changed;
 }

gcc/testsuite/ChangeLog

+Sat Jan 25 21:06:49 CET 2003  Jan Hubicka  <jh@suse.cz>
+
+	PR opt/8492
+	* gcc.c-torture/compile/20030125-1.c
+
 2003-01-25  Nathan Sidwell  <nathan@codesourcery.com>
 
 	PR c++/9403
@@ -19,7 +24,7 @@
 
 	* gcc.c-torture/execute/switch-1.c: New test case.
 
-Sat Jan 25 12:32:55 CET 2003  Jan HUbicka  <jh@suse.cz>
+Sat Jan 25 12:32:55 CET 2003  Jan Hubicka  <jh@suse.cz>
 
 	* gcc.c-torture/execute/20030125-1.[cx]: New test.
 

gcc/testsuite/gcc.c-torture/compile/20030125-1.c

+ int count;
+
+ int func(int *valp) {
+   int val, locked = 0;
+
+   while ((val = *valp) != 0) {
+     if (count) {
+       if (count)
+         locked = 1;
+       else
+         locked = 1;
+
+     if (!locked)
+       continue;
+     }
+
+     if (!count)
+       count--;
+
+     break;
+   }
+
+   return val;
+ }