[Patch, PR 57812] Wasted work in computed_jump_p()

[pchang9@cs.wisc.edu]

Hi,

The problem appears in revision 201034 in version 4.9. I also reported
this problem at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57812.

Bootstrap and regression-tested on x86_64-linux.

In method "computed_jump_p()" in gcc/rtlanal.c, the loop on line 2801
should break immediately after "has_use_labelref" is set to "1".


2013-07-22  Chang  <pchang9@cs.wisc.edu>

        * rtlanal.c (computed_jump_p): Exit loop once we find label
          reference is used.

Index: gcc/rtlanal.c
===================================================================
--- gcc/rtlanal.c	(revision 201034)
+++ gcc/rtlanal.c	(working copy)
@@ -2802,7 +2802,10 @@
 	    if (GET_CODE (XVECEXP (pat, 0, i)) == USE
 		&& (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
 		    == LABEL_REF))
-	      has_use_labelref = 1;
+	      {
+	        has_use_labelref = 1;
+	        break;
+	      }

 	  if (! has_use_labelref)
 	    for (i = len - 1; i >= 0; i--)


-Chang
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