[committed] Fix PR middle-end/53823

[John David Anglin]

This change fixes PR middle-end/53823.  The negative variant of
synth_mult doesn't handle modes larger than a host wide int.

Approved by rth in PR.

Tested on hppa2.0w-hp-hpux11.11 and hppa64-hp-hpux11.11.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)

2012-08-18  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>

	PR middle-end/53823
	* expmed.c (expand_mult): Skip synth_mult for negative coefficients
	if the mode is larger than a wide int and it is too costly to multiply
	by a positive multiplier and negate the result.

Index: expmed.c
===================================================================
--- expmed.c	(revision 190317)
+++ expmed.c	(working copy)
@@ -3261,7 +3261,6 @@
       /* Attempt to handle multiplication of DImode values by negative
 	 coefficients, by performing the multiplication by a positive
 	 multiplier and then inverting the result.  */
-      /* ??? How is this not slightly redundant with the neg variant?  */
       if (is_neg && mode_bitsize > HOST_BITS_PER_WIDE_INT)
 	{
 	  /* Its safe to use -coeff even for INT_MIN, as the
@@ -3278,6 +3277,7 @@
 					    &algorithm, variant);
 	      return expand_unop (mode, neg_optab, temp, target, 0);
 	    }
+	  goto skip_synth;
 	}
 
       /* Exclude cost of op0 from max_cost to match the cost