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Giv combination problem
- To: egcs-patches at cygnus dot com
- Subject: Giv combination problem
- From: Bernd Schmidt <crux at Pool dot Informatik dot RWTH-Aachen dot DE>
- Date: Mon, 5 Oct 1998 09:53:02 +0200 (MET DST)
Yesterday, I ran across a piece of code for which loop failed to combine
five identical givs. I believe the problem is in combine_givs_p, where
the return value of express_from is compared to the wrong value. If the
givs are identical, express_from should return g1->dest_reg, not const0_rtx.
* loop.c (combine_givs_p): Fix test for identical givs.
Index: loop.c
===================================================================
RCS file: /usr/local/cvs/gcs/gcc/loop.c,v
retrieving revision 1.1.1.41
diff -u -p -r1.1.1.41 loop.c
--- loop.c 1998/10/01 14:39:32 1.1.1.41
+++ loop.c 1998/10/03 09:13:17
@@ -6313,7 +6313,7 @@ combine_givs_p (g1, g2)
/* If these givs are identical, they can be combined. We use the results
of express_from because the addends are not in a canonical form, so
rtx_equal_p is a weaker test. */
- if (tem == const0_rtx)
+ if (tem == g1->dest_reg)
{
return g1->dest_reg;
}