------- Comment #6 from jingyu at google dot com 2010-01-13 01:18 -------
Subject: Re: problematic REG_EQUAL note added to
SUBREG
> We should try and set changed_i3_dest to 1 in this particular case as well.
Here is the patch which only changes changed_i3_dest for two
particular cases, where the dest of i3 really changed. The test case
attached to this bug is case2.
case 1:
i1 = 0. i2=(parallel [(set p, ?)...]), i3=(set q, p)
-> newpat=(parallel[(set q, ?),...])
-> i3.pattern=newpat
case2:
i1 = 0, i2=(set p, q), i3=(set subreg(s, reg(p), offset), a)
->newpat=(set p, <new value>)
-> i3.pattern=newpat
Index: combine.c
===================================================================
--- combine.c (revision 155801)
+++ combine.c (working copy)
@@ -2531,6 +2531,10 @@ try_combine (rtx i3, rtx i2, rtx i1, int
newpat = p2;
i3_subst_into_i2 = 1;
+
+ /* If the result of the combination is recognized, the note of
i3
+ * needs to be removed. */
+ changed_i3_dest = 1;
goto validate_replacement;
}
}
@@ -2667,6 +2671,10 @@ try_combine (rtx i3, rtx i2, rtx i1, int
immed_double_const (olo, ohi, GET_MODE (SET_DEST (temp))));
newpat = PATTERN (i2);
+
+ /* If the result of combination is recognized, the note of
i3 needs to
+ * to be removed. */
+ changed_i3_dest = 1;
goto validate_replacement;
}
}
@@ -3060,6 +3068,9 @@ try_combine (rtx i3, rtx i2, rtx i1, int
/* Is the result of combination a valid instruction? */
insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
+ if (insn_code_number < 0)
+ changed_i3_dest = 0;
+
/* If the result isn't valid, see if it is a PARALLEL of two SETs where
the second SET's destination is a register that is unused and isn't
marked as an instruction that might trap in an EH region. In that case,
This patch fixes the bug.
Do you think if this patch is favorable? If yes, I will do dejagnu
test and send it to gcc-patches for review.
Thanks,
Jing
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42691
