------- Comment #1 from kkojima at gcc dot gnu dot org 2009-05-16 00:08 -------
I've tried to see what is going on with -da.
.expand rtl dump shows that t *= 1000000000 is compiled to
a sequence of insns and the last two insns are:
(insn 87 86 88 ice.i:6 (parallel [
(set (subreg:SI (reg:DI 220) 0)
(ashift:SI (subreg:SI (reg:DI 218) 0)
(const_int 9 [0x9])))
(clobber (scratch:SI))
]) -1 (expr_list:REG_EQUAL (mult:DI (reg:DI 169)
(const_int 1000000000 [0x3b9aca00]))
(nil)))
(insn 88 87 0 ice.i:6 (set (mem/c/i:DI (plus:SI (reg/f:SI 167)
(const_int 56 [0x38])) [0 t+0 S8 A32])
(reg:DI 220)) -1 (nil))
Then CSE pass folds the constant multiplication and replaces
the above insn 87 with
(insn 87 86 108 2 ice.i:6 (set (reg:SI 229)
(const_int -1539607552 [0xffffffffa43b7400])) 175 {movsi_ie}
(expr_list:REG_EQUAL (const_int 50000000000 [0xba43b7400])
(nil)))
and do_SUBST complains that SImode reg can't hold 50000000000
at the combine pass.
I guess that the REG_EQUAL note of the original insn 87 is
suspicious. It seems that the patch below avoids the problem,
though it may be completely wrong. I'll ask the middle-end
experts on the gcc list about this issue.
--- ORIG/trunk/gcc/expmed.c 2009-05-12 19:17:54.000000000 +0900
+++ trunk/gcc/expmed.c 2009-05-16 08:34:14.000000000 +0900
@@ -2958,7 +2958,7 @@ expand_mult_const (enum machine_mode mod
enum mult_variant variant)
{
HOST_WIDE_INT val_so_far;
- rtx insn, accum, tem;
+ rtx insn, accum, tem, set;
int opno;
enum machine_mode nmode;
@@ -3074,9 +3074,12 @@ expand_mult_const (enum machine_mode mod
}
insn = get_last_insn ();
- set_unique_reg_note (insn, REG_EQUAL,
- gen_rtx_MULT (nmode, tem,
- GEN_INT (val_so_far)));
+ set = single_set (insn);
+ if (set != 0
+ && GET_MODE (SET_DEST (set)) == nmode)
+ set_unique_reg_note (insn, REG_EQUAL,
+ gen_rtx_MULT (nmode, tem,
+ GEN_INT (val_so_far)));
}
if (variant == negate_variant)
--
kkojima at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |kkojima at gcc dot gnu dot
| |org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |ice-on-valid-code
Known to fail| |4.4.0 4.5.0
Known to work| |4.3.3
Priority|P3 |P4
Last reconfirmed|0000-00-00 00:00:00 |2009-05-16 00:08:06
date| |
Summary|internal compiler error: in |[4.4/4.5 Regression]
|do_SUBST, at combine.c:681 |internal compiler error: in
| |do_SUBST, at combine.c:681
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40154
