This is a problem with note distribution in the combiner present on the
mainline. From:
(insn 19 18 21 2 (parallel [
(set (reg:SI 83 [ D.1762 ])
(neg:SI (reg:SI 90 [ D.1762 ])))
(clobber (reg:CC 17 flags))
]) ../pr58662.c:17 464 {*negsi2_1}
(expr_list:REG_DEAD (reg:SI 90 [ D.1762 ])
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil))))
(insn 21 19 23 2 (parallel [
(set (reg:SI 104)
(ashift:SI (reg:SI 83 [ D.1762 ])
(const_int 1 [0x1])))
(clobber (reg:CC 17 flags))
]) ../pr58662.c:17 516 {*ashlsi3_1}
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))
(insn 23 21 24 2 (parallel [
(set (reg:SI 105)
(ashift:SI (reg:SI 83 [ D.1762 ])
(const_int 4 [0x4])))
(clobber (reg:CC 17 flags))
]) ../pr58662.c:17 516 {*ashlsi3_1}
(expr_list:REG_DEAD (reg:SI 83 [ D.1762 ])
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil))))
(insn 26 25 27 2 (parallel [
(set (reg:CCZ 17 flags)
(compare:CCZ (minus:SI (reg:SI 104)
(reg:SI 105))
(const_int 0 [0])))
(set (reg:SI 83 [ D.1762 ])
(minus:SI (reg:SI 104)
(reg:SI 105)))
]) ../pr58662.c:18 302 {*subsi_2}
(expr_list:REG_DEAD (reg:SI 105)
(expr_list:REG_DEAD (reg:SI 104)
(nil))))
we go through the intermediate (and correct) stage:
(parallel [
(set (pc)
(pc))
(set (reg:SI 83 [ D.1762 ])
(const_int 0 [0]))
])
which is split into:
(gdb) p debug_rtx(newpat)
(set (pc)
(pc))
(gdb) p debug_rtx(newi2pat)
(set (reg:SI 83 [ D.1762 ])
(const_int 0 [0]))
The problem is that the REG_DEAD note for (reg:SI 83) on insn 23 is put back
onto the new i2 insn by distribute_notes, thus making it wrongly dead code.
Fixed by explicitly checking for this case in the code that decides how to
split the PARALLEL. I didn't find anything less ad-hoc and there is a similar
check for REG_UNUSED notes in the first part of the code.
Tested on x86_64-suse-linux, applied on the mainline.
2013-10-13 Eric Botcazou <ebotca...@adacore.com>
PR rtl-optimization/58662
* combine.c (try_combine): Take into account death nodes on I2 when
splitting a PARALLEL of two independent SETs. Fix dump message.
2013-10-13 Richard Biener <rguent...@suse.de>
* gcc.c-torture/execute/pr58662.c: New test.
--
Eric BotcazouIndex: combine.c
===================================================================
--- combine.c (revision 203486)
+++ combine.c (working copy)
@@ -3693,29 +3693,42 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx
&& ! (contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 0)))
&& contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 1)))))
{
+ rtx set0 = XVECEXP (newpat, 0, 0);
+ rtx set1 = XVECEXP (newpat, 0, 1);
+
/* Normally, it doesn't matter which of the two is done first,
but the one that references cc0 can't be the second, and
one which uses any regs/memory set in between i2 and i3 can't
- be first. */
- if (!use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
- DF_INSN_LUID (i2))
+ be first. The PARALLEL might also have been pre-existing in i3,
+ so we need to make sure that we won't wrongly hoist a SET to i2
+ that would conflict with a death note present in there. */
+ if (!use_crosses_set_p (SET_SRC (set1), DF_INSN_LUID (i2))
+ && !(REG_P (SET_DEST (set1))
+ && find_reg_note (i2, REG_DEAD, SET_DEST (set1)))
+ && !(GET_CODE (SET_DEST (set1)) == SUBREG
+ && find_reg_note (i2, REG_DEAD,
+ SUBREG_REG (SET_DEST (set1))))
#ifdef HAVE_cc0
- && !reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0))
+ && !reg_referenced_p (cc0_rtx, set0)
#endif
)
{
- newi2pat = XVECEXP (newpat, 0, 1);
- newpat = XVECEXP (newpat, 0, 0);
+ newi2pat = set1;
+ newpat = set0;
}
- else if (!use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 0)),
- DF_INSN_LUID (i2))
+ else if (!use_crosses_set_p (SET_SRC (set0), DF_INSN_LUID (i2))
+ && !(REG_P (SET_DEST (set0))
+ && find_reg_note (i2, REG_DEAD, SET_DEST (set0)))
+ && !(GET_CODE (SET_DEST (set0)) == SUBREG
+ && find_reg_note (i2, REG_DEAD,
+ SUBREG_REG (SET_DEST (set0))))
#ifdef HAVE_cc0
- && !reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 1))
+ && !reg_referenced_p (cc0_rtx, set1)
#endif
)
{
- newi2pat = XVECEXP (newpat, 0, 0);
- newpat = XVECEXP (newpat, 0, 1);
+ newi2pat = set0;
+ newpat = set1;
}
else
{
@@ -4261,9 +4274,8 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx
}
/* Update reg_stat[].nonzero_bits et al for any changes that may have
- been made to this insn. The order of
- set_nonzero_bits_and_sign_copies() is important. Because newi2pat
- can affect nonzero_bits of newpat */
+ been made to this insn. The order is important, because newi2pat
+ can affect nonzero_bits of newpat. */
if (newi2pat)
note_stores (newi2pat, set_nonzero_bits_and_sign_copies, NULL);
note_stores (newpat, set_nonzero_bits_and_sign_copies, NULL);
@@ -4283,7 +4295,7 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx
{
if (dump_file)
{
- fprintf (dump_file, "modifying insn i1 ");
+ fprintf (dump_file, "modifying insn i0 ");
dump_insn_slim (dump_file, i0);
}
df_insn_rescan (i0);
@@ -4321,7 +4333,6 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx
/* Set new_direct_jump_p if a new return or simple jump instruction
has been created. Adjust the CFG accordingly. */
-
if (returnjump_p (i3) || any_uncondjump_p (i3))
{
*new_direct_jump_p = 1;extern void abort (void);
int a, c, d;
volatile int b;
static int
foo (int p1, short p2)
{
return p1 / p2;
}
int
main ()
{
char e;
d = foo (a == 0, (0, 35536));
e = d % 14;
b = e && c;
if (b != 0)
abort ();
return 0;
}
