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* [Bug tree-optimization/50319] New: if-conversion produces unvectorizable conditions
@ 2011-09-07 12:13 rguenth at gcc dot gnu.org
2011-09-07 12:49 ` [Bug tree-optimization/50319] " rguenth at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-09-07 12:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50319
Bug #: 50319
Summary: if-conversion produces unvectorizable conditions
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: rguenth@gcc.gnu.org
For
double s1[4], s2[4], s3[64];
void
foo (void)
{
int i;
for (i = 0; i < 4; i++)
s3[0 * 4 + i] = __builtin_isgreater (s1[i], s2[i]) ? -1.0 : 0.0;
for (i = 0; i < 4; i++)
s3[1 * 4 + i] = (!__builtin_isgreater (s1[i], s2[i])) ? -1.0 : 0.0;
}
if-conversion generates a) lots of garbage statements, b) it fails to
avoid inversions which causes the code to be non-vectorizable for the
first loop.
Before if-conversion:
<bb 2>:
<bb 3>:
# i_30 = PHI <i_12(6), 0(2)>
# ivtmp.7_1 = PHI <ivtmp.7_28(6), 4(2)>
D.2735_6 = s1[i_30];
D.2736_7 = s2[i_30];
if (D.2735_6 u<= D.2736_7)
goto <bb 5>;
else
goto <bb 4>;
<bb 4>:
<bb 5>:
# iftmp.0_3 = PHI <-1.0e+0(4), 0.0(3)>
s3[i_30] = iftmp.0_3;
i_12 = i_30 + 1;
ivtmp.7_28 = ivtmp.7_1 - 1;
if (ivtmp.7_28 != 0)
goto <bb 6>;
else
goto <bb 7>;
<bb 6>:
goto <bb 3>;
after if-conversion:
<bb 3>:
# i_30 = PHI <i_12(4), 0(2)>
# ivtmp.7_1 = PHI <ivtmp.7_28(4), 4(2)>
D.2735_6 = s1[i_30];
D.2736_7 = s2[i_30];
D.2760_34 = D.2735_6 u<= D.2736_7;
D.2761_35 = ~D.2760_34;
iftmp.0_3 = D.2761_35 ? -1.0e+0 : 0.0;
s3[i_30] = iftmp.0_3;
i_12 = i_30 + 1;
ivtmp.7_28 = ivtmp.7_1 - 1;
D.2762_36 = D.2735_6 u<= D.2736_7;
D.2763_37 = D.2762_36 | D.2761_35;
if (ivtmp.7_28 != 0)
goto <bb 4>;
else
goto <bb 5>;
the statements computing D.2762_36 and D.2763_37 are dead. The statement
computing D.2761_35 can be avoided by swapping the arms of the generated
cond-expr.
if-conversion tries to do this but fails for numerous reasons in
find_phi_replacement_condition.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/50319] if-conversion produces unvectorizable conditions
2011-09-07 12:13 [Bug tree-optimization/50319] New: if-conversion produces unvectorizable conditions rguenth at gcc dot gnu.org
@ 2011-09-07 12:49 ` rguenth at gcc dot gnu.org
2011-09-07 14:22 ` rguenth at gcc dot gnu.org
2011-09-07 15:07 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-09-07 12:49 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50319
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2011-09-07
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-07 12:41:35 UTC ---
I have a patch.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/50319] if-conversion produces unvectorizable conditions
2011-09-07 12:13 [Bug tree-optimization/50319] New: if-conversion produces unvectorizable conditions rguenth at gcc dot gnu.org
2011-09-07 12:49 ` [Bug tree-optimization/50319] " rguenth at gcc dot gnu.org
@ 2011-09-07 14:22 ` rguenth at gcc dot gnu.org
2011-09-07 15:07 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-09-07 14:22 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50319
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-07 14:19:38 UTC ---
Author: rguenth
Date: Wed Sep 7 14:19:33 2011
New Revision: 178638
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178638
Log:
2011-09-07 Richard Guenther <rguenther@suse.de>
PR tree-optimization/50319
* tree-if-conv.c (set_bb_predicate): Assert we only set
canonical predicates.
(add_to_predicate_list): Simplify. Allow TRUTH_NOT_EXPR
around canonical predicates.
(predicate_bbs): Do not re-gimplify already canonical
predicates. Properly unshare them though.
(find_phi_replacement_condition): Simplify.
Modified:
trunk/gcc/ChangeLog
trunk/gcc/tree-if-conv.c
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/50319] if-conversion produces unvectorizable conditions
2011-09-07 12:13 [Bug tree-optimization/50319] New: if-conversion produces unvectorizable conditions rguenth at gcc dot gnu.org
2011-09-07 12:49 ` [Bug tree-optimization/50319] " rguenth at gcc dot gnu.org
2011-09-07 14:22 ` rguenth at gcc dot gnu.org
@ 2011-09-07 15:07 ` rguenth at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-09-07 15:07 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50319
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-07 15:05:08 UTC ---
Fixed.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-09-07 12:13 [Bug tree-optimization/50319] New: if-conversion produces unvectorizable conditions rguenth at gcc dot gnu.org
2011-09-07 12:49 ` [Bug tree-optimization/50319] " rguenth at gcc dot gnu.org
2011-09-07 14:22 ` rguenth at gcc dot gnu.org
2011-09-07 15:07 ` rguenth at gcc dot gnu.org
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