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* [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store
@ 2012-09-28 10:03 joey.ye at arm dot com
2012-09-28 10:47 ` [Bug tree-optimization/54733] " rguenth at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: joey.ye at arm dot com @ 2012-09-28 10:03 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54733
Bug #: 54733
Summary: Missing opportunity to optimize endian independent
load/store
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: joey.ye@arm.com
This case tries to load from memory in little-endian way, no matter what
endianess current target is.
On trunk 4.8 little-endian target, two byte loads should be able to combined
into a single 16-byte load.
int read_aux(void *, int);
int read_le()
{
unsigned char data[2];
read_aux(data, 2);
return data[0] | (data[1]<<8);
}
Current Tree (optimized):
unsigned char data[2];
read_aux (&data, 2);
D.4064_1 = data[0];
D.4065_2 = (int) D.4064_1;
D.4066_3 = data[1];
D.4067_4 = (int) D.4066_3;
D.4068_5 = D.4067_4 << 8;
D.4063_6 = D.4068_5 | D.4065_2;
data ={v} {CLOBBER};
return D.4063_6;
Expected Tree (optimized):
unsigned char data[2];
unsigned short *temp;
unsigned in D.4064;
read_aux (&data, 2);
temp=&data;
D.4064_1 = *temp;
return D.4064_1;
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/54733] Missing opportunity to optimize endian independent load/store
2012-09-28 10:03 [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store joey.ye at arm dot com
@ 2012-09-28 10:47 ` rguenth at gcc dot gnu.org
2014-03-19 6:31 ` thomas.preudhomme at arm dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-09-28 10:47 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54733
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-09-28
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-09-28 10:47:44 UTC ---
Confirmed. The original idea was to leverage the byte-swap pass for this.
First you need to extend that to work on a memory source (which it currently
does not handle), then you, in addition to detecting bswap, emit a word
load and detect the "noop" pattern which then skips bswap. (the byte-swap
pass was also supposed to utilize the vector shuffle engine for non-bswap
shuffles).
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/54733] Missing opportunity to optimize endian independent load/store
2012-09-28 10:03 [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store joey.ye at arm dot com
2012-09-28 10:47 ` [Bug tree-optimization/54733] " rguenth at gcc dot gnu.org
@ 2014-03-19 6:31 ` thomas.preudhomme at arm dot com
2014-05-23 3:34 ` thopre01 at gcc dot gnu.org
2014-05-26 13:49 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: thomas.preudhomme at arm dot com @ 2014-03-19 6:31 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54733
Thomas Preud'homme <thomas.preudhomme at arm dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |thomas.preudhomme at arm dot com
--- Comment #2 from Thomas Preud'homme <thomas.preudhomme at arm dot com> ---
A patch to fix this is currently under discussion on gcc-patches at:
http://gcc.gnu.org/ml/gcc-patches/2014-03/msg00925.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/54733] Missing opportunity to optimize endian independent load/store
2012-09-28 10:03 [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store joey.ye at arm dot com
2012-09-28 10:47 ` [Bug tree-optimization/54733] " rguenth at gcc dot gnu.org
2014-03-19 6:31 ` thomas.preudhomme at arm dot com
@ 2014-05-23 3:34 ` thopre01 at gcc dot gnu.org
2014-05-26 13:49 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: thopre01 at gcc dot gnu.org @ 2014-05-23 3:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54733
--- Comment #3 from thopre01 at gcc dot gnu.org ---
Author: thopre01
Date: Fri May 23 03:33:28 2014
New Revision: 210843
URL: http://gcc.gnu.org/viewcvs?rev=210843&root=gcc&view=rev
Log:
2014-05-23 Thomas Preud'homme <thomas.preudhomme@arm.com>
PR tree-optimization/54733
gcc/
* tree-ssa-math-opts.c (nop_stats): New "bswap_stats" structure.
(CMPNOP): Define.
(find_bswap_or_nop_load): New.
(find_bswap_1): Renamed to ...
(find_bswap_or_nop_1): This. Also add support for memory source.
(find_bswap): Renamed to ...
(find_bswap_or_nop): This. Also add support for memory source and
detection of bitwise operations equivalent to load in host endianness.
(execute_optimize_bswap): Likewise. Also move its leading comment back
in place and split statement transformation into ...
(bswap_replace): This.
gcc/testsuite
* gcc.dg/optimize-bswapdi-3.c: New test to check extension of bswap
optimization to support memory sources and bitwise operations
equivalent to load in host endianness.
* gcc.dg/optimize-bswaphi-1.c: Likewise.
* gcc.dg/optimize-bswapsi-2.c: Likewise.
* gcc.c-torture/execute/bswap-2.c: Likewise.
Added:
trunk/gcc/testsuite/gcc.c-torture/execute/bswap-2.c
trunk/gcc/testsuite/gcc.dg/optimize-bswapdi-3.c
trunk/gcc/testsuite/gcc.dg/optimize-bswaphi-1.c
trunk/gcc/testsuite/gcc.dg/optimize-bswapsi-2.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-math-opts.c
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/54733] Missing opportunity to optimize endian independent load/store
2012-09-28 10:03 [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store joey.ye at arm dot com
` (2 preceding siblings ...)
2014-05-23 3:34 ` thopre01 at gcc dot gnu.org
@ 2014-05-26 13:49 ` rguenth at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2014-05-26 13:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54733
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |4.10.0
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2012-09-28 10:03 [Bug tree-optimization/54733] New: Missing opportunity to optimize endian independent load/store joey.ye at arm dot com
2012-09-28 10:47 ` [Bug tree-optimization/54733] " rguenth at gcc dot gnu.org
2014-03-19 6:31 ` thomas.preudhomme at arm dot com
2014-05-23 3:34 ` thopre01 at gcc dot gnu.org
2014-05-26 13:49 ` rguenth at gcc dot gnu.org
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