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* [Bug c/23845] New: missed strength reduction costs performance
@ 2005-09-13 0:06 tprince at computer dot org
2005-09-13 0:09 ` [Bug middle-end/23845] " pinskia at gcc dot gnu dot org
` (5 more replies)
0 siblings, 6 replies; 8+ messages in thread
From: tprince at computer dot org @ 2005-09-13 0:06 UTC (permalink / raw)
To: gcc-bugs
Dictation of strength reduction in source is required for adequate performance
on this target. The same source "optimization" is counter-productive for ia32.
This is a portion of the diff file between 2 versions of
libgfortran/generated/matmul_r8.c.
for (n = 0; n < count; n++)
{
! abase_n = abase + n * aystride;
sum += abase_n[x] * bbase_y[n];
sum1 += abase_n[x+1] * bbase_y[n];
--- 199,208 ----
{
rtype_name sum = 0, sum1 = 0;
+ index_type nay = 0;
for (n = 0; n < count; n++)
{
! /* FIXME: gcc ought to strength reduce from n * aystride */
! abase_n = abase + nay;
! nay += aystride;
sum += abase_n[x] * bbase_y[n];
sum1 += abase_n[x+1] * bbase_y[n];
--
Summary: missed strength reduction costs performance
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tprince at computer dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: ia64-unknown-linux-gnu
GCC host triplet: ia64-unknown-linux-gnu
GCC target triplet: ia64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845
^ permalink raw reply [flat|nested] 8+ messages in thread* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org @ 2005-09-13 0:09 ` pinskia at gcc dot gnu dot org 2005-09-13 0:13 ` tprince at computer dot org ` (4 subsequent siblings) 5 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-09-13 0:09 UTC (permalink / raw) To: gcc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- Component|c |middle-end Keywords| |missed-optimization http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org 2005-09-13 0:09 ` [Bug middle-end/23845] " pinskia at gcc dot gnu dot org @ 2005-09-13 0:13 ` tprince at computer dot org 2005-09-13 2:13 ` pinskia at gcc dot gnu dot org ` (3 subsequent siblings) 5 siblings, 0 replies; 8+ messages in thread From: tprince at computer dot org @ 2005-09-13 0:13 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From tprince at computer dot org 2005-09-13 00:13 ------- Created an attachment (id=9714) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9714&action=view) alternate version of libgfortran/generated/matmul_r8.c The C file in the attachment performs well on ia32. The patch in the .diff file must be applied to work around the missing strength reduction, in order to perform adequately on ia64. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org 2005-09-13 0:09 ` [Bug middle-end/23845] " pinskia at gcc dot gnu dot org 2005-09-13 0:13 ` tprince at computer dot org @ 2005-09-13 2:13 ` pinskia at gcc dot gnu dot org 2005-09-13 14:50 ` pinskia at gcc dot gnu dot org ` (2 subsequent siblings) 5 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-09-13 2:13 UTC (permalink / raw) To: gcc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org ` (2 preceding siblings ...) 2005-09-13 2:13 ` pinskia at gcc dot gnu dot org @ 2005-09-13 14:50 ` pinskia at gcc dot gnu dot org 2005-09-13 18:30 ` rguenth at gcc dot gnu dot org 2005-09-13 23:16 ` tprince at computer dot org 5 siblings, 0 replies; 8+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-09-13 14:50 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-09-13 14:50 ------- This is done for me correctly on PPC-darwin. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org ` (3 preceding siblings ...) 2005-09-13 14:50 ` pinskia at gcc dot gnu dot org @ 2005-09-13 18:30 ` rguenth at gcc dot gnu dot org 2005-09-13 23:16 ` tprince at computer dot org 5 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu dot org @ 2005-09-13 18:30 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From rguenth at gcc dot gnu dot org 2005-09-13 18:29 ------- Please provide a standalone testcase. gcc -O2 -S matmul_r8.c matmul_r8.c:31:20: error: config.h: No such file or directory matmul_r8.c:35:25: error: libgfortran.h: No such file or directory matmul_r8.c:49: error: syntax error before '*' token matmul_r8.c:50: warning: parameter names (without types) in function declaration matmul_r8.c:50: warning: data definition has no type or storage class matmul_r8.c:53: error: syntax error before '*' token ... -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/23845] missed strength reduction costs performance 2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org ` (4 preceding siblings ...) 2005-09-13 18:30 ` rguenth at gcc dot gnu dot org @ 2005-09-13 23:16 ` tprince at computer dot org 5 siblings, 0 replies; 8+ messages in thread From: tprince at computer dot org @ 2005-09-13 23:16 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From tprince at computer dot org 2005-09-13 23:15 ------- Created an attachment (id=9726) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9726&action=view) include files from libgfortran, required in build -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
[parent not found: <bug-23845-33@http.gcc.gnu.org/bugzilla/>]
* [Bug middle-end/23845] missed strength reduction costs performance [not found] <bug-23845-33@http.gcc.gnu.org/bugzilla/> @ 2007-07-29 20:58 ` tprince at computer dot org 0 siblings, 0 replies; 8+ messages in thread From: tprince at computer dot org @ 2007-07-29 20:58 UTC (permalink / raw) To: gcc-bugs ------- Comment #5 from tprince at computer dot org 2007-07-29 20:57 ------- No longer relevant, due to changes in gfortran. -- tprince at computer dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23845 ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2007-07-29 20:58 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2005-09-13 0:06 [Bug c/23845] New: missed strength reduction costs performance tprince at computer dot org
2005-09-13 0:09 ` [Bug middle-end/23845] " pinskia at gcc dot gnu dot org
2005-09-13 0:13 ` tprince at computer dot org
2005-09-13 2:13 ` pinskia at gcc dot gnu dot org
2005-09-13 14:50 ` pinskia at gcc dot gnu dot org
2005-09-13 18:30 ` rguenth at gcc dot gnu dot org
2005-09-13 23:16 ` tprince at computer dot org
[not found] <bug-23845-33@http.gcc.gnu.org/bugzilla/>
2007-07-29 20:58 ` tprince at computer dot org
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