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* [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements
@ 2010-02-25 23:54 changpeng dot fang at amd dot com
2010-02-25 23:58 ` [Bug middle-end/43184] " pinskia at gcc dot gnu dot org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: changpeng dot fang at amd dot com @ 2010-02-25 23:54 UTC (permalink / raw)
To: gcc-bugs
gcc 4.5 could not vectorize floating point reductions.
float sum(float a[], int n) {
int i;
float total=0.0;
for(i=0; i< n; i++)
total += a[i];
return total;
}
"gcc -O3 -fdump-tree-vect-all" shows:
foo.c:4: note: Unsupported pattern.
foo.c:4: note: not vectorized: unsupported use in stmt.
foo.c:4: note: unexpected pattern.
foo.c:1: note: vectorized 0 loops in function.
I have verified that gcc can vectorize integer reduction, but not float and
double.
--
Summary: gcc could not vectorize floating point reduction
statements
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: changpeng dot fang at amd dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/43184] gcc could not vectorize floating point reduction statements 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com @ 2010-02-25 23:58 ` pinskia at gcc dot gnu dot org 2010-02-26 0:28 ` changpeng dot fang at amd dot com ` (3 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2010-02-25 23:58 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from pinskia at gcc dot gnu dot org 2010-02-25 23:57 ------- >gcc 4.5 could not vectorize floating point reductions. Yes it can; add -ffast-math. floating point reductions need -ffast-math as it can change the results in some cases (negative zero and I think clamping cases too). -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/43184] gcc could not vectorize floating point reduction statements 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com 2010-02-25 23:58 ` [Bug middle-end/43184] " pinskia at gcc dot gnu dot org @ 2010-02-26 0:28 ` changpeng dot fang at amd dot com 2010-02-26 0:47 ` pinskia at gcc dot gnu dot org ` (2 subsequent siblings) 4 siblings, 0 replies; 6+ messages in thread From: changpeng dot fang at amd dot com @ 2010-02-26 0:28 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from changpeng dot fang at amd dot com 2010-02-26 00:28 ------- Subject: RE: gcc could not vectorize floating point reduction statements Thanks for pointing this out. Actually I am working on a fortran program and found the the reduction statement. The fortran code can not be vectorized even with -ffast-math. Do you think this is the problem of fortran frontend? Thanks, -- Changpeng c%3.1 subroutine s311 (ntimes,ld,n,ctime,dtime,a,b,c,d,e,aa,bb,cc) c c reductions c sum reduction c integer ntimes, ld, n, i, nl double precision a(n), b(n), c(n), d(n), e(n), aa(ld,n), + bb(ld,n), cc(ld,n) double precision chksum, sum real t1, t2, second, ctime, dtime call init(ld,n,a,b,c,d,e,aa,bb,cc,'s311 ') t1 = second() do 1 nl = 1,ntimes sum = 0.d0 do 10 i = 1,n sum = sum + a(i) 10 continue call dummy(ld,n,a,b,c,d,e,aa,bb,cc,sum) 1 continue t2 = second() - t1 - ctime - ( dtime * float(ntimes) ) chksum = sum call check (chksum,ntimes*n,n,t2,'s311 ') return end ________________________________________ From: pinskia at gcc dot gnu dot org [gcc-bugzilla@gcc.gnu.org] Sent: Thursday, February 25, 2010 5:57 PM To: Fang, Changpeng Subject: [Bug middle-end/43184] gcc could not vectorize floating point reduction statements ------- Comment #1 from pinskia at gcc dot gnu dot org 2010-02-25 23:57 ------- >gcc 4.5 could not vectorize floating point reductions. Yes it can; add -ffast-math. floating point reductions need -ffast-math as it can change the results in some cases (negative zero and I think clamping cases too). -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ------- You are receiving this mail because: ------- You reported the bug, or are watching the reporter. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/43184] gcc could not vectorize floating point reduction statements 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com 2010-02-25 23:58 ` [Bug middle-end/43184] " pinskia at gcc dot gnu dot org 2010-02-26 0:28 ` changpeng dot fang at amd dot com @ 2010-02-26 0:47 ` pinskia at gcc dot gnu dot org 2010-02-26 13:20 ` manu at gcc dot gnu dot org 2010-02-26 13:21 ` manu at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: pinskia at gcc dot gnu dot org @ 2010-02-26 0:47 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from pinskia at gcc dot gnu dot org 2010-02-26 00:47 ------- t.f:15: note: not vectorized: unsupported use in stmt. (In reply to comment #2) > Subject: RE: gcc could not vectorize floating point > reduction statements > > Thanks for pointing this out. Actually I am working on a fortran program and > found the > the reduction statement. And that is PR 32824 (which I filed awhile back). -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/43184] gcc could not vectorize floating point reduction statements 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com ` (2 preceding siblings ...) 2010-02-26 0:47 ` pinskia at gcc dot gnu dot org @ 2010-02-26 13:20 ` manu at gcc dot gnu dot org 2010-02-26 13:21 ` manu at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: manu at gcc dot gnu dot org @ 2010-02-26 13:20 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from manu at gcc dot gnu dot org 2010-02-26 13:20 ------- So this is not invalid... -- manu at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |manu at gcc dot gnu dot org Status|RESOLVED |UNCONFIRMED Resolution|INVALID | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug middle-end/43184] gcc could not vectorize floating point reduction statements 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com ` (3 preceding siblings ...) 2010-02-26 13:20 ` manu at gcc dot gnu dot org @ 2010-02-26 13:21 ` manu at gcc dot gnu dot org 4 siblings, 0 replies; 6+ messages in thread From: manu at gcc dot gnu dot org @ 2010-02-26 13:21 UTC (permalink / raw) To: gcc-bugs ------- Comment #5 from manu at gcc dot gnu dot org 2010-02-26 13:20 ------- ,,. but a duplicate *** This bug has been marked as a duplicate of 32824 *** -- manu at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |DUPLICATE http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43184 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-02-26 13:21 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2010-02-25 23:54 [Bug middle-end/43184] New: gcc could not vectorize floating point reduction statements changpeng dot fang at amd dot com 2010-02-25 23:58 ` [Bug middle-end/43184] " pinskia at gcc dot gnu dot org 2010-02-26 0:28 ` changpeng dot fang at amd dot com 2010-02-26 0:47 ` pinskia at gcc dot gnu dot org 2010-02-26 13:20 ` manu at gcc dot gnu dot org 2010-02-26 13:21 ` manu at gcc dot gnu dot org
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