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* [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently
@ 2012-02-03 13:05 amodra at gmail dot com
2012-02-03 13:34 ` [Bug target/52107] " rguenth at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: amodra at gmail dot com @ 2012-02-03 13:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
Bug #: 52107
Summary: IBM 128bit long double constant loaded inefficiently
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: amodra@gmail.com
/* -m64 -O2 -mcmodel=small */
typedef float TFtype __attribute__ ((mode (TF)));
TFtype f2 (TFtype x)
{
return x * 0x1p-64f;
}
gives
[snip]
.LC2:
.tc ID_0_0[TC],0x000000000
.LC3:
.tc ID_0_3bf00000[TC],0x03bf00000
[snip]
.L.f2:
mflr 0
lfd 3,.LC3@toc(2)
std 0,16(1)
stdu 1,-128(1)
lfd 4,.LC2@toc(2)
stfd 3,112(1)
ld 9,112(1)
sldi 9,9,32
std 9,112(1)
lfd 3,112(1)
bl __gcc_qmul
[snip]
Horrible! How come the bit pattern is stored right-shifted, and so needs
shifting back into place? By comparison, gcc-4.4.1 generated
[snip]
.LC1:
.tc ID_3bf00000_0[TC],0x3bf0000000000000
.LC2:
.tc ID_0_0[TC],0x000000000
[snip]
.L.f2:
mflr 0
lfd 4,.LC2@toc(2)
lfd 3,.LC1@toc(2)
std 0,16(1)
stdu 1,-112(1)
bl __gcc_qmul
[snip]
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
@ 2012-02-03 13:34 ` rguenth at gcc dot gnu.org
2012-02-03 23:18 ` amodra at gmail dot com
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-02-03 13:34 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-02-03
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-03 13:34:18 UTC ---
I suppose to save data space? ...
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
2012-02-03 13:34 ` [Bug target/52107] " rguenth at gcc dot gnu.org
@ 2012-02-03 23:18 ` amodra at gmail dot com
2012-02-03 23:21 ` amodra at gmail dot com
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gmail dot com @ 2012-02-03 23:18 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
--- Comment #2 from Alan Modra <amodra at gmail dot com> 2012-02-03 23:17:36 UTC ---
.tc generates an 8-byte word in both cases, so no space saved in the toc. This
bit of code in rs6000_emit_move does the loads in DImode, then cse1 shows the
toc load being converted to a load immediate and it all goes downhill from
there.
/* 128-bit constant floating-point values on Darwin should really be
loaded as two parts. */
if (!TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128
&& mode == TFmode && GET_CODE (operands[1]) == CONST_DOUBLE)
{
/* DImode is used, not DFmode, because simplify_gen_subreg doesn't
know how to get a DFmode SUBREG of a TFmode. */
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
2012-02-03 13:34 ` [Bug target/52107] " rguenth at gcc dot gnu.org
2012-02-03 23:18 ` amodra at gmail dot com
@ 2012-02-03 23:21 ` amodra at gmail dot com
2012-02-06 22:09 ` amodra at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gmail dot com @ 2012-02-03 23:21 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
Alan Modra <amodra at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |amodra at gmail dot com
|gnu.org |
--- Comment #3 from Alan Modra <amodra at gmail dot com> 2012-02-03 23:20:56 UTC ---
Investigating a fix.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
` (2 preceding siblings ...)
2012-02-03 23:21 ` amodra at gmail dot com
@ 2012-02-06 22:09 ` amodra at gcc dot gnu.org
2012-02-06 23:42 ` amodra at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gcc dot gnu.org @ 2012-02-06 22:09 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
--- Comment #4 from Alan Modra <amodra at gcc dot gnu.org> 2012-02-06 22:09:17 UTC ---
Author: amodra
Date: Mon Feb 6 22:09:13 2012
New Revision: 183945
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183945
Log:
PR target/52107
* config/rs6000/rs6000.c (rs6000_emit_move): Don't create DImode
subregs of TFmode.
Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/rs6000/rs6000.c
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
` (3 preceding siblings ...)
2012-02-06 22:09 ` amodra at gcc dot gnu.org
@ 2012-02-06 23:42 ` amodra at gcc dot gnu.org
2012-02-06 23:43 ` amodra at gmail dot com
2012-02-06 23:46 ` amodra at gmail dot com
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gcc dot gnu.org @ 2012-02-06 23:42 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
--- Comment #5 from Alan Modra <amodra at gcc dot gnu.org> 2012-02-06 23:41:49 UTC ---
Author: amodra
Date: Mon Feb 6 23:41:45 2012
New Revision: 183947
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183947
Log:
PR target/52107
* config/rs6000/rs6000.c (rs6000_emit_move): Don't create DImode
subregs of TFmode.
Modified:
branches/gcc-4_6-branch/gcc/ChangeLog
branches/gcc-4_6-branch/gcc/config/rs6000/rs6000.c
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
` (4 preceding siblings ...)
2012-02-06 23:42 ` amodra at gcc dot gnu.org
@ 2012-02-06 23:43 ` amodra at gmail dot com
2012-02-06 23:46 ` amodra at gmail dot com
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gmail dot com @ 2012-02-06 23:43 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
Alan Modra <amodra at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.8.0
--- Comment #6 from Alan Modra <amodra at gmail dot com> 2012-02-06 23:43:15 UTC ---
Fixed mainline and 4.6
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug target/52107] IBM 128bit long double constant loaded inefficiently
2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
` (5 preceding siblings ...)
2012-02-06 23:43 ` amodra at gmail dot com
@ 2012-02-06 23:46 ` amodra at gmail dot com
6 siblings, 0 replies; 8+ messages in thread
From: amodra at gmail dot com @ 2012-02-06 23:46 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
Alan Modra <amodra at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|4.8.0 |4.7.0
^ permalink raw reply [flat|nested] 8+ messages in thread
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2012-02-03 13:05 [Bug target/52107] New: IBM 128bit long double constant loaded inefficiently amodra at gmail dot com
2012-02-03 13:34 ` [Bug target/52107] " rguenth at gcc dot gnu.org
2012-02-03 23:18 ` amodra at gmail dot com
2012-02-03 23:21 ` amodra at gmail dot com
2012-02-06 22:09 ` amodra at gcc dot gnu.org
2012-02-06 23:42 ` amodra at gcc dot gnu.org
2012-02-06 23:43 ` amodra at gmail dot com
2012-02-06 23:46 ` amodra at gmail dot com
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