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* [Bug rtl-optimization/23100] New: poor code generation for i686
@ 2005-07-27 19:13 dann at godzilla dot ics dot uci dot edu
2005-07-27 19:21 ` [Bug rtl-optimization/23100] " pinskia at gcc dot gnu dot org
` (6 more replies)
0 siblings, 7 replies; 9+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2005-07-27 19:13 UTC (permalink / raw)
To: gcc-bugs
Compiling the code below (extracted from xterm-202) with
-fno-inline -O2 -march=i686
typedef unsigned long Atom;
static int
CutBuffer(unsigned code)
{
int cutbuffer;
switch (code) {
case ((Atom) 9):
cutbuffer = 0;
break;
case ((Atom) 10):
cutbuffer = 1;
break;
case ((Atom) 11):
cutbuffer = 2;
break;
case ((Atom) 12):
cutbuffer = 3;
break;
case ((Atom) 13):
cutbuffer = 4;
break;
case ((Atom) 14):
cutbuffer = 5;
break;
case ((Atom) 15):
cutbuffer = 6;
break;
case ((Atom) 16):
cutbuffer = 7;
break;
default:
cutbuffer = -1;
break;
}
return cutbuffer;
}
int foo (unsigned code)
{
return CutBuffer (code);
}
generates:
CutBuffer:
subl $9, %eax
movl $-1, %edx
pushl %ebp
cmpl $7, %eax
movl %esp, %ebp
ja .L12
jmp *.L11(,%eax,4)
.section .rodata
.align 4
.align 4
.L11:
.long .L3
.long .L4
.long .L5
.long .L6
.long .L7
.long .L8
.long .L9
.long .L10
.text
.L9:
movl $6, %edx
.p2align 4,,15
.L12:
popl %ebp
movl %edx, %eax
ret
.L3:
popl %ebp
xorl %edx, %edx
movl %edx, %eax
.p2align 4,,2
ret
.L10:
popl %ebp
movl $7, %edx
movl %edx, %eax
ret
.L8:
popl %ebp
movl $5, %edx
movl %edx, %eax
ret
.L7:
popl %ebp
movl $4, %edx
movl %edx, %eax
ret
.L6:
popl %ebp
movl $3, %edx
movl %edx, %eax
ret
[snip]
Note the sequences: movl NUMBER, %edx
movl %edx, %eax
instead of using only one instruction for the same thing: movl NUMBER, %eax
--
Summary: poor code generation for i686
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dann at godzilla dot ics dot uci dot edu
CC: gcc-bugs at gcc dot gnu dot org
GCC host triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
@ 2005-07-27 19:21 ` pinskia at gcc dot gnu dot org
2005-07-27 21:18 ` dann at godzilla dot ics dot uci dot edu
` (5 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-07-27 19:21 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-07-27 19:20 -------
This is the same issue as PR 16796 really, see comment #3.
--
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization, ra
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
2005-07-27 19:21 ` [Bug rtl-optimization/23100] " pinskia at gcc dot gnu dot org
@ 2005-07-27 21:18 ` dann at godzilla dot ics dot uci dot edu
2005-07-27 22:22 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2005-07-27 21:18 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From dann at godzilla dot ics dot uci dot edu 2005-07-27 21:06 -------
The problem does not happen for i386: (ie using -fno-inline -O2 -march=i386)
CutBuffer:
pushl %ebp
movl %esp, %ebp
subl $9, %eax
cmpl $7, %eax
ja .L2
jmp *.L11(,%eax,4)
.section .rodata
.align 4
.align 4
.L11:
.long .L3
.long .L4
.long .L5
.long .L6
.long .L7
.long .L8
.long .L9
.long .L10
.text
.p2align 2,,3
.L2:
movl $-1, %eax
leave
ret
.L3:
xorl %eax, %eax
leave
ret
.L10:
movl $7, %eax
leave
ret
.L9:
movl $6, %eax
leave
ret
.L8:
movl $5, %eax
leave
ret
.L7:
movl $4, %eax
leave
ret
.L6:
movl $3, %eax
leave
ret
[snip]
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
2005-07-27 19:21 ` [Bug rtl-optimization/23100] " pinskia at gcc dot gnu dot org
2005-07-27 21:18 ` dann at godzilla dot ics dot uci dot edu
@ 2005-07-27 22:22 ` pinskia at gcc dot gnu dot org
2005-07-27 22:37 ` dann at godzilla dot ics dot uci dot edu
` (3 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-07-27 22:22 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-07-27 22:22 -------
Actually am I missing something, I get:
.L8:
popl %ebp
movl $5, %eax
.p2align 4,,4
ret
--
What |Removed |Added
----------------------------------------------------------------------------
GCC host triplet|i686-pc-linux-gnu |
GCC target triplet| |i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
` (2 preceding siblings ...)
2005-07-27 22:22 ` pinskia at gcc dot gnu dot org
@ 2005-07-27 22:37 ` dann at godzilla dot ics dot uci dot edu
2005-07-30 15:40 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2005-07-27 22:37 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From dann at godzilla dot ics dot uci dot edu 2005-07-27 22:33 -------
(In reply to comment #3)
> Actually am I missing something, I get:
> .L8:
> popl %ebp
> movl $5, %eax
> .p2align 4,,4
> ret
Is that with -O2 -fno-inline -march=i686 ?
I am using:
"GCC: (GNU) 4.1.0 20050727 (experimental)"
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
` (3 preceding siblings ...)
2005-07-27 22:37 ` dann at godzilla dot ics dot uci dot edu
@ 2005-07-30 15:40 ` pinskia at gcc dot gnu dot org
2005-07-30 15:43 ` pinskia at gcc dot gnu dot org
2005-08-01 18:36 ` dann at godzilla dot ics dot uci dot edu
6 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-07-30 15:40 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-07-30 15:39 -------
Yes it is the same issue as PR 16796.
To reproduce this before 3.4.0, you have to add __attribute__((regparam(1))). Though the code is worse
than before 3.3.3.
--
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |16796
nThis| |
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Known to fail| |3.4.0 4.0.0 4.1.0
Last reconfirmed|0000-00-00 00:00:00 |2005-07-30 15:39:09
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
` (4 preceding siblings ...)
2005-07-30 15:40 ` pinskia at gcc dot gnu dot org
@ 2005-07-30 15:43 ` pinskia at gcc dot gnu dot org
2005-08-01 18:36 ` dann at godzilla dot ics dot uci dot edu
6 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-07-30 15:43 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
` (5 preceding siblings ...)
2005-07-30 15:43 ` pinskia at gcc dot gnu dot org
@ 2005-08-01 18:36 ` dann at godzilla dot ics dot uci dot edu
6 siblings, 0 replies; 9+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2005-08-01 18:36 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From dann at godzilla dot ics dot uci dot edu 2005-08-01 18:36 -------
Could another pass of "flow" (or some other pass that can clean-up the extra
moves) be scheduled to run after reorder-blocks?
reorder-blocks is the pass that inserts the function epilogue in each switch case...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rtl-optimization/23100] poor code generation for i686
[not found] <bug-23100-1008@http.gcc.gnu.org/bugzilla/>
@ 2008-09-14 4:14 ` pinskia at gcc dot gnu dot org
0 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-09-14 4:14 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from pinskia at gcc dot gnu dot org 2008-09-14 04:13 -------
Fixed for 4.4.0 with IRA.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |18427
nThis| |
Status|NEW |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.4.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23100
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2008-09-14 4:14 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-07-27 19:13 [Bug rtl-optimization/23100] New: poor code generation for i686 dann at godzilla dot ics dot uci dot edu
2005-07-27 19:21 ` [Bug rtl-optimization/23100] " pinskia at gcc dot gnu dot org
2005-07-27 21:18 ` dann at godzilla dot ics dot uci dot edu
2005-07-27 22:22 ` pinskia at gcc dot gnu dot org
2005-07-27 22:37 ` dann at godzilla dot ics dot uci dot edu
2005-07-30 15:40 ` pinskia at gcc dot gnu dot org
2005-07-30 15:43 ` pinskia at gcc dot gnu dot org
2005-08-01 18:36 ` dann at godzilla dot ics dot uci dot edu
[not found] <bug-23100-1008@http.gcc.gnu.org/bugzilla/>
2008-09-14 4:14 ` pinskia at gcc dot gnu dot org
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