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* [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register
@ 2006-06-01 11:35 etienne_lorrain at yahoo dot fr
2006-06-01 17:21 ` [Bug target/27856] " pinskia at gcc dot gnu dot org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: etienne_lorrain at yahoo dot fr @ 2006-06-01 11:35 UTC (permalink / raw)
To: gcc-bugs
$ cat tmp.c
unsigned athird (unsigned val)
{
return val / 3;
}
$ /home/etienne/projet/toolchain/bin/gcc -S -Os -o tmp.s -fomit-frame-pointer
-fverbose-asm tmp.c
$ cat tmp.s
.file "tmp.c"
# GNU C version 4.1.1 (i686-pc-linux-gnu)
# compiled by GNU C version 4.1.1.
# GGC heuristics: --param ggc-min-expand=62 --param ggc-min-heapsize=60570
# options passed: -mtune=pentiumpro -auxbase-strip -Os
# -fomit-frame-pointer -fverbose-asm
# options enabled: -falign-loops -fargument-alias -fbranch-count-reg
# -fcaller-saves -fcommon -fcprop-registers -fcrossjumping
# -fcse-follow-jumps -fcse-skip-blocks -fdefer-pop
# -fdelete-null-pointer-checks -fearly-inlining
# -feliminate-unused-debug-types -fexpensive-optimizations -ffunction-cse
# -fgcse -fgcse-lm -fguess-branch-probability -fident -fif-conversion
# -fif-conversion2 -finline-functions -finline-functions-called-once
# -fipa-pure-const -fipa-reference -fipa-type-escape -fivopts
# -fkeep-static-consts -fleading-underscore -floop-optimize
# -floop-optimize2 -fmath-errno -fmerge-constants -fomit-frame-pointer
# -foptimize-register-move -foptimize-sibling-calls -fpcc-struct-return
# -fpeephole -fpeephole2 -fregmove -freorder-functions
# -frerun-cse-after-loop -frerun-loop-opt -fsched-interblock -fsched-spec
# -fsched-stalled-insns-dep -fschedule-insns2 -fshow-column
# -fsplit-ivs-in-unroller -fstrength-reduce -fstrict-aliasing
# -fthread-jumps -ftrapping-math -ftree-ccp -ftree-copy-prop
# -ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse -ftree-fre
# -ftree-loop-im -ftree-loop-ivcanon -ftree-loop-optimize -ftree-lrs
# -ftree-salias -ftree-sink -ftree-sra -ftree-store-ccp
# -ftree-store-copy-prop -ftree-ter -ftree-vect-loop-version -ftree-vrp
# -funit-at-a-time -fverbose-asm -fzero-initialized-in-bss -m32 -m80387
# -m96bit-long-double -malign-stringops -mfancy-math-387 -mfp-ret-in-387
# -mieee-fp -mno-red-zone -mpush-args -mtls-direct-seg-refs
# Compiler executable checksum: acc0f3237f8807740daa75cf2b5b2d98
.text
.globl athird
.type athird, @function
athird:
movl 4(%esp), %eax # val, val
movl $3, %edx #, tmp63
movl %edx, %ecx # tmp63,
xorl %edx, %edx # tmp62
divl %ecx #
ret
.size athird, .-athird
.ident "GCC: (GNU) 4.1.1"
.section .note.GNU-stack,"",@progbits
Here tmp63 is not needed and the two lines:
movl $3, %edx #, tmp63
movl %edx, %ecx # tmp63,
Should be replaced by:
movl $3, %ecx
--
Summary: With -Os, loading a constant to a register can use
another register
Product: gcc
Version: 4.1.1
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: etienne_lorrain at yahoo dot fr
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/27856] With -Os, loading a constant to a register can use another register
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
@ 2006-06-01 17:21 ` pinskia at gcc dot gnu dot org
2006-06-01 17:24 ` pinskia at gcc dot gnu dot org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-06-01 17:21 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2006-06-01 17:21 -------
Confirmed, this is a RA issue.
Before register allocation:
(insn:HI 10 7 11 2 (set (reg:SI 63)
(const_int 3 [0x3])) 34 {*movsi_1} (nil)
(expr_list:REG_EQUIV (const_int 3 [0x3])
(nil)))
(insn:HI 11 10 15 2 (parallel [
(set (reg:SI 61)
(udiv:SI (reg/v:SI 59 [ val ])
(reg:SI 63)))
(set (reg:SI 62)
(umod:SI (reg/v:SI 59 [ val ])
(reg:SI 63)))
(clobber (reg:CC 17 flags))
]) 197 {udivmodsi4} (insn_list:REG_DEP_TRUE 6 (insn_list:REG_DEP_TRUE
10 (nil)))
(expr_list:REG_UNUSED (reg:CC 17 flags)
(expr_list:REG_UNUSED (reg:SI 62)
(expr_list:REG_DEAD (reg/v:SI 59 [ val ])
(expr_list:REG_DEAD (reg:SI 63)
(expr_list:REG_UNUSED (reg:CC 17 flags)
(expr_list:REG_UNUSED (reg:SI 62)
(nil))))))))
-----------
After:
(insn:HI 10 7 30 2 (set (reg:SI 1 dx [63])
(const_int 3 [0x3])) 34 {*movsi_1} (nil)
(expr_list:REG_EQUIV (const_int 3 [0x3])
(nil)))
(insn 30 10 11 2 (set (reg:SI 2 cx)
(reg:SI 1 dx [63])) 34 {*movsi_1} (nil)
(nil))
(insn:HI 11 30 15 2 (parallel [
(set (reg:SI 0 ax [61])
(udiv:SI (reg/v:SI 0 ax [orig:59 val ] [59])
(reg:SI 2 cx)))
(set (reg:SI 1 dx [62])
(umod:SI (reg/v:SI 0 ax [orig:59 val ] [59])
(reg:SI 2 cx)))
(clobber (reg:CC 17 flags))
]) 197 {udivmodsi4} (insn_list:REG_DEP_TRUE 6 (insn_list:REG_DEP_TRUE
10 (nil)))
(nil))
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |ra
Last reconfirmed|0000-00-00 00:00:00 |2006-06-01 17:21:06
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/27856] With -Os, loading a constant to a register can use another register
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
2006-06-01 17:21 ` [Bug target/27856] " pinskia at gcc dot gnu dot org
@ 2006-06-01 17:24 ` pinskia at gcc dot gnu dot org
2006-09-05 11:32 ` etienne_lorrain at yahoo dot fr
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-06-01 17:24 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from pinskia at gcc dot gnu dot org 2006-06-01 17:24 -------
And "yara" gets this correct.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
BugsThisDependsOn| |18427
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/27856] With -Os, loading a constant to a register can use another register
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
2006-06-01 17:21 ` [Bug target/27856] " pinskia at gcc dot gnu dot org
2006-06-01 17:24 ` pinskia at gcc dot gnu dot org
@ 2006-09-05 11:32 ` etienne_lorrain at yahoo dot fr
2007-04-04 11:19 ` steven at gcc dot gnu dot org
2008-09-14 4:32 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: etienne_lorrain at yahoo dot fr @ 2006-09-05 11:32 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from etienne_lorrain at yahoo dot fr 2006-09-05 11:32 -------
Just for info, does that means we need to wait for YARA to be included,
considering
http://gcc.gnu.org/ml/gcc/2006-08/msg00164.html
it will probably happen after 4.2 ?
I am seeing a lot of them, even some pattern like that to clear %eax:
xor %edx,%edx
...
mov %edx,%eax
... use %eax ...
mov 10,%edx
Thanks.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/27856] With -Os, loading a constant to a register can use another register
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
` (2 preceding siblings ...)
2006-09-05 11:32 ` etienne_lorrain at yahoo dot fr
@ 2007-04-04 11:19 ` steven at gcc dot gnu dot org
2008-09-14 4:32 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: steven at gcc dot gnu dot org @ 2007-04-04 11:19 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from steven at gcc dot gnu dot org 2007-04-04 12:19 -------
Still see this.
--
steven at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug target/27856] With -Os, loading a constant to a register can use another register
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
` (3 preceding siblings ...)
2007-04-04 11:19 ` steven at gcc dot gnu dot org
@ 2008-09-14 4:32 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-09-14 4:32 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from pinskia at gcc dot gnu dot org 2008-09-14 04:30 -------
The same issue is really 22072.
*** This bug has been marked as a duplicate of 22072 ***
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
BugsThisDependsOn| |22072
Status|NEW |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27856
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2008-09-14 4:32 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2006-06-01 11:35 [Bug rtl-optimization/27856] New: With -Os, loading a constant to a register can use another register etienne_lorrain at yahoo dot fr
2006-06-01 17:21 ` [Bug target/27856] " pinskia at gcc dot gnu dot org
2006-06-01 17:24 ` pinskia at gcc dot gnu dot org
2006-09-05 11:32 ` etienne_lorrain at yahoo dot fr
2007-04-04 11:19 ` steven at gcc dot gnu dot org
2008-09-14 4:32 ` pinskia at gcc dot gnu dot org
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