From: Shen Hui <shenhui@mprc.pku.edu.cn>
To: "gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: help?
Date: Sat, 12 Jul 2003 10:05:00 -0000 [thread overview]
Message-ID: <200307120704.h6C74C1H019491@mprc.pku.edu.cn> (raw)
gcc-help-help,hi!
I am using gcc-2.95.3 form ARM.
i have a c program file as follow:
void foo1 ()
{
int j[]={1,2};
}
void foo2 ()
{
int j[]={1,2,3};
}
but the code generated for foo1 are:
foo1:
@ args = 0, pretend = 0, frame = 8
@ frame_needed = 1, current_function_anonymous_args = 0
mov ip, sp
stmfd sp!, {r4, fp, ip, lr, pc}
sub fp, ip, #4
sub sp, sp, #8
sub r3, fp, #24
ldr r2, .L4
ldmia r2, {r3-r4}
sub r1, fp, #16
stmdb r1, {r3-r4}
b .L3
and the code generated for foo2 are:
foo2:
@ args = 0, pretend = 0, frame = 12
@ frame_needed = 1, current_function_anonymous_args = 0
mov ip, sp
stmfd sp!, {fp, ip, lr, pc}
sub fp, ip, #4
sub sp, sp, #12
sub r3, fp, #24
ldr r2, .L8
sub r3, fp, #24 @**************************it is the redundant instruction, the same as above two.
mov ip, r2
ldmia ip, {r0-r2} @ load multiple
stmia r3, {r0-r2} @ str multiple
b .L7
my question is that in function foo2 there is a redundant instruction (sub r3, fp, #24),
i donot think it's needed, whereas, there hasnot this instruction in function foo1.
why compiler generate it ?
thanks!
Shen Hui
shenhui@mprc.pku.edu.cn
2003-07-12
next reply other threads:[~2003-07-12 6:50 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-12 10:05 Shen Hui [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-06-01 15:58 Help!! Tomas Ukkonen
2006-12-26 13:38 help!! manish manish
2006-12-27 17:01 ` help!! Ian Lance Taylor
2006-01-28 5:42 Help? Garvin Pang
2006-01-28 7:41 ` Help? Brian Dessent
2005-06-02 15:54 help_ imacat
2003-03-03 17:37 help!!! Jim Frost
2003-03-07 5:46 ` help!!! LLeweLLyn Reese
[not found] <20021204042724.64819.qmail@web15002.mail.bjs.yahoo.com>
2002-12-04 0:16 ` help! Ben Elliston
2002-11-19 10:16 help!!! mingo lu
[not found] <20020617195757.13842.qmail@uwdvg001.cms.usa.net>
2002-06-17 13:05 ` help!! Phil Edwards
2002-04-04 23:41 Help! 朱 少波
2001-01-02 18:27 Help? Kwanghoon Choi
2001-01-02 19:37 ` Help? Alexandre Oliva
2000-05-15 9:15 HELP!!! Michael Michael
2000-05-16 23:27 ` HELP!!! Martin v. Loewis
2000-03-08 14:14 HELP !!! FabrÃcio Souza
2000-03-09 17:00 ` Alexandre Oliva
2000-04-01 0:00 ` Alexandre Oliva
2000-04-01 0:00 ` FabrÃcio Souza
2000-02-24 0:56 Help! 陳鵬升
2000-04-01 0:00 ` Help! 陳鵬升
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