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* [Bug target/67797] New: [ARM] Unnecessary r0 saving for memset call
@ 2015-10-01 14:19 d.salikhov at samsung dot com
2021-12-27 4:25 ` [Bug middle-end/67797] builtin functions should be able to know when their first argument is returned pinskia at gcc dot gnu.org
2021-12-27 4:28 ` [Bug tree-optimization/67797] builtin functions should be able to know when their first argument is returned for tail calls pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: d.salikhov at samsung dot com @ 2015-10-01 14:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67797
Bug ID: 67797
Summary: [ARM] Unnecessary r0 saving for memset call
Product: gcc
Version: 5.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: d.salikhov at samsung dot com
Target Milestone: ---
Compiled with -Os and with -O2 (result is the same):
#include <string.h>
void *my_func(void *s, size_t n)
{
memset(s, 0, n);
return s;
}
The generated code is following:
00000000 <my_func>:
0: e92d4010 push {r4, lr}
4: e1a02001 mov r2, r1
8: e1a04000 mov r4, r0
c: e3a01000 mov r1, #0
10: ebfffffe bl 0 <memset>
14: e1a00004 mov r0, r4
18: e8bd8010 pop {r4, pc}
First, copying r0 into r4 is redundant as memset doesn't clobber r0. So the
code could be reduced to:
push {r4, lr}
mov r2, r1
mov r1, #0
bl 0 <memset>
pop {r4, pc}
That in turn can be simplified more to:
mov r2, r1
mov r1, #0
b 0 <memset>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/67797] builtin functions should be able to know when their first argument is returned
2015-10-01 14:19 [Bug target/67797] New: [ARM] Unnecessary r0 saving for memset call d.salikhov at samsung dot com
@ 2021-12-27 4:25 ` pinskia at gcc dot gnu.org
2021-12-27 4:28 ` [Bug tree-optimization/67797] builtin functions should be able to know when their first argument is returned for tail calls pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-27 4:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67797
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 92867 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/67797] builtin functions should be able to know when their first argument is returned for tail calls
2015-10-01 14:19 [Bug target/67797] New: [ARM] Unnecessary r0 saving for memset call d.salikhov at samsung dot com
2021-12-27 4:25 ` [Bug middle-end/67797] builtin functions should be able to know when their first argument is returned pinskia at gcc dot gnu.org
@ 2021-12-27 4:28 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-27 4:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67797
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 83142 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-12-27 4:28 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2015-10-01 14:19 [Bug target/67797] New: [ARM] Unnecessary r0 saving for memset call d.salikhov at samsung dot com
2021-12-27 4:25 ` [Bug middle-end/67797] builtin functions should be able to know when their first argument is returned pinskia at gcc dot gnu.org
2021-12-27 4:28 ` [Bug tree-optimization/67797] builtin functions should be able to know when their first argument is returned for tail calls pinskia at gcc dot gnu.org
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