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* [Bug rtl-optimization/41455] New: memcpy not tail called if it's a struct assignment
@ 2009-09-24 3:29 TabonyEE at austin dot rr dot com
2009-09-24 6:29 ` [Bug rtl-optimization/41455] " ramana at gcc dot gnu dot org
2009-12-14 9:56 ` ramana at gcc dot gnu dot org
0 siblings, 2 replies; 4+ messages in thread
From: TabonyEE at austin dot rr dot com @ 2009-09-24 3:29 UTC (permalink / raw)
To: gcc-bugs
For the following code,
typedef struct {
char c[11111];
} s;
void f(s *a, s *b){
*a = *b;
}
compiling for ARM, with -Os, mainline GCC generates the following:
str lr, [sp, #-4]!
ldr r2, .L2
bl memcpy
ldr pc, [sp], #4
.L3:
.align 2
.L2:
.word 11112
GCC 3.4.6 generates a tail call:
ldr r2, .L2
@ lr needed for prologue
b memcpy
.L3:
.align 2
.L2:
.word 11112
The first release of GCC to regress in this way was 4.0.0.
Here is a backtrace from emit_block_move_hints.
#0 emit_block_move_hints (x=0x2ba56160cae0, y=0x2ba56160cb20,
size=0x2ba5615cedc0, method=BLOCK_OP_NORMAL, expected_align=0,
expected_size=-1)
at ../../gcc/expr.c:1163
#1 0x0000000000656f33 in emit_block_move (x=0x2ba56160cae0, y=0x2ba56160cb20,
size=0x2ba5615cedc0, method=BLOCK_OP_NORMAL) at ../../gcc/expr.c:1233
#2 0x000000000066076d in store_expr (exp=0x2ba5610fa0c0,
target=0x2ba56160cae0, call_param_p=0, nontemporal=0 '\0') at
../../gcc/expr.c:4779
#3 0x000000000065ee57 in expand_assignment (to=0x2ba5610fa080,
from=0x2ba5610fa0c0, nontemporal=0 '\0') at ../../gcc/expr.c:4428
Is there any way store_expr() could pass BLOCK_OP_TAILCALL to
emit_block_move()? If not, then can this be transformed into a tail call
later?
--
Summary: memcpy not tail called if it's a struct assignment
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: TabonyEE at austin dot rr dot com
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: arm-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41455
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/41455] memcpy not tail called if it's a struct assignment
2009-09-24 3:29 [Bug rtl-optimization/41455] New: memcpy not tail called if it's a struct assignment TabonyEE at austin dot rr dot com
@ 2009-09-24 6:29 ` ramana at gcc dot gnu dot org
2009-12-14 9:56 ` ramana at gcc dot gnu dot org
1 sibling, 0 replies; 4+ messages in thread
From: ramana at gcc dot gnu dot org @ 2009-09-24 6:29 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from ramana at gcc dot gnu dot org 2009-09-24 06:29 -------
Confirmed with trunk
Because Tail calling is now done at the tree level. I remember me or someone
fixing this by detecting block moves in tree-tail-call.c and then set up the
flags accordingly. IIRC the same problem applied to builtins earlier.
Let me take a look.
--
ramana at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-09-24 06:29:30
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41455
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/41455] memcpy not tail called if it's a struct assignment
2009-09-24 3:29 [Bug rtl-optimization/41455] New: memcpy not tail called if it's a struct assignment TabonyEE at austin dot rr dot com
2009-09-24 6:29 ` [Bug rtl-optimization/41455] " ramana at gcc dot gnu dot org
@ 2009-12-14 9:56 ` ramana at gcc dot gnu dot org
1 sibling, 0 replies; 4+ messages in thread
From: ramana at gcc dot gnu dot org @ 2009-12-14 9:56 UTC (permalink / raw)
To: gcc-bugs
--
ramana at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41455
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/41455] memcpy not tail called if it's a struct assignment
[not found] <bug-41455-4@http.gcc.gnu.org/bugzilla/>
@ 2012-06-06 10:29 ` rguenth at gcc dot gnu.org
0 siblings, 0 replies; 4+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-06-06 10:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41455
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target|arm-elf |arm-elf, x86_64-*-*
Last reconfirmed|2009-09-24 06:29:30 |2012-06-06 6:29:30
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-06 10:29:39 UTC ---
Re-confirmed. Can be reproduced on x86_64 with -Os -mstringop-strategy=libcall
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-06-06 10:29 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-09-24 3:29 [Bug rtl-optimization/41455] New: memcpy not tail called if it's a struct assignment TabonyEE at austin dot rr dot com
2009-09-24 6:29 ` [Bug rtl-optimization/41455] " ramana at gcc dot gnu dot org
2009-12-14 9:56 ` ramana at gcc dot gnu dot org
[not found] <bug-41455-4@http.gcc.gnu.org/bugzilla/>
2012-06-06 10:29 ` rguenth at gcc dot gnu.org
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