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* [Bug target/40900] New: redundant sign extend of short function returned value
@ 2009-07-29 8:56 carrot at google dot com
2009-07-29 8:57 ` [Bug target/40900] " carrot at google dot com
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: carrot at google dot com @ 2009-07-29 8:56 UTC (permalink / raw)
To: gcc-bugs
Compile the following code with options -Os -mthumb -march=armv5te
extern short shortv2();
short shortv1()
{
return shortv2();
}
Gcc generates
push {r3, lr}
bl shortv2
lsl r0, r0, #16 // A
asr r0, r0, #16 // B
pop {r3, pc}
The returned value in register r0 is already a sign extended short value, but
instructions A and B sign extend it again. So these two instructions are
redundant.
--
Summary: redundant sign extend of short function returned value
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: carrot at google dot com
GCC build triplet: i686-linux
GCC host triplet: i686-linux
GCC target triplet: arm-eabi
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug target/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
@ 2009-07-29 8:57 ` carrot at google dot com
2009-07-29 9:34 ` ramana at gcc dot gnu dot org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: carrot at google dot com @ 2009-07-29 8:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from carrot at google dot com 2009-07-29 08:57 -------
Created an attachment (id=18266)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18266&action=view)
test case
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug target/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
2009-07-29 8:57 ` [Bug target/40900] " carrot at google dot com
@ 2009-07-29 9:34 ` ramana at gcc dot gnu dot org
2009-07-29 10:33 ` [Bug rtl-optimization/40900] " ramana at gcc dot gnu dot org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ramana at gcc dot gnu dot org @ 2009-07-29 9:34 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from ramana at gcc dot gnu dot org 2009-07-29 09:33 -------
You don't see it on ARM for this case because of tail-calling. But for Thumb or
without sibcall optimizations you do see this problem.
--
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 |2009-07-29 09:33:56
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
2009-07-29 8:57 ` [Bug target/40900] " carrot at google dot com
2009-07-29 9:34 ` ramana at gcc dot gnu dot org
@ 2009-07-29 10:33 ` ramana at gcc dot gnu dot org
2009-12-12 1:13 ` rearnsha at gcc dot gnu dot org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: ramana at gcc dot gnu dot org @ 2009-07-29 10:33 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from ramana at gcc dot gnu dot org 2009-07-29 10:33 -------
I don't think this is a backend specific problem but more an rtl-optimization
problem where combine with its sign extension detection machinery should be
extended to detect such cases.
--
ramana at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |rtl-optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
` (2 preceding siblings ...)
2009-07-29 10:33 ` [Bug rtl-optimization/40900] " ramana at gcc dot gnu dot org
@ 2009-12-12 1:13 ` rearnsha at gcc dot gnu dot org
2010-06-18 16:39 ` ebotcazou at gcc dot gnu dot org
2010-06-18 16:41 ` ebotcazou at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: rearnsha at gcc dot gnu dot org @ 2009-12-12 1:13 UTC (permalink / raw)
To: gcc-bugs
--
rearnsha at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
` (3 preceding siblings ...)
2009-12-12 1:13 ` rearnsha at gcc dot gnu dot org
@ 2010-06-18 16:39 ` ebotcazou at gcc dot gnu dot org
2010-06-18 16:41 ` ebotcazou at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: ebotcazou at gcc dot gnu dot org @ 2010-06-18 16:39 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from ebotcazou at gcc dot gnu dot org 2010-06-18 16:39 -------
Subject: Bug 40900
Author: ebotcazou
Date: Fri Jun 18 16:38:29 2010
New Revision: 161006
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=161006
Log:
PR rtl-optimization/40900
* expr.c (expand_expr_real_1) <SSA_NAME>: Fix long line. Save the
original expression for later reuse.
<expand_decl_rtl>: Use promote_function_mode to compute the signedness
of the promoted RTL for a SSA_NAME on the LHS of a call statement.
Added:
trunk/gcc/testsuite/gcc.target/arm/pr40900.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/expr.c
trunk/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/40900] redundant sign extend of short function returned value
2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
` (4 preceding siblings ...)
2010-06-18 16:39 ` ebotcazou at gcc dot gnu dot org
@ 2010-06-18 16:41 ` ebotcazou at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: ebotcazou at gcc dot gnu dot org @ 2010-06-18 16:41 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from ebotcazou at gcc dot gnu dot org 2010-06-18 16:40 -------
On the mainline.
--
ebotcazou at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.6.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40900
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2010-06-18 16:41 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2009-07-29 8:56 [Bug target/40900] New: redundant sign extend of short function returned value carrot at google dot com
2009-07-29 8:57 ` [Bug target/40900] " carrot at google dot com
2009-07-29 9:34 ` ramana at gcc dot gnu dot org
2009-07-29 10:33 ` [Bug rtl-optimization/40900] " ramana at gcc dot gnu dot org
2009-12-12 1:13 ` rearnsha at gcc dot gnu dot org
2010-06-18 16:39 ` ebotcazou at gcc dot gnu dot org
2010-06-18 16:41 ` ebotcazou at gcc dot gnu dot org
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