public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug tree-optimization/25558] New: Arguments cannot alias local variables
@ 2005-12-25 4:13 pinskia at gcc dot gnu dot org
2005-12-25 4:16 ` [Bug tree-optimization/25558] " pinskia at gcc dot gnu dot org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 4:13 UTC (permalink / raw)
To: gcc-bugs
I cannot remember if I filed a bug about this or not but I noticed this while
looking at some Fortran code. Here is testcase which shows the issue:
void link_error(void);
int *t;
int g(int *a)
{
t = a;
*a = 2;
}
void f(int *a)
{
int b;
b = 1;
g(&b);
b = 2;
*a = 1; <--- a cannot point to b here.
if (b == 2)
link_error();
}
int main(void)
{
int t;
f(&t);
return 0;
}
--
Summary: Arguments cannot alias local variables
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Keywords: missed-optimization, alias
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pinskia at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
@ 2005-12-25 4:16 ` pinskia at gcc dot gnu dot org
2005-12-25 4:19 ` pinskia at gcc dot gnu dot org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 4:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from pinskia at gcc dot gnu dot org 2005-12-25 04:16 -------
Woops I had messed up the testcase, anyways the following line:
if (b == 2)
Should be replaced with:
if (b != 2)
This is already done on the RTL level.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |TREE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
2005-12-25 4:16 ` [Bug tree-optimization/25558] " pinskia at gcc dot gnu dot org
@ 2005-12-25 4:19 ` pinskia at gcc dot gnu dot org
2005-12-25 4:20 ` pinskia at gcc dot gnu dot org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 4:19 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from pinskia at gcc dot gnu dot org 2005-12-25 04:19 -------
CSE is the one which does this on the rtl level.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |19721
nThis| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
2005-12-25 4:16 ` [Bug tree-optimization/25558] " pinskia at gcc dot gnu dot org
2005-12-25 4:19 ` pinskia at gcc dot gnu dot org
@ 2005-12-25 4:20 ` pinskia at gcc dot gnu dot org
2005-12-25 4:56 ` pinskia at gcc dot gnu dot org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 4:20 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
` (2 preceding siblings ...)
2005-12-25 4:20 ` pinskia at gcc dot gnu dot org
@ 2005-12-25 4:56 ` pinskia at gcc dot gnu dot org
2005-12-25 5:05 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 4:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from pinskia at gcc dot gnu dot org 2005-12-25 04:56 -------
What is interesting is that ICC does not even do this optimization.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
` (3 preceding siblings ...)
2005-12-25 4:56 ` pinskia at gcc dot gnu dot org
@ 2005-12-25 5:05 ` pinskia at gcc dot gnu dot org
2005-12-25 5:30 ` pinskia at gcc dot gnu dot org
2006-01-11 1:07 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 5:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2005-12-25 05:04 -------
(In reply to comment #3)
> What is interesting is that ICC does not even do this optimization.
Even LLVM does this optimization, I am starting to think ICC is not really a
good compiler.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
` (4 preceding siblings ...)
2005-12-25 5:05 ` pinskia at gcc dot gnu dot org
@ 2005-12-25 5:30 ` pinskia at gcc dot gnu dot org
2006-01-11 1:07 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-12-25 5:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from pinskia at gcc dot gnu dot org 2005-12-25 05:30 -------
(In reply to comment #4)
> (In reply to comment #3)
> > What is interesting is that ICC does not even do this optimization.
>
> Even LLVM does this optimization, I am starting to think ICC is not really a
> good compiler.
Ifort actually does this optimization, it is just weird that. Here is the
equivalent Fortran code:
module f1
contains
function g(a)
integer g
integer a
g = 1
a = 2
end function
function f(a)
real f
integer a
integer b
integer c
b=1
c = g(b)
b = 1
a = 2
if (b .ne. 1) then
call link_error ()
end if
f = 1
end function
end module
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/25558] Arguments cannot alias local variables
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
` (5 preceding siblings ...)
2005-12-25 5:30 ` pinskia at gcc dot gnu dot org
@ 2006-01-11 1:07 ` pinskia at gcc dot gnu dot org
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-01-11 1:07 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from pinskia at gcc dot gnu dot org 2006-01-11 01:07 -------
Oh, this is a dup of bug 23086.
*** This bug has been marked as a duplicate of 23086 ***
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25558
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2006-01-11 1:07 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-12-25 4:13 [Bug tree-optimization/25558] New: Arguments cannot alias local variables pinskia at gcc dot gnu dot org
2005-12-25 4:16 ` [Bug tree-optimization/25558] " pinskia at gcc dot gnu dot org
2005-12-25 4:19 ` pinskia at gcc dot gnu dot org
2005-12-25 4:20 ` pinskia at gcc dot gnu dot org
2005-12-25 4:56 ` pinskia at gcc dot gnu dot org
2005-12-25 5:05 ` pinskia at gcc dot gnu dot org
2005-12-25 5:30 ` pinskia at gcc dot gnu dot org
2006-01-11 1:07 ` pinskia at gcc dot gnu dot org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).