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* [Bug middle-end/16187] New: extra casts to unsigned int generated for array references
@ 2004-06-25 0:52 dann at godzilla dot ics dot uci dot edu
2004-06-25 22:58 ` [Bug middle-end/16187] " dann at godzilla dot ics dot uci dot edu
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2004-06-25 0:52 UTC (permalink / raw)
To: gcc-bugs
The .vars dump for this function:
int f1(int * data, int j)
{
return data[j];
}
looks like:
return *((int *)((unsigned int)j * 4) + data);
The cast to "unsigned int" is probably not needed, emitting it increases the
number of statements generated, so it probably increases the memory consumption
and the amount of work the optimizers have to perform.
--
Summary: extra casts to unsigned int generated for array
references
Product: gcc
Version: 3.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: middle-end
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dann at godzilla dot ics dot uci dot edu
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/16187] extra casts to unsigned int generated for array references
2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
@ 2004-06-25 22:58 ` dann at godzilla dot ics dot uci dot edu
2004-06-25 23:04 ` pinskia at gcc dot gnu dot org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: dann at godzilla dot ics dot uci dot edu @ 2004-06-25 22:58 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From dann at godzilla dot ics dot uci dot edu 2004-06-25 22:47 -------
The cast to unsigned int is generated by c-common.c:pointer_int_sum
See the difference in the gimple code generated for the following 2 functions:
int f1(int * data, int j) | int f1(int * data, unsigned int j)
{ {
return data[j]; return data[j];
} }
j.1 = (unsigned int)j; | T.1 = j * 4;
T.2 = j.1 * 4; | T.2 = (int *)T.1;
T.3 = (int *)T.2; | T.3 = T.2 + data;
T.4 = T.3 + data; | T.0 = *T.3;
T.0 = *T.4; <
return T.0; return T.0;
The first case generates one extra gimple statement.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/16187] extra casts to unsigned int generated for array references
2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
2004-06-25 22:58 ` [Bug middle-end/16187] " dann at godzilla dot ics dot uci dot edu
@ 2004-06-25 23:04 ` pinskia at gcc dot gnu dot org
2004-06-26 11:49 ` falk at debian dot org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-06-25 23:04 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-06-25 23:04 -------
Confirmed, what should be happening is that we should support ARRAY_REF for pointers too.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Keywords| |memory-hog
Last reconfirmed|0000-00-00 00:00:00 |2004-06-25 23:04:21
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/16187] extra casts to unsigned int generated for array references
2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
2004-06-25 22:58 ` [Bug middle-end/16187] " dann at godzilla dot ics dot uci dot edu
2004-06-25 23:04 ` pinskia at gcc dot gnu dot org
@ 2004-06-26 11:49 ` falk at debian dot org
2005-03-26 5:38 ` [Bug middle-end/16187] ARRAY_REF should be used for pointers also pinskia at gcc dot gnu dot org
2005-07-24 1:03 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: falk at debian dot org @ 2004-06-26 11:49 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From falk at debian dot org 2004-06-26 10:58 -------
What architecture is that on? On 64-bit architectures, these two functions are
not equivalent; with
int a[10] = { 0 };
f1(a + 2, -2)
the first one works and the second crashes.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/16187] ARRAY_REF should be used for pointers also
2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
` (2 preceding siblings ...)
2004-06-26 11:49 ` falk at debian dot org
@ 2005-03-26 5:38 ` pinskia at gcc dot gnu dot org
2005-07-24 1:03 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-03-26 5:38 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-03-26 05:38 -------
http://gcc.gnu.org/wiki/Add%20MEM_REF%20operation
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |dberlin at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug middle-end/16187] ARRAY_REF should be used for pointers also
2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
` (3 preceding siblings ...)
2005-03-26 5:38 ` [Bug middle-end/16187] ARRAY_REF should be used for pointers also pinskia at gcc dot gnu dot org
@ 2005-07-24 1:03 ` pinskia at gcc dot gnu dot org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-07-24 1:03 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-07-24 01:00 -------
http://gcc.gnu.org/ml/gcc-patches/2005-06/msg02025.html
--
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2005-06-25 18:40:29 |2005-07-24 01:00:30
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16187
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2005-07-24 1:00 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2004-06-25 0:52 [Bug middle-end/16187] New: extra casts to unsigned int generated for array references dann at godzilla dot ics dot uci dot edu
2004-06-25 22:58 ` [Bug middle-end/16187] " dann at godzilla dot ics dot uci dot edu
2004-06-25 23:04 ` pinskia at gcc dot gnu dot org
2004-06-26 11:49 ` falk at debian dot org
2005-03-26 5:38 ` [Bug middle-end/16187] ARRAY_REF should be used for pointers also pinskia at gcc dot gnu dot org
2005-07-24 1:03 ` pinskia at gcc dot gnu dot org
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