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* [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
@ 2007-03-16 18:14 jakub at gcc dot gnu dot org
2007-03-16 19:17 ` [Bug tree-optimization/31227] " jakub at gcc dot gnu dot org
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: jakub at gcc dot gnu dot org @ 2007-03-16 18:14 UTC (permalink / raw)
To: gcc-bugs
typedef __SIZE_TYPE__ size_t;
extern size_t strlen (const char *);
struct iovec
{
void *iov_base;
size_t iov_len;
};
struct S
{
const char *abday[7];
const char *day[7];
const char *abmon[12];
const char *mon[12];
const char *am_pm[2];
};
extern void foo (size_t, struct iovec *);
void
bar (struct S *time)
{
struct iovec iov[43];
size_t cnt;
iov[0].iov_base = (void *) "abc";
iov[0].iov_len = 3;
iov[1].iov_base = (void *) "def";
iov[1].iov_len = 3;
for (cnt = 0; cnt <= 7; ++cnt)
{
iov[2 + cnt].iov_base = (void *) (time->abday[cnt] ?: "");
iov[2 + cnt].iov_len = strlen (iov[2 + cnt].iov_base) + 1;
}
for (; cnt <= 14; ++cnt)
{
iov[2 + cnt].iov_base = (void *) (time->day[cnt - 7] ?: "");
iov[2 + cnt].iov_len = strlen (iov[2 + cnt].iov_base) + 1;
}
for (; cnt <= 26; ++cnt)
{
iov[2 + cnt].iov_base = (void *) (time->abmon[cnt - 14] ?: "");
iov[2 + cnt].iov_len = strlen (iov[2 + cnt].iov_base) + 1;
}
for (; cnt <= 38; ++cnt)
{
iov[2 + cnt].iov_base = (void *) (time->mon[cnt - 26] ?: "");
iov[2 + cnt].iov_len = strlen (iov[2 + cnt].iov_base) + 1;
}
for (; cnt <= 40; ++cnt)
{
iov[2 + cnt].iov_base = (void *) (time->am_pm[cnt - 38] ?: "");
iov[2 + cnt].iov_len = strlen (iov[2 + cnt].iov_base) + 1;
}
foo (2 + cnt, iov);
}
issues at -O2 -Wall bogus warnings:
/tmp/w.c:24: warning: array subscript is above array bounds
/tmp/w.c:24: warning: array subscript is above array bounds
Apparently tree loop optimizations decide to use &time->abmon[14] and
&time->mon[30] pointers (which are outside of the range of the arrays) and then
dereferences that pointer - 112B (96B is the size of abmon array and 16B are
extra 2 pointers because the other array is biased by 2).
The testcase is extracted from glibc.
--
Summary: [4.3 Regression] -Warray-bounds doesn't play together
with loop optimizations
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jakub at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
@ 2007-03-16 19:17 ` jakub at gcc dot gnu dot org
2007-03-16 21:45 ` rguenth at gcc dot gnu dot org
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: jakub at gcc dot gnu dot org @ 2007-03-16 19:17 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from jakub at gcc dot gnu dot org 2007-03-16 19:17 -------
Another testcase, this time from glibc's malloc.c:
struct malloc_chunk {
long prev_size;
long size;
struct malloc_chunk* fd;
struct malloc_chunk* bk;
};
typedef struct malloc_chunk* mchunkptr;
struct malloc_state {
mchunkptr top;
mchunkptr last_remainder;
mchunkptr bins[128 * 2 - 2];
};
#define bin_at(m, i) \
(mchunkptr) (((char *) &((m)->bins[((i) - 1) * 2])) \
- __builtin_offsetof (struct malloc_chunk, fd))
void malloc_init_state(struct malloc_state *av)
{
int i;
mchunkptr bin;
for (i = 1; i < 128; ++i) {
bin = bin_at(av,i);
bin->fd = bin->bk = bin;
}
}
at -O2 -Wall this warns:
warning: array subscript is below array bounds
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
2007-03-16 19:17 ` [Bug tree-optimization/31227] " jakub at gcc dot gnu dot org
@ 2007-03-16 21:45 ` rguenth at gcc dot gnu dot org
2007-03-16 21:47 ` pinskia at gcc dot gnu dot org
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2007-03-16 21:45 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2007-03-16 21:45 -------
# cnt_67 = PHI <27(13)>
<L22>:;
D.1796_118 = &time_14(D)->mon[27];
ivtmp.56_8 = (unsigned int) D.1796_118;
D.1797_117 = &iov[27];
ivtmp.59_7 = (unsigned int) D.1797_117;
# ivtmp.59_76 = PHI <ivtmp.59_112(17), ivtmp.59_7(14)>
# ivtmp.56_62 = PHI <ivtmp.56_61(17), ivtmp.56_8(14)>
# cnt_105 = PHI <cnt_60(17), 27(14)>
<L18>:;
D.1671_51 = MEM[index: ivtmp.56_62, offset: 0x0ffffff98];
if (D.1671_51 != 0B) goto <L19>; else goto <L21>;
The proper way to warn about &time_14(D)->mon[27] (even if it's invalid C
and arguably invalid IL) is to look at the possible dereference sites.
Of course a MEM without base but using (unsigned int)&time_14(D)->mon[27]
as index and a negative offset doesn't make this easy.
This looks related to PR26726.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rakdver at gcc dot gnu dot
| |org
BugsThisDependsOn| |26726
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-03-16 21:45:23
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
2007-03-16 19:17 ` [Bug tree-optimization/31227] " jakub at gcc dot gnu dot org
2007-03-16 21:45 ` rguenth at gcc dot gnu dot org
@ 2007-03-16 21:47 ` pinskia at gcc dot gnu dot org
2007-03-21 9:05 ` mueller at gcc dot gnu dot org
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-03-16 21:47 UTC (permalink / raw)
To: gcc-bugs
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (2 preceding siblings ...)
2007-03-16 21:47 ` pinskia at gcc dot gnu dot org
@ 2007-03-21 9:05 ` mueller at gcc dot gnu dot org
2007-03-21 14:16 ` mueller at gcc dot gnu dot org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: mueller at gcc dot gnu dot org @ 2007-03-21 9:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from mueller at gcc dot gnu dot org 2007-03-21 09:05 -------
both are caused by our well known offender -fivopts.
the problem why the existing workarounds don't work is because the adress is
first converted to unsigned int before +/- modification is done. the traversal
stops at the type conversion. I'm currently working on fixing that.
--
mueller at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |mueller at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (3 preceding siblings ...)
2007-03-21 9:05 ` mueller at gcc dot gnu dot org
@ 2007-03-21 14:16 ` mueller at gcc dot gnu dot org
2007-03-21 14:17 ` mueller at gcc dot gnu dot org
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: mueller at gcc dot gnu dot org @ 2007-03-21 14:16 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from mueller at gcc dot gnu dot org 2007-03-21 14:16 -------
Created an attachment (id=13242)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13242&action=view)
patch
this is the patch I'm currently testing. would be nice if you could confirm
that this is also fixing your obj-c++ bootstrap problem (which I cannot
reproduce).
Thanks.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (4 preceding siblings ...)
2007-03-21 14:16 ` mueller at gcc dot gnu dot org
@ 2007-03-21 14:17 ` mueller at gcc dot gnu dot org
2007-03-21 14:53 ` jakub at gcc dot gnu dot org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: mueller at gcc dot gnu dot org @ 2007-03-21 14:17 UTC (permalink / raw)
To: gcc-bugs
--
mueller at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |WAITING
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (5 preceding siblings ...)
2007-03-21 14:17 ` mueller at gcc dot gnu dot org
@ 2007-03-21 14:53 ` jakub at gcc dot gnu dot org
2007-04-18 20:09 ` mueller at gcc dot gnu dot org
2007-04-18 20:10 ` mueller at gcc dot gnu dot org
8 siblings, 0 replies; 10+ messages in thread
From: jakub at gcc dot gnu dot org @ 2007-03-21 14:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from jakub at gcc dot gnu dot org 2007-03-21 14:53 -------
obj-c++ bootstrap is actually where the warning triggered correctly, this
was on trunk checkout from yesterday and some tree codes were >= 256,
while an array had just 256 entries and thus e.g.
tree_contains_struct[CLASS_METHOD_DECL][TS_DECL_NON_COMMON] = 1;
(where CLASS_METHOD_DECL == 259 and TS_DECL_NON_COMMON == 1
and extern unsigned char tree_contains_struct[256][64];)
is supposed to warn.
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (6 preceding siblings ...)
2007-03-21 14:53 ` jakub at gcc dot gnu dot org
@ 2007-04-18 20:09 ` mueller at gcc dot gnu dot org
2007-04-18 20:10 ` mueller at gcc dot gnu dot org
8 siblings, 0 replies; 10+ messages in thread
From: mueller at gcc dot gnu dot org @ 2007-04-18 20:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from mueller at gcc dot gnu dot org 2007-04-18 21:09 -------
Subject: Bug 31227
Author: mueller
Date: Wed Apr 18 21:09:21 2007
New Revision: 123958
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=123958
Log:
2007-04-18 Dirk Mueller <dmueller@suse.de>
PR diagnostic/31227
* tree-vrp.c (search_for_addr_array): New.
(check_array_bounds): Suppress warning about
address taken of array refs if its not de-referenced.
* gcc.dg/Warray-bounds-3.c: New.
Added:
trunk/gcc/testsuite/gcc.dg/Warray-bounds-3.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-vrp.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/31227] [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations
2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
` (7 preceding siblings ...)
2007-04-18 20:09 ` mueller at gcc dot gnu dot org
@ 2007-04-18 20:10 ` mueller at gcc dot gnu dot org
8 siblings, 0 replies; 10+ messages in thread
From: mueller at gcc dot gnu dot org @ 2007-04-18 20:10 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from mueller at gcc dot gnu dot org 2007-04-18 21:10 -------
Fixed in 4.3.
--
mueller at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31227
^ permalink raw reply [flat|nested] 10+ messages in thread
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2007-03-16 18:14 [Bug tree-optimization/31227] New: [4.3 Regression] -Warray-bounds doesn't play together with loop optimizations jakub at gcc dot gnu dot org
2007-03-16 19:17 ` [Bug tree-optimization/31227] " jakub at gcc dot gnu dot org
2007-03-16 21:45 ` rguenth at gcc dot gnu dot org
2007-03-16 21:47 ` pinskia at gcc dot gnu dot org
2007-03-21 9:05 ` mueller at gcc dot gnu dot org
2007-03-21 14:16 ` mueller at gcc dot gnu dot org
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2007-04-18 20:09 ` mueller at gcc dot gnu dot org
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