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* [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057
@ 2023-07-20 16:09 shaohua.li at inf dot ethz.ch
2023-07-20 16:19 ` [Bug ipa/110753] [14 Regression] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: shaohua.li at inf dot ethz.ch @ 2023-07-20 16:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
Bug ID: 110753
Summary: ICE in meet_with_1, at ipa-cp.cc:1057
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
Target Milestone: ---
This looks like a recent regression.
Compiler explorer: https://godbolt.org/z/sGjbfYj16
$ cat a.c
int a, b, c;
int d(long e, long f) { return f == 0 || e && f == 1 ?: f; }
int g() {}
static int h(long e) {
b = e + 4294967295;
a = d(b || d(e, 8), g());
}
int i() {
c = i;
h(c);
}
int main() {}
$
$ gcc-tk -O3 a.c
<source>: In function 'i':
<source>:9:5: warning: assignment to 'int' from 'int (*)()' makes integer from
pointer without a cast [-Wint-conversion]
9 | c = i;
| ^
during IPA pass: cp
<source>: At top level:
<source>:12:1: internal compiler error: in meet_with_1, at ipa-cp.cc:1057
12 | int main() {}
| ^~~
0x215ca2e internal_error(char const*, ...)
???:0
0x9cfbf0 fancy_abort(char const*, int, char const*)
???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
$
$ gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-322d17ae51ea0137167424e0018d7fa355948f9f/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-322d17ae51ea0137167424e0018d7fa355948f9f
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20230711 (experimental) (GCC)
$
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug ipa/110753] [14 Regression] ICE in meet_with_1, at ipa-cp.cc:1057
2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
@ 2023-07-20 16:19 ` pinskia at gcc dot gnu.org
2023-07-30 20:45 ` shaohua.li at inf dot ethz.ch
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-07-20 16:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|ICE in meet_with_1, at |[14 Regression] ICE in
|ipa-cp.cc:1057 |meet_with_1, at
| |ipa-cp.cc:1057
Target Milestone|--- |14.0
Ever confirmed|0 |1
Last reconfirmed| |2023-07-20
Status|UNCONFIRMED |NEW
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
Slightly less undefined code:
```
int a, b, c;
static int d(long e, long f) { return f == 0 || e && f == 1 ?: f; }
int g(void) {static int t; return t;}
static int h(long e) {
b = e - 1;
a = d(b || d(e, 8), g());
}
int tt;
void i(void) {
c = (__SIZE_TYPE__)&tt;
h(c);
}
//int main() {}
```
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug ipa/110753] [14 Regression] ICE in meet_with_1, at ipa-cp.cc:1057
2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
2023-07-20 16:19 ` [Bug ipa/110753] [14 Regression] " pinskia at gcc dot gnu.org
@ 2023-07-30 20:45 ` shaohua.li at inf dot ethz.ch
2023-08-03 9:10 ` aldyh at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: shaohua.li at inf dot ethz.ch @ 2023-07-30 20:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
--- Comment #2 from Shaohua Li <shaohua.li at inf dot ethz.ch> ---
Bisect to r14-2379-gc496d15954c, which was committed by @aldyh@redhat.com
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug ipa/110753] [14 Regression] ICE in meet_with_1, at ipa-cp.cc:1057
2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
2023-07-20 16:19 ` [Bug ipa/110753] [14 Regression] " pinskia at gcc dot gnu.org
2023-07-30 20:45 ` shaohua.li at inf dot ethz.ch
@ 2023-08-03 9:10 ` aldyh at gcc dot gnu.org
2023-08-18 15:39 ` cvs-commit at gcc dot gnu.org
2023-08-18 15:42 ` aldyh at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: aldyh at gcc dot gnu.org @ 2023-08-03 9:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |aldyh at gcc dot gnu.org
Assignee|unassigned at gcc dot gnu.org |aldyh at gcc dot gnu.org
--- Comment #3 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
The intersection of two mask/value pairs is being pessimized incorrectly.
MASK 0x0 VALUE 0x1 (value is known to be 1)
MASK 0xfffffffffffffffc VALUE 0x0 (low 2 bits are known to be 1, everything
else is unknown).
irange_bitmask::intersect() is intersecting these to:
MASK 0xffffffffffffffff VALUE 0x0
(i.e. totally unknown value).
This is causing union_bitmask() to return a change when none actually occurred,
because we end up losing the bitmask.
Mine.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug ipa/110753] [14 Regression] ICE in meet_with_1, at ipa-cp.cc:1057
2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
` (2 preceding siblings ...)
2023-08-03 9:10 ` aldyh at gcc dot gnu.org
@ 2023-08-18 15:39 ` cvs-commit at gcc dot gnu.org
2023-08-18 15:42 ` aldyh at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-08-18 15:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Aldy Hernandez <aldyh@gcc.gnu.org>:
https://gcc.gnu.org/g:53fcd3bdbc9104a8acdc79134d8d272d7eead0fd
commit r14-3326-g53fcd3bdbc9104a8acdc79134d8d272d7eead0fd
Author: Aldy Hernandez <aldyh@redhat.com>
Date: Fri Aug 18 12:41:46 2023 +0200
[irange] Return FALSE if updated bitmask is unchanged [PR110753]
The mask/value pair we track in the irange is a bit fickle in that it
can sometimes contradict the bitmask inherent in the range. This can
happen when a series of calculations yield a combination such as:
[3, 1000] MASK 0xfffffffe VALUE 0x0
The mask/value above implies that the lowest bit is a known 0, which
would exclude the 3 in the range. At one time we tried keeping mask
and ranges 100% consistent, but the performance penalty was too high
(5% in VRP). Also, it's unclear whether the intersection of two
incompatible known bits should make the whole range undefined, or
just the contradicting bits. This is all documented in
irange::get_bitmask(). We could revisit both of these assumptions
in the future.
In this testcase IPA ends up with a range where the lower 2 bits are
expected to be 0, but the range is [1,1].
[irange] long int [1, 1] MASK 0xfffffffffffffffc VALUE 0x0
This causes irange::union_bitmask() to think an update occurred, when
no semantic change happened, thus triggering an assert in IPA-cp. We
could get rid of the assert, but it's cleaner to make
irange::{union,intersect}_bitmask always tell the truth. Beside, the
ranger's cache also depends on union being truthful.
PR ipa/110753
gcc/ChangeLog:
* value-range.cc (irange::union_bitmask): Return FALSE if updated
bitmask is semantically equivalent to the original mask.
(irange::intersect_bitmask): Same.
(irange::get_bitmask): Add comment.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr110753.c: New test.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug ipa/110753] [14 Regression] ICE in meet_with_1, at ipa-cp.cc:1057
2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
` (3 preceding siblings ...)
2023-08-18 15:39 ` cvs-commit at gcc dot gnu.org
@ 2023-08-18 15:42 ` aldyh at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: aldyh at gcc dot gnu.org @ 2023-08-18 15:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110753
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Aldy Hernandez from comment #3)
> MASK 0xfffffffffffffffc VALUE 0x0 (low 2 bits are known to be 1, everything
> else is unknown).
FWIW, the above implies the low 2 bits are known to be 0, not 1. Not that it
matters, as I just fixed this PR in trunk :).
^ permalink raw reply [flat|nested] 6+ messages in thread
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2023-07-20 16:09 [Bug c/110753] New: ICE in meet_with_1, at ipa-cp.cc:1057 shaohua.li at inf dot ethz.ch
2023-07-20 16:19 ` [Bug ipa/110753] [14 Regression] " pinskia at gcc dot gnu.org
2023-07-30 20:45 ` shaohua.li at inf dot ethz.ch
2023-08-03 9:10 ` aldyh at gcc dot gnu.org
2023-08-18 15:39 ` cvs-commit at gcc dot gnu.org
2023-08-18 15:42 ` aldyh at gcc dot gnu.org
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