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* [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
@ 2023-10-13 15:56 theodort at inf dot ethz.ch
2023-10-13 15:58 ` [Bug tree-optimization/111801] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: theodort at inf dot ethz.ch @ 2023-10-13 15:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Bug ID: 111801
Summary: [14 Regression] Missed Dead Code Elimination since
r14-4141-gbf6b107e2a3
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: theodort at inf dot ethz.ch
Target Milestone: ---
https://godbolt.org/z/47fbssWd3
Given the following code:
void foo(void);
static struct {
signed a;
} b, c, *e = &b;
static struct {
unsigned d;
} g = {109};
static int f;
static int *h;
static int **i = &h;
int main() {
f = 1;
if (b.a) f = 8;
int *j = *i;
if (j == &g == 0)
if (!(((g.d) >= 109) && ((g.d) <= 109))) {
__builtin_unreachable();
}
if (f)
;
else {
c = *e;
foo();
}
}
gcc-trunk -O2 does not eliminate the call to foo:
main:
movl $1, f(%rip)
movl b(%rip), %esi
testl %esi, %esi
je .L10
movl $8, f(%rip)
.L10:
cmpq $g, h(%rip)
je .L7
movl f(%rip), %ecx
testl %ecx, %ecx
je .L12
.L7:
xorl %eax, %eax
ret
.L12:
pushq %rax
call foo
xorl %eax, %eax
popq %rdx
ret
gcc-13.2.0 -O2 eliminates the call to foo:
main:
movl $1, f(%rip)
movl b(%rip), %eax
testl %eax, %eax
je .L2
movl $8, f(%rip)
.L2:
xorl %eax, %eax
ret
Bisects to r14-4141-gbf6b107e2a3
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/111801] [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
@ 2023-10-13 15:58 ` pinskia at gcc dot gnu.org
2023-10-13 16:11 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-10-13 15:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |14.0
Keywords| |missed-optimization
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/111801] [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
2023-10-13 15:58 ` [Bug tree-optimization/111801] " pinskia at gcc dot gnu.org
@ 2023-10-13 16:11 ` pinskia at gcc dot gnu.org
2024-03-07 21:04 ` law at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-10-13 16:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-10-13
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
What happens after the patch is `if (j == &g == 0)` still is kept around and we
decide to jump thread into that block and duplicate the `if (f)` there (I
think) and then there is a missing PRE (I think) where we could see that f is
stored and we load from f.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/111801] [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
2023-10-13 15:58 ` [Bug tree-optimization/111801] " pinskia at gcc dot gnu.org
2023-10-13 16:11 ` pinskia at gcc dot gnu.org
@ 2024-03-07 21:04 ` law at gcc dot gnu.org
2024-03-09 5:37 ` law at gcc dot gnu.org
2024-05-07 7:42 ` [Bug tree-optimization/111801] [14/15 " rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: law at gcc dot gnu.org @ 2024-03-07 21:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
CC| |law at gcc dot gnu.org
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/111801] [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
` (2 preceding siblings ...)
2024-03-07 21:04 ` law at gcc dot gnu.org
@ 2024-03-09 5:37 ` law at gcc dot gnu.org
2024-05-07 7:42 ` [Bug tree-optimization/111801] [14/15 " rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: law at gcc dot gnu.org @ 2024-03-09 5:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Interestingly enough this is picked up at -O3. Looks like PRE does a better
job and the result is easier to discover the range for first operand of the
controlling conditional.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/111801] [14/15 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3
2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
` (3 preceding siblings ...)
2024-03-09 5:37 ` law at gcc dot gnu.org
@ 2024-05-07 7:42 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-05-07 7:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111801
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|14.0 |14.2
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14.1 is being released, retargeting bugs to GCC 14.2.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-05-07 7:42 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2023-10-13 15:56 [Bug tree-optimization/111801] New: [14 Regression] Missed Dead Code Elimination since r14-4141-gbf6b107e2a3 theodort at inf dot ethz.ch
2023-10-13 15:58 ` [Bug tree-optimization/111801] " pinskia at gcc dot gnu.org
2023-10-13 16:11 ` pinskia at gcc dot gnu.org
2024-03-07 21:04 ` law at gcc dot gnu.org
2024-03-09 5:37 ` law at gcc dot gnu.org
2024-05-07 7:42 ` [Bug tree-optimization/111801] [14/15 " rguenth at gcc dot gnu.org
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