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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) -- links below jump to the message on this page -- 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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