[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 --- Comment #7 from Jeffrey A. Law --- As you note, this feels like a failure to recognize that only one value can actually satisfy the condition.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Jeffrey A. Law changed: What|Removed |Added CC||law at gcc dot gnu.org Priority|P3 |P2
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Andrew Pinski changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org Last reconfirmed|2023-06-30 00:00:00 |2023-8-25 --- Comment #6 from Andrew Pinski --- This will be fixed with my test_for_singularity patch.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Andrew Pinski changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=108360 --- Comment #5 from Andrew Pinski --- (In reply to Andrew Pinski from comment #1) > I noticed there is a missing optimization here (during VRP1): > _29 = _11 == 0; > _30 = (unsigned int) _29; > _14 = -_30; > if (_14 > 2) > > That is just: > if (_14 != 0) > or: > if (_29 != 0) > or rather: > if (_11 == 0) That shows up similarly in PR 108360.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Richard Biener changed: What|Removed |Added Target Milestone|13.2|13.3 --- Comment #4 from Richard Biener --- GCC 13.2 is being released, retargeting bugs to GCC 13.3.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503
--- Comment #3 from Andrew Pinski ---
(In reply to Andrew Pinski from comment #2)
>
> Oh and had:
> # RANGE [irange] int [-128, 127]
> _10 = (intD.6) _9;
> # RANGE [irange] int [0, 1] NONZERO 0x1
> _11 = 1 % _10;
>
> I wonder if we could optimize `1 % b` into just `b != 1` (since 1 % 0 is
> undefined) which will further reduce things here.
That does not change the size of the loop though and we are still left with:
size: 1 _10 = _9 == 1;
size: 0 _11 = (unsigned int) _10;
size: 1 _12 = -_11;
size: 2 if (_12 > 2)
But at least now we just need to optimize the above to just `if (_9 == 1)`
Something like:
(simplify
(gt (negative zero_one_value@0) INTEGER_CST@1)
(if (wi::to_wide (@1) >= 1 && TYPE_UNSIGNED (TREE_TYPE (@1)))
(ne @0 { build_zero_cst (TREE_TYPE (@1)); } )
(if (wi::to_wide (@1) >= 0 && !TYPE_UNSIGNED (TREE_TYPE (@1)))
(eq @0 { build_zero_cst (TREE_TYPE (@1)); } )
)
)
)
But I get the feeling this should be done in VRP instead of match ...
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Andrew Pinski changed: What|Removed |Added Ever confirmed|0 |1 Last reconfirmed||2023-06-30 Status|UNCONFIRMED |NEW --- Comment #2 from Andrew Pinski --- (In reply to Andrew Pinski from comment #1) > I noticed there is a missing optimization here (during VRP1): > _29 = _11 == 0; > _30 = (unsigned int) _29; > _14 = -_30; > if (_14 > 2) > > That is just: > if (_14 != 0) > or: > if (_29 != 0) > or rather: > if (_11 == 0) I wonder if the above will decrease the "size" estimates enough to optimize this again ... Oh and had: # RANGE [irange] int [-128, 127] _10 = (intD.6) _9; # RANGE [irange] int [0, 1] NONZERO 0x1 _11 = 1 % _10; I wonder if we could optimize `1 % b` into just `b != 1` (since 1 % 0 is undefined) which will further reduce things here.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 --- Comment #1 from Andrew Pinski --- I noticed there is a missing optimization here (during VRP1): _29 = _11 == 0; _30 = (unsigned int) _29; _14 = -_30; if (_14 > 2) That is just: if (_14 != 0) or: if (_29 != 0) or rather: if (_11 == 0) Oh the difference between GCC 12 and GCC 13 is that completely unroll does not happen. GCC 13: size: 13-6, last_iteration: 13-6 Loop size: 13 Estimated size after unrolling: 14 Not unrolling loop 1: contains call and code would grow. Not peeling: upper bound is known so can unroll completely GCC 12: size: 13-6, last_iteration: 13-6 Loop size: 13 Estimated size after unrolling: 14 Making edge 11->7 impossible by redistributing probability to other edges. Making edge 15->7 impossible by redistributing probability to other edges. Making edge 6->8 impossible by redistributing probability to other edges. /app/example.cpp:17:14: optimized: loop with 2 iterations completely unrolled (header execution count 1073741833) Exit condition of peeled iterations was eliminated. Basically the comparatively size would increase too much ... So this was just by accident I think.
[Bug tree-optimization/110503] [13/14 Regression] Dead Code Elimination Regression at -O3 since r13-322-g7f04b0d786e
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110503 Andrew Pinski changed: What|Removed |Added Keywords||missed-optimization Target Milestone|--- |13.2
