[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-1729-ga0af6fd825d533
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #16 from GCC Commits --- The master branch has been updated by Richard Biener : https://gcc.gnu.org/g:bc5570f7ef796fa7f5ab89b34ed9de2be5299f0e commit r16-2299-gbc5570f7ef796fa7f5ab89b34ed9de2be5299f0e Author: Richard Biener Date: Wed Jul 16 15:07:58 2025 +0200 tree-optimization/121049 - avoid loop masking with even/odd reduction The following disables loop masking when we are using an even/odd widening operation in a reduction because the loop mask then aligns to the wrong elements. PR tree-optimization/121049 * internal-fn.h (widening_evenodd_fn_p): Declare. * internal-fn.cc (widening_evenodd_fn_p): New function. * tree-vect-stmts.cc (vectorizable_conversion): When using an even/odd widening function disable loop masking. * gcc.dg/vect/pr121049.c: New testcase.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-1729-ga0af6fd825d533
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049
--- Comment #15 from Richard Biener ---
I think the issue is that we do
_79 = _78 > { 0, 1, 2, 3, 4, 5, 6, 7 };
vect__12.20_57 = .MASK_LOAD (vectp_mon_lengths.19_51, 256B, _79, { 0, 0, 0,
0, 0, 0, 0, 0 });
vect_patt_18.21_58 = WIDEN_MULT_EVEN_EXPR ;
vect_patt_18.21_59 = WIDEN_MULT_ODD_EXPR ;
_63 = VIEW_CONVERT_EXPR>(_79);
vect_value_4.23_64 = .COND_ADD (_63, vect_patt_18.21_58, _60, _60);
_65 = VIEW_CONVERT_EXPR(_79);
_66 = _65 >> 4;
_67 = VIEW_CONVERT_EXPR>(_66);
vect_value_4.23_68 = .COND_ADD (_67, vect_patt_18.21_59, vect_value_4.23_64,
vect_value_4.23_64);
so we use an even/odd widen mult for the reduction - which ultimatively is OK,
but when we do loop masking it is not, since we the mask the wrong elements.
We'd need an lo/hi widen mult or alternatively do an even/odd extract of the
loop mask instead of taking the lo/hi when distributing.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-1729-ga0af6fd825d533
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Sam James changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=116142 --- Comment #14 from Sam James --- (In reply to Sam James from comment #13) > (In reply to [email protected] from comment #11) > > Probably related to PR120927 then. > > Thanks for the hint. Indeed that lets me bisect it back to > r16-1729-ga0af6fd825d533 (w/ --param vect-partial-vector-usage=1 -O3 > -march=x86-64-v4 -mtune=znver4). I fear that is not too helpful either > though. If I also heap on r16-1729-ga0af6fd825d533, I can bisect it back to r15-2791-g2083389a18d366.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-1729-ga0af6fd825d533
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Sam James changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=120927 Summary|[16 regression] |[16 regression] |timezone-data miscompiled |timezone-data miscompiled |with -O3 -march=x86-64-v4 |with -O3 -march=x86-64-v4 |-mtune=znver4 since |-mtune=znver4 since |r16-2088-ge9079e4f43d135|r16-1729-ga0af6fd825d533 --- Comment #13 from Sam James --- (In reply to [email protected] from comment #11) > Probably related to PR120927 then. Thanks for the hint. Indeed that lets me bisect it back to r16-1729-ga0af6fd825d533 (w/ --param vect-partial-vector-usage=1 -O3 -march=x86-64-v4 -mtune=znver4). I fear that is not too helpful either though.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Richard Biener changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Status|NEW |ASSIGNED --- Comment #12 from Richard Biener --- I will look at this at some point but will prioritize the issues also affecting GCC 15 first.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #11 from rguenther at suse dot de --- On Sun, 13 Jul 2025, sjames at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 > > --- Comment #9 from Sam James --- > Yes, I tried to go further but the compiler hangs with the needed param before > that commit for a large part of the range. Probably related to PR120927 then.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Andrew Pinski changed: What|Removed |Added Target||x86_64 --- Comment #10 from Andrew Pinski --- Unlike the other one, `-O3 -march=x86-64-v4 --param vect-partial-vector-usage=1` still works.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #9 from Sam James --- Yes, I tried to go further but the compiler hangs with the needed param before that commit for a large part of the range.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #8 from Andrew Pinski --- (In reply to Sam James from comment #7) > r16-2088-ge9079e4f43d135 This looks like it just exposed the issue with a costing model change in the backend.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4 since r16-2088-ge9079e4f43d135
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Sam James changed: What|Removed |Added Keywords|needs-bisection | CC||rguenth at gcc dot gnu.org Summary|[16 regression] |[16 regression] |timezone-data miscompiled |timezone-data miscompiled |with -O3 -march=x86-64-v4 |with -O3 -march=x86-64-v4 |-mtune=znver4 |-mtune=znver4 since ||r16-2088-ge9079e4f43d135 --- Comment #7 from Sam James --- r16-2088-ge9079e4f43d135
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Andrew Pinski changed: What|Removed |Added Attachment #61852|0 |1 is obsolete|| --- Comment #6 from Andrew Pinski --- Created attachment 61853 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61853&action=edit Slightly more reduced Looks like only the first and last values of the array are added and missing the middle one.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Andrew Pinski changed: What|Removed |Added Attachment #61851|0 |1 is obsolete|| --- Comment #4 from Andrew Pinski --- Created attachment 61852 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61852&action=edit Removed the header
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Andrew Pinski changed: What|Removed |Added Last reconfirmed||2025-07-13 Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #5 from Andrew Pinski --- Confirmed.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Andrew Pinski changed: What|Removed |Added Attachment #61850|0 |1 is obsolete|| --- Comment #3 from Andrew Pinski --- Created attachment 61851 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61851&action=edit Reduced further
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #2 from Sam James --- Created attachment 61850 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61850&action=edit localtime.c Reduced it a bit more.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 --- Comment #1 from Sam James --- May have overreduced, sec.
[Bug tree-optimization/121049] [16 regression] timezone-data miscompiled with -O3 -march=x86-64-v4 -mtune=znver4
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121049 Sam James changed: What|Removed |Added Keywords||wrong-code Target Milestone|--- |16.0
