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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/110852] [14 Regression] ICE: in get_predictor_value, at predict.cc:2695 with -O -fno-tree-fre and __builtin_expect() since r14-2219-geab57b825bcc35 Date: Thu, 04 Jan 2024 16:17:32 +0000 [thread overview] Message-ID: <bug-110852-4-Msxj3N627m@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110852-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110852 --- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Jan Hubicka from comment #9) > By removing the logic we lose ability to optimize things like > a = b * c; > where b is predicted to value 0 and c has no useful prediction on it. No, that is what my unposted WIP patch did, but predict-18.c test catched that. > > @@ -2631,6 +2623,9 @@ expr_expected_value_1 (tree type, tree o > > > > if (predictor2 < *predictor) > > *predictor = predictor2; > > + if (*predictor != PRED_BUILTIN_EXPECT > > + && *predictor != PRED_BUILTIN_EXPECT_WITH_PROBABILITY) > > + *probability = -1; > > This still can "upgrade" prediction to a predictor of lower enm value > but higher probability that is not conservative thing to do. > > > > return res; > > } > I ended up with the folloing patch that also takes care of various cases > of phi merging and downgrading the predictor to new > PRED_COMBINED_VALUE_PREDICTION which can, like PRED_BUILTIN_EXPECT hold > custom probability but it is not trued as FIRST_MATCH. > What do you think? > + int p1 = get_predictor_value (*predictor, *probability); > + int p2 = get_predictor_value (predictor2, probability2); > + /* If both predictors agrees, it does not matter from which s/agrees/agree/ > + Consequently failing to fold both means that we will not suceed > determinging s/suceed/succeed/;s/determinging/determining/ Otherwise yes, but I think the code could be still simplified the way I had in my patch (i.e. drop parts of the r14-2219 changes, and simply assume that failed recursion for one operand is PRED_UNCONDITIONAL instead of returning early, and not requiring the operands are INTEGER_CSTs, just that the result of the binop folds to INTEGER_CST.
next prev parent reply other threads:[~2024-01-04 16:17 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-07-30 9:02 [Bug tree-optimization/110852] New: [14 Regression] ICE: in get_predictor_value, at predict.cc:2695 with -O -fno-tree-fre and __builtin_expect() zsojka at seznam dot cz 2023-07-30 20:04 ` [Bug tree-optimization/110852] " pinskia at gcc dot gnu.org 2023-08-01 13:57 ` hubicka at gcc dot gnu.org 2023-10-17 12:23 ` rguenth at gcc dot gnu.org 2023-10-17 12:23 ` rguenth at gcc dot gnu.org 2023-10-22 23:40 ` [Bug tree-optimization/110852] [14 Regression] ICE: in get_predictor_value, at predict.cc:2695 with -O -fno-tree-fre and __builtin_expect() since r14-2219-geab57b825bcc35 sjames at gcc dot gnu.org 2023-11-13 3:27 ` pinskia at gcc dot gnu.org 2024-01-04 14:42 ` jakub at gcc dot gnu.org 2024-01-04 15:24 ` hubicka at ucw dot cz 2024-01-04 15:30 ` jakub at gcc dot gnu.org 2024-01-04 15:59 ` jakub at gcc dot gnu.org 2024-01-04 16:06 ` hubicka at ucw dot cz 2024-01-04 16:17 ` jakub at gcc dot gnu.org [this message] 2024-01-04 16:26 ` hubicka at ucw dot cz 2024-01-04 16:35 ` jakub at gcc dot gnu.org 2024-01-04 16:37 ` jakub at gcc dot gnu.org 2024-01-04 17:06 ` hubicka at ucw dot cz 2024-01-17 14:20 ` cvs-commit at gcc dot gnu.org 2024-01-17 14:22 ` hubicka at gcc dot gnu.org
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