[Bug c/110491] Wrong code at -O2 on x86_64-linux-gnu (a recent regression)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110491 Richard Biener changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #4 from Richard Biener --- Fixed.
[Bug c/110491] Wrong code at -O2 on x86_64-linux-gnu (a recent regression)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110491 --- Comment #3 from CVS Commits --- The master branch has been updated by Richard Biener : https://gcc.gnu.org/g:819285ef10a87d663f8c181c06aa88d1d9f75aed commit r14-2296-g819285ef10a87d663f8c181c06aa88d1d9f75aed Author: Richard Biener Date: Tue Jul 4 12:52:27 2023 +0200 tree-optimization/110491 - PHI-OPT and undefs The following makes sure to not make conditional undefs in PHI arguments unconditional by folding cond ? arg1 : arg2. PR tree-optimization/110491 * tree-ssa-phiopt.cc (match_simplify_replacement): Check whether the PHI args are possibly undefined before folding the COND_EXPR. * gcc.dg/torture/pr110491.c: New testcase.
[Bug c/110491] Wrong code at -O2 on x86_64-linux-gnu (a recent regression)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110491 Richard Biener changed: What|Removed |Added Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Status|RESOLVED|ASSIGNED Resolution|DUPLICATE |--- Last reconfirmed||2023-07-04 --- Comment #2 from Richard Biener --- So the issue here is phiopt4 doing [local count: 1073741824]: - if (c_lsm_flag.14_16 != 0) -goto ; [66.67%] - else -goto ; [33.33%] - - [local count: 357913944]: - - [local count: 1073741824]: + _26 = ~c_lsm_flag.14_16; + _14 = (int) _26; # RANGE [irange] int [0, 1] NONZERO 0x1 - # prephitmp_27 = PHI <1(7), c_lsm.13_3(6)> - c = prephitmp_27; + _4 = c_lsm.13_3 | _14; + c = _4; return; via phiopt match-simplify trying: c_lsm_flag.14_16 != 0 ? c_lsm.13_3 : 1 Matching expression match.pd:1991, gimple-match-5.cc:23 Matching expression match.pd:1991, gimple-match-5.cc:23 Matching expression match.pd:1991, gimple-match-5.cc:23 Matching expression match.pd:1948, gimple-match-7.cc:20 Matching expression match.pd:2480, gimple-match-4.cc:35 Matching expression match.pd:2483, gimple-match-3.cc:66 Matching expression match.pd:2490, gimple-match-2.cc:58 Applying pattern match.pd:6459, gimple-match-10.cc:12767 Applying pattern match.pd:1378, gimple-match-5.cc:7352 Applying pattern match.pd:1886, gimple-match-1.cc:1232 Applying pattern match.pd:4748, gimple-match-4.cc:15651 Folded into the sequence: _13 = (int) c_lsm_flag.14_16; _26 = ~c_lsm_flag.14_16; _14 = (int) _26; _4 = c_lsm.13_3 | _14; Removing basic block 7 but [local count: 9761289309]: # RANGE [irange] int [0, 1] NONZERO 0x1 # c_lsm.13_3 = PHI <_17(D)(2), _11(5)> so we have an uninitialized use here. The following fixes this. diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc index 31a7c39e405..467c9fd108a 100644 --- a/gcc/tree-ssa-phiopt.cc +++ b/gcc/tree-ssa-phiopt.cc @@ -785,6 +785,13 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb, arg_false = arg0; } + /* Do not make conditional undefs unconditional. */ + if ((TREE_CODE (arg_true) == SSA_NAME + && ssa_name_maybe_undef_p (arg_true)) + || (TREE_CODE (arg_false) == SSA_NAME + && ssa_name_maybe_undef_p (arg_false))) +return false; + tree type = TREE_TYPE (gimple_phi_result (phi)); result = gimple_simplify_phiopt (early_p, type, stmt, arg_true, arg_false,
[Bug c/110491] Wrong code at -O2 on x86_64-linux-gnu (a recent regression)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110491 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution|--- |DUPLICATE --- Comment #1 from Andrew Pinski --- Dup of bug 110228. # RANGE [irange] int [0, 1] NONZERO 0x1 # c_lsm.10_3 = PHI <_17(D)(2), _11(5)> ... if (c_lsm_flag.11_16 != 0) goto ; [66.67%] else goto ; [33.33%] ;;succ: 7 [33.3% (adjusted)] count:357913944 (estimated locally) (FALSE_VALUE,EXECUTABLE) ;;8 [66.7% (adjusted)] count:715827880 (estimated locally) (TRUE_VALUE,EXECUTABLE) ;; basic block 7, loop depth 0, count 357913944 (estimated locally), maybe hot ;;prev block 6, next block 8, flags: (NEW) ;;pred: 6 [33.3% (adjusted)] count:357913944 (estimated locally) (FALSE_VALUE,EXECUTABLE) ;;succ: 8 [always] count:357913944 (estimated locally) (FALLTHRU) ;; basic block 8, loop depth 0, count 1073741824 (estimated locally), maybe hot ;;prev block 7, next block 1, flags: (NEW, REACHABLE, VISITED) ;;pred: 7 [always] count:357913944 (estimated locally) (FALLTHRU) ;;6 [66.7% (adjusted)] count:715827880 (estimated locally) (TRUE_VALUE,EXECUTABLE) # RANGE [irange] int [0, 1] NONZERO 0x1 # prephitmp_27 = PHI <1(7), c_lsm.10_3(6)> *** This bug has been marked as a duplicate of bug 110228 ***
