[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 vladlazar at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED CC||vladlazar at gcc dot gnu.org Resolution|--- |FIXED --- Comment #8 from vladlazar at gcc dot gnu.org --- Fixed by r263973. The issue was that in case of underflow, the overflow flag was not set. The solution was to use wi::sub when decrementing.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 --- Comment #7 from vladlazar at gcc dot gnu.org --- Author: vladlazar Date: Thu Aug 30 09:30:49 2018 New Revision: 263973 URL: https://gcc.gnu.org/viewcvs?rev=263973=gcc=rev Log: Enable underflow check in canonicalize_comparison. (PR86995) gcc/ 2018-08-30 Vlad Lazar PR middle-end/86995 * expmed.c (canonicalize_comparison): Use wi::sub instead of wi::add if to_add is negative. Modified: trunk/gcc/ChangeLog trunk/gcc/expmed.c
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 --- Comment #6 from Vlad Lazar --- Here's the patch: https://gcc.gnu.org/ml/gcc-patches/2018-08/msg01889.html
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 --- Comment #5 from Jakub Jelinek --- Like: --- gcc/expmed.c.jj 2018-08-26 22:42:22.526779583 +0200 +++ gcc/expmed.c2018-08-29 14:04:32.669509929 +0200 @@ -6239,7 +6239,9 @@ canonicalize_comparison (machine_mode mo wrapping around in the case of unsigned values. If any occur cancel the optimization. */ wi::overflow_type overflow = wi::OVF_NONE; - wide_int imm_modif = wi::add (imm_val, to_add, sgn, ); + wide_int imm_modif += (to_add > 0 ? wi::add (imm_val, 1, sgn, ) + : wi::sub (imm_val, 1, sgn, )); if (overflow) return; If so, please submit it as soon as possible, leaving such important wrong-code bug for so long is highly undesirable.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 --- Comment #4 from Vlad Lazar --- That's right. It's not the right fix. The actual cause is the use of wi::add in r263591, which does not set the flag in case of underflow. The correct way is to use wi::add for addition and wi::sub for substraction. I'm testing a patch which does that.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 Jakub Jelinek changed: What|Removed |Added CC||jakub at gcc dot gnu.org --- Comment #3 from Jakub Jelinek --- How could a cost adjustment be a right fix to a wrong-code bug? That seems just to make it latent.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 Vlad Lazar changed: What|Removed |Added CC||vlad.lazar at arm dot com --- Comment #2 from Vlad Lazar --- On x86 this was caused by the cost model and has been fixed in r263652. However, upon further inspection, it surfaced that wi::add does not detect underflow for unsigned operations. I am currently testing a patch which should solve the issue.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 Richard Biener changed: What|Removed |Added Keywords||wrong-code Priority|P3 |P1 CC||law at gcc dot gnu.org --- Comment #1 from Richard Biener --- From looking at svn log it must be caused by r263591 | law | 2018-08-16 18:33:43 +0200 (Thu, 16 Aug 2018) | 8 lines * expmed.h (canonicalize_comparison): New declaration. * expmed.c (canonicalize_comparison, equivalent_cmp_code): New function. * expmed.c (emit_store_flag_1): Add call to canonicalize_comparison. * optabs.c (prepare_cmp_insn): Likewise. * rtl.h (unsigned_condition_p): New function which checks if a comparison operator is unsigned. * gcc.target/aarch64/imm_choice_comparison.c: New test. Vlad doesn't seem to have a bugzilla account.
[Bug middle-end/86995] [9 regression] c-c++-common/torture/builtin-arith-overflow-17.c etc. FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86995 Rainer Orth changed: What|Removed |Added Target Milestone|--- |9.0
