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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/106513] [10/11/12/13 Regression] bswap pass misses that >>56 for signed types can be replicate the sign bit Date: Fri, 05 Aug 2022 22:15:25 +0000 [thread overview] Message-ID: <bug-106513-4-wtzJEkdIVy@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106513-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106513 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Known to fail| |4.5.3, 4.6.4 Summary|bswap is incorrectly |[10/11/12/13 Regression] |generated |bswap pass misses that >>56 | |for signed types can be | |replicate the sign bit Known to work| |4.4.7 Target Milestone|--- |10.5 Status|UNCONFIRMED |NEW Last reconfirmed| |2022-08-05 --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. Better testcase (without the questionable undefined behavior): typedef long long int int64_t; __attribute__((noinline)) int64_t swap64 (int64_t n) { return (((n & (((int64_t) 0xff) )) << 56) | ((n & (((int64_t) 0xff) << 8)) << 40) | ((n & (((int64_t) 0xff) << 16)) << 24) | ((n & (((int64_t) 0xff) << 24)) << 8) | ((n & (((int64_t) 0xff) << 32)) >> 8) | ((n & (((int64_t) 0xff) << 40)) >> 24) | ((n & (((int64_t) 0xff) << 48)) >> 40) | ((n & ((int64_t)(0xffull << 56))) >> 56)); } int main (void) { volatile int64_t n = 0x8000000000000000l; if (swap64(n) != 0xffffffffffffff80l) __builtin_abort (); return 0; }
next prev parent reply other threads:[~2022-08-05 22:15 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-03 11:56 [Bug tree-optimization/106513] New: bswap is incorrectly generated kristerw at gcc dot gnu.org 2022-08-03 12:12 ` [Bug tree-optimization/106513] " schwab@linux-m68k.org 2022-08-03 12:41 ` kristerw at gcc dot gnu.org 2022-08-05 22:15 ` pinskia at gcc dot gnu.org [this message] 2022-08-10 13:43 ` [Bug tree-optimization/106513] [10/11/12/13 Regression] bswap pass misses that >>56 for signed types can be replicate the sign bit rguenth at gcc dot gnu.org 2022-08-10 13:51 ` rguenth at gcc dot gnu.org 2022-08-10 14:39 ` cvs-commit at gcc dot gnu.org 2022-08-10 14:40 ` cvs-commit at gcc dot gnu.org 2022-10-11 13:04 ` [Bug tree-optimization/106513] [10/11 " cvs-commit at gcc dot gnu.org 2022-10-14 10:47 ` [Bug tree-optimization/106513] [10 " cvs-commit at gcc dot gnu.org 2022-10-14 10:48 ` rguenth at gcc dot gnu.org
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