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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/100342] [10/11 Regression] wrong code with -O2 -fno-dse -fno-forward-propagate -mno-sse2 Date: Tue, 04 May 2021 12:50:02 +0000 [thread overview] Message-ID: <bug-100342-4-tQsRHt10uw@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-100342-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100342 --- Comment #3 from Uroš Bizjak <ubizjak at gmail dot com> --- For some reason the *input* value at BSWAP insn is truncated to 32bits. v256u128 v256u128_1 = SHLV (SHLSV (__builtin_bswap64 (u128_0), (v256u128) (0 < v256u128_0)) <= 0, v256u128_0); u128_0 is an argument to foo0, passes value of 123842323652213865 (decimal). The binary has only one BSWAP insn, so: $ objdump -dr a.out | grep bswap 401ddd: 48 0f ca bswap %rdx (gdb) b *0x401ddd Breakpoint 1 at 0x401ddd: file pr100342.c, line 72. Breakpoint 1, 0x0000000000401ddd in foo0 (u8_0=u8_0@entry=0 '\000', v128u8_0=v128u8_0@entry=..., v512u8_0=..., u16_0=u16_0@entry=10, v128u16_0=v128u16_0@entry=..., u32_0=u32_0@entry=4, u64_0=u64_0@entry=2, v512u64_0=..., u128_0=<optimized out>, v256u128_0=..., v512u128_0=...) at zzz.c:72 72 SHLV (SHLSV (__builtin_bswap64 (u128_0), (v256u128) (0 < v256u128_0)) <= (gdb) p $rdx $2 = 3983735913 (gdb) p/x $rdx $3 = 0xed72fc69 We can "fix" the clobbered value manually in gdb session: (gdb) set $rdx = 123842323652213865 (gdb) p/x $rdx $4 = 0x1b7f9efed72fc69 (gdb) c Continuing. [Inferior 1 (process 20630) exited normally]
next prev parent reply other threads:[~2021-05-04 12:50 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-29 20:10 [Bug target/100342] New: " zsojka at seznam dot cz 2021-04-30 6:51 ` [Bug rtl-optimization/100342] " rguenth at gcc dot gnu.org 2021-04-30 8:54 ` jakub at gcc dot gnu.org 2021-05-04 12:50 ` ubizjak at gmail dot com [this message] 2021-05-04 13:08 ` ubizjak at gmail dot com 2021-05-04 15:14 ` ubizjak at gmail dot com 2021-05-04 15:29 ` jakub at gcc dot gnu.org 2021-05-04 15:33 ` ubizjak at gmail dot com 2021-05-04 15:34 ` ubizjak at gmail dot com 2021-05-04 16:36 ` jakub at gcc dot gnu.org 2021-05-04 16:57 ` jakub at gcc dot gnu.org 2021-05-05 10:59 ` jakub at gcc dot gnu.org 2021-05-05 15:12 ` jakub at gcc dot gnu.org 2021-05-06 5:22 ` crazylht at gmail dot com 2021-05-15 8:14 ` cvs-commit at gcc dot gnu.org 2021-05-31 14:08 ` cvs-commit at gcc dot gnu.org 2021-05-31 14:56 ` [Bug rtl-optimization/100342] [10 " jakub at gcc dot gnu.org 2022-05-10 8:18 ` cvs-commit at gcc dot gnu.org 2022-05-10 10:45 ` jakub at gcc dot gnu.org
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