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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107833] wrong code at -Os and above on x86_64-linux-gnu since r12-5138-ge82c382971664d6f Date: Wed, 23 Nov 2022 14:12:18 +0000 [thread overview] Message-ID: <bug-107833-4-xJsZT73FLd@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-107833-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107833 --- Comment #2 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- (In reply to Zhendong Su from comment #0) > Compiler Explorer: https://godbolt.org/z/Tc8vbearG > > It appears to be a regression from 11.3. > > [561] % gcctk -v > Using built-in specs. > COLLECT_GCC=gcctk > COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/ > x86_64-pc-linux-gnu/13.0.0/lto-wrapper > Target: x86_64-pc-linux-gnu > Configured with: ../gcc-trunk/configure --disable-bootstrap > --enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk > --enable-sanitizers --enable-languages=c,c++ --disable-werror > --enable-multilib --with-system-zlib > Thread model: posix > Supported LTO compression algorithms: zlib > gcc version 13.0.0 20221123 (experimental) [master r13-4262-g1cac00d0138] > (GCC) > [562] % > [562] % gcctk -O1 small.c; ./a.out > [563] % > [563] % gcctk -Os small.c > [564] % ./a.out > Segmentation fault > [565] % > [565] % cat small.c > int printf(const char *, ...); > int a, b[1] = {0}, c, *d = b, e, *f, g; > int main() { > int h = 0; > for (; a < 2; a++) { > int i; > for (g = 0; g < 2; g++) > if (a < h) { > e = i % 2; Isn't there an uninitialized read from "i" here? At least on the second time through the outer loop, if (a < h) is true since 1 < 0. > c = *f; > } > for (h = 0; h < 3; h++) { > if (d) > break; d is nonzero so h will always be 0 in this function. > i--; > printf("0"); > } > } > return 0; > } Unless I'm missing something....
next prev parent reply other threads:[~2022-11-23 14:12 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-23 12:48 [Bug tree-optimization/107833] New: wrong code at -Os and above on x86_64-linux-gnu zhendong.su at inf dot ethz.ch 2022-11-23 13:14 ` [Bug tree-optimization/107833] wrong code at -Os and above on x86_64-linux-gnu since r12-5138-ge82c382971664d6f marxin at gcc dot gnu.org 2022-11-23 14:12 ` aldyh at gcc dot gnu.org [this message] 2022-11-23 14:17 ` marxin at gcc dot gnu.org 2022-11-23 15:07 ` aldyh at gcc dot gnu.org 2022-11-23 19:22 ` marxin at gcc dot gnu.org 2022-11-23 20:56 ` [Bug tree-optimization/107833] [12/13 Regression] " rguenth at gcc dot gnu.org 2022-12-01 16:14 ` jakub at gcc dot gnu.org 2022-12-01 16:52 ` jakub at gcc dot gnu.org 2022-12-01 17:32 ` jakub at gcc dot gnu.org 2022-12-01 19:54 ` pinskia at gcc dot gnu.org 2022-12-02 8:19 ` rguenth at gcc dot gnu.org 2022-12-02 10:16 ` jakub at gcc dot gnu.org 2022-12-02 13:24 ` rguenther at suse dot de 2022-12-02 13:55 ` rguenth at gcc dot gnu.org 2022-12-05 9:32 ` cvs-commit at gcc dot gnu.org 2022-12-12 11:20 ` [Bug tree-optimization/107833] [12 " cvs-commit at gcc dot gnu.org 2022-12-12 11:22 ` rguenth at gcc dot gnu.org
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