public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug c/113702] New: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 @ 2024-02-01 9:35 jiajing_zheng at 163 dot com 2024-02-01 9:43 ` [Bug c/113702] " jiajing_zheng at 163 dot com ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: jiajing_zheng at 163 dot com @ 2024-02-01 9:35 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113702 Bug ID: 113702 Summary: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 Product: gcc Version: 12.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: jiajing_zheng at 163 dot com Target Milestone: --- Created attachment 57278 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57278&action=edit source C file causing the problem I'm sorry, but I'm not sure which component causes this problem. The sub expression '(int)(g_B * g_A[1])' in source.c has a signed overflow problem. I checked the file using 'gcc source.c -fsanitize=undefined <optimization level> && ./a.out' at the -O0,-O1,-O2,-O3,-Os optimization levels under GCC12.2.0 and GCC13.2.0. The results showed that 'signed integer overflow' was given under GCC13.2.0, but missed under GCC12.2.0. I then compared the assembly parts of '(int)(g_B * g_A[1])' of the two GCC versions at the -O0 level using 'gcc source.c -fsanitize=undefined -O0 -S'. Under GCC13.2.0: .L13: movzbl g_A(%rip), %r12d movzbl g_A+1(%rip), %eax movzbl %al, %eax movl g_B(%rip), %edx movl %eax, %ebx imull %edx, %ebx jno .L3 movslq %edx, %rdx cltq movq %rax, %rsi movl $.Lubsan_data3, %edi call __ubsan_handle_mul_overflow Under GCC12.2.0: .L11: movzbl g_A(%rip), %edx movzbl g_A+1(%rip), %eax movl g_B(%rip), %ecx imull %ecx, %eax Under GCC12.2.0, it shows that it lacks overflow judgment after 'imul' operation. So I modified the last line 'imull %ecx, %eax ' to the follwing lines that I expected: movl %eax, %ebx imull %ecx, %eax jno .L20 movslq %ecx, %rdx cltq movq %rbx, %rsi movl $.Lubsan_data3, %edi call __ubsan_handle_mul_overflow .L20: Then I run 'gcc source.s -fsanitize=undefined -O0 && ./a.out', and it gave the expected 'signed integer overflow' message. I wonder why GCC12.2.0 not perform overflow judgment after imull., and what components of 13.2.0 were modified for this issue. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/113702] -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 2024-02-01 9:35 [Bug c/113702] New: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 jiajing_zheng at 163 dot com @ 2024-02-01 9:43 ` jiajing_zheng at 163 dot com 2024-02-01 10:01 ` xry111 at gcc dot gnu.org 2024-02-01 10:02 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: jiajing_zheng at 163 dot com @ 2024-02-01 9:43 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113702 --- Comment #1 from Jiajing_Zheng <jiajing_zheng at 163 dot com> --- jing@jing-ubuntu:~$ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/home/jing/gcc-12.2.0/usr/local/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.2.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../configure -enable-checking=release -enable-languages=c,c++ -disable-multilib Thread model: posix Supported LTO compression algorithms: zlib gcc version 12.2.0 (GCC) jing@jing-ubuntu:~$ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/home/jing/gcc-13.2.0-install/libexec/gcc/x86_64-pc-linux-gnu/13.2.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../configure --prefix=/home/jing/gcc-13.2.0-install --enable-threads=posix -enable-checking=release -enable-languages=c,c++ -disable-multilib Thread model: posix Supported LTO compression algorithms: zlib gcc version 13.2.0 (GCC) ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/113702] -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 2024-02-01 9:35 [Bug c/113702] New: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 jiajing_zheng at 163 dot com 2024-02-01 9:43 ` [Bug c/113702] " jiajing_zheng at 163 dot com @ 2024-02-01 10:01 ` xry111 at gcc dot gnu.org 2024-02-01 10:02 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: xry111 at gcc dot gnu.org @ 2024-02-01 10:01 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113702 Xi Ruoyao <xry111 at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |xry111 at gcc dot gnu.org --- Comment #2 from Xi Ruoyao <xry111 at gcc dot gnu.org> --- With GCC 12 the expression is "optimized" early (already in original tree) into: g_A[0] = g_A[0] + (unsigned char) ((signed char) ((unsigned char) g_A[1] * (unsigned char) g_B) & (signed char) (g_A[1] & g_A[0]) | (signed char) g_A[0]) and the optimization is arguably wrong (or at lease undesired) with sanitizer. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/113702] -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 2024-02-01 9:35 [Bug c/113702] New: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 jiajing_zheng at 163 dot com 2024-02-01 9:43 ` [Bug c/113702] " jiajing_zheng at 163 dot com 2024-02-01 10:01 ` xry111 at gcc dot gnu.org @ 2024-02-01 10:02 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-02-01 10:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113702 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |DUPLICATE --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Dup of bug 108256. Yes a newer version of GCC fixed this. *** This bug has been marked as a duplicate of bug 108256 *** ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-02-01 10:02 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-02-01 9:35 [Bug c/113702] New: -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 jiajing_zheng at 163 dot com 2024-02-01 9:43 ` [Bug c/113702] " jiajing_zheng at 163 dot com 2024-02-01 10:01 ` xry111 at gcc dot gnu.org 2024-02-01 10:02 ` pinskia at gcc dot gnu.org
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).