Package: gcc-4.2 Version: 4.2.4-6 Severity: important Tags: fixed-upstream gcc 4.2.4-6 generates bad code when -f no-strict-overflow is used.
This causes kernel 2.6.27.27 and 2.6.30.2 to be miscompiled and hang. It may be a cause of suble errors elsewhere in the kernel, too. I don't know if the pattern of code that triggers the problem is common in userspace. gcc 4.3.2-1.1 doesn't exibit the bug, so it is already fixed upstream, but probably not in the 4.2 branch. Refer to http://lkml.org/lkml/2009/7/21/493 for details. Refer to http://lkml.org/lkml/2009/7/22/181 for a minimal test case. --- Test case by Krzysztof Oledzki, from the link above: --- --- fno-strict-overflow-fixed-bug.c --- #include <stdio.h> int main() { unsigned char i; for (i = 0; i < 128; i++) printf("loop %u\n", i); return 0; } --- cut here --- The code should be compiled with: cc -o fno-strict-overflow-fixed-bug -Os -fno-strict-overflow fno-strict-overflow-fixed-bug.c or: cc -o fno-strict-overflow-fixed-bug -O2 -fno-strict-overflow fno-strict-overflow-fixed-bug.c This bug does not exist with -O1 or if the loop is controlled by "i < 127" or "i < 129". --------------------------------------------------------------- -- System Information: Debian Release: 5.0.2 APT prefers stable APT policy: (500, 'stable') Architecture: i386 (i686) Kernel: Linux 2.6.29.6-t43 (PREEMPT) Locale: LANG=pt_BR.ISO-8859-1, LC_CTYPE=pt_BR.ISO-8859-1 (charmap=ISO-8859-1) Shell: /bin/sh linked to /bin/dash Versions of packages gcc-4.2 depends on: ii binutils 2.18.1~cvs20080103-7 The GNU assembler, linker and bina ii cpp-4.2 4.2.4-6 The GNU C preprocessor ii gcc-4.2-base 4.2.4-6 The GNU Compiler Collection (base ii libc6 2.7-18 GNU C Library: Shared libraries ii libgcc1 1:4.3.2-1.1 GCC support library Versions of packages gcc-4.2 recommends: ii libc6-dev 2.7-18 GNU C Library: Development Librari Versions of packages gcc-4.2 suggests: ii gcc-4.2-doc 4.2.4.nf1-3 documentation for the GNU compiler pn gcc-4.2-locales <none> (no description available) pn gcc-4.2-multilib <none> (no description available) pn libgcc1-dbg <none> (no description available) pn libgomp1-dbg <none> (no description available) pn libmudflap0-4.2-dev <none> (no description available) pn libmudflap0-dbg <none> (no description available) -- no debconf information -- To UNSUBSCRIBE, email to debian-gcc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org