Your message dated Fri, 25 Jan 2013 09:31:44 -0800 with message-id <CADf0C44QrD0UWx6LxdQzexjEmndj4m54TAhWAeZXUdM6r=v...@mail.gmail.com> and subject line Isn't a bug to "miscompile" invalid code has caused the Debian Bug report #698950, regarding gcc-4.7: Miscompilation of simple loop depending on integer overflow for termination to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact ow...@bugs.debian.org immediately.) -- 698950: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=698950 Debian Bug Tracking System Contact ow...@bugs.debian.org with problems
--- Begin Message ---Package: gcc-4.7 Version: 4.7.2-5 Severity: normal With the following very simple test program: extern int foo(int); extern void bar(); void test_fn() { int i; for (i = 1; 0 < i; i *= 2) foo(i); bar(); } and compiling with "gcc -S -O2 -Wall bugtest.c -o -" (on amd64) I get output: .file "bugtest.c" .text .p2align 4,,15 .globl test_fn .type test_fn, @function test_fn: .LFB0: .cfi_startproc pushq %rbx .cfi_def_cfa_offset 16 .cfi_offset 3, -16 movl $1, %ebx .p2align 4,,10 .p2align 3 .L2: movl %ebx, %edi addl %ebx, %ebx call foo jmp .L2 .cfi_endproc .LFE0: .size test_fn, .-test_fn .ident "GCC: (Debian 4.7.2-5) 4.7.2" .section .note.GNU-stack,"",@progbits So it misoptimized this into an infinite loop, and then also optimized out the code after the loop. With -O1 it appears to produce a correct loop executing the body 31 times. This bug also happens with 4.7.2-19 from experimental. (I found this issue while tracking down why a "checking for working mktime" autoconf check was timing out.) -- Daniel Schepler
--- End Message ---
--- Begin Message ---Sorry for the noise, it was just pointed out to me that the test program depends on undefined behavior and is a known property of gcc that can be worked around by passing -fwrapv. So packages with the failing mktime test should upgrade their autoconf version to get a proper implementation of AC_FUNC_MKTIME. -- Daniel Schepler
--- End Message ---
