Bug#569902: gcc-4.3: gcc/g++ generates incorrect code with -O2

[Philip Ashmore <contact@philipashmore.com>]

Package: gcc-4.3
Version: 4.3.2-1.1
Severity: important

Steps to reproduce:
===================
Download v3c-1.3.8 from http://sourceforge.net/projects/v3c/ and 
unpack/build/install it.
Download treedb-0.0.1 from http://sourceforge.net/projects/treedb/ and 
unpack it.
 cd treedb
 make release check

7 of the 8 tests pass.
c_offset_fixed_string_tree segfaults
cpp_offset_fixed_string_tree produces inconsistent results.

All the tests pass when you run "make debug check".

This is easier to see with kdbg.

First you need a release build with debugging symbols.
 CFLAGS='-g -ggdb -O2' CXXFLAGS='-g -ggdb -O2' make release check
The build system does a distclean when the build flags change.

run "./setup_kdbg" to create symlinks in v3c/1-andromeda/tests.
 kdbg v3c/1-andromeda/c_offset_fixed_string_tree
Stepping through the code compared to a debug build, it's obvious that
the compiler optimised out some code that it really shouldn't have!

-- System Information:
Debian Release: 5.0.4
 APT prefers stable
 APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.26-2-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages gcc-4.3 depends on:
ii  binutils            2.18.1~cvs20080103-7 The GNU assembler, linker 
and bina
ii  cpp-4.3             4.3.2-1.1            The GNU C preprocessor
ii  gcc-4.3-base        4.3.2-1.1            The GNU Compiler Collection 
(base
ii  libc6               2.7-18lenny2         GNU C Library: Shared libraries
ii  libgcc1             1:4.3.2-1.1          GCC support library
ii  libgomp1            4.3.2-1.1            GCC OpenMP (GOMP) support 
library

Versions of packages gcc-4.3 recommends:
ii  libc6-dev                   2.7-18lenny2 GNU C Library: Development 
Librari

Versions of packages gcc-4.3 suggests:
ii  gcc-4.3-doc                  4.3.2.nf1-1 documentation for the GNU 
compiler
pn  gcc-4.3-locales              <none>      (no description available)
ii  gcc-4.3-multilib             4.3.2-1.1   The GNU C compiler 
(multilib files
pn  libgcc1-dbg                  <none>      (no description available)
pn  libgomp1-dbg                 <none>      (no description available)
pn  libmudflap0-4.3-dev          <none>      (no description available)
pn  libmudflap0-dbg              <none>      (no description available)

-- no debconf information