[Bug c++/51323] New: g++ confuses this with function argument in optimized call

[dak at gnu dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51323

             Bug #: 51323
           Summary: g++ confuses this with function argument in optimized
                    call
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dak@gnu.org


Created attachment 25921
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25921
Boiled down source code.  Bad code for last function.

The following boiled down code produces a jmp to Grob::internal_set_property
where the implicit first call argument (this) is equal to the explicit second
call argument instead of the actual this pointer.  The guilty code sequence is

.L4:
    movl    %ebx, 40(%esp)
    movl    %ebx, 32(%esp)
    movl    %eax, 36(%esp)
    addl    $24, %esp
    .cfi_remember_state
    .cfi_def_cfa_offset 8
    popl    %ebx
    .cfi_def_cfa_offset 4
    .cfi_restore 3
    jmp    _ZN4Grob21internal_set_propertyEPvS0_

Version is
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-linux-gnu/4.6.1/lto-wrapper
Target: i686-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.6.1-9ubuntu3' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++,go --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-plugin
--enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=i686-linux-gnu
--host=i686-linux-gnu --target=i686-linux-gnu
Thread model: posix
gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu3) 

Compilation options are -O2

This is from Lilypond source code and causes a segfault.