GCC 4.6.x miscompiling arm-linux?

[David Jander]

On Tue, 11 Sep 2012 13:35:40 +0200
Mikael Pettersson <mikpe at it.uu.se> wrote:

> David Jander writes:
>  > > I can make the patches available if there's confirmation that a vanilla
>  > > upstream gcc-4.6.3 doesn't work.
>  > 
>  > I am pretty sure this is the case... do you have a patch series that you can
>  > easily tar and mail to me? I'd like to try those patches with OSELAS, to see
>  > if I can indeed build a gcc-4.6.3 toolchain that generates correct code.... I
>  > already know that I can generate one that doesn't ;-)
>  > 
> ...
>  > > If you're sure no add-on patches were applied, then yes please do.
>  > 
>  > Pretty sure, but not 100%, so I'd like to try your patches first if you don't
>  > mind....
> 
> And I'd like to confirm first. Please tell us the following:
> 
>  > >  > > 2: include the output of gcc -v which tells how that gcc was configured,

Using built-in specs.
COLLECT_GCC=/opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/bin/arm-v5te-linux-gnueabi-gcc-4.6.3
COLLECT_LTO_WRAPPER=/opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/libexec/gcc/arm-v5te-linux-gnueabi/4.6.3/lto-wrapper
Target: arm-v5te-linux-gnueabi
Configured with: /home/djander/ptxdist/OSELAS.Toolchain-2011.11.1/platform-arm-v5te-linux-gnueabi-gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/build-cross/gcc-4.6.3/configure --target=arm-v5te-linux-gnueabi --with-sysroot=/opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3
-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/sysroot-arm-v5te-linux-gnueabi --disable-multilib --with-float=soft --with-fpu=vfp --with-cpu=arm926ej-s --enable-__cxa_atexit --disable-sjlj-exceptions --disable-nls --disable-decimal-float --disable-fixed-point --disable-win32-registry --enable-symvers=gnu --with-pkgversion=OSELAS.Toolchain-2011.11.1 --with-system-zlib --with-gmp=/home/djander/ptxdist/OSELAS.Toolchain-2011.11.1/platform-arm-v5te
-linux-gnueabi-gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/sysroot-host --with-mpfr=/home/djander/ptxdist/OSELAS.Toolchain-2011.11.1/platform-arm-v5te-linux-gnueabi-gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/sysroot-host --prefix=/opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized --enable-languages=c,c++ --enable-threads=posix --enable-c99 --enable-long-long --enable-libstdcxx-debug --enable-profile --enable-shared --disable-libssp --enable-checking=release
Thread model: posix
gcc version 4.6.3 (OSELAS.Toolchain-2011.11.1)

>  > >  > > 3: give the exact set of gcc options used then compiling the test case.

If I type this in a terminal:


$ /opt/OSELAS.Toolchain-2011.11.1/arm-v5te-linux-gnueabi/gcc-4.6.3-glibc-2.14.1-binutils-2.21.1a-kernel-2.6.39-sanitized/bin/arm-v5te-linux-gnueabi-gcc-4.6.3 -Os -S -o - -x c -

struct flexcan_regs {
        unsigned int mcr;
        unsigned int rxfgmask;
};

#define flexcan_read(a) (*(volatile unsigned int *)(a))
#define flexcan_write(v,a)      (*(volatile unsigned int *)(a) = (v))

int flexcan_chip_start(int ver, struct flexcan_regs *regs)
{
        flexcan_write(0, &regs->mcr);

        if (ver >= 10)
                flexcan_write(0, &regs->rxfgmask);

        return 0;
}


I get this output after hitting <CTRL-D>:

        .cpu arm926ej-s
        .fpu softvfp
        .eabi_attribute 20, 1
        .eabi_attribute 21, 1
        .eabi_attribute 23, 3
        .eabi_attribute 24, 1
        .eabi_attribute 25, 1
        .eabi_attribute 26, 2
        .eabi_attribute 30, 4
        .eabi_attribute 18, 4
        .file   ""
        .text
        .align  2
        .global flexcan_chip_start
        .type   flexcan_chip_start, %function
flexcan_chip_start:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        mov     r3, #0
        cmp     r0, #9
        str     r3, [r1, #0]
        ldrle   r3, [r1, #4]
        mov     r0, #0
        str     r3, [r1, #4]
        bx      lr
        .size   flexcan_chip_start, .-flexcan_chip_start
        .ident  "GCC: (OSELAS.Toolchain-2011.11.1) 4.6.3"
        .section        .note.GNU-stack,"",%progbits


Do you need more information?

Best regards,

-- 
David Jander
Protonic Holland.