Re: M0 and M3 patches in linaro toolchains

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 7 October 2013 11:30, Matthew Gretton-Dann
<matthew.gretton-dann@linaro.org> wrote:
> On 7 October 2013 05:20, Keith Packard <keithp@keithp.com> wrote:

[...]

>>  2) The thumb version of libgcc.a is not built with thumb instructions
>>     because GCC doesn't pass -mthumb to the assembler when it receives
>>     -mthumb on the command line.
>
> I would be expecting the compiler to pass .thumb in the assembler source to as.
>

My experience with arm/thumb assembler are similar. With my Ubuntu
stock 4.8 configured as

Using built-in specs.
COLLECT_GCC=arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/arm-linux-gnueabihf/4.8/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.8.1-7ubuntu1'
--with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix
--with-gxx-include-dir=/usr/arm-linux-gnueabihf/include/c++/4.8.1
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-gnu-unique-object --disable-libitm --disable-libquadmath
--enable-plugin --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-armhf-cross/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-armhf-cross
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-armhf-cross
--with-arch-directory=arm
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libgcj
--enable-objc-gc --enable-multiarch --enable-multilib
--disable-sjlj-exceptions --with-arch=armv7-a --with-fpu=vfpv3-d16
--with-float=hard --with-mode=thumb --disable-werror
--enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=arm-linux-gnueabihf
--program-prefix=arm-linux-gnueabihf-
--includedir=/usr/arm-linux-gnueabihf/include
Thread model: posix
gcc version 4.8.1 (Ubuntu/Linaro 4.8.1-7ubuntu1)

I get the following unexpected results:

$ arm-linux-gnueabihf-gcc -mthumb -c -o /dev/null -xassembler - <<<"adrl r0,."
$ arm-linux-gnueabihf-gcc -mthumb -c -o /dev/null -xassembler -
<<<".thumb; adrl r0,."
{standard input}: Assembler messages:
{standard input}:1: Error: selected processor does not support Thumb
mode `adrl r0,.'

i.e., the former passes while I would expect the assembler to be
kicked into thumb mode by the compiler.

-- 
Ard.