On 20 October 2012 09:41, Jubi Taneja <jubitan...@gmail.com> wrote:
> Hi Mathew
>
> On Tue, Oct 9, 2012 at 11:37 PM, Matthew Gretton-Dann
> <matthew.gretton-d...@linaro.org> wrote:
>>
>> On 9 October 2012 14:44, Jubi Taneja <jubitan...@gmail.com> wrote:
>> >
>> >
>> > On Tue, Oct 9, 2012 at 5:21 PM, Matthew Gretton-Dann
>> > <matthew.gretton-d...@linaro.org> wrote:
>> >>
>> >> >> /* arm-none-linux-gnueabi-gcc -mcpu=cortex-a15 -mfpu=vfpv4 -S -o-
>> >> >> /tmp/fma.c -mfloat-abi=hard -O2 */
>> >> >> float f(float a, float b, float c)
>> >> >> {
>> >> >> return a * b + c;
>> >> >> }
>> >> >> /* end of tmp.c */
>> >> >>
>> >> >> (Note that -mfloat-abi=softfp will also work in this example. Which
>> >> >> one you want to use depends on whether you have configured your
>> >> >> system
>> >> >> for hard or soft-float ABIs).
>> >> >>
>> >> > I checked both with -mfpu=vfpv3 and -mfpu=vfpv4 and it generates the
>> >> > same
>> >> > assembly code. VMLA insn is emitted for both the cases. I was
>> >> > wondering
>> >> > if I
>> >> > can get any test case so that I may observe the difference in the two
>> >> > objdumps.
>> >>
>> >> Which compiler are you using? VFMA support is only in trunk FSF GCC.
>> >> Linaro has not yet backported support to 4.7.
>> >
>> >
>> > I am using FSF GCC only.
>>
>> What version of GCC (what does arm-none-linux-gneabi-gcc -v report?).
>
> # arm-none-linux-gneabi-gcc -v
> Using built-in specs.
> COLLECT_GCC=arm-none-linux-gneabi-gcc
> COLLECT_LTO_WRAPPER=/opt/toolchains/arm/bin/../libexec/gcc/arm-none-linux-gneabi/4.6.3/lto-wrapper
> Target: arm-none-linux-gneabi
> Configured with: /home/user/arm-src/build/sources/gcc_1/configure
> --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu
> --target=arm-none-linux-gneabi --prefix=/opt/arm
> --with-sysroot=/opt/arm/arm-none-linux-gneabi/sys-root --disable-libmudflap
> --disable-libssp --disable-libgomp --disable-nls --disable-libstdcxx-pch
> --with-interwork --with-mode=arm --with-fpu=vfp3 --with-cpu=cortex-a9
> --with-tune=cortex-a9 --with-float=softfp --enable-extra-vd-multilibs
> --enable-poison-system-directories --enable-long-long --enable-threads
> --enable-languages=c,c++ --enable-shared --enable-lto --enable-symvers=gnu
> --enable-__cxa_atexit --with-pkgversion=arm-toolchain.v1 --with-gnu-as
> --with-gnu-ld --with-host-libstdcxx='-static-libgcc
> -Wl,-Bstatic,-lstdc++,-Bdynamic -lm' --with-build-time-tools=/opt/arm/bin
> --with-gmp=/opt/arm --with-mpfr=/opt/arm --with-ppl=/opt/arm
> --with-cloog=/opt/arm --with-libelf=/opt/arm
> Thread model: posix
> gcc version 4.6.3 (arm-toolchain.v1)
This is gcc 4.6.3 not current trunk (which would report gcc version 4.8.0).
GCC 4.6.3 does not support VFMA.
Thanks,
Matt
--
Matthew Gretton-Dann
Linaro Toolchain Working Group
matthew.gretton-d...@linaro.org
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