On 9 October 2012 11:58, Jubi Taneja <jubitan...@gmail.com> wrote:
> Hi Matt,
>
> Thanks for sharing the information.
>
> On Tue, Oct 9, 2012 at 3:51 PM, Matthew Gretton-Dann
> <matthew.gretton-d...@linaro.org> wrote:
>>
>> On 9 October 2012 10:37, Jubi Taneja <jubitan...@gmail.com> wrote:
>> > Hi All,
>> >
>> > I wanted to see the difference in objdump of an application where I can
>> > make
>> > the difference between the VFPV3 and VFPV4 support. I tried enabling the
>> > flag -mfpu=vfpv3 and -mfpu=vfpv4 for ARM Cortex A15 toolchain in my test
>> > code but cannot see the difference in two objdumps.
>>
>> Try the following (tested against FSF GCC:
>>
>> /* 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.
Thanks,
Matt
--
Matthew Gretton-Dann
Linaro Toolchain Working Group
matthew.gretton-d...@linaro.org
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