On Tue, Oct 9, 2012 at 5:21 PM, Matthew Gretton-Dann < matthew.gretton-dann@linaro.org> wrote:
On 9 October 2012 11:58, Jubi Taneja jubitaneja@gmail.com wrote:
Hi Matt,
Thanks for sharing the information.
On Tue, Oct 9, 2012 at 3:51 PM, Matthew Gretton-Dann matthew.gretton-dann@linaro.org wrote:
On 9 October 2012 10:37, Jubi Taneja jubitaneja@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.
I am using FSF GCC only.
Thanks,
Matt
-- Matthew Gretton-Dann Linaro Toolchain Working Group matthew.gretton-dann@linaro.org