How to use VFP instructions on ARM
Tom Cooksey
thomas.cooksey@trolltech.com
Tue Jan 8 07:09:00 GMT 2008
Hi,
Please forgive this post but I've tried the archives & google and am unable to
find much info on gcc & ARM's VFP instruction set. I have a few questions:
1) How is the VFP coprocessor utilised by GCC when compiling
with -mfpu=vfp -mfloat-abi=softfp? Will GCC emit vfp instructions for doing
regular (scalor) floating point operations? I.e. will "float a =3.14; a *=
20.0;" be done by the coprocessor?
2) How should I use the VFP instructions in my own code? I beleive there are
GCC macros for using SSE instructions, is there anything similar for ARM VFP?
(A quick traul through my GCC sources say no, but I may have missed
something.) If not, can I use inline assembly instead and are the mnemonics
and syntax the same as described in the ARM Architecture Reference Manual?
3) Does the GCC -ftree-vectorize work with VFP?
4) Is there a better place to look for this information? :-)
Cheers,
Tom
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