Regarding SIMD features of GCC

Tim Prince timothyprince@sbcglobal.net
Sat Oct 7 01:25:00 GMT 2006


ranjith kumar wrote:
> Hi,
>     I have the following queries:
> 
> 1) Apart from general optimizations (enabled by -O3
> flag), what is the total list of optimizations done by
> gcc(GNU C compiler) for Pentium-4 processor?
> ie)processor specific optimizations only
> 
> Can any one tell any source where I can find them?
An answer which comes to mind is to look in gcc/config/i386, in the 
source distribution.
> 
> 2)Where can I find list of functions and data types
> defined to exploit SIMD features of Pentium-4
> processor  by GCC. (I am familiar with SIMD features
> of Pentium-4.)
How about the architecture specific include files, like <xmmintrin.h>?
 From the title, I thought you might be interested in gcc-4.2 vectorization.
> 
> 3) Pentium-4 has special instructions like MOVNTQ,
> MOVNTPS ...to enable data from XMM and MMX registers
> to be stored to memory using a non-temporal hint.
> 
> How to do the same in a  C language?
Not unless a compiler has a feature for substituting those instructions, 
or you take advantage of <xmmintrin.h>.



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