[Pixman] [ssse3]Optimization for fetch_scanline_x8r8g8b8

Soeren Sandmann sandmann at daimi.au.dk
Wed Sep 8 19:16:28 PDT 2010

"Xu, Samuel" <samuel.xu at intel.com> writes:

> Hi, Soeren Sandmann and Siarhei Siamashka:
> As a wrap of current discussion, combining you two's comments, can we assume this new patch of SSSE3 is ok?
> New patch might contains:
> 1. Fix 64 bit CPU detection issue for MMX and SSE2
> 2. Add more comments for git commit log
> 3. change SSSE3 intrinsics check to SSSE3 asm check in makefile
> 4. remove #include "pixman-combine32.h" and composite_over_8888_n_8888in pixman-ssse3.c
> 5. ASM files changes:
> 	1) change asm file name to pixman-ssse3-x86-32-asm.S and pixman-ssse3-x86-64-asm.S
> 	2) change the asm function name to "composite_line_src_x888_8888_ssse3"
> 	3) remove "defined(_M_AMD64))"
> 	4) Comments in the assembly about the store forwarding

Such changes will certainly improve the patch.

> We know there are some discussion on asm code, e.g. MOVD, unify 32
> bit and 64 bit code. While it won't introduce real defection. We
> still can put further change in next wave, to avoid current
> sticking.

No, we are not going to apply any patches that we know will need to be
fixed later, because I don't believe anyone is going to do that work.

It's fine to send a patch series if you think it's easier that way.

I am also interested in the answer to the question of whether this
code was generated by passing intrinsics through the Intel compiler.

> I am not sure for the issue of sun studio. Sun studio declares GNU
> asm compatibility, I am not sure whether it is 100% compatible. If
> issue is caused by Sun Studio itself, can we add #ifdef to avoid
> SSSE3 patch of Sun studio? In this case, how to determine Sun
> studio?

There are various approaches you can take with respect to unusual
compilers such as Sun Studio. The most common approach is to only
enable the new optimizations for the compilers that you are personally
interested in, and leave other compilers to people who are interested.

However, *you* introduced all this Sun Studio handling for SSSE3,
which means *you* need to be able to explain what it does, and justify
why it is there. 

Or to put it even more bluntly: Do not cut and paste code you don't
understand and can't test, and then ask me to rewrite the code for you
until it is good enough to go in.


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