[avr-gcc-list] RE: [patch,avr-gcc] optimizing mov SI/SF

[Weddington, Eric]

Hi Georg-Johann,

What is the status of your FSF Copyright Assignment? For us to eventually 
incorporate your work, we would need to be able to commit it to GCC, which 
requires the copyright assignment.

Thanks,
Eric Weddington 

> -----Original Message-----
> From: Georg-Johann Lay [mailto:address@hidden 
> Sent: Tuesday, March 24, 2009 3:02 PM
> To: Weddington, Eric; Anatoly Sokolov; address@hidden
> Subject: [patch,avr-gcc] optimizing mov SI/SF
> 
> Hi,
> 
> this patch is a minor optimization when moving a compile time const 
> SI/SF to a reg that is not in LD_REGS. The patch tracks the 
> value in the 
> scratch register and saves some moves here and there.
> 
> A small test program is attached to see the effect. Compile, e.g. with
>    -Os -dp -S
>    -Os -dp -S -fno-split-wide-types
> and look out for the movsf/reload_insi patterns.
> 
> The drawback is that the constant's value is obfuscated in 
> the asm output.
> 
> Same could be done for cmpsi. Things with cmpsi would be 
> easier with the 
> adjust_insn_len skeleton, so that work can wait until sometimes.
> 
> For SI there some masks like 0xffff0000 and 0x0000ffff in 
> libgcc where 
> the patch will take effekt.
> 
> Greets,
> 
> Georg-Johann
> 
>