[tremor] [PATCH] significantly reduce Tremor ROM size requirement

[Segher Boessenkool]

> > In what case did you observe a negative impact?
> 
> During original work with arm-elf-gcc when working on code prior to
> Tremor.  Going to byte arrays there was a significant performance on
> the Netwinder.  However, it was not my compiler install and I did not
> inspect the asm; I merely noted the hit and moved on.
> 
> Regardless, the above is indeed evidence that the char arrays are more
> efficient, at very least for ARM (which is currently the platform we
> care about most).  I'll apply that patch, and make a note to check
> performance on word-aligned-access platforms.

Reasons char pointers can be slower on ARM:

1) as Nicolas notes, -fsigned-char screws up ARM code real bad, and is
   only needed on bad/lazy/ancient code, anyway.
2) objects indexed by char pointers alias all other objects.

The solution to 1) is to say  signed char  and  unsigned char  instead
of plain  char  when you care about a char's numerical value; the
solution to 2) is to use  restrict  and/or  register .

<p>Cheers,

Segher

<p>--- >8 ----
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