[cc65] Optimization ideas

Here are some ideas for optimizations that could be
implemented relatively easily:

1. Save/restore "register" (zero page) variables with
a JSR to a subroutine, such as:

[...more...]
save3:
    dey
    lda regbank+2
    sta (sp),y
save2:
    dey
    lda regbank+1
    sta (sp),y
save1:
    dey
    lda regbank
    sta (sp),y
    rts
[...more...]
restore3:
    lda (sp),y
    sta regbank+2
    dey
restore2:
    lda (sp),y
    sta regbank+1
    dey
restore1:
    lda (sp),y
    sta regbank
    rts

I wonder if there's any way to trick the linker into
automatically selecting a routine of exactly the right
size?

2. Implement a second "register" area in zero page
that would only be used by leaf functions (i.e.
functions that don't call other functions). These
would not need to be saved/restored.

3. Automatically assign local pointer/char/int
"register" status, and increase the default maximum
(only 6 bytes?)

Comments?

Dan



       
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