Re: Locals revisited

In article <2025Mar27.084835@mips.complang.tuwien.ac.at>,
Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:

Paul Rubin <no.email@nospam.invalid> writes:

albert@spenarnc.xs4all.nl writes:

(I get 30 registers in RISCV that can serve as a stack pointer.)

>
All 31 can serve as a stack pointer, but not all at the same time.
You want at least two registers for temporary values, for implementing
a word such as "+".  And you typically want to keep the top-of-stack
of many stacks in a register, too.  Or several stack items.
>

In some models of the RISCV, only 14, I think.

>
There is the E subspecification of the RISC-V specification with 16
registers.  I don't know if anybody has implemented this.
>

And in almost all
models, 8 of them are more efficient to address than the rest, because
of the compressed instruction format.

>
More efficient in code size.  In instruction execution, typically the
same speed.

The orange pi RV2 is a risc with 8 Gbyte at euro 64 with NVMe slots, wifi, sdcard,
gbyte internet, usb, hdmi, mipi etc. and still the 26 pin Raspberry 1 slot.

Worrying about code size is so seventies unless you are into 10 cent
riscv embedded soc's (see noforth).

>
- anton

Groetjes Albert
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