What calling convention does SBFv2 use?

Question

I'm trying to optimize my Solana program to minimize stack accesses.

How do the C/Rust compilers arrange function call arguments on an assembly level?

Specifically, what registers get used for transferring arguments, what registers are preserved, and how does a stack frame on SBFv2 typically look?

uint64_t call (
    uint64_t v1,
    uint64_t v2,
    uint64_t v3,
    uint64_t v4,
    uint64_t v5,
    uint64_t v6,
    ...
);

Answer 1

From what I could find, the GPRs r1, r2, r3, r4 are used for 64-bit arguments. r5 is set to the frame pointer. The other GPRs are preserved. (Except r11, the stack pointer)

The rest is placed on the stack with 8 byte alignment.