Thursday, April 15, 2010

So, I'm looking at arguments passed on the stack, so here's some random notes.

My test function:
void a()

resulting assembly:
ai r10, -6
mov r11, @4(r10)

li r1, 97 --.
mov r1, *r10 | Push arguments to the stack
li r1, 98 |
mov r1, @2(r10) --'

li r1, 91
li r2, 92
li r3, 93
li r4, 94
li r5, 95
li r6, 96
bl @zprintf
ai r10, 4
mov *r10+, r11

So the stack looks like this in zprintf:
[ volatiles saved by A
[ A's frame
[ zprintf stack arguments
[ volatiles saved by zprintf
[ zprintf's frame
stack pointer

on the callee side, stack arguments are indexed as if from address zero.
need to fix sizes so ELIMINABLE_REGS works for arg-to-stack calculations

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