I setup an IRC channel on the Freenode network, for those that use IRC it should be easier to get support.
Getting closer on the method call:
.0: afa4fffc sw a0,-4(sp) .4: afa5fff8 sw a1,-8(sp) .8: afa6fff4 sw a2,-12(sp) .c: afbdffec sw sp,-20(sp) 10: 27bdffec addiu sp,sp,-20 14: 8f810034 lw at,52(gp)
Since method calls are more often perform, it would be most efficient to have the stack pointer restoration on the callee since there are usually less return points.
Actually that is for the frame pointer.
But that is not truly needed.
Actually, I write above the stack and not below it. Although it really does not matter unless I correctly restore it.
So do I preforward the stack and potentially waste it, or use the frame pointer? The frame pointer should simplify things. But it still is not needed at all.
Well for PowerPC, the stack is increased to its needed size and the old size is stored just before the end.
So I suppose use it, since it would simplify things a bit.
The simplest but most wasteful route would be to preallocate all of the slots that are used and make it only use a stack register. However the preallocation would waste much space on 64-bit systems because object can be 64-bits. This would mean that long/double would cost 16 bytes to store a single value. So that would definitely be wasteful. I just need the calls to be natively compatible.
So essentially the stack pointer is accessed using the base and is incremented as needed.
So at the start of a method:
- Store the frame pointer.
- Copy the frame pointer value to the stack value.
Before a return:
- Restore the old stack pointer.
Before a method call:
- Store the frame pointer
After a method call:
- Restore the frame pointer
So actually this will be quite complex to determine and to support multiple
targets using the same logic. So I will essentially need a
class along with a builder that can be set in the ABI. This class would
contain the information needed for method calls, where arguments are placed
and if frame pointers and such are used.
So yes, I will need a class which knows how to handle how stack frames are to be done for a given ABI. Then with this, I should be able to call native libraries without requiring that I setup a specific state before a call.
So I will definitely need a class to show the layout, since some architectures may require reserved space and such (such as PowerPC).