The calling sequence and stack frame for 32-bit OS X/AIX

When control is passed to the called routine, the stack pointer points to the callee's frame, which looks like:

	fp reg save area (optional)
	ireg save area (optional)
	padding (optional)
	Local storage (optional)
24(r1)	Parameter area ($>= 8$ words)
20(r1)	TOC save area
16(r1)	Link editor doubleword
12(r1)	Compiler doubleword
8(r1)	Link register (LR) save
4(r1)	Condition register (CR) save
0(r1)	ptr to callee's stack

• Stack pointer must be quadword aligned
• Start of fp & ireg save areas always double word aligned
• Before calling another func, must save the LR in LR save area
• Have 224-byte (OSX) / 220-byte (AIX) red zone below stack ptr so leaf func frame