[fpc-devel] AArch64 Register efficiency

[J. Gareth Moreton]

Oh dear, that's a shame.  Havoc sounds fun though!  Part of me wants to try anyway because I'm masochistic like that, but I'll do that privately.

As an example, here's something from the classes unit - see how many references there are to [sp, #16].  It might not be exactly the same as what you get as I'm working on improving some peephole optimisations, 
especially the large numbers of "ldr x0,[sp. #16]" instructions:

.section .text.n_classes$_$tbits_$__$$_create$longint$$tbits,"ax"
	.balign 8
.globl	CLASSES$_$TBITS_$__$$_CREATE$LONGINT$$TBITS
	.type	CLASSES$_$TBITS_$__$$_CREATE$LONGINT$$TBITS, at function
CLASSES$_$TBITS_$__$$_CREATE$LONGINT$$TBITS:
	stp	x29,x30,[sp, #-16]!
	mov	x29,sp
	sub	sp,sp,#432
	str	x0,[sp, #16]
	str	x1,[sp, #8]
	str	w2,[sp]
	ldr	x0,[sp, #8]
	cmp	x0,#1
	b.ne	.Lj90
	ldr	x0,[sp, #16]
	ldr	x1,[sp, #16]
	ldr	x1,[x1, #104]
	blr	x1
	str	x0,[sp, #16]
.Lj90:
	ldr	x0,[sp, #16]
	cbz	x0,.Lj87
.Lj92:
	add	x2,sp,#32
	add	x1,sp,#56
	movz	w0,#1
	bl	fpc_pushexceptaddr
	bl	fpc_setjmp
	ubfiz	x0,x0,#0,#32
	sxtw	x1,w0
	str	x1,[sp, #224]
	cbnz	w0,.Lj97
	movn	x0,#0
	str	x0,[sp, #24]
	ldr	x0,[sp, #16]
	str	wzr,[x0, #16]
	ldr	x0,[sp, #16]
	str	wzr,[x0, #20]
	ldr	x0,[sp, #16]
	str	xzr,[x0, #8]
	ldr	x0,[sp, #16]
	movn	w1,#0
	str	w1,[x0, #24]
	ldr	x0,[sp, #16]
	movz	w1,#1
	strb	w1,[x0, #28]
	ldr	w0,[sp]
	cmp	w0,#0
	b.le	.Lj100
	ldr	w1,[sp]
	ldr	x0,[sp, #16]
	bl	CLASSES$_$TBITS_$__$$_GROW$LONGINT
.Lj100:
	movz	x0,#1
	str	x0,[sp, #24]
	ldr	x0,[sp, #16]
	cmp	x0,#0
	cset	w0,ne
	ldr	x1,[sp, #8]
	cmp	x1,#0
	cset	w1,ne
	and	w0,w1,w0
	cbz	w0,.Lj102
	ldr	x0,[sp, #16]
	ldr	x1,[sp, #16]
	ldr	x1,[x1]
	ldr	x1,[x1, #136]
	blr	x1
.Lj102:
.Lj97:
	bl	fpc_popaddrstack
	ldr	x0,[sp, #224]
	cbz	x0,.Lj95
	add	x2,sp,#232
	add	x1,sp,#256
	movz	w0,#1
	bl	fpc_pushexceptaddr
	bl	fpc_setjmp
	ubfiz	x0,x0,#0,#32
	sxtw	x1,w0
	str	x1,[sp, #424]
	cbnz	w0,.Lj103
	ldr	x0,[sp, #8]
	cbz	x0,.Lj105
	ldr	x1,[sp, #24]
	ldr	x0,[sp, #16]
	ldr	x2,[sp, #16]
	ldr	x2,[x2]
	ldr	x2,[x2, #96]
	blr	x2
.Lj105:
	bl	fpc_popaddrstack
	bl	fpc_reraise
.Lj103:
	bl	fpc_popaddrstack
	ldr	x0,[sp, #424]
	cbz	x0,.Lj106
	bl	fpc_raise_nested
.Lj106:
	bl	fpc_doneexception
.Lj95:
.Lj87:
	ldr	x0,[sp, #16]
	mov	sp,x29
	ldp	x29,x30,[sp], #16
	ret
.Le9:
	.size	CLASSES$_$TBITS_$__$$_CREATE$LONGINT$$TBITS, .Le9 - CLASSES$_$TBITS_$__$$_CREATE$LONGINT$$TBITS