Assembly output of the original example for https://github.com/rust-lang/rust/pull/37921

bluss.s

	.text
	.file	"bluss.cgu-0.rs"
	.section	.text._ZN5bluss16round_trip_slice17h8927e0fb49da9351E,"ax",@progbits
	.globl	_ZN5bluss16round_trip_slice17h8927e0fb49da9351E
	.p2align	4, 0x90
	.type	_ZN5bluss16round_trip_slice17h8927e0fb49da9351E,@function
_ZN5bluss16round_trip_slice17h8927e0fb49da9351E:
	.cfi_startproc
	movq	%rdi, %rax
	movq	%rsi, %rdx
	retq
.Lfunc_end0:
	.size	_ZN5bluss16round_trip_slice17h8927e0fb49da9351E, .Lfunc_end0-_ZN5bluss16round_trip_slice17h8927e0fb49da9351E
	.cfi_endproc

	.section	.text._ZN5bluss10iter_split17h00653b7bf82da642E,"ax",@progbits
	.globl	_ZN5bluss10iter_split17h00653b7bf82da642E
	.p2align	4, 0x90
	.type	_ZN5bluss10iter_split17h00653b7bf82da642E,@function
_ZN5bluss10iter_split17h00653b7bf82da642E:
	.cfi_startproc
	movq	(%rsi), %rax
	movq	8(%rsi), %rcx
	subq	%rax, %rcx
	movq	%rcx, %rdx
	andq	$-4, %rdx
	shrq	$3, %rcx
	leaq	(%rax,%rcx,4), %rcx
	addq	%rax, %rdx
	movq	%rax, (%rdi)
	movq	%rcx, 8(%rdi)
	movq	%rcx, 16(%rdi)
	movq	%rdx, 24(%rdi)
	movq	%rdi, %rax
	retq
.Lfunc_end1:
	.size	_ZN5bluss10iter_split17h00653b7bf82da642E, .Lfunc_end1-_ZN5bluss10iter_split17h00653b7bf82da642E
	.cfi_endproc

	.section	.text._ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E,"ax",@progbits
	.globl	_ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E
	.p2align	4, 0x90
	.type	_ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E,@function
_ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E:
	.cfi_startproc
	movq	(%rsi), %rax
	movq	8(%rsi), %rcx
	movq	%rcx, %rdx
	subq	%rax, %rdx
	shrq	$3, %rdx
	leaq	(%rax,%rdx,4), %rdx
	movq	%rax, (%rdi)
	movq	%rdx, 8(%rdi)
	movq	%rdx, 16(%rdi)
	movq	%rcx, 24(%rdi)
	movq	%rdi, %rax
	retq
.Lfunc_end2:
	.size	_ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E, .Lfunc_end2-_ZN5bluss14iter_split_raw17h5e5f7f1294ac0f52E
	.cfi_endproc


	.section	".note.GNU-stack","",@progbits