asmIff.c:

#include <stdio.h>

int test(int a) {
    if ( a == 1 ) {
        return 1;
    } else if ( a > 1 ) {
        return 2;
    } else {
        return 0;
    }
}

int main(int argc, char **argv) {

    int i, j, t;
    i = argc;

    t = test(i);

    printf("%d\n", t);
}

asmSwi.c:

#include <stdio.h>

int test(int a) {
    switch (a) {
        case 1:
            return 0;
        case 2:
            return 1;
        default:
            return 2;
    }
}

int main(int argc, char **argv) {

    int i, t;
    i = argc;

    t = test(i);

    printf("%d\n", t);
}

asmIff.s:

	.section	__TEXT,__text,regular,pure_instructions
	.macosx_version_min 10, 12
	.globl	_test
	.p2align	4, 0x90
_test:                                  ## @test
	.cfi_startproc
## BB#0:
	pushq	%rbp
Lcfi0:
	.cfi_def_cfa_offset 16
Lcfi1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Lcfi2:
	.cfi_def_cfa_register %rbp
	movl	%edi, -8(%rbp)
	cmpl	$1, -8(%rbp)
	jne	LBB0_2
## BB#1:
	movl	$0, -4(%rbp)
	jmp	LBB0_5
LBB0_2:
	cmpl	$2, -8(%rbp)
	jne	LBB0_4
## BB#3:
	movl	$1, -4(%rbp)
	jmp	LBB0_5
LBB0_4:
	movl	$2, -4(%rbp)
LBB0_5:
	movl	-4(%rbp), %eax
	popq	%rbp
	retq
	.cfi_endproc

	.globl	_main
	.p2align	4, 0x90
_main:                                  ## @main
	.cfi_startproc
## BB#0:
	pushq	%rbp
Lcfi3:
	.cfi_def_cfa_offset 16
Lcfi4:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Lcfi5:
	.cfi_def_cfa_register %rbp
	subq	$32, %rsp
	movl	%edi, -4(%rbp)
	movq	%rsi, -16(%rbp)
	movl	-4(%rbp), %edi
	movl	%edi, -20(%rbp)
	movl	-20(%rbp), %edi
	callq	_test
	leaq	L_.str(%rip), %rdi
	movl	%eax, -28(%rbp)
	movl	-28(%rbp), %esi
	movb	$0, %al
	callq	_printf
	xorl	%esi, %esi
	movl	%eax, -32(%rbp)         ## 4-byte Spill
	movl	%esi, %eax
	addq	$32, %rsp
	popq	%rbp
	retq
	.cfi_endproc

	.section	__TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
	.asciz	"%d\n"


.subsections_via_symbols

asmSwi.s:

	.section	__TEXT,__text,regular,pure_instructions
	.macosx_version_min 10, 12
	.globl	_test
	.p2align	4, 0x90
_test:                                  ## @test
	.cfi_startproc
## BB#0:
	pushq	%rbp
Lcfi0:
	.cfi_def_cfa_offset 16
Lcfi1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Lcfi2:
	.cfi_def_cfa_register %rbp
	movl	%edi, -8(%rbp)
	movl	-8(%rbp), %edi
	movl	%edi, %eax
	subl	$1, %eax
	movl	%edi, -12(%rbp)         ## 4-byte Spill
	movl	%eax, -16(%rbp)         ## 4-byte Spill
	je	LBB0_1
	jmp	LBB0_5
LBB0_5:
	movl	-12(%rbp), %eax         ## 4-byte Reload
	subl	$2, %eax
	movl	%eax, -20(%rbp)         ## 4-byte Spill
	je	LBB0_2
	jmp	LBB0_3
LBB0_1:
	movl	$0, -4(%rbp)
	jmp	LBB0_4
LBB0_2:
	movl	$1, -4(%rbp)
	jmp	LBB0_4
LBB0_3:
	movl	$2, -4(%rbp)
LBB0_4:
	movl	-4(%rbp), %eax
	popq	%rbp
	retq
	.cfi_endproc

	.globl	_main
	.p2align	4, 0x90
_main:                                  ## @main
	.cfi_startproc
## BB#0:
	pushq	%rbp
Lcfi3:
	.cfi_def_cfa_offset 16
Lcfi4:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Lcfi5:
	.cfi_def_cfa_register %rbp
	subq	$32, %rsp
	movl	%edi, -4(%rbp)
	movq	%rsi, -16(%rbp)
	movl	-4(%rbp), %edi
	movl	%edi, -20(%rbp)
	movl	-20(%rbp), %edi
	callq	_test
	leaq	L_.str(%rip), %rdi
	movl	%eax, -24(%rbp)
	movl	-24(%rbp), %esi
	movb	$0, %al
	callq	_printf
	xorl	%esi, %esi
	movl	%eax, -28(%rbp)         ## 4-byte Spill
	movl	%esi, %eax
	addq	$32, %rsp
	popq	%rbp
	retq
	.cfi_endproc

	.section	__TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
	.asciz	"%d\n"


.subsections_via_symbols

Executions comparing the output of the two programs (to prove that they are the same:

R5057499:C rpn01$ ./asmIff
0
R5057499:C rpn01$ ./asmIff one
1
R5057499:C rpn01$ ./asmIff one two
2
R5057499:C rpn01$ ./asmIff one two three
2
R5057499:C rpn01$ ./asmSwi
0
R5057499:C rpn01$ ./asmSwi one
1
R5057499:C rpn01$ ./asmSwi one two
2
R5057499:C rpn01$ ./asmSwi one two three
2
R5057499:C rpn01$

Comparing the number of source lines, both in C and S:

R5057499:C rpn01$ diff <(wc -l asmIff.c) <(wc -l asmSwi.c)
1c1
<       21 asmIff.c
---
>       22 asmSwi.c
R5057499:C rpn01$ diff <(wc -l asmIff.s) <(wc -l asmSwi.s)
1c1
<       74 asmIff.s
---
>       82 asmSwi.s
R5057499:C rpn01$

Executing each program 10,000 times via the time command to compare the times yields no significant win for either:

R5057499:C rpn01$ time ( for (( i=1; i < 10000; i++ )) ; do ./asmIff one > /dev/null ; done )

real	0m30.988s
user	0m8.056s
sys	0m8.469s
R5057499:C rpn01$ time ( for (( i=1; i < 10000; i++ )) ; do ./asmSwi one > /dev/null ; done )

real	0m30.584s
user	0m7.965s
sys	0m8.310s
R5057499:C rpn01$ time ( for (( i=1; i < 10000; i++ )) ; do ./asmIff one > /dev/null ; done )

real	0m30.650s
user	0m7.977s
sys	0m8.337s
R5057499:C rpn01$ time ( for (( i=1; i < 10000; i++ )) ; do ./asmSwi one > /dev/null ; done )

real	0m30.777s
user	0m7.979s
sys	0m8.363s
R5057499:C rpn01$