Example of C compiler tail recursion

recursion.c

int isEven(int i) {
    if (i == 0) {
        return 1;
    }
    else if (i == 1) {
        return 0;
    }
    else if (i < 0) {
        return isEven(i + 2);
    }
    else {
        return isEven(i - 2);
    }
}

recursion.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_isEven
	.align	4, 0x90
_isEven:                                ## @isEven
	.cfi_startproc
## BB#0:
	pushq	%rbp
Ltmp2:
	.cfi_def_cfa_offset 16
Ltmp3:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Ltmp4:
	.cfi_def_cfa_register %rbp
                                        ## kill: EDI<def> EDI<kill> RDI<def>
	jmp	LBB0_1
	.align	4, 0x90
LBB0_3:                                 ##   in Loop: Header=BB0_1 Depth=1
	leal	2(%rdi), %eax
	testl	%edi, %edi
	leal	-2(%rdi), %ecx
	cmovsl	%eax, %ecx
	movl	%ecx, %edi
LBB0_1:                                 ## %tailrecurse
                                        ## =>This Inner Loop Header: Depth=1
	testl	%edi, %edi
	je	LBB0_4
## BB#2:                                ## %tailrecurse
                                        ##   in Loop: Header=BB0_1 Depth=1
	xorl	%eax, %eax
	cmpl	$1, %edi
	jne	LBB0_3
	jmp	LBB0_5
LBB0_4:                                 ## %.loopexit.loopexit
	movl	$1, %eax
LBB0_5:                                 ## %.loopexit
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols