clang-600.0.34.4 @ Mac OS X optimization for unused variables.

test1.c

int main(int argc, char *argv[])
{
	int i,j;
	i = 0;
	return 0;
}

test1.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, %eax
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols

test2.c

int main(int argc, char *argv[])
{
	int i;
	i = 0;
	return 0;
}

test2.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, %eax
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols

test3.c

int main(int argc, char *argv[])
{
	int i,j;
	i = 0;
	j = 0;
	return 0;
}

test3.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, %eax
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	movl	$0, -24(%rbp)
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols

test4.c

int main(int argc, char *argv[])
{
	int i,j;
	i = 0;
	j = 0;

	for(i = 0; i < 100; i++) {
		i + 1;
	}

	return 0;
}

test4.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	movl	$0, -24(%rbp)
	movl	$0, -20(%rbp)
LBB0_1:                                 ## =>This Inner Loop Header: Depth=1
	cmpl	$100, -20(%rbp)
	jge	LBB0_4
## BB#2:                                ##   in Loop: Header=BB0_1 Depth=1
## BB#3:                                ##   in Loop: Header=BB0_1 Depth=1
	movl	-20(%rbp), %eax
	addl	$1, %eax
	movl	%eax, -20(%rbp)
	jmp	LBB0_1
LBB0_4:
	movl	$0, %eax
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols

test5.c

int main(int argc, char *argv[])
{
	int i,j;
	i = 0;

	for(i = 0; i < 100; i++) {
		i + 1;
	}

	j = 0;

	return 0;
}

test5.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	movl	$0, -20(%rbp)
LBB0_1:                                 ## =>This Inner Loop Header: Depth=1
	cmpl	$100, -20(%rbp)
	jge	LBB0_4
## BB#2:                                ##   in Loop: Header=BB0_1 Depth=1
## BB#3:                                ##   in Loop: Header=BB0_1 Depth=1
	movl	-20(%rbp), %eax
	addl	$1, %eax
	movl	%eax, -20(%rbp)
	jmp	LBB0_1
LBB0_4:
	movl	$0, %eax
	movl	$0, -24(%rbp)
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols

test6.c

int main(int argc, char *argv[])
{
	int i;
	i = 0;

	for(i = 0; i < 100; i++) {
		i + 1;
	}

	int j = 0;
	return 0;
}

test6.s

	.section	__TEXT,__text,regular,pure_instructions
	.globl	_main
	.align	4, 0x90
_main:                                  ## @main
	.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
	movl	$0, -4(%rbp)
	movl	%edi, -8(%rbp)
	movq	%rsi, -16(%rbp)
	movl	$0, -20(%rbp)
	movl	$0, -20(%rbp)
LBB0_1:                                 ## =>This Inner Loop Header: Depth=1
	cmpl	$100, -20(%rbp)
	jge	LBB0_4
## BB#2:                                ##   in Loop: Header=BB0_1 Depth=1
## BB#3:                                ##   in Loop: Header=BB0_1 Depth=1
	movl	-20(%rbp), %eax
	addl	$1, %eax
	movl	%eax, -20(%rbp)
	jmp	LBB0_1
LBB0_4:
	movl	$0, %eax
	movl	$0, -24(%rbp)
	popq	%rbp
	retq
	.cfi_endproc


.subsections_via_symbols