array.c

#include <stdio.h>

int main(int argc, char *argv[]) {
    char arr[40] = "this is a string referenced by an array";
    printf("arr = %s; sizeof arr = %ld\n", arr, sizeof arr);
    return 0;
}

array.S

	.section	__TEXT,__text,regular,pure_instructions
	.macosx_version_min 10, 10
	.globl	_main
_main:                                  ## @main
	.cfi_startproc
## BB#0:
	pushq	%rbp
Ltmp0:
	.cfi_def_cfa_offset 16
Ltmp1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Ltmp2:
	.cfi_def_cfa_register %rbp
	pushq	%rbx
	subq	$56, %rsp
Ltmp3:
	.cfi_offset %rbx, -24
	movq	___stack_chk_guard@GOTPCREL(%rip), %rbx
	movq	(%rbx), %rbx
	movq	%rbx, -16(%rbp)
	movabsq	$34165616355123310, %rax ## imm = 0x7961727261206E
	movq	%rax, -32(%rbp)
	movaps	L_main.arr+16(%rip), %xmm0
	movaps	%xmm0, -48(%rbp)
	movaps	L_main.arr(%rip), %xmm0
	movaps	%xmm0, -64(%rbp)
	leaq	L_.str(%rip), %rdi
	leaq	-64(%rbp), %rsi
	movl	$40, %edx
	xorl	%eax, %eax
	callq	_printf
	cmpq	-16(%rbp), %rbx
	jne	LBB0_2
## BB#1:
	xorl	%eax, %eax
	addq	$56, %rsp
	popq	%rbx
	popq	%rbp
	retq
LBB0_2:
	callq	___stack_chk_fail
	.cfi_endproc

	.section	__TEXT,__cstring,cstring_literals
	.align	4                       ## @main.arr
L_main.arr:
	.asciz	"this is a string referenced by an array"

L_.str:                                 ## @.str
	.asciz	"arr = %s; sizeof arr = %ld\n"


.subsections_via_symbols

array.S_pointer.S.diff

--- array.S	2015-10-01 10:04:35.000000000 -0400
+++ pointer.S	2015-10-01 10:04:35.000000000 -0400
@@ -12,43 +12,22 @@
 	movq	%rsp, %rbp
 Ltmp2:
 	.cfi_def_cfa_register %rbp
-	pushq	%rbx
-	subq	$56, %rsp
-Ltmp3:
-	.cfi_offset %rbx, -24
-	movq	___stack_chk_guard@GOTPCREL(%rip), %rbx
-	movq	(%rbx), %rbx
-	movq	%rbx, -16(%rbp)
-	movabsq	$34165616355123310, %rax ## imm = 0x7961727261206E
-	movq	%rax, -32(%rbp)
-	movaps	L_main.arr+16(%rip), %xmm0
-	movaps	%xmm0, -48(%rbp)
-	movaps	L_main.arr(%rip), %xmm0
-	movaps	%xmm0, -64(%rbp)
-	leaq	L_.str(%rip), %rdi
-	leaq	-64(%rbp), %rsi
-	movl	$40, %edx
+	leaq	L_.str1(%rip), %rdi
+	leaq	L_.str(%rip), %rsi
+	movl	$8, %edx
 	xorl	%eax, %eax
 	callq	_printf
-	cmpq	-16(%rbp), %rbx
-	jne	LBB0_2
-## BB#1:
 	xorl	%eax, %eax
-	addq	$56, %rsp
-	popq	%rbx
 	popq	%rbp
 	retq
-LBB0_2:
-	callq	___stack_chk_fail
 	.cfi_endproc
 
 	.section	__TEXT,__cstring,cstring_literals
-	.align	4                       ## @main.arr
-L_main.arr:
-	.asciz	"this is a string referenced by an array"
-
 L_.str:                                 ## @.str
-	.asciz	"arr = %s; sizeof arr = %ld\n"
+	.asciz	"this is a string referenced by a pointer"
+
+L_.str1:                                ## @.str1
+	.asciz	"ptr = %s; sizeof ptr = %ld\n"
 
 
 .subsections_via_symbols

build.sh

#!/bin/bash
clang -S -Os -o array.S array.c
clang -S -Os -o static_array.S static_array.c
clang -S -Os -o pointer.S pointer.c

pointer.c

#include <stdio.h>

int main(int argc, char *argv[]) {
    char *ptr = "this is a string referenced by a pointer";
    printf("ptr = %s; sizeof ptr = %ld\n", ptr, sizeof ptr);
    return 0;
}

pointer.S

	.section	__TEXT,__text,regular,pure_instructions
	.macosx_version_min 10, 10
	.globl	_main
_main:                                  ## @main
	.cfi_startproc
## BB#0:
	pushq	%rbp
Ltmp0:
	.cfi_def_cfa_offset 16
Ltmp1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Ltmp2:
	.cfi_def_cfa_register %rbp
	leaq	L_.str1(%rip), %rdi
	leaq	L_.str(%rip), %rsi
	movl	$8, %edx
	xorl	%eax, %eax
	callq	_printf
	xorl	%eax, %eax
	popq	%rbp
	retq
	.cfi_endproc

	.section	__TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
	.asciz	"this is a string referenced by a pointer"

L_.str1:                                ## @.str1
	.asciz	"ptr = %s; sizeof ptr = %ld\n"


.subsections_via_symbols

static_array.c

#include <stdio.h>

int main(int argc, char *argv[]) {
    static char arr[40] = "this is a string referenced by an array";
    printf("arr = %s; sizeof arr = %ld\n", arr, sizeof arr);
    return 0;
}

static_array.S

	.section	__TEXT,__text,regular,pure_instructions
	.macosx_version_min 10, 10
	.globl	_main
_main:                                  ## @main
	.cfi_startproc
## BB#0:
	pushq	%rbp
Ltmp0:
	.cfi_def_cfa_offset 16
Ltmp1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
Ltmp2:
	.cfi_def_cfa_register %rbp
	leaq	L_.str(%rip), %rdi
	leaq	_main.arr(%rip), %rsi
	movl	$40, %edx
	xorl	%eax, %eax
	callq	_printf
	xorl	%eax, %eax
	popq	%rbp
	retq
	.cfi_endproc

	.section	__DATA,__data
	.align	4                       ## @main.arr
_main.arr:
	.asciz	"this is a string referenced by an array"

	.section	__TEXT,__cstring,cstring_literals
L_.str:                                 ## @.str
	.asciz	"arr = %s; sizeof arr = %ld\n"


.subsections_via_symbols

static_array.S_pointer.S.diff

--- static_array.S	2015-10-01 10:04:35.000000000 -0400
+++ pointer.S	2015-10-01 10:04:35.000000000 -0400
@@ -12,9 +12,9 @@
 	movq	%rsp, %rbp
 Ltmp2:
 	.cfi_def_cfa_register %rbp
-	leaq	L_.str(%rip), %rdi
-	leaq	_main.arr(%rip), %rsi
-	movl	$40, %edx
+	leaq	L_.str1(%rip), %rdi
+	leaq	L_.str(%rip), %rsi
+	movl	$8, %edx
 	xorl	%eax, %eax
 	callq	_printf
 	xorl	%eax, %eax
@@ -22,14 +22,12 @@
 	retq
 	.cfi_endproc
 
-	.section	__DATA,__data
-	.align	4                       ## @main.arr
-_main.arr:
-	.asciz	"this is a string referenced by an array"
-
 	.section	__TEXT,__cstring,cstring_literals
 L_.str:                                 ## @.str
-	.asciz	"arr = %s; sizeof arr = %ld\n"
+	.asciz	"this is a string referenced by a pointer"
+
+L_.str1:                                ## @.str1
+	.asciz	"ptr = %s; sizeof ptr = %ld\n"
 
 
 .subsections_via_symbols