Simple C code as compiled by different compilers

main()

{

int a = 7;

int b = 15;

int c;

c = b + a;

}

SPIM assembly

##################################################################

# addasm.s

# addition of two integers

#that are automatic variables.

# the result is stored on stack.

#

#################################################################.verstamp 3 19

.text

.align 2

.globl main

# 1 main()

# 2 {

main:

# 3 int a = 7;

li $14, 7

sw $14, 12($sp)

# 4 int b = 15;

li $15, 15

sw $15, 8($sp)

# 5 int c;

# 6 c = b + a;

li $24, 22 # the compiler is smart:

# performs addtion of two constants

# at compile time!

sw $24, 4($sp)

# 7 }

.end main

MIPS assembly

Pentium Assembly

TITLE F:\Cs342fall99\Sep27\testadd\addasm.c

.386P

include listing.inc

if @Version gt 510

.model FLAT

else

_TEXT SEGMENT PARA USE32 PUBLIC 'CODE'

_TEXT ENDS

_DATA SEGMENT DWORD USE32 PUBLIC 'DATA'

_DATA ENDS

CONST SEGMENT DWORD USE32 PUBLIC 'CONST'

CONST ENDS

_BSS SEGMENT DWORD USE32 PUBLIC 'BSS'

_BSS ENDS

$$SYMBOLS SEGMENT BYTE USE32 'DEBSYM'

$$SYMBOLS ENDS

$$TYPES SEGMENT BYTE USE32 'DEBTYP'

$$TYPES ENDS

_TLS SEGMENT DWORD USE32 PUBLIC 'TLS'

_TLS ENDS

; COMDAT _main

_TEXT SEGMENT PARA USE32 PUBLIC 'CODE'

_TEXT ENDS

FLAT GROUP _DATA, CONST, _BSS

ASSUME CS: FLAT, DS: FLAT, SS: FLAT

endif

PUBLIC _main

; COMDAT _main

_TEXT SEGMENT

_a$ = -4

_b$ = -8

_c$ = -12

_main PROC NEAR ; COMDAT

; 2 : {

push ebp

mov ebp, esp

sub esp, 76 ; 0000004cH

push ebx

push esi

push edi

lea edi, DWORD PTR [ebp-76]

mov ecx, 19 ; 00000013H

mov eax, -858993460 ; ccccccccH

rep stosd

; 3 : int a = 7;

mov DWORD PTR _a$[ebp], 7

; 4 : int b = 15;

mov DWORD PTR _b$[ebp], 15 ; 0000000fH

; 5 : int c;

; 6 : c = b + a;

mov eax, DWORD PTR _b$[ebp]

add eax, DWORD PTR _a$[ebp]

mov DWORD PTR _c$[ebp], eax

; 7 : }

pop edi

pop esi

pop ebx

mov esp, ebp

pop ebp

ret 0

_main ENDP

_TEXT ENDS

END