Difference between revisions of "Code Generation/Example 3"

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< Code Generation
(Postfix Code)
(Compiling and Running)
 
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Consider the following C function:
 
Consider the following C function:
  
<c>
+
<source lang="c">
 
int *click(int *x, int dim) {
 
int *click(int *x, int dim) {
 
   int *res, i;
 
   int *res, i;
Line 10: Line 10:
 
   return res;
 
   return res;
 
}
 
}
</c>
+
</source>
  
 
== Postfix Code ==
 
== Postfix Code ==
Line 16: Line 16:
 
The Postfix code for the above function is as follows:  
 
The Postfix code for the above function is as follows:  
 
{{CollapsedCode|Postfix code|
 
{{CollapsedCode|Postfix code|
<asm>
+
<source lang="asm">
 
TEXT
 
TEXT
 
ALIGN
 
ALIGN
Line 121: Line 121:
 
LEAVE
 
LEAVE
 
RET
 
RET
</asm>
+
</source>
 
}}
 
}}
  
 
== Compiling and Running ==
 
== Compiling and Running ==
  
To compile the Postfix code directly, [[pf2asm]] can be used:
+
To compile the Postfix code directly, [[Compiladores/Projecto de Compiladores/Compiladores Exemplo|pf2asm]] can be used:
  
* pf2asm click.pf
+
pf2asm click.pf
* yasm -felf click.asm
+
yasm -felf click.asm
  
 
[[category:Compiladores]]
 
[[category:Compiladores]]
 
[[category:Ensino]]
 
[[category:Ensino]]

Latest revision as of 18:52, 6 May 2019

The Original Code

Consider the following C function:

int *click(int *x, int dim) {
  int *res, i;
  for (i = dim-2, res = x+dim-1; i >= 0; i--)
    if (x[i] > *res) res = &x[i];
  return res;
}

Postfix Code

The Postfix code for the above function is as follows:

Postfix code
TEXT
ALIGN
GLOBL click, FUNC
LABEL click
ENTER 8  ;-- x@+8 dim@+12 res@-4 i@-8

;; for init

;; i = dim-2
LOCAL 12
LDINT
INT 2
SUB
DUP32
LOCAL -8
STINT
TRASH 4

;; res = x + dim - 1
LOCAL 8
LDINT
LOCAL 12
LDINT
INT 4
MUL
ADD
INT 1
INT 4
MUL
SUB
DUP32
LOCAL -4
STINT
TRASH 4

;; for test
ALIGN
LABEL for
LOCAL -8
LDINT
INT 0
GE
JZ forend

;; for block

;; if test
LOCAL 8
LDINT ; x
LOCAL -8
LDINT; i
INT 4
MUL
ADD ; x+i
LDINT ; x[i] = *(x+i)

LOCAL -4
LDINT ; res
LDINT ; *res

GT
JZ ifend

;; if block
LOCAL 8
LDINT ; x
LOCAL -8
LDINT ; i
INT 4
MUL
ADD ; x+i = &x[i]
DUP32
LOCAL -4
STINT ; res = &x[i]
TRASH 4

ALIGN
LABEL ifend

;; for increment
ALIGN
LABEL forincr
LOCAL -8
LDINT ; i
DUP32
INT 1
SUB
LOCAL -8
STINT
TRASH 4

;; for jump to cycle
JMP for

ALIGN
LABEL forend

;; return
LOCAL -4
LDINT ; res

STFVAL32
LEAVE
RET

Compiling and Running

To compile the Postfix code directly, pf2asm can be used:

pf2asm click.pf
yasm -felf click.asm