Three-Address Code Generation: Suppose we have the following C code. int dtrsv(c

Question

Three-Address Code Generation:

Suppose we have the following C code.

int dtrsv(const int M, const double *A,const int lda,
double *X,const double *Y)
{
int i,j;
for (i = 0; i < M; i += 1)
{
for (j = 0; j < i; j += 1)
{
X[i] = X[i] - A[j*lda+i] * Y[j];
}
}
return i;
}

Convert the given code to three-address code. Please rst clarify your assumptions about

the memory layout of this functions' activation record. Your three address code could use

the following types of instructions, where x, z are register names, a is a constant value, y is
a constant or a register, and L1/L2 are labels.

loadi a => x; load x, a => z; store z => x, a; mov x => y;
mult x y => z; multi x, a => z;
add x, y => z; addi x, a => z;
minus x, y=>z; minusi x, a => z;
if (x < y) goto L1; goto L2; if (x <=y) goto L1; jump x;

Regards,

Explanation / Answer

Following is the C code for Three address code generator.

#include<stdio.h>

#include<conio.h>

#include<string.h>

struct three

{

char data[10],temp[7];

}s[30];

void main()

{

            char *d1,*d2;

            int i=0,len=0;

            FILE *f1,*f2;

            clrscr();

            f1=fopen("exe1.txt","r");

            f2=fopen("exe2.txt","w");

            while(fscanf(f1,"%s",s[len].data)!=EOF)

            len++;

            for(i=0;i<=len;i++)

            {

            if(!strcmp(s[i].data,"="))

            {

            fprintf(f2," LDA %s",s[i+1].data);

            if(!strcmp(s[i+2].data,"+"))

            fprintf(f2," ADD %s",s[i+3].data);

            if(!strcmp(s[i+2].data,"-"))

            fprintf(f2," SUB %s",s[i+3].data);

            fprintf(f2," STA %s",s[i-1].data);

            }

     }

     fclose(f1);

     fclose(f2);

     getch();

}

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