Compilers: Principles and Practice by Pearson

150 Compilers – Principles and Practice

int nextlabel = 1;

char *genlabel(){

char *s;

s = malloc(8);

sprintf(s, "LAB%d ", nextlabel++);

return

s;

}

In our example program tb_rdp_if_sstk2.c, the main() function, besides doing routine

setup, reads the input string and prints out the final Intermediate representation in RPN.

We gave a string a = s * (d + f) as input and received RPN s d f + * a = as output.

The following trace of the program shows the working of the synchronized Semantic stack.

Return-Stack Semantic-Stack In calling func.

Entry: stsmt-list

Entry: stsmt push

Entry: basic-stsmt push

Entry: pa() push,pop push(a),pop ...