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Typecasting information in MEM[...] GIMPLE


We are interested in extracting the type of a tree node that appears within MEM_REF.

Given a C program:

    struct node * * pvar;
    struct node qvar;
    pvar = (struct node * *) malloc (sizeof (struct node *));
    *pvar = &qvar;

It is transformed into the following GIMPLE code:

    void * * pvar.1;
    void * pvar.0;
    pvar.0_1 = malloc (4);
    pvar = pvar.0_1;
    MEM[(struct node * *)pvar.0_1] = &qvar;

We wish to discover the type of the argument of MEM[...] in the last
GIMPLE statement. We can see from the GIMPLE dump that the argument's
type is "struct node * *". How do we extract this from the tree
definition of MEM[...]?

We speculate the following solution: Given a variable var (whose tree is tree_of_var) and a tree, say t,

    if (TREE_CODE(t) is MEM_REF) and (TREE_OPERAND(t, 0) is tree_of_var)
    then
        the type of the expression inside MEM[...] of tree t is
        POINTER_TYPE to TREE_TYPE(t).

Is is correct? It is general enough?

Thanks and regards,

Uday.

------------------------------------------------------------------------
Dr. Uday Khedker, Professor
Department of Computer Science & Engg.
IIT Bombay, Powai, Mumbai 400 076, India. 	
Email : 	 uday@cse.iitb.ac.in
Homepage: 	 http://www.cse.iitb.ac.in/~uday
Phone : 	  91 (22) 2572 2545 x 7717, 91 (22) 2576 7717 (Direct)


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