Method codegen_index

src/liboslcomp/codegen.cpp:1245–1275

A struct select needs to decypher whether there is an array index necessary in the chain of events. The only kind of assignment that makes sense is a series of struct field selections, array indexings, or (last) a direct variable reference (for the top level struct). This function generates code for the index and returns the resulting symbol, or returns NULL if no dereference is necessary.

// This function generates code for the index and returns the resulting
// symbol, or returns NULL if no dereference is necessary.
Symbol *
ASTstructselect::codegen_index ()
{
    // Must account for array indices farther up the chain.  
    ASTNode *node = this;
    Symbol *indexsym = NULL;
    while (node) {
        if (node->nodetype() == variable_ref_node) {
            // Hit final variable ref -- done
            break;
        }
        else if (node->nodetype() == structselect_node) {
            // Hit another struct select -- recurse up
            node = ((ASTstructselect *)node)->lvalue().get();
        }
        else if (node->nodetype() == index_node) {
            // Hit an array index node -- find the index and recurse
            ASTindex *arrayref = (ASTindex *)node;
            indexsym = arrayref->index()->codegen();
            // FIXME -- to allow multiple levels of array indexing,
            // this should "append", i.e. multiply, the old index
            // with the new one.
            node = arrayref->lvalue().get();
        }
        else {
            ASSERT (0);
        }
    }

    return indexsym;
}