//---------------------------chain_rule----------------------------------------
// Starting at 'operand', check if we know how to automatically generate other results
void ArchDesc::chain_rule(FILE *fp, const char *indent, const char *operand,
const Expr *icost, const char *irule, Dict &operands_chained_from, ProductionState &status) {
// Check if we have already generated chains from this starting point
if( operands_chained_from[operand] != NULL ) {
return;
} else {
operands_chained_from.Insert( operand, operand);
}
if( debug_output ) {
fprintf(fp, "// chain rules starting from: %s and %s \n", (char *)operand, (char *)irule); // %%%%% Explanation
}
ChainList *lst = (ChainList *)_chainRules[operand];
if (lst) {
// printf("\nChain from <%s> at cost #%s\n",operand, icost ? icost : "_");
const char *result, *cost, *rule;
for(lst->reset(); (lst->iter(result,cost,rule)) == true; ) {
// Do not generate operands that are already available
if( operands_chained_from[result] != NULL ) {
continue;
} else {
// Compute the cost for previous match + chain_rule_cost
// total_cost = icost + cost;
Expr *total_cost = icost->clone(); // icost + cost
total_cost->add(cost, *this);
// Check for transitive chain rules
Form *form = (Form *)_globalNames[rule];
if ( ! form->is_instruction()) {
// printf(" result=%s cost=%s rule=%s\n", result, total_cost, rule);
// Check against other match costs, and update cost & rule vectors
const char *reduce_rule = strcmp(irule,"Invalid") ? irule : rule;
cost_check(fp, indent, ArchDesc::getMachOperEnum(result), total_cost, reduce_rule, status);
chain_rule(fp, indent, result, total_cost, irule, operands_chained_from, status);
} else {
// printf(" result=%s cost=%s rule=%s\n", result, total_cost, rule);
// Check against other match costs, and update cost & rule vectors
cost_check(fp, indent, ArchDesc::getMachOperEnum(result), total_cost, rule, status);
chain_rule(fp, indent, result, total_cost, rule, operands_chained_from, status);
}
// If this is a member of an operand class, update class cost & rule
expand_opclass( fp, indent, total_cost, result, status );
}
}
}
}
