зеркало из https://github.com/mozilla/pjs.git
45 строки
1.3 KiB
JavaScript
45 строки
1.3 KiB
JavaScript
/* May-return analysis.
|
|
* This makes sense only for functions that return a value. The analysis
|
|
* determines the set of variables that may transitively reach the return
|
|
* statement. */
|
|
|
|
function MayReturnAnalysis() {
|
|
BackwardAnalysis.apply(this, arguments);
|
|
// May-return variables. We collect them all here.
|
|
this.vbls = create_decl_set();
|
|
// The return value variable itself
|
|
this.retvar = undefined;
|
|
}
|
|
|
|
MayReturnAnalysis.prototype = new BackwardAnalysis;
|
|
|
|
MayReturnAnalysis.prototype.flowState = function(isn, state) {
|
|
if (TREE_CODE(isn) == RETURN_EXPR) {
|
|
let gms = TREE_OPERAND(isn, 0);
|
|
if (gms) {
|
|
// gms is usually a GIMPLE_MODIFY_STMT but can be a RESULT_DECL
|
|
if (TREE_CODE(gms) == GIMPLE_MODIFY_STMT) {
|
|
let v = GIMPLE_STMT_OPERAND(gms, 1);
|
|
this.vbls.add(v);
|
|
state.add(v);
|
|
this.retvar = v;
|
|
} else if (TREE_CODE(gms) == RESULT_DECL) {
|
|
throw new Error("Weird case hit");
|
|
}
|
|
}
|
|
} else if (TREE_CODE(isn) == GIMPLE_MODIFY_STMT) {
|
|
let lhs = GIMPLE_STMT_OPERAND(isn, 0);
|
|
let rhs = GIMPLE_STMT_OPERAND(isn, 1);
|
|
if (DECL_P(rhs) && DECL_P(lhs) && state.has(lhs)) {
|
|
this.vbls.add(rhs);
|
|
state.add(rhs);
|
|
}
|
|
|
|
for (let e in isn_defs(isn, 'strong')) {
|
|
if (DECL_P(e)) {
|
|
state.remove(e);
|
|
}
|
|
}
|
|
}
|
|
};
|