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