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package jdk.nashorn.internal.codegen;
import java.util.ArrayDeque;
import java.util.Collections;
import java.util.Deque;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.Node;
import jdk.nashorn.internal.ir.Statement;
import jdk.nashorn.internal.ir.visitor.SimpleNodeVisitor;
import jdk.nashorn.internal.runtime.RecompilableScriptFunctionData;
class CacheAst extends SimpleNodeVisitor {
private final Deque<RecompilableScriptFunctionData> dataStack = new ArrayDeque<>();
private final Compiler compiler;
CacheAst(final Compiler compiler) {
this.compiler = compiler;
assert !compiler.isOnDemandCompilation();
}
@Override
public boolean enterFunctionNode(final FunctionNode functionNode) {
final int id = functionNode.getId();
// It isn't necessary to keep a stack of RecompilableScriptFunctionData, but then we'd need to do a
// potentially transitive lookup with compiler.getScriptFunctionData(id) for deeper functions; this way
// we keep it constant time.
dataStack.push(dataStack.isEmpty() ? compiler.getScriptFunctionData(id) : dataStack.peek().getScriptFunctionData(id));
return true;
}
@Override
public Node leaveFunctionNode(final FunctionNode functionNode) {
final RecompilableScriptFunctionData data = dataStack.pop();
if (functionNode.isSplit()) {
// NOTE: cache only split function ASTs from eager pass. Caching non-split functions would require
// some additional work, namely creating the concept of "uncacheable" function and reworking
// ApplySpecialization to ensure that functions undergoing apply-to-call transformations are not
// cacheable as well as recomputing Symbol.useCount when caching the eagerly parsed AST.
// Recomputing Symbol.useCount would be needed so it will only reflect uses from within the
// function being cached (and not reflect uses from its own nested functions or functions it is
// nested in). This is consistent with the count an on-demand recompilation of the function would
// produce. This is important as the decision to emit shared scope calls is based on this count,
// and if it is not matched between a previous version of the code and its deoptimizing rest-of
// compilation, it can result in rest-of not emitting a shared scope call where a previous version
// of the code (compiled from a cached eager pre-pass seeing higher (global) useCount) would emit
// it, causing a mismatch in stack shapes between previous code and its rest-of.
data.setCachedAst(functionNode);
}
if (!dataStack.isEmpty() && ((dataStack.peek().getFunctionFlags() & FunctionNode.IS_SPLIT) != 0)) {
// Return a function node with no body so that caching outer functions doesn't hold on to nested
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