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Truffle SL is an example language implemented using the Truffle API.
/*
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* The Universal Permissive License (UPL), Version 1.0
*
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* (a) the Software, and
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* minimum a reference to the UPL must be included in all copies or substantial
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package com.oracle.truffle.sl.nodes.controlflow;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.BlockNode;
import com.oracle.truffle.api.nodes.BlockNode.ElementExecutor;
import com.oracle.truffle.api.nodes.ControlFlowException;
import com.oracle.truffle.api.nodes.ExplodeLoop;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.NodeInfo;
import com.oracle.truffle.api.nodes.NodeUtil;
import com.oracle.truffle.api.nodes.NodeVisitor;
import com.oracle.truffle.sl.nodes.SLStatementNode;
import com.oracle.truffle.sl.nodes.local.SLScopedNode;
import com.oracle.truffle.sl.nodes.local.SLWriteLocalVariableNode;
/**
* A statement node that just executes a list of other statements.
*/
@NodeInfo(shortName = "block", description = "The node implementing a source code block")
public final class SLBlockNode extends SLStatementNode implements BlockNode.ElementExecutor {
/**
* The block of child nodes. Using the block node allows Truffle to split the block into
* multiple groups for compilation if the method is too big. This is an optional API.
* Alternatively, you may just use your own block node, with a
* {@link com.oracle.truffle.api.nodes.Node.Children @Children} field. However, this prevents
* Truffle from compiling big methods, so these methods might fail to compile with a compilation
* bailout.
*/
@Child private BlockNode block;
/**
* All declared variables visible from this block (including all parent blocks). Variables
* declared in this block only are from zero index up to {@link #parentBlockIndex} (exclusive).
*/
@CompilationFinal(dimensions = 1) private SLWriteLocalVariableNode[] writeNodesCache;
/**
* Index of the parent block's variables in the {@link #writeNodesCache list of variables}.
*/
@CompilationFinal private int parentBlockIndex = -1;
public SLBlockNode(SLStatementNode[] bodyNodes) {
/*
* Truffle block nodes cannot be empty, that is why we just set the entire block to null if
* there are no elements. This is good practice as it safes memory.
*/
this.block = bodyNodes.length > 0 ? BlockNode.create(bodyNodes, this) : null;
}
/**
* Execute all block statements. The block node makes sure that {@link ExplodeLoop full
* unrolling} of the loop is triggered during compilation. This allows the
* {@link SLStatementNode#executeVoid} method of all children to be inlined.
*/
@Override
public void executeVoid(VirtualFrame frame) {
if (this.block != null) {
this.block.executeVoid(frame, BlockNode.NO_ARGUMENT);
}
}
public List getStatements() {
if (block == null) {
return Collections.emptyList();
}
return Collections.unmodifiableList(Arrays.asList(block.getElements()));
}
/**
* Truffle nodes don't have a fixed execute signature. The {@link ElementExecutor} interface
* tells the framework how block element nodes should be executed. The executor allows to add a
* custom exception handler for each element, e.g. to handle a specific
* {@link ControlFlowException} or to pass a customizable argument, that allows implement
* startsWith semantics if needed. For SL we don't need to pass any argument as we just have
* plain block nodes, therefore we pass {@link BlockNode#NO_ARGUMENT}. In our case the executor
* does not need to remember any state so we reuse a singleton instance.
*/
@Override
public void executeVoid(VirtualFrame frame, SLStatementNode node, int index, int argument) {
node.executeVoid(frame);
}
/**
* All declared local variables accessible in this block. Variables declared in parent blocks
* are included.
*/
public SLWriteLocalVariableNode[] getDeclaredLocalVariables() {
SLWriteLocalVariableNode[] writeNodes = writeNodesCache;
if (writeNodes == null) {
CompilerDirectives.transferToInterpreterAndInvalidate();
writeNodesCache = writeNodes = findDeclaredLocalVariables();
}
return writeNodes;
}
public int getParentBlockIndex() {
return parentBlockIndex;
}
private SLWriteLocalVariableNode[] findDeclaredLocalVariables() {
if (block == null) {
return new SLWriteLocalVariableNode[]{};
}
// Search for those write nodes, which declare variables
List writeNodes = new ArrayList<>(4);
int[] varsIndex = new int[]{0};
NodeUtil.forEachChild(block, new NodeVisitor() {
@Override
public boolean visit(Node node) {
if (node instanceof WrapperNode) {
NodeUtil.forEachChild(node, this);
return true;
}
if (node instanceof SLScopedNode) {
SLScopedNode scopedNode = (SLScopedNode) node;
scopedNode.setVisibleVariablesIndexOnEnter(varsIndex[0]);
}
// Do not enter any nested blocks.
if (!(node instanceof SLBlockNode)) {
NodeUtil.forEachChild(node, this);
}
// Write to a variable is a declaration unless it exists already in a parent scope.
if (node instanceof SLWriteLocalVariableNode) {
SLWriteLocalVariableNode wn = (SLWriteLocalVariableNode) node;
if (wn.isDeclaration()) {
writeNodes.add(wn);
varsIndex[0]++;
}
}
if (node instanceof SLScopedNode) {
SLScopedNode scopedNode = (SLScopedNode) node;
scopedNode.setVisibleVariablesIndexOnExit(varsIndex[0]);
}
return true;
}
});
Node parentBlock = findBlock();
SLWriteLocalVariableNode[] parentVariables = null;
if (parentBlock instanceof SLBlockNode) {
parentVariables = ((SLBlockNode) parentBlock).getDeclaredLocalVariables();
}
SLWriteLocalVariableNode[] variables = writeNodes.toArray(new SLWriteLocalVariableNode[writeNodes.size()]);
parentBlockIndex = variables.length;
if (parentVariables == null || parentVariables.length == 0) {
return variables;
} else {
int parentVariablesIndex = ((SLBlockNode) parentBlock).getParentBlockIndex();
int visibleVarsIndex = getVisibleVariablesIndexOnEnter();
int allVarsLength = variables.length + visibleVarsIndex + parentVariables.length - parentVariablesIndex;
SLWriteLocalVariableNode[] allVariables = Arrays.copyOf(variables, allVarsLength);
System.arraycopy(parentVariables, 0, allVariables, variables.length, visibleVarsIndex);
System.arraycopy(parentVariables, parentVariablesIndex, allVariables, variables.length + visibleVarsIndex, parentVariables.length - parentVariablesIndex);
return allVariables;
}
}
}