Adds variable usage extractor and phi eliminator (incomplete)

teavm-core/src/main/java/org/teavm/javascript/PhiEliminator.java

@@ -0,0 +1,94 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.javascript;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.teavm.model.*;
+import org.teavm.model.util.InstructionTransitionExtractor;
+import org.teavm.model.util.UsageExtractor;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+class PhiEliminator {
+    public static void eliminatePhis(Program program) {
+        // Count how many times each variable is used
+        int[] variableUsageCount = new int[program.variableCount()];
+        int[] definitionRenamings = new int[program.variableCount()];
+        for (int i = 0; i < definitionRenamings.length; ++i) {
+            definitionRenamings[i] = i;
+        }
+        UsageExtractor usageExtractor = new UsageExtractor();
+        InstructionTransitionExtractor transitionExtractor = new InstructionTransitionExtractor();
+        int blockCount = program.basicBlockCount();
+        for (int i = 0; i < blockCount; ++i) {
+            BasicBlock block = program.basicBlockAt(i);
+            for (Instruction insn : block.getInstructions()) {
+                insn.acceptVisitor(usageExtractor);
+                for (Variable var : usageExtractor.getUsedVariables()) {
+                    variableUsageCount[var.getIndex()]++;
+                }
+            }
+            for (Phi phi : block.getPhis()) {
+                for (Incoming incoming : phi.getIncomings()) {
+                    variableUsageCount[incoming.getValue().getIndex()]++;
+                }
+            }
+        }
+
+        // Places assignments at the end of each block
+        for (int i = 0; i < blockCount; ++i) {
+            BasicBlock block = program.basicBlockAt(i);
+            block.getLastInstruction().acceptVisitor(transitionExtractor);
+            BasicBlock[] targets = transitionExtractor.getTargets();
+            if (targets.length == 1) {
+
+            } else {
+                for (BasicBlock targetBlock : transitionExtractor.getTargets()) {
+                    List<Incoming> incomings = new ArrayList<>();
+                    for (Incoming incoming : getIncomings(block, targetBlock)) {
+                        if (variableUsageCount[incoming.getSource().getIndex()] <= 1) {
+                            definitionRenamings[incoming.getValue().getIndex()] =
+                                    incoming.getPhi().getReceiver().getIndex();
+                        } else {
+                            incomings.add(incoming);
+                        }
+                    }
+                }
+            }
+        }
+
+        // Removes phi functions
+        for (int i = 0; i < blockCount; ++i) {
+            BasicBlock block = program.basicBlockAt(i);
+            block.getPhis().clear();
+        }
+    }
+
+    private static List<Incoming> getIncomings(BasicBlock block, BasicBlock targetBlock) {
+        List<Incoming> incomings = new ArrayList<>();
+        for (Phi phi : targetBlock.getPhis()) {
+            for (Incoming incoming : phi.getIncomings()) {
+                if (incoming.getSource() == block) {
+                    incomings.add(incoming);
+                }
+            }
+        }
+        return incomings;
+    }
+}

teavm-core/src/main/java/org/teavm/model/util/UsageExtractor.java

@@ -0,0 +1,203 @@
+/*
+ *  Copyright 2014 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.model.util;
+
+import org.teavm.model.Variable;
+import org.teavm.model.instructions.*;
+
+/**
+ *
+ * @author Alexey Andreev
+ */
+public class UsageExtractor implements InstructionVisitor {
+    private Variable[] usedVariables;
+
+    public Variable[] getUsedVariables() {
+        return usedVariables;
+    }
+
+    @Override
+    public void visit(EmptyInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(ClassConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(NullConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(IntegerConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(LongConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(FloatConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(DoubleConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(StringConstantInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(BinaryInstruction insn) {
+        usedVariables = new Variable[] { insn.getFirstOperand(), insn.getSecondOperand() };
+    }
+
+    @Override
+    public void visit(NegateInstruction insn) {
+        usedVariables = new Variable[] { insn.getOperand() };
+    }
+
+    @Override
+    public void visit(AssignInstruction insn) {
+        usedVariables = new Variable[] { insn.getAssignee() };
+    }
+
+    @Override
+    public void visit(CastInstruction insn) {
+        usedVariables = new Variable[] { insn.getValue() };
+    }
+
+    @Override
+    public void visit(CastNumberInstruction insn) {
+        usedVariables = new Variable[] { insn.getValue() };
+    }
+
+    @Override
+    public void visit(CastIntegerInstruction insn) {
+        usedVariables = new Variable[] { insn.getValue() };
+    }
+
+    @Override
+    public void visit(BranchingInstruction insn) {
+        usedVariables = new Variable[] { insn.getOperand() };
+    }
+
+    @Override
+    public void visit(BinaryBranchingInstruction insn) {
+        usedVariables = new Variable[] { insn.getFirstOperand(), insn.getSecondOperand() };
+    }
+
+    @Override
+    public void visit(JumpInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(SwitchInstruction insn) {
+        usedVariables = new Variable[] { insn.getCondition() };
+    }
+
+    @Override
+    public void visit(ExitInstruction insn) {
+        usedVariables = insn.getValueToReturn() != null ? new Variable[] { insn.getValueToReturn() } : new Variable[0];
+    }
+
+    @Override
+    public void visit(RaiseInstruction insn) {
+        usedVariables = new Variable[] { insn.getException() };
+    }
+
+    @Override
+    public void visit(ConstructArrayInstruction insn) {
+        usedVariables = new Variable[] { insn.getSize() };
+    }
+
+    @Override
+    public void visit(ConstructInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+
+    @Override
+    public void visit(ConstructMultiArrayInstruction insn) {
+        usedVariables = insn.getDimensions().toArray(new Variable[0]);
+    }
+
+    @Override
+    public void visit(GetFieldInstruction insn) {
+        usedVariables = insn.getInstance() != null ? new Variable[] { insn.getInstance() } : new Variable[0];
+    }
+
+    @Override
+    public void visit(PutFieldInstruction insn) {
+        usedVariables = insn.getInstance() != null ? new Variable[] { insn.getInstance(), insn.getValue() } :
+                new Variable[] { insn.getValue() };
+    }
+
+    @Override
+    public void visit(ArrayLengthInstruction insn) {
+        usedVariables = new Variable[] { insn.getArray() };
+    }
+
+    @Override
+    public void visit(CloneArrayInstruction insn) {
+        usedVariables = new Variable[] { insn.getArray() };
+    }
+
+    @Override
+    public void visit(UnwrapArrayInstruction insn) {
+        usedVariables = new Variable[] { insn.getArray() };
+    }
+
+    @Override
+    public void visit(GetElementInstruction insn) {
+        usedVariables = new Variable[] { insn.getArray(), insn.getIndex() };
+    }
+
+    @Override
+    public void visit(PutElementInstruction insn) {
+        usedVariables = new Variable[] { insn.getArray(), insn.getIndex(), insn.getValue() };
+    }
+
+    @Override
+    public void visit(InvokeInstruction insn) {
+        if (insn.getInstance() != null) {
+            usedVariables = new Variable[insn.getArguments().size() + 1];
+            usedVariables[insn.getArguments().size()] = insn.getInstance();
+        } else {
+            usedVariables = new Variable[insn.getArguments().size()];
+        }
+        insn.getArguments().toArray(usedVariables);
+    }
+
+    @Override
+    public void visit(IsInstanceInstruction insn) {
+        usedVariables = new Variable[] { insn.getValue() };
+    }
+
+    @Override
+    public void visit(InitClassInstruction insn) {
+        usedVariables = new Variable[0];
+    }
+}