Switch Optimization
This commit is contained in:
Denis Zharkov
committed by
Evgeny Gerashchenko
Evgeny Gerashchenko
parent
ecaa7b61dd
commit
c73533d214
@@ -20,6 +20,7 @@ import com.google.common.collect.Lists;
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import com.google.common.collect.Maps;
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import com.intellij.openapi.editor.Document;
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import com.intellij.openapi.progress.ProcessCanceledException;
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import com.intellij.openapi.util.Pair;
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import com.intellij.psi.PsiElement;
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import com.intellij.psi.tree.IElementType;
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import com.intellij.util.ArrayUtil;
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@@ -46,6 +47,7 @@ import org.jetbrains.jet.lang.resolve.DescriptorUtils;
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import org.jetbrains.jet.lang.resolve.calls.model.*;
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import org.jetbrains.jet.lang.resolve.calls.util.CallMaker;
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import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
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import org.jetbrains.jet.lang.resolve.constants.IntValue;
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import org.jetbrains.jet.lang.resolve.constants.IntegerValueTypeConstant;
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import org.jetbrains.jet.lang.resolve.java.AsmTypeConstants;
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import org.jetbrains.jet.lang.resolve.java.JvmAbi;
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@@ -3641,7 +3643,13 @@ The "returned" value of try expression with no finally is either the last expres
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JetExpression expr = expression.getSubjectExpression();
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JetType subjectJetType = bindingContext.get(BindingContext.EXPRESSION_TYPE, expr);
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Type subjectType = asmTypeOrVoid(subjectJetType);
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Type resultType = isStatement ? Type.VOID_TYPE : expressionType(expression);
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if (canSwitchBeUsedIn(expression, subjectType)) {
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return generateSwitch(expression, subjectType, resultType, isStatement);
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}
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int subjectLocal = expr != null ? myFrameMap.enterTemp(subjectType) : -1;
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if (subjectLocal != -1) {
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gen(expr, subjectType);
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@@ -3724,6 +3732,130 @@ The "returned" value of try expression with no finally is either the last expres
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}
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}
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private StackValue generateSwitch(JetWhenExpression expression, Type subjectType, Type resultType, boolean isStatement) {
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JetType subjectJetType = bindingContext.get(BindingContext.EXPRESSION_TYPE, expression.getSubjectExpression());
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assert subjectJetType != null;
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Map<Integer, Label> transitions = Maps.newTreeMap();
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Label[] entryLabels = new Label[expression.getEntries().size()];
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int entryLabelsCounter = 0;
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Label elseLabel = new Label();
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Label endLabel = new Label();
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boolean hasElse = expression.getElseExpression() != null;
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for (JetWhenEntry entry : expression.getEntries()) {
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Label entryLabel = new Label();
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for (JetWhenCondition condition : entry.getConditions()) {
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assert condition instanceof JetWhenConditionWithExpression;
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JetExpression conditionExpression = ((JetWhenConditionWithExpression) condition).getExpression();
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assert conditionExpression != null;
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CompileTimeConstant constant = getCompileTimeConstant(conditionExpression, bindingContext);
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assert constant != null && constant instanceof IntValue;
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int value = ((IntValue) constant).getValue();
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if (!transitions.containsKey(value)) {
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transitions.put(value, entryLabel);
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}
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}
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if (entry.isElse()) {
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elseLabel = entryLabel;
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}
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entryLabels[entryLabelsCounter++] = entryLabel;
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}
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gen(expression.getSubjectExpression(), subjectType);
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generateSwitchLookupCall(
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transitions,
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//if there is no else-entry and it's statement then default --- endLabel
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(hasElse || !isStatement) ? elseLabel : endLabel
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);
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//resolving entries' labels
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int i = 0;
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for (JetWhenEntry entry : expression.getEntries()) {
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v.visitLabel(entryLabels[i++]);
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FrameMap.Mark mark = myFrameMap.mark();
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gen(entry.getExpression(), resultType);
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mark.dropTo();
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if (!entry.isElse()) {
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v.goTo(endLabel);
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}
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}
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//there is no else-entry but this is not statement, so we should return Unit
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if (!hasElse && !isStatement) {
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v.visitLabel(elseLabel);
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// a result is expected
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if (Boolean.TRUE.equals(bindingContext.get(BindingContext.EXHAUSTIVE_WHEN, expression))) {
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// when() is supposed to be exhaustive
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throwNewException("kotlin/NoWhenBranchMatchedException");
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}
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else {
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// non-exhaustive when() with no else -> Unit must be expected
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StackValue.putUnitInstance(v);
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}
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}
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markLineNumber(expression);
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v.mark(endLabel);
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return StackValue.onStack(resultType);
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}
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private void generateSwitchLookupCall(Map<Integer, Label> transitions, Label defaultLabel) {
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int[] keys = new int[transitions.size()];
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Label[] labels = new Label[transitions.size()];
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int i = 0;
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for (Map.Entry<Integer,Label> transition : transitions.entrySet()) {
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keys[i] = transition.getKey();
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labels[i] = transition.getValue();
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i++;
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}
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//switch code
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v.lookupswitch(defaultLabel, keys, labels);
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}
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private boolean canSwitchBeUsedIn(JetWhenExpression expression, Type subjectType) {
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if (subjectType.getSort() != Type.INT) {
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return false;
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}
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for (JetWhenEntry entry : expression.getEntries()) {
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for (JetWhenCondition condition : entry.getConditions()) {
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if (!(condition instanceof JetWhenConditionWithExpression)) {
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return false;
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}
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//ensure that expression is constant
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JetExpression patternExpression = ((JetWhenConditionWithExpression) condition).getExpression();
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if (patternExpression == null) {
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return false;
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}
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CompileTimeConstant constant = getCompileTimeConstant(patternExpression, bindingContext);
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if (constant == null || !(constant instanceof IntValue)) {
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return false;
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}
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}
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}
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return true;
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}
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private void invokeFunctionByReference(JetSimpleNameExpression operationReference) {
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ResolvedCall<?> resolvedCall = bindingContext.get(RESOLVED_CALL, operationReference);
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Call call = bindingContext.get(CALL, operationReference);
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@@ -0,0 +1,75 @@
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fun foo1(x : Int) : Int {
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return when (x % 10) {
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1,2,3 -> 1
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4,5,6 -> 2
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7,8,9 -> 3
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else -> 4
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}
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}
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fun foo2(x : Int) : Int {
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when (x % 10) {
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1,2,3 -> return 1
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4,5,6 -> return 2
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7,8,9 -> return 3
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}
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return 4
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}
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fun foo3(x : Int) : Int {
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when (x % 10) {
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1 -> return 1
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2 -> return 1
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3 -> return 1
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4 -> return 2
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5 -> return 2
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6 -> return 2
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7 -> return 3
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8 -> return 3
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9 -> return 3
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}
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return 4
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}
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fun foo4(x : Int) : Int {
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return when (x % 10) {
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1 -> 1
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2 -> 1
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3 -> 1
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4 -> 2
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5 -> 2
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6 -> 2
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7 -> 3
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8 -> 3
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9 -> 3
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else -> 4
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}
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}
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fun test(foo : (Int) -> Int, name : String) : String {
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val foo0 = foo(10)
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var result = if (foo0 == 4) "" else "$name[10/$foo0/4]"
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for (i in 11..19) {
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val shouldBe = (i-11) / 3 + 1
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val fooI = foo(i)
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if (fooI != shouldBe) {
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result += "$name[$i/$fooI/$shouldBe]"
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}
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}
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return result
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}
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fun box(): String {
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val testResult = test({x -> foo1(x)}, "foo1") +
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test({x -> foo2(x)}, "foo2") +
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test({x -> foo3(x)}, "foo3") +
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test({x -> foo4(x)}, "foo4")
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if (testResult != "") return testResult
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return "OK"
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}
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@@ -5583,6 +5583,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
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doTest("compiler/testData/codegen/box/when/range.kt");
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}
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@TestMetadata("switchOptimization.kt")
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public void testSwitchOptimization() throws Exception {
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doTest("compiler/testData/codegen/box/when/switchOptimization.kt");
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}
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@TestMetadata("whenArgumentIsEvaluatedOnlyOnce.kt")
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public void testWhenArgumentIsEvaluatedOnlyOnce() throws Exception {
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doTest("compiler/testData/codegen/box/when/whenArgumentIsEvaluatedOnlyOnce.kt");
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