Dead code elimination

#KT-6602 Fixed
 #KT-6305 Fixed
 #KT-5656 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/DeadCodeEliminationMethodTransformer.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * 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.jetbrains.kotlin.codegen.optimization
+
+import org.jetbrains.org.objectweb.asm.tree.MethodNode
+import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
+import org.jetbrains.kotlin.codegen.optimization.common.OptimizationBasicInterpreter
+import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
+
+public class DeadCodeEliminationMethodTransformer : MethodTransformer() {
+    override fun transform(internalClassName: String, methodNode: MethodNode) {
+        val frames = MethodTransformer.analyze(internalClassName, methodNode, OptimizationBasicInterpreter())
+        val insnList = methodNode.instructions
+        val insnsArray = insnList.toArray()
+
+        // Do not remove not meaningful nodes (labels/linenumbers) because they can be referred
+        // by try/catch blocks or local variables table
+        // We remove unneeded ones further after all optimizations by calling CommonPackage.prepareForEmitting(methodNode)
+        insnsArray.zip(frames).filter {
+            it.second == null && it.first.isMeaningful
+        }.forEach { insnList.remove(it.first) }
+    }
+}

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/OptimizationMethodVisitor.java

@@ -21,6 +21,7 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.codegen.inline.InlineCodegenUtil;
 import org.jetbrains.kotlin.codegen.optimization.boxing.RedundantBoxingMethodTransformer;
 import org.jetbrains.kotlin.codegen.optimization.boxing.RedundantNullCheckMethodTransformer;
+import org.jetbrains.kotlin.codegen.optimization.common.CommonPackage;
 import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer;
 import org.jetbrains.org.objectweb.asm.MethodVisitor;
 import org.jetbrains.org.objectweb.asm.Opcodes;
@@ -35,8 +36,11 @@ import java.util.List;
 public class OptimizationMethodVisitor extends MethodVisitor {
     private static final int MEMORY_LIMIT_BY_METHOD_MB = 50;
     private static final MethodTransformer[] TRANSFORMERS = new MethodTransformer[]{
-            new RedundantNullCheckMethodTransformer(), new RedundantBoxingMethodTransformer(),
+            new RedundantNullCheckMethodTransformer(),
-            new RedundantGotoMethodTransformer(), new StoreStackBeforeInlineMethodTransformer()
+            new RedundantBoxingMethodTransformer(),
+            new DeadCodeEliminationMethodTransformer(),
+            new RedundantGotoMethodTransformer(),
+            new StoreStackBeforeInlineMethodTransformer()
     };
 
     private final MethodNode methodNode;
@@ -70,6 +74,7 @@ public class OptimizationMethodVisitor extends MethodVisitor {
             for (MethodTransformer transformer : TRANSFORMERS) {
                 transformer.transform("fake", methodNode);
             }
+            CommonPackage.prepareForEmitting(methodNode);
         }
 
         methodNode.accept(new EndIgnoringMethodVisitorDecorator(Opcodes.ASM5, delegate));

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/RedundantGotoMethodTransformer.kt

@@ -22,6 +22,7 @@ import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
 import org.jetbrains.org.objectweb.asm.tree.LabelNode
 import org.jetbrains.org.objectweb.asm.Opcodes
 import org.jetbrains.org.objectweb.asm.tree.JumpInsnNode
+import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
 
 public class RedundantGotoMethodTransformer : MethodTransformer() {
     /**
@@ -53,9 +54,3 @@ public class RedundantGotoMethodTransformer : MethodTransformer() {
         }
     }
 }
-
-private val AbstractInsnNode.isMeaningful : Boolean get() =
-    when (this.getType()) {
-        AbstractInsnNode.LABEL, AbstractInsnNode.LINE, AbstractInsnNode.FRAME -> false
-        else -> true
-    }

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/common/Util.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * 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.jetbrains.kotlin.codegen.optimization.common
+
+import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
+import org.jetbrains.org.objectweb.asm.Opcodes
+import org.jetbrains.org.objectweb.asm.tree.analysis.Frame
+import org.jetbrains.org.objectweb.asm.tree.analysis.BasicValue
+import org.jetbrains.org.objectweb.asm.tree.MethodNode
+
+val AbstractInsnNode.isMeaningful : Boolean get() =
+    when (this.getType()) {
+        AbstractInsnNode.LABEL, AbstractInsnNode.LINE, AbstractInsnNode.FRAME -> false
+        else -> true
+    }
+
+class InsnStream(val from: AbstractInsnNode, val to: AbstractInsnNode?) : Stream<AbstractInsnNode> {
+    override fun iterator(): Iterator<AbstractInsnNode> {
+        return object : Iterator<AbstractInsnNode> {
+            var current = from
+            override fun next(): AbstractInsnNode {
+                val result = current
+                current = current.getNext()
+                return result
+            }
+            override fun hasNext() = current != to
+        }
+    }
+}
+
+fun MethodNode.prepareForEmitting() {
+    tryCatchBlocks = tryCatchBlocks.filter { tcb ->
+        InsnStream(tcb.start, tcb.end).any { insn ->
+            insn.isMeaningful
+        }
+    }
+
+    // local variables with live ranges starting after last meaningful instruction lead to VerifyError
+    localVariables = localVariables.filter { lv ->
+        InsnStream(lv.start, instructions.getLast()).any { insn ->
+            insn.isMeaningful
+        }
+    }
+
+    // We should remove linenumbers after last meaningful instruction
+    // because they point to index of non-existing instruction and it leads to VerifyError
+    var current = instructions.getLast()
+    while (!current.isMeaningful) {
+        val prev = current.getPrevious()
+
+        if (current.getType() == AbstractInsnNode.LINE) {
+            instructions.remove(current)
+        }
+
+        current = prev
+    }
+}

compiler/testData/codegen/boxWithStdlib/deadCodeElimination/emptyVariableRange.kt

@@ -0,0 +1,12 @@
+import kotlin.test.assertEquals
+
+fun foo(): Int {
+    return 1
+    // val xyz has empty live range because everything after return will be removed as dead
+    val xyz = 1
+}
+
+fun box(): String {
+    assertEquals(1, foo())
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/deadCodeElimination/boxing.kt

@@ -0,0 +1,16 @@
+fun foo(x: Any?) {}
+
+fun box() {
+    val x: Int? = 1
+    x!!
+
+    val z: Int? = if (1 == 1) x else null
+    z!!
+
+    foo(1 as java.lang.Integer)
+}
+
+// 0 IFNULL
+// 1 IFNONNULL
+// 1 throwNpe
+// 0 ATHROW

compiler/testData/codegen/bytecodeText/deadCodeElimination/emptyVariableRange.kt

@@ -0,0 +1,7 @@
+fun foo() {
+    return
+    // val xyz has empty live range because everything after return will be removed as dead
+    val xyz = 1
+}
+
+// 0 xyz

compiler/testData/codegen/bytecodeText/deadCodeElimination/lastReturn.kt

@@ -0,0 +1,23 @@
+import kotlin.test.assertEquals
+
+fun foo(value: Boolean): Int {
+    if (value)
+        return 1
+    else
+        return 2
+}
+
+fun box(): String {
+    assertEquals(1, foo(true))
+    assertEquals(2, foo(false))
+    
+    return "OK"
+}
+
+/*
+    3 return's are defined in functions
+    2 are from package facade
+    1 is from package clinit
+*/
+
+// 6 RETURN

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -30,7 +30,7 @@ import java.util.regex.Pattern;
 @SuppressWarnings("all")
 @TestMetadata("compiler/testData/codegen/bytecodeText")
 @TestDataPath("$PROJECT_ROOT")
-@InnerTestClasses({BytecodeTextTestGenerated.BoxingOptimization.class, BytecodeTextTestGenerated.Constants.class, BytecodeTextTestGenerated.DirectInvoke.class, BytecodeTextTestGenerated.Inline.class, BytecodeTextTestGenerated.LazyCodegen.class, BytecodeTextTestGenerated.LineNumbers.class, BytecodeTextTestGenerated.Statements.class, BytecodeTextTestGenerated.StaticFields.class, BytecodeTextTestGenerated.StoreStackBeforeInline.class, BytecodeTextTestGenerated.When.class, BytecodeTextTestGenerated.WhenEnumOptimization.class, BytecodeTextTestGenerated.WhenStringOptimization.class})
+@InnerTestClasses({BytecodeTextTestGenerated.BoxingOptimization.class, BytecodeTextTestGenerated.Constants.class, BytecodeTextTestGenerated.DeadCodeElimination.class, BytecodeTextTestGenerated.DirectInvoke.class, BytecodeTextTestGenerated.Inline.class, BytecodeTextTestGenerated.LazyCodegen.class, BytecodeTextTestGenerated.LineNumbers.class, BytecodeTextTestGenerated.Statements.class, BytecodeTextTestGenerated.StaticFields.class, BytecodeTextTestGenerated.StoreStackBeforeInline.class, BytecodeTextTestGenerated.When.class, BytecodeTextTestGenerated.WhenEnumOptimization.class, BytecodeTextTestGenerated.WhenStringOptimization.class})
 @RunWith(JUnit3RunnerWithInners.class)
 public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
     @TestMetadata("accessorForProtected.kt")
@@ -301,6 +301,33 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         }
     }
 
+    @TestMetadata("compiler/testData/codegen/bytecodeText/deadCodeElimination")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class DeadCodeElimination extends AbstractBytecodeTextTest {
+        public void testAllFilesPresentInDeadCodeElimination() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/bytecodeText/deadCodeElimination"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("boxing.kt")
+        public void testBoxing() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/deadCodeElimination/boxing.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("emptyVariableRange.kt")
+        public void testEmptyVariableRange() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/deadCodeElimination/emptyVariableRange.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("lastReturn.kt")
+        public void testLastReturn() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/deadCodeElimination/lastReturn.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("compiler/testData/codegen/bytecodeText/directInvoke")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java

@@ -30,7 +30,7 @@ import java.util.regex.Pattern;
 @SuppressWarnings("all")
 @TestMetadata("compiler/testData/codegen/boxWithStdlib")
 @TestDataPath("$PROJECT_ROOT")
-@InnerTestClasses({BlackBoxWithStdlibCodegenTestGenerated.Annotations.class, BlackBoxWithStdlibCodegenTestGenerated.Arrays.class, BlackBoxWithStdlibCodegenTestGenerated.BoxingOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.CallableReference.class, BlackBoxWithStdlibCodegenTestGenerated.Casts.class, BlackBoxWithStdlibCodegenTestGenerated.Classes.class, BlackBoxWithStdlibCodegenTestGenerated.DataClasses.class, BlackBoxWithStdlibCodegenTestGenerated.DefaultArguments.class, BlackBoxWithStdlibCodegenTestGenerated.Enum.class, BlackBoxWithStdlibCodegenTestGenerated.Evaluate.class, BlackBoxWithStdlibCodegenTestGenerated.FullJdk.class, BlackBoxWithStdlibCodegenTestGenerated.HashPMap.class, BlackBoxWithStdlibCodegenTestGenerated.Intrinsics.class, BlackBoxWithStdlibCodegenTestGenerated.JdkAnnotations.class, BlackBoxWithStdlibCodegenTestGenerated.LazyCodegen.class, BlackBoxWithStdlibCodegenTestGenerated.LocalFunInLambda.class, BlackBoxWithStdlibCodegenTestGenerated.MultiDeclForArray.class, BlackBoxWithStdlibCodegenTestGenerated.Native.class, BlackBoxWithStdlibCodegenTestGenerated.NonLocalReturns.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformNames.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformStatic.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformTypes.class, BlackBoxWithStdlibCodegenTestGenerated.Ranges.class, BlackBoxWithStdlibCodegenTestGenerated.Reflection.class, BlackBoxWithStdlibCodegenTestGenerated.Regressions.class, BlackBoxWithStdlibCodegenTestGenerated.Reified.class, BlackBoxWithStdlibCodegenTestGenerated.StoreStackBeforeInline.class, BlackBoxWithStdlibCodegenTestGenerated.Strings.class, BlackBoxWithStdlibCodegenTestGenerated.ToArray.class, BlackBoxWithStdlibCodegenTestGenerated.Vararg.class, BlackBoxWithStdlibCodegenTestGenerated.When.class, BlackBoxWithStdlibCodegenTestGenerated.WhenEnumOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.WhenStringOptimization.class})
+@InnerTestClasses({BlackBoxWithStdlibCodegenTestGenerated.Annotations.class, BlackBoxWithStdlibCodegenTestGenerated.Arrays.class, BlackBoxWithStdlibCodegenTestGenerated.BoxingOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.CallableReference.class, BlackBoxWithStdlibCodegenTestGenerated.Casts.class, BlackBoxWithStdlibCodegenTestGenerated.Classes.class, BlackBoxWithStdlibCodegenTestGenerated.DataClasses.class, BlackBoxWithStdlibCodegenTestGenerated.DeadCodeElimination.class, BlackBoxWithStdlibCodegenTestGenerated.DefaultArguments.class, BlackBoxWithStdlibCodegenTestGenerated.Enum.class, BlackBoxWithStdlibCodegenTestGenerated.Evaluate.class, BlackBoxWithStdlibCodegenTestGenerated.FullJdk.class, BlackBoxWithStdlibCodegenTestGenerated.HashPMap.class, BlackBoxWithStdlibCodegenTestGenerated.Intrinsics.class, BlackBoxWithStdlibCodegenTestGenerated.JdkAnnotations.class, BlackBoxWithStdlibCodegenTestGenerated.LazyCodegen.class, BlackBoxWithStdlibCodegenTestGenerated.LocalFunInLambda.class, BlackBoxWithStdlibCodegenTestGenerated.MultiDeclForArray.class, BlackBoxWithStdlibCodegenTestGenerated.Native.class, BlackBoxWithStdlibCodegenTestGenerated.NonLocalReturns.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformNames.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformStatic.class, BlackBoxWithStdlibCodegenTestGenerated.PlatformTypes.class, BlackBoxWithStdlibCodegenTestGenerated.Ranges.class, BlackBoxWithStdlibCodegenTestGenerated.Reflection.class, BlackBoxWithStdlibCodegenTestGenerated.Regressions.class, BlackBoxWithStdlibCodegenTestGenerated.Reified.class, BlackBoxWithStdlibCodegenTestGenerated.StoreStackBeforeInline.class, BlackBoxWithStdlibCodegenTestGenerated.Strings.class, BlackBoxWithStdlibCodegenTestGenerated.ToArray.class, BlackBoxWithStdlibCodegenTestGenerated.Vararg.class, BlackBoxWithStdlibCodegenTestGenerated.When.class, BlackBoxWithStdlibCodegenTestGenerated.WhenEnumOptimization.class, BlackBoxWithStdlibCodegenTestGenerated.WhenStringOptimization.class})
 @RunWith(JUnit3RunnerWithInners.class)
 public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
     public void testAllFilesPresentInBoxWithStdlib() throws Exception {
@@ -1186,6 +1186,21 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
         }
     }
 
+    @TestMetadata("compiler/testData/codegen/boxWithStdlib/deadCodeElimination")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class DeadCodeElimination extends AbstractBlackBoxCodegenTest {
+        public void testAllFilesPresentInDeadCodeElimination() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/boxWithStdlib/deadCodeElimination"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("emptyVariableRange.kt")
+        public void testEmptyVariableRange() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/deadCodeElimination/emptyVariableRange.kt");
+            doTestWithStdlib(fileName);
+        }
+    }
+
     @TestMetadata("compiler/testData/codegen/boxWithStdlib/defaultArguments")
     @TestDataPath("$PROJECT_ROOT")
     @InnerTestClasses({DefaultArguments.Constructor.class})