8022186: javac generates dead code if a try with an empty body has a finalizer
Reviewed-by: jjg
--- a/langtools/src/share/classes/com/sun/tools/javac/jvm/Gen.java Wed Jul 31 08:37:34 2013 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javac/jvm/Gen.java Tue Aug 06 15:08:49 2013 +0100
@@ -1478,74 +1478,82 @@
code.statBegin(TreeInfo.endPos(body));
genFinalizer(env);
code.statBegin(TreeInfo.endPos(env.tree));
- Chain exitChain = code.branch(goto_);
+ Chain exitChain;
+ if (startpc != endpc) {
+ exitChain = code.branch(goto_);
+ } else {
+ exitChain = code.branch(dontgoto);
+ }
endFinalizerGap(env);
- if (startpc != endpc) for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
- // start off with exception on stack
- code.entryPoint(stateTry, l.head.param.sym.type);
- genCatch(l.head, env, startpc, endpc, gaps);
- genFinalizer(env);
- if (hasFinalizer || l.tail.nonEmpty()) {
- code.statBegin(TreeInfo.endPos(env.tree));
- exitChain = Code.mergeChains(exitChain,
- code.branch(goto_));
+ if (startpc != endpc) {
+ for (List<JCCatch> l = catchers; l.nonEmpty(); l = l.tail) {
+ // start off with exception on stack
+ code.entryPoint(stateTry, l.head.param.sym.type);
+ genCatch(l.head, env, startpc, endpc, gaps);
+ genFinalizer(env);
+ if (hasFinalizer || l.tail.nonEmpty()) {
+ code.statBegin(TreeInfo.endPos(env.tree));
+ exitChain = Code.mergeChains(exitChain,
+ code.branch(goto_));
+ }
+ endFinalizerGap(env);
}
- endFinalizerGap(env);
- }
- if (hasFinalizer) {
- // Create a new register segement to avoid allocating
- // the same variables in finalizers and other statements.
- code.newRegSegment();
-
- // Add a catch-all clause.
-
- // start off with exception on stack
- int catchallpc = code.entryPoint(stateTry, syms.throwableType);
- // Register all exception ranges for catch all clause.
- // The range of the catch all clause is from the beginning
- // of the try or synchronized block until the present
- // code pointer excluding all gaps in the current
- // environment's GenContext.
- int startseg = startpc;
- while (env.info.gaps.nonEmpty()) {
- int endseg = env.info.gaps.next().intValue();
- registerCatch(body.pos(), startseg, endseg,
- catchallpc, 0);
- startseg = env.info.gaps.next().intValue();
- }
- code.statBegin(TreeInfo.finalizerPos(env.tree));
- code.markStatBegin();
+ if (hasFinalizer) {
+ // Create a new register segement to avoid allocating
+ // the same variables in finalizers and other statements.
+ code.newRegSegment();
+
+ // Add a catch-all clause.
+
+ // start off with exception on stack
+ int catchallpc = code.entryPoint(stateTry, syms.throwableType);
- Item excVar = makeTemp(syms.throwableType);
- excVar.store();
- genFinalizer(env);
- excVar.load();
- registerCatch(body.pos(), startseg,
- env.info.gaps.next().intValue(),
- catchallpc, 0);
- code.emitop0(athrow);
- code.markDead();
-
- // If there are jsr's to this finalizer, ...
- if (env.info.cont != null) {
- // Resolve all jsr's.
- code.resolve(env.info.cont);
-
- // Mark statement line number
+ // Register all exception ranges for catch all clause.
+ // The range of the catch all clause is from the beginning
+ // of the try or synchronized block until the present
+ // code pointer excluding all gaps in the current
+ // environment's GenContext.
+ int startseg = startpc;
+ while (env.info.gaps.nonEmpty()) {
+ int endseg = env.info.gaps.next().intValue();
+ registerCatch(body.pos(), startseg, endseg,
+ catchallpc, 0);
+ startseg = env.info.gaps.next().intValue();
+ }
code.statBegin(TreeInfo.finalizerPos(env.tree));
code.markStatBegin();
- // Save return address.
- LocalItem retVar = makeTemp(syms.throwableType);
- retVar.store();
+ Item excVar = makeTemp(syms.throwableType);
+ excVar.store();
+ genFinalizer(env);
+ excVar.load();
+ registerCatch(body.pos(), startseg,
+ env.info.gaps.next().intValue(),
+ catchallpc, 0);
+ code.emitop0(athrow);
+ code.markDead();
+
+ // If there are jsr's to this finalizer, ...
+ if (env.info.cont != null) {
+ // Resolve all jsr's.
+ code.resolve(env.info.cont);
- // Generate finalizer code.
- env.info.finalize.genLast();
+ // Mark statement line number
+ code.statBegin(TreeInfo.finalizerPos(env.tree));
+ code.markStatBegin();
+
+ // Save return address.
+ LocalItem retVar = makeTemp(syms.throwableType);
+ retVar.store();
- // Return.
- code.emitop1w(ret, retVar.reg);
- code.markDead();
+ // Generate finalizer code.
+ env.info.finalize.genLast();
+
+ // Return.
+ code.emitop1w(ret, retVar.reg);
+ code.markDead();
+ }
}
}
// Resolve all breaks.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/T8022186/DeadCodeGeneratedForEmptyTryTest.java Tue Aug 06 15:08:49 2013 +0100
@@ -0,0 +1,166 @@
+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8022186
+ * @summary javac generates dead code if a try with an empty body has a finalizer
+ */
+
+import com.sun.tools.classfile.Attribute;
+import com.sun.tools.classfile.ClassFile;
+import com.sun.tools.classfile.Code_attribute;
+import com.sun.tools.classfile.ConstantPool;
+import com.sun.tools.classfile.ConstantPool.CONSTANT_String_info;
+import com.sun.tools.classfile.ConstantPool.CPInfo;
+import com.sun.tools.classfile.ConstantPool.InvalidIndex;
+import com.sun.tools.classfile.Instruction;
+import com.sun.tools.classfile.Instruction.KindVisitor;
+import com.sun.tools.classfile.Instruction.TypeKind;
+import com.sun.tools.classfile.Method;
+import com.sun.tools.javac.util.Assert;
+import java.io.BufferedInputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class DeadCodeGeneratedForEmptyTryTest {
+
+ public static void main(String[] args) throws Exception {
+ new DeadCodeGeneratedForEmptyTryTest().run();
+ }
+
+ void run() throws Exception {
+ checkClassFile(Paths.get(System.getProperty("test.classes"),
+ this.getClass().getName() + "$Test.class"));
+ }
+
+ int utf8Index;
+ int numberOfRefToStr = 0;
+ ConstantPool constantPool;
+
+ void checkClassFile(final Path path) throws Exception {
+ ClassFile classFile = ClassFile.read(
+ new BufferedInputStream(Files.newInputStream(path)));
+ constantPool = classFile.constant_pool;
+ utf8Index = constantPool.getUTF8Index("STR_TO_LOOK_FOR");
+ for (Method method: classFile.methods) {
+ if (method.getName(constantPool).equals("methodToLookFor")) {
+ Code_attribute codeAtt = (Code_attribute)method.attributes.get(Attribute.Code);
+ for (Instruction inst: codeAtt.getInstructions()) {
+ inst.accept(codeVisitor, null);
+ }
+ }
+ }
+ Assert.check(numberOfRefToStr == 1,
+ "There should only be one reference to a CONSTANT_String_info structure in the generated code");
+ }
+
+ CodeVisitor codeVisitor = new CodeVisitor();
+
+ class CodeVisitor implements KindVisitor<Void, Void> {
+
+ void checkIndirectRefToString(int cp_index) {
+ try {
+ CPInfo cInfo = constantPool.get(cp_index);
+ if (cInfo instanceof CONSTANT_String_info) {
+ CONSTANT_String_info strInfo = (CONSTANT_String_info)cInfo;
+ if (strInfo.string_index == utf8Index) {
+ numberOfRefToStr++;
+ }
+ }
+ } catch (InvalidIndex ex) {
+ throw new AssertionError("invalid constant pool index at " + cp_index);
+ }
+ }
+
+ @Override
+ public Void visitNoOperands(Instruction instr, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitArrayType(Instruction instr, TypeKind kind, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitBranch(Instruction instr, int offset, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitConstantPoolRef(Instruction instr, int index, Void p) {
+ checkIndirectRefToString(index);
+ return null;
+ }
+
+ @Override
+ public Void visitConstantPoolRefAndValue(Instruction instr, int index, int value, Void p) {
+ checkIndirectRefToString(index);
+ return null;
+ }
+
+ @Override
+ public Void visitLocal(Instruction instr, int index, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitLocalAndValue(Instruction instr, int index, int value, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitLookupSwitch(Instruction instr, int default_, int npairs, int[] matches, int[] offsets, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitTableSwitch(Instruction instr, int default_, int low, int high, int[] offsets, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitValue(Instruction instr, int value, Void p) {
+ return null;
+ }
+
+ @Override
+ public Void visitUnknown(Instruction instr, Void p) {
+ return null;
+ }
+
+ }
+
+ public class Test {
+ void methodToLookFor() {
+ try {
+ } finally {
+ System.out.println("STR_TO_LOOK_FOR");
+ }
+ }
+ }
+}