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8357185: Redundant local variables with unconditionally matching primitive patterns

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Reviewed-by: jlahoda, abimpoudis
This commit is contained in:
Chen Liang 2025-07-09 12:14:14 +00:00
parent eec04dd010
commit d886ae12a2
4 changed files with 145 additions and 38 deletions
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76
src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
View File

@ -2831,47 +2831,55 @@ public class Lower extends TreeTranslator {
*/
public void visitTypeTest(JCInstanceOf tree) {
if (tree.expr.type.isPrimitive() || tree.pattern.type.isPrimitive()) {
JCExpression exactnessCheck = null;
JCStatement prefixStatement;
JCExpression exactnessCheck;
JCExpression instanceOfExpr = translate(tree.expr);
// preserving the side effects of the value
VarSymbol dollar_s = new VarSymbol(FINAL | SYNTHETIC,
names.fromString("tmp" + variableIndex++ + this.target.syntheticNameChar()),
types.erasure(tree.expr.type),
currentMethodSym);
JCStatement var = make.at(tree.pos())
.VarDef(dollar_s, instanceOfExpr);
if (types.isUnconditionallyExact(tree.expr.type, tree.pattern.type)) {
// instanceOfExpr; true
prefixStatement = make.Exec(instanceOfExpr);
exactnessCheck = make.Literal(BOOLEAN, 1).setType(syms.booleanType.constType(1));
}
else if (tree.expr.type.isReference()) {
JCExpression nullCheck =
makeBinary(NE,
make.Ident(dollar_s),
makeNull());
} else if (tree.expr.type.isPrimitive()) {
// ExactConversionSupport.isXxxExact(instanceOfExpr)
prefixStatement = null;
exactnessCheck = getExactnessCheck(tree, instanceOfExpr);
} else if (tree.expr.type.isReference()) {
if (types.isUnconditionallyExact(types.unboxedType(tree.expr.type), tree.pattern.type)) {
exactnessCheck = nullCheck;
} else if (types.unboxedType(tree.expr.type).isPrimitive()) {
exactnessCheck =
makeBinary(AND,
nullCheck,
getExactnessCheck(tree, boxIfNeeded(make.Ident(dollar_s), types.unboxedType(tree.expr.type))));
// instanceOfExpr != null
prefixStatement = null;
exactnessCheck = makeBinary(NE, instanceOfExpr, makeNull());
} else {
exactnessCheck =
makeBinary(AND,
nullCheck,
make.at(tree.pos())
.TypeTest(make.Ident(dollar_s), make.Type(types.boxedClass(tree.pattern.type).type))
.setType(syms.booleanType));
}
}
else if (tree.expr.type.isPrimitive()) {
exactnessCheck = getExactnessCheck(tree, make.Ident(dollar_s));
}
// We read the result of instanceOfExpr, so create variable
VarSymbol dollar_s = new VarSymbol(FINAL | SYNTHETIC,
names.fromString("tmp" + variableIndex++ + this.target.syntheticNameChar()),
types.erasure(tree.expr.type),
currentMethodSym);
prefixStatement = make.at(tree.pos())
.VarDef(dollar_s, instanceOfExpr);
result = make.LetExpr(List.of(var), exactnessCheck)
JCExpression nullCheck =
makeBinary(NE,
make.Ident(dollar_s),
makeNull());
if (types.unboxedType(tree.expr.type).isPrimitive()) {
exactnessCheck =
makeBinary(AND,
nullCheck,
getExactnessCheck(tree, boxIfNeeded(make.Ident(dollar_s), types.unboxedType(tree.expr.type))));
} else {
exactnessCheck =
makeBinary(AND,
nullCheck,
make.at(tree.pos())
.TypeTest(make.Ident(dollar_s), make.Type(types.boxedClass(tree.pattern.type).type))
.setType(syms.booleanType));
}
}
} else {
throw Assert.error("Non primitive or reference type: " + tree.expr.type);
}
result = (prefixStatement == null ? exactnessCheck : make.LetExpr(List.of(prefixStatement), exactnessCheck))
.setType(syms.booleanType);
} else {
tree.expr = translate(tree.expr);

83
test/langtools/tools/javac/patterns/PrimitiveInstanceOfBytecodeTest.java Normal file
View File

@ -0,0 +1,83 @@
/*
* Copyright (c) 2025, 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.
*
* 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.
*/
import java.lang.classfile.Attributes;
import java.lang.classfile.ClassFile;
import java.lang.classfile.instruction.LoadInstruction;
import java.lang.classfile.instruction.StoreInstruction;
import java.util.BitSet;
import java.util.Map;
import jdk.test.lib.compiler.InMemoryJavaCompiler;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
/*
* @test
* @bug 8357185
* @enablePreview
* @summary No unused local variable in unconditionally exact primitive patterns
* @library /test/lib
* @run junit PrimitiveInstanceOfBytecodeTest
*/
public class PrimitiveInstanceOfBytecodeTest {
private static final String SOURCE = """
public class Test {
public record A(int i) {}
public Integer get(A a) {
if (a instanceof A(int i)) {
return i;
}
return null;
}
}
""";
@Test
public void testNoUnusedVarInRecordPattern() {
var testBytes = InMemoryJavaCompiler.compile(Map.of("Test", SOURCE)).get("Test");
var code = ClassFile.of().parse(testBytes).methods().stream()
.filter(m -> m.methodName().equalsString("get")).findFirst()
.orElseThrow().findAttribute(Attributes.code()).orElseThrow();
BitSet stores = new BitSet(code.maxLocals());
BitSet loads = new BitSet(code.maxLocals());
code.forEach(ce -> {
switch (ce) {
case StoreInstruction store -> stores.set(store.slot());
case LoadInstruction load -> loads.set(load.slot());
default -> {}
}
});
// [this, a] are built-in locals that may be unused
loads.clear(0, 2);
stores.clear(0, 2);
if (!loads.equals(stores)) {
System.err.println("Loads: " + loads);
System.err.println("Stores: " + stores);
System.err.println(code.toDebugString());
fail("Store and load mismatch, see stderr");
}
}
}

12
test/langtools/tools/javac/patterns/PrimitiveInstanceOfPatternOpWithTopLevelPatterns.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2024, 2025, 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
@ -23,7 +23,7 @@
/*
* @test
* @bug 8304487 8325257 8327683 8330387
* @bug 8304487 8325257 8327683 8330387 8357185
* @summary Compiler Implementation for Primitive types in patterns, instanceof, and switch (Preview)
* @enablePreview
* @compile PrimitiveInstanceOfPatternOpWithTopLevelPatterns.java
@ -52,6 +52,7 @@ public class PrimitiveInstanceOfPatternOpWithTopLevelPatterns {
assertEquals(true, narrowingAndUnboxing());
assertEquals(true, patternExtractRecordComponent());
assertEquals(true, exprMethod());
assertEquals(true, exprMethodSideEffect());
assertEquals(true, exprStaticallyQualified());
}
@ -173,6 +174,13 @@ public class PrimitiveInstanceOfPatternOpWithTopLevelPatterns {
return meth() instanceof int ii;
}
static int sideEffect;
public static Integer methSideEffect() { sideEffect++; return 42;}
public static boolean exprMethodSideEffect() {
sideEffect = 5;
return methSideEffect() instanceof int ii && sideEffect == 6;
}
public class A1 {
public static int i = 42;
}

12
test/langtools/tools/javac/patterns/PrimitiveInstanceOfTypeComparisonOp.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2024, 2025, 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
@ -23,7 +23,7 @@
/*
* @test
* @bug 8304487 8325257 8327683 8330387
* @bug 8304487 8325257 8327683 8330387 8357185
* @summary Compiler Implementation for Primitive types in patterns, instanceof, and switch (Preview)
* @enablePreview
* @compile PrimitiveInstanceOfTypeComparisonOp.java
@ -52,6 +52,7 @@ public class PrimitiveInstanceOfTypeComparisonOp {
assertEquals(true, narrowingAndUnboxing());
assertEquals(true, patternExtractRecordComponent());
assertEquals(true, exprMethod());
assertEquals(true, exprMethodSideEffect());
assertEquals(true, exprStaticallyQualified());
}
@ -173,6 +174,13 @@ public class PrimitiveInstanceOfTypeComparisonOp {
return meth() instanceof int;
}
static int sideEffect;
public static Integer methSideEffect() { sideEffect++; return 42;}
public static boolean exprMethodSideEffect() {
sideEffect = 5;
return methSideEffect() instanceof int && sideEffect == 6;
}
public class A1 {
public static int i = 42;
}