Do not copy immediately created arrays in spread arguments

E.g., 'foo(x = *intArrayOf(42))'.

 #KT-20462 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java

@@ -2656,6 +2656,15 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
         return cur;
     }
 
+    private boolean canSkipArrayCopyForSpreadArgument(KtExpression spreadArgument) {
+        ResolvedCall<? extends CallableDescriptor> resolvedCall = CallUtilKt.getResolvedCall(spreadArgument, bindingContext);
+        if (resolvedCall == null) return false;
+
+        CallableDescriptor calleeDescriptor = resolvedCall.getResultingDescriptor();
+        return (calleeDescriptor instanceof ConstructorDescriptor) ||
+               CompileTimeConstantUtils.isArrayFunctionCall(resolvedCall) ||
+               (DescriptorUtils.getFqName(calleeDescriptor).asString().equals("kotlin.arrayOfNulls"));
+    }
 
     @NotNull
     public StackValue genVarargs(@NotNull VarargValueArgument valueArgument, @NotNull KotlinType outType) {
@@ -2678,10 +2687,13 @@ public class ExpressionCodegen extends KtVisitor<StackValue, StackValue> impleme
             if (size == 1) {
                 Type arrayType = getArrayType(arrayOfReferences ? AsmTypes.OBJECT_TYPE : elementType);
                 return StackValue.operation(type, adapter -> {
-                    gen(arguments.get(0).getArgumentExpression(), type);
+                    KtExpression spreadArgument = arguments.get(0).getArgumentExpression();
-                    v.dup();
+                    gen(spreadArgument, type);
-                    v.arraylength();
+                    if (!canSkipArrayCopyForSpreadArgument(spreadArgument)) {
-                    v.invokestatic("java/util/Arrays", "copyOf", Type.getMethodDescriptor(arrayType, arrayType, Type.INT_TYPE), false);
+                        v.dup();
+                        v.arraylength();
+                        v.invokestatic("java/util/Arrays", "copyOf", Type.getMethodDescriptor(arrayType, arrayType, Type.INT_TYPE), false);
+                    }
                     if (arrayOfReferences) {
                         v.checkcast(type);
                     }

compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt

@@ -0,0 +1,102 @@
+fun booleanVararg(vararg xs: Boolean) {
+    if (xs.size != 1 && xs[0] != true) throw AssertionError()
+}
+
+fun byteVararg(vararg xs: Byte) {
+    if (xs.size != 1 && xs[0] != 1.toByte()) throw AssertionError()
+}
+
+fun shortVararg(vararg xs: Short) {
+    if (xs.size != 1 && xs[0] != 1.toShort()) throw AssertionError()
+}
+
+fun intVararg(vararg xs: Int) {
+    if (xs.size != 1 && xs[0] != 1) throw AssertionError()
+}
+
+fun longVararg(vararg xs: Long) {
+    if (xs.size != 1 && xs[0] != 1L) throw AssertionError()
+}
+
+fun floatVararg(vararg xs: Float) {
+    if (xs.size != 1 && xs[0] != 1.0f) throw AssertionError()
+}
+
+fun doubleVararg(vararg xs: Double) {
+    if (xs.size != 1 && xs[0] != 1.0) throw AssertionError()
+}
+
+fun anyVararg(vararg xs: Any?) {
+    if (xs.size != 1 && (xs[0] != 1 && xs[0] != null)) throw AssertionError()
+}
+
+fun <T> genericVararg(vararg xs: T) {
+    if (xs.size != 1 && (xs[0] != 1 && xs[0] != null)) throw AssertionError()
+}
+
+fun box(): String {
+    booleanVararg(*booleanArrayOf(true))
+    booleanVararg(*BooleanArray(1))
+    booleanVararg(*BooleanArray(1) { true })
+    booleanVararg(xs = *booleanArrayOf(true))
+    booleanVararg(xs = *BooleanArray(1))
+    booleanVararg(xs = *BooleanArray(1) { true })
+
+    byteVararg(*byteArrayOf(1))
+    byteVararg(*ByteArray(1))
+    byteVararg(*ByteArray(1) { 1 })
+    byteVararg(xs = *byteArrayOf(1))
+    byteVararg(xs = *ByteArray(1))
+    byteVararg(xs = *ByteArray(1) { 1 })
+
+    shortVararg(*shortArrayOf(1))
+    shortVararg(*ShortArray(1))
+    shortVararg(*ShortArray(1) { 1 })
+    shortVararg(xs = *shortArrayOf(1))
+    shortVararg(xs = *ShortArray(1))
+    shortVararg(xs = *ShortArray(1) { 1 })
+
+    intVararg(*intArrayOf(1))
+    intVararg(*IntArray(1))
+    intVararg(*IntArray(1) { 1 })
+    intVararg(xs = *intArrayOf(1))
+    intVararg(xs = *IntArray(1))
+    intVararg(xs = *IntArray(1) { 1 })
+
+    longVararg(*longArrayOf(1L))
+    longVararg(*LongArray(1))
+    longVararg(*LongArray(1) { 1L })
+    longVararg(xs = *longArrayOf(1L))
+    longVararg(xs = *LongArray(1))
+    longVararg(xs = *LongArray(1) { 1L })
+
+    floatVararg(*floatArrayOf(1.0f))
+    floatVararg(*FloatArray(1))
+    floatVararg(*FloatArray(1) { 1.0f })
+    floatVararg(xs = *floatArrayOf(1.0f))
+    floatVararg(xs = *FloatArray(1))
+    floatVararg(xs = *FloatArray(1) { 1.0f })
+
+    doubleVararg(*doubleArrayOf(1.0))
+    doubleVararg(*DoubleArray(1))
+    doubleVararg(*DoubleArray(1) { 1.0 })
+    doubleVararg(xs = *doubleArrayOf(1.0))
+    doubleVararg(xs = *DoubleArray(1))
+    doubleVararg(xs = *DoubleArray(1) { 1.0 })
+
+    anyVararg(*arrayOf(1))
+    anyVararg(*Array(1) { 1 })
+    anyVararg(*arrayOfNulls(1))
+    anyVararg(xs = *arrayOf(1))
+    anyVararg(xs = *Array(1) { 1 })
+    anyVararg(xs = *arrayOfNulls(1))
+
+    genericVararg(*arrayOf(1))
+    genericVararg(*Array(1) { 1 })
+    genericVararg(*arrayOfNulls<Int>(1))
+    genericVararg(xs = *arrayOf(1))
+    genericVararg(xs = *Array(1) { 1 })
+    genericVararg(xs = *arrayOfNulls<Int>(1))
+
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/varargs/doNotCopyImmediatelyCreatedArrays.kt

@@ -0,0 +1,77 @@
+fun booleanVararg(vararg xs: Boolean) {}
+fun byteVararg(vararg xs: Byte) {}
+fun shortVararg(vararg xs: Short) {}
+fun intVararg(vararg xs: Int) {}
+fun longVararg(vararg xs: Long) {}
+fun floatVararg(vararg xs: Float) {}
+fun doubleVararg(vararg xs: Double) {}
+fun anyVararg(vararg xs: Any?) {}
+fun <T> genericVararg(vararg xs: T) {}
+
+fun test() {
+    booleanVararg(*booleanArrayOf(true))
+    booleanVararg(*BooleanArray(1))
+    booleanVararg(*BooleanArray(1) { true })
+    booleanVararg(xs = *booleanArrayOf(true))
+    booleanVararg(xs = *BooleanArray(1))
+    booleanVararg(xs = *BooleanArray(1) { true })
+
+    byteVararg(*byteArrayOf(1))
+    byteVararg(*ByteArray(1))
+    byteVararg(*ByteArray(1) { 1 })
+    byteVararg(xs = *byteArrayOf(1))
+    byteVararg(xs = *ByteArray(1))
+    byteVararg(xs = *ByteArray(1) { 1 })
+
+    shortVararg(*shortArrayOf(1))
+    shortVararg(*ShortArray(1))
+    shortVararg(*ShortArray(1) { 1 })
+    shortVararg(xs = *shortArrayOf(1))
+    shortVararg(xs = *ShortArray(1))
+    shortVararg(xs = *ShortArray(1) { 1 })
+
+    intVararg(*intArrayOf(1))
+    intVararg(*IntArray(1))
+    intVararg(*IntArray(1) { 1 })
+    intVararg(xs = *intArrayOf(1))
+    intVararg(xs = *IntArray(1))
+    intVararg(xs = *IntArray(1) { 1 })
+
+    longVararg(*longArrayOf(1L))
+    longVararg(*LongArray(1))
+    longVararg(*LongArray(1) { 1L })
+    longVararg(xs = *longArrayOf(1L))
+    longVararg(xs = *LongArray(1))
+    longVararg(xs = *LongArray(1) { 1L })
+
+    floatVararg(*floatArrayOf(1.0f))
+    floatVararg(*FloatArray(1))
+    floatVararg(*FloatArray(1) { 1.0f })
+    floatVararg(xs = *floatArrayOf(1.0f))
+    floatVararg(xs = *FloatArray(1))
+    floatVararg(xs = *FloatArray(1) { 1.0f })
+
+    doubleVararg(*doubleArrayOf(1.0))
+    doubleVararg(*DoubleArray(1))
+    doubleVararg(*DoubleArray(1) { 1.0 })
+    doubleVararg(xs = *doubleArrayOf(1.0))
+    doubleVararg(xs = *DoubleArray(1))
+    doubleVararg(xs = *DoubleArray(1) { 1.0 })
+
+    anyVararg(*arrayOf(1))
+    anyVararg(*Array(1) { 1 })
+    anyVararg(*arrayOfNulls(1))
+    anyVararg(xs = *arrayOf(1))
+    anyVararg(xs = *Array(1) { 1 })
+    anyVararg(xs = *arrayOfNulls(1))
+
+    genericVararg(*arrayOf(1))
+    genericVararg(*Array(1) { 1 })
+    genericVararg(*arrayOfNulls<Int>(1))
+    genericVararg(xs = *arrayOf(1))
+    genericVararg(xs = *Array(1) { 1 })
+    genericVararg(xs = *arrayOfNulls<Int>(1))
+}
+
+// 0 copyOf
+// 0 clone

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -19688,6 +19688,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("doNotCopyImmediatelyCreatedArrays.kt")
+        public void testDoNotCopyImmediatelyCreatedArrays() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1978.kt")
         public void testKt1978() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/kt1978.kt");

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

@@ -19688,6 +19688,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("doNotCopyImmediatelyCreatedArrays.kt")
+        public void testDoNotCopyImmediatelyCreatedArrays() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1978.kt")
         public void testKt1978() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/kt1978.kt");

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

@@ -2202,6 +2202,21 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         }
     }
 
+    @TestMetadata("compiler/testData/codegen/bytecodeText/varargs")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Varargs extends AbstractBytecodeTextTest {
+        public void testAllFilesPresentInVarargs() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/bytecodeText/varargs"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("doNotCopyImmediatelyCreatedArrays.kt")
+        public void testDoNotCopyImmediatelyCreatedArrays() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeText/varargs/doNotCopyImmediatelyCreatedArrays.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("compiler/testData/codegen/bytecodeText/when")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

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

@@ -19688,6 +19688,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             doTest(fileName);
         }
 
+        @TestMetadata("doNotCopyImmediatelyCreatedArrays.kt")
+        public void testDoNotCopyImmediatelyCreatedArrays() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1978.kt")
         public void testKt1978() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/kt1978.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -23666,6 +23666,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
+        @TestMetadata("doNotCopyImmediatelyCreatedArrays.kt")
+        public void testDoNotCopyImmediatelyCreatedArrays() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt1978.kt")
         public void testKt1978() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/vararg/kt1978.kt");