diff options
6 files changed, 242 insertions, 103 deletions
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala index a28d4b0083..8a90eb9780 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala @@ -202,14 +202,14 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { val hasElse = !elsep.isEmpty val postIf = if (hasElse) new asm.Label else failure - genCond(condp, success, failure) + genCond(condp, success, failure, targetIfNoJump = success) + markProgramPoint(success) val thenKind = tpeTK(thenp) val elseKind = if (!hasElse) UNIT else tpeTK(elsep) def hasUnitBranch = (thenKind == UNIT || elseKind == UNIT) val resKind = if (hasUnitBranch) UNIT else tpeTK(tree) - markProgramPoint(success) genLoad(thenp, resKind) if (hasElse) { bc goTo postIf } markProgramPoint(failure) @@ -234,14 +234,14 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { else if (isArrayOp(code)) genArrayOp(tree, code, expectedType) else if (isLogicalOp(code) || isComparisonOp(code)) { val success, failure, after = new asm.Label - genCond(tree, success, failure) + genCond(tree, success, failure, targetIfNoJump = success) // success block - markProgramPoint(success) - bc boolconst true - bc goTo after + markProgramPoint(success) + bc boolconst true + bc goTo after // failure block - markProgramPoint(failure) - bc boolconst false + markProgramPoint(failure) + bc boolconst false // after markProgramPoint(after) @@ -717,7 +717,7 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { // for callsites marked `f(): @inline/noinline`. For nullary calls, the attachment // is on the Select node (not on the Apply node added by UnCurry). def checkInlineAnnotated(t: Tree): Unit = { - if (t.hasAttachment[InlineAnnotatedAttachment]) bc.jmethod.instructions.getLast match { + if (t.hasAttachment[InlineAnnotatedAttachment]) lastInsn match { case m: MethodInsnNode => if (app.hasAttachment[NoInlineCallsiteAttachment.type]) noInlineAnnotatedCallsites += m else inlineAnnotatedCallsites += m @@ -888,10 +888,24 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { * emitted instruction was an ATHROW. As explained above, it is OK to emit a second ATHROW, * the verifiers will be happy. */ - emit(asm.Opcodes.ATHROW) + if (lastInsn.getOpcode != asm.Opcodes.ATHROW) + emit(asm.Opcodes.ATHROW) } else if (from.isNullType) { - bc drop from - emit(asm.Opcodes.ACONST_NULL) + /* After loading an expression of type `scala.runtime.Null$`, introduce POP; ACONST_NULL. + * This is required to pass the verifier: in Scala's type system, Null conforms to any + * reference type. In bytecode, the type Null is represented by scala.runtime.Null$, which + * is not a subtype of all reference types. Example: + * + * def nl: Null = null // in bytecode, nl has return type scala.runtime.Null$ + * val a: String = nl // OK for Scala but not for the JVM, scala.runtime.Null$ does not conform to String + * + * In order to fix the above problem, the value returned by nl is dropped and ACONST_NULL is + * inserted instead - after all, an expression of type scala.runtime.Null$ can only be null. + */ + if (lastInsn.getOpcode != asm.Opcodes.ACONST_NULL) { + bc drop from + emit(asm.Opcodes.ACONST_NULL) + } } else (from, to) match { case (BYTE, LONG) | (SHORT, LONG) | (CHAR, LONG) | (INT, LONG) => bc.emitT2T(INT, LONG) @@ -1108,53 +1122,58 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { } /* Emit code to compare the two top-most stack values using the 'op' operator. */ - private def genCJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType) { - if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT - bc.emitIF_ICMP(op, success) - } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) - bc.emitIF_ACMP(op, success) - } else { - (tk: @unchecked) match { - case LONG => emit(asm.Opcodes.LCMP) - case FLOAT => - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) - else emit(asm.Opcodes.FCMPL) - case DOUBLE => - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) - else emit(asm.Opcodes.DCMPL) + private def genCJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType, targetIfNoJump: asm.Label) { + if (targetIfNoJump == success) genCJUMP(failure, success, op.negate, tk, targetIfNoJump) + else { + if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT + bc.emitIF_ICMP(op, success) + } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) + bc.emitIF_ACMP(op, success) + } else { + (tk: @unchecked) match { + case LONG => emit(asm.Opcodes.LCMP) + case FLOAT => + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) + else emit(asm.Opcodes.FCMPL) + case DOUBLE => + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) + else emit(asm.Opcodes.DCMPL) + } + bc.emitIF(op, success) } - bc.emitIF(op, success) + if (targetIfNoJump != failure) bc goTo failure } - bc goTo failure } /* Emits code to compare (and consume) stack-top and zero using the 'op' operator */ - private def genCZJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType) { - if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT - bc.emitIF(op, success) - } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) - // @unchecked because references aren't compared with GT, GE, LT, LE. - (op : @unchecked) match { - case TestOp.EQ => bc emitIFNULL success - case TestOp.NE => bc emitIFNONNULL success - } - } else { - (tk: @unchecked) match { - case LONG => - emit(asm.Opcodes.LCONST_0) - emit(asm.Opcodes.LCMP) - case FLOAT => - emit(asm.Opcodes.FCONST_0) - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) - else emit(asm.Opcodes.FCMPL) - case DOUBLE => - emit(asm.Opcodes.DCONST_0) - if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) - else emit(asm.Opcodes.DCMPL) + private def genCZJUMP(success: asm.Label, failure: asm.Label, op: TestOp, tk: BType, targetIfNoJump: asm.Label) { + if (targetIfNoJump == success) genCZJUMP(failure, success, op.negate, tk, targetIfNoJump) + else { + if (tk.isIntSizedType) { // BOOL, BYTE, CHAR, SHORT, or INT + bc.emitIF(op, success) + } else if (tk.isRef) { // REFERENCE(_) | ARRAY(_) + op match { // references are only compared with EQ and NE + case TestOp.EQ => bc emitIFNULL success + case TestOp.NE => bc emitIFNONNULL success + } + } else { + (tk: @unchecked) match { + case LONG => + emit(asm.Opcodes.LCONST_0) + emit(asm.Opcodes.LCMP) + case FLOAT => + emit(asm.Opcodes.FCONST_0) + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.FCMPG) + else emit(asm.Opcodes.FCMPL) + case DOUBLE => + emit(asm.Opcodes.DCONST_0) + if (op == TestOp.LT || op == TestOp.LE) emit(asm.Opcodes.DCMPG) + else emit(asm.Opcodes.DCMPL) + } + bc.emitIF(op, success) } - bc.emitIF(op, success) + if (targetIfNoJump != failure) bc goTo failure } - bc goTo failure } def testOpForPrimitive(primitiveCode: Int) = (primitiveCode: @switch) match { @@ -1179,29 +1198,26 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { * Generate code for conditional expressions. * The jump targets success/failure of the test are `then-target` and `else-target` resp. */ - private def genCond(tree: Tree, success: asm.Label, failure: asm.Label) { + private def genCond(tree: Tree, success: asm.Label, failure: asm.Label, targetIfNoJump: asm.Label) { def genComparisonOp(l: Tree, r: Tree, code: Int) { - val op: TestOp = testOpForPrimitive(code) - // special-case reference (in)equality test for null (null eq x, x eq null) - var nonNullSide: Tree = null - if (scalaPrimitives.isReferenceEqualityOp(code) && - { nonNullSide = ifOneIsNull(l, r); nonNullSide != null } - ) { + val op = testOpForPrimitive(code) + val nonNullSide = if (scalaPrimitives.isReferenceEqualityOp(code)) ifOneIsNull(l, r) else null + if (nonNullSide != null) { + // special-case reference (in)equality test for null (null eq x, x eq null) genLoad(nonNullSide, ObjectRef) - genCZJUMP(success, failure, op, ObjectRef) - } - else { + genCZJUMP(success, failure, op, ObjectRef, targetIfNoJump) + } else { val tk = tpeTK(l).maxType(tpeTK(r)) genLoad(l, tk) genLoad(r, tk) - genCJUMP(success, failure, op, tk) + genCJUMP(success, failure, op, tk, targetIfNoJump) } } - def default() = { + def loadAndTestBoolean() = { genLoad(tree, BOOL) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } lineNumber(tree) @@ -1212,37 +1228,35 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { // lhs and rhs of test lazy val Select(lhs, _) = fun - val rhs = if (args.isEmpty) EmptyTree else args.head; // args.isEmpty only for ZNOT + val rhs = if (args.isEmpty) EmptyTree else args.head // args.isEmpty only for ZNOT - def genZandOrZor(and: Boolean) { // TODO WRONG + def genZandOrZor(and: Boolean) { // reaching "keepGoing" indicates the rhs should be evaluated too (ie not short-circuited). val keepGoing = new asm.Label - if (and) genCond(lhs, keepGoing, failure) - else genCond(lhs, success, keepGoing) + if (and) genCond(lhs, keepGoing, failure, targetIfNoJump = keepGoing) + else genCond(lhs, success, keepGoing, targetIfNoJump = keepGoing) markProgramPoint(keepGoing) - genCond(rhs, success, failure) + genCond(rhs, success, failure, targetIfNoJump) } getPrimitive(fun.symbol) match { - case ZNOT => genCond(lhs, failure, success) + case ZNOT => genCond(lhs, failure, success, targetIfNoJump) case ZAND => genZandOrZor(and = true) case ZOR => genZandOrZor(and = false) case code => - // TODO !!!!!!!!!! isReferenceType, in the sense of TypeKind? (ie non-array, non-boxed, non-nothing, may be null) if (scalaPrimitives.isUniversalEqualityOp(code) && tpeTK(lhs).isClass) { - // `lhs` has reference type - if (code == EQ) genEqEqPrimitive(lhs, rhs, success, failure, tree.pos) - else genEqEqPrimitive(lhs, rhs, failure, success, tree.pos) - } - else if (scalaPrimitives.isComparisonOp(code)) + // rewrite `==` to null tests and `equals`. not needed for arrays (`equals` is reference equality). + if (code == EQ) genEqEqPrimitive(lhs, rhs, success, failure, targetIfNoJump, tree.pos) + else genEqEqPrimitive(lhs, rhs, failure, success, targetIfNoJump, tree.pos) + } else if (scalaPrimitives.isComparisonOp(code)) { genComparisonOp(lhs, rhs, code) - else - default + } else + loadAndTestBoolean() } - case _ => default + case _ => loadAndTestBoolean() } } // end of genCond() @@ -1254,7 +1268,7 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { * @param l left-hand-side of the '==' * @param r right-hand-side of the '==' */ - def genEqEqPrimitive(l: Tree, r: Tree, success: asm.Label, failure: asm.Label, pos: Position) { + def genEqEqPrimitive(l: Tree, r: Tree, success: asm.Label, failure: asm.Label, targetIfNoJump: asm.Label, pos: Position) { /* True if the equality comparison is between values that require the use of the rich equality * comparator (scala.runtime.Comparator.equals). This is the case when either side of the @@ -1264,7 +1278,6 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { */ val mustUseAnyComparator: Boolean = { val areSameFinals = l.tpe.isFinalType && r.tpe.isFinalType && (l.tpe =:= r.tpe) - !areSameFinals && platform.isMaybeBoxed(l.tpe.typeSymbol) && platform.isMaybeBoxed(r.tpe.typeSymbol) } @@ -1279,23 +1292,22 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { genLoad(l, ObjectRef) genLoad(r, ObjectRef) genCallMethod(equalsMethod, InvokeStyle.Static, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) - } - else { + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) + } else { if (isNull(l)) { // null == expr -> expr eq null genLoad(r, ObjectRef) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump) } else if (isNull(r)) { // expr == null -> expr eq null genLoad(l, ObjectRef) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump) } else if (isNonNullExpr(l)) { // SI-7852 Avoid null check if L is statically non-null. genLoad(l, ObjectRef) genLoad(r, ObjectRef) genCallMethod(Object_equals, InvokeStyle.Virtual, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } else { // l == r -> if (l eq null) r eq null else l.equals(r) val eqEqTempLocal = locals.makeLocal(ObjectRef, nme.EQEQ_LOCAL_VAR.toString) @@ -1306,17 +1318,17 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder { genLoad(r, ObjectRef) locals.store(eqEqTempLocal) bc dup ObjectRef - genCZJUMP(lNull, lNonNull, TestOp.EQ, ObjectRef) + genCZJUMP(lNull, lNonNull, TestOp.EQ, ObjectRef, targetIfNoJump = lNull) markProgramPoint(lNull) bc drop ObjectRef locals.load(eqEqTempLocal) - genCZJUMP(success, failure, TestOp.EQ, ObjectRef) + genCZJUMP(success, failure, TestOp.EQ, ObjectRef, targetIfNoJump = lNonNull) markProgramPoint(lNonNull) locals.load(eqEqTempLocal) genCallMethod(Object_equals, InvokeStyle.Virtual, pos) - genCZJUMP(success, failure, TestOp.NE, BOOL) + genCZJUMP(success, failure, TestOp.NE, BOOL, targetIfNoJump) } } } diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala index 1b5ece772c..f423f3c7fe 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala @@ -1355,6 +1355,15 @@ object BCodeHelpers { } class TestOp(val op: Int) extends AnyVal { + import TestOp._ + def negate = this match { + case EQ => NE + case NE => EQ + case LT => GE + case GE => LT + case GT => LE + case LE => GT + } def opcodeIF = asm.Opcodes.IFEQ + op def opcodeIFICMP = asm.Opcodes.IF_ICMPEQ + op } diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeSkelBuilder.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeSkelBuilder.scala index 9dea21154f..96796b3244 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeSkelBuilder.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeSkelBuilder.scala @@ -437,9 +437,7 @@ abstract class BCodeSkelBuilder extends BCodeHelpers { var varsInScope: List[Tuple2[Symbol, asm.Label]] = null // (local-var-sym -> start-of-scope) // helpers around program-points. - def lastInsn: asm.tree.AbstractInsnNode = { - mnode.instructions.getLast - } + def lastInsn: asm.tree.AbstractInsnNode = mnode.instructions.getLast def currProgramPoint(): asm.Label = { lastInsn match { case labnode: asm.tree.LabelNode => labnode.getLabel @@ -598,13 +596,11 @@ abstract class BCodeSkelBuilder extends BCodeHelpers { genLoad(rhs, returnType) rhs match { - case Block(_, Return(_)) => () - case Return(_) => () + case Return(_) | Block(_, Return(_)) | Throw(_) | Block(_, Throw(_)) => () case EmptyTree => globalError("Concrete method has no definition: " + dd + ( if (settings.debug) "(found: " + methSymbol.owner.info.decls.toList.mkString(", ") + ")" - else "") - ) + else "")) case _ => bc emitRETURN returnType } diff --git a/test/junit/scala/issues/BytecodeTest.scala b/test/junit/scala/issues/BytecodeTest.scala index 7260f43c87..ca1b33ed20 100644 --- a/test/junit/scala/issues/BytecodeTest.scala +++ b/test/junit/scala/issues/BytecodeTest.scala @@ -3,7 +3,7 @@ package scala.issues import org.junit.runner.RunWith import org.junit.runners.JUnit4 import org.junit.Test -import scala.tools.asm.Opcodes +import scala.tools.asm.Opcodes._ import scala.tools.nsc.backend.jvm.AsmUtils import scala.tools.nsc.backend.jvm.CodeGenTools._ import org.junit.Assert._ @@ -105,12 +105,10 @@ class BytecodeTest extends ClearAfterClass { val unapplyLineNumbers = getSingleMethod(module, "unapply").instructions.filter(_.isInstanceOf[LineNumber]) assert(unapplyLineNumbers == List(LineNumber(2, Label(0))), unapplyLineNumbers) - import Opcodes._ val expected = List( LineNumber(4, Label(0)), LineNumber(5, Label(5)), - Jump(IFNE, Label(11)), - Jump(GOTO, Label(20)), + Jump(IFEQ, Label(20)), LineNumber(6, Label(11)), Invoke(INVOKEVIRTUAL, "scala/Predef$", "println", "(Ljava/lang/Object;)V", false), @@ -133,4 +131,81 @@ class BytecodeTest extends ClearAfterClass { } assertSameCode(mainIns, expected) } + + @Test + def bytecodeForBranches(): Unit = { + val code = + """class C { + | def t1(b: Boolean) = if (b) 1 else 2 + | def t2(x: Int) = if (x == 393) 1 else 2 + | def t3(a: Array[String], b: AnyRef) = a != b && b == a + | def t4(a: AnyRef) = a == null || null != a + | def t5(a: AnyRef) = (a eq null) || (null ne a) + | def t6(a: Int, b: Boolean) = if ((a == 10) && b || a != 1) 1 else 2 + | def t7(a: AnyRef, b: AnyRef) = a == b + | def t8(a: AnyRef) = Nil == a || "" != a + |} + """.stripMargin + + val List(c) = compileClasses(compiler)(code) + + // t1: no unnecessary GOTOs + assertSameCode(getSingleMethod(c, "t1").instructions.dropNonOp, List( + VarOp(ILOAD, 1), Jump(IFEQ, Label(6)), + Op(ICONST_1), Jump(GOTO, Label(9)), + Label(6), Op(ICONST_2), + Label(9), Op(IRETURN))) + + // t2: no unnecessary GOTOs + assertSameCode(getSingleMethod(c, "t2").instructions.dropNonOp, List( + VarOp(ILOAD, 1), IntOp(SIPUSH, 393), Jump(IF_ICMPNE, Label(7)), + Op(ICONST_1), Jump(GOTO, Label(10)), + Label(7), Op(ICONST_2), + Label(10), Op(IRETURN))) + + // t3: Array == is translated to reference equality, AnyRef == to null checks and equals + assertSameCode(getSingleMethod(c, "t3").instructions.dropNonOp, List( + // Array == + VarOp(ALOAD, 1), VarOp(ALOAD, 2), Jump(IF_ACMPEQ, Label(23)), + // AnyRef == + VarOp(ALOAD, 2), VarOp(ALOAD, 1), VarOp(ASTORE, 3), Op(DUP), Jump(IFNONNULL, Label(14)), + Op(POP), VarOp(ALOAD, 3), Jump(IFNULL, Label(19)), Jump(GOTO, Label(23)), + Label(14), VarOp(ALOAD, 3), Invoke(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false), Jump(IFEQ, Label(23)), + Label(19), Op(ICONST_1), Jump(GOTO, Label(26)), + Label(23), Op(ICONST_0), + Label(26), Op(IRETURN))) + + val t4t5 = List( + VarOp(ALOAD, 1), Jump(IFNULL, Label(6)), + VarOp(ALOAD, 1), Jump(IFNULL, Label(10)), + Label(6), Op(ICONST_1), Jump(GOTO, Label(13)), + Label(10), Op(ICONST_0), + Label(13), Op(IRETURN)) + + // t4: one side is known null, so just a null check on the other + assertSameCode(getSingleMethod(c, "t4").instructions.dropNonOp, t4t5) + + // t5: one side known null, so just a null check on the other + assertSameCode(getSingleMethod(c, "t5").instructions.dropNonOp, t4t5) + + // t6: no unnecessary GOTOs + assertSameCode(getSingleMethod(c, "t6").instructions.dropNonOp, List( + VarOp(ILOAD, 1), IntOp(BIPUSH, 10), Jump(IF_ICMPNE, Label(7)), + VarOp(ILOAD, 2), Jump(IFNE, Label(12)), + Label(7), VarOp(ILOAD, 1), Op(ICONST_1), Jump(IF_ICMPEQ, Label(16)), + Label(12), Op(ICONST_1), Jump(GOTO, Label(19)), + Label(16), Op(ICONST_2), + Label(19), Op(IRETURN))) + + // t7: universal equality + assertInvoke(getSingleMethod(c, "t7"), "scala/runtime/BoxesRunTime", "equals") + + // t8: no null checks invoking equals on modules and constants + assertSameCode(getSingleMethod(c, "t8").instructions.dropNonOp, List( + Field(GETSTATIC, "scala/collection/immutable/Nil$", "MODULE$", "Lscala/collection/immutable/Nil$;"), VarOp(ALOAD, 1), Invoke(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false), Jump(IFNE, Label(10)), + Ldc(LDC, ""), VarOp(ALOAD, 1), Invoke(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false), Jump(IFNE, Label(14)), + Label(10), Op(ICONST_1), Jump(GOTO, Label(17)), + Label(14), Op(ICONST_0), + Label(17), Op(IRETURN))) + } } diff --git a/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala b/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala index 942b62b32c..70f3060027 100644 --- a/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala +++ b/test/junit/scala/tools/nsc/backend/jvm/opt/InlinerTest.scala @@ -1507,7 +1507,6 @@ class InlinerTest extends ClearAfterClass { |} """.stripMargin val List(c) = compile(code) - val t = getSingleMethod(c, "t") // box-unbox will clean it up assertEquals(getSingleMethod(c, "t").instructions.summary, diff --git a/test/junit/scala/tools/nsc/backend/jvm/opt/UnreachableCodeTest.scala b/test/junit/scala/tools/nsc/backend/jvm/opt/UnreachableCodeTest.scala index 86c8baa3c6..62ee09e9de 100644 --- a/test/junit/scala/tools/nsc/backend/jvm/opt/UnreachableCodeTest.scala +++ b/test/junit/scala/tools/nsc/backend/jvm/opt/UnreachableCodeTest.scala @@ -215,4 +215,52 @@ class UnreachableCodeTest extends ClearAfterClass { assertTrue(List(FrameEntry(F_FULL, List(INTEGER, DOUBLE, Label(3)), List("java/lang/Object", Label(4))), Label(3), Label(4)) === List(FrameEntry(F_FULL, List(INTEGER, DOUBLE, Label(1)), List("java/lang/Object", Label(3))), Label(1), Label(3))) } + + @Test + def loadNullNothingBytecode(): Unit = { + val code = + """class C { + | def nl: Null = null + | def nt: Nothing = throw new Error("") + | def cons(a: Any) = () + | + | def t1 = cons(null) + | def t2 = cons(nl) + | def t3 = cons(throw new Error("")) + | def t4 = cons(nt) + |} + """.stripMargin + val List(c) = compileClasses(noOptCompiler)(code) + + assertEquals(getSingleMethod(c, "nl").instructions.summary, List(ACONST_NULL, ARETURN)) + + assertEquals(getSingleMethod(c, "nt").instructions.summary, List( + NEW, DUP, LDC, "<init>", ATHROW)) + + assertEquals(getSingleMethod(c, "t1").instructions.summary, List( + ALOAD, ACONST_NULL, "cons", RETURN)) + + // GenBCode introduces POP; ACONST_NULL after loading an expression of type scala.runtime.Null$, + // see comment in BCodeBodyBuilder.adapt + assertEquals(getSingleMethod(c, "t2").instructions.summary, List( + ALOAD, ALOAD, "nl", POP, ACONST_NULL, "cons", RETURN)) + + // the bytecode generated by GenBCode is ... ATHROW; INVOKEVIRTUAL C.cons; RETURN + // the ASM classfile writer creates a new basic block (creates a label) right after the ATHROW + // and replaces all instructions by NOP*; ATHROW, see comment in BCodeBodyBuilder.adapt + // NOTE: DCE is enabled by default and gets rid of the redundant code (tested below) + assertEquals(getSingleMethod(c, "t3").instructions.summary, List( + ALOAD, NEW, DUP, LDC, "<init>", ATHROW, NOP, NOP, NOP, ATHROW)) + + // GenBCode introduces an ATHROW after the invocation of C.nt, see BCodeBodyBuilder.adapt + // NOTE: DCE is enabled by default and gets rid of the redundant code (tested below) + assertEquals(getSingleMethod(c, "t4").instructions.summary, List( + ALOAD, ALOAD, "nt", ATHROW, NOP, NOP, NOP, ATHROW)) + + val List(cDCE) = compileClasses(dceCompiler)(code) + assertEquals(getSingleMethod(cDCE, "t3").instructions.summary, List( + ALOAD, NEW, DUP, LDC, "<init>", ATHROW)) + assertEquals(getSingleMethod(cDCE, "t4").instructions.summary, List( + ALOAD, ALOAD, "nt", ATHROW)) + } } |