diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala')
-rw-r--r-- | src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala index 0ec550981a..df8dcc690a 100644 --- a/src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala +++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/BytecodeUtils.scala @@ -12,7 +12,7 @@ import scala.collection.mutable import scala.reflect.internal.util.Collections._ import scala.tools.asm.commons.CodeSizeEvaluator import scala.tools.asm.tree.analysis._ -import scala.tools.asm.{MethodWriter, ClassWriter, Label, Opcodes} +import scala.tools.asm.{MethodWriter, ClassWriter, Label, Opcodes, Type} import scala.tools.asm.tree._ import GenBCode._ import scala.collection.convert.decorateAsScala._ @@ -104,6 +104,8 @@ object BytecodeUtils { def isStrictfpMethod(methodNode: MethodNode): Boolean = (methodNode.access & Opcodes.ACC_STRICT) != 0 + def isReference(t: Type) = t.getSort == Type.OBJECT || t.getSort == Type.ARRAY + def nextExecutableInstruction(instruction: AbstractInsnNode, alsoKeep: AbstractInsnNode => Boolean = Set()): Option[AbstractInsnNode] = { var result = instruction do { result = result.getNext } @@ -331,6 +333,26 @@ object BytecodeUtils { } /** + * This method is used by optimizer components to eliminate phantom values of instruction + * that load a value of type `Nothing$` or `Null$`. Such values on the stack don't interact well + * with stack map frames. + * + * For example, `opt.getOrElse(throw e)` is re-written to an invocation of the lambda body, a + * method with return type `Nothing$`. Similarly for `opt.getOrElse(null)` and `Null$`. + * + * During bytecode generation this is handled by BCodeBodyBuilder.adapt. See the comment in that + * method which explains the issue with such phantom values. + */ + def fixLoadedNothingOrNullValue(loadedType: Type, loadInstr: AbstractInsnNode, methodNode: MethodNode, bTypes: BTypes): Unit = { + if (loadedType == bTypes.coreBTypes.RT_NOTHING.toASMType) { + methodNode.instructions.insert(loadInstr, new InsnNode(Opcodes.ATHROW)) + } else if (loadedType == bTypes.coreBTypes.RT_NULL.toASMType) { + methodNode.instructions.insert(loadInstr, new InsnNode(Opcodes.ACONST_NULL)) + methodNode.instructions.insert(loadInstr, new InsnNode(Opcodes.POP)) + } + } + + /** * A wrapper to make ASM's Analyzer a bit easier to use. */ class AsmAnalyzer[V <: Value](methodNode: MethodNode, classInternalName: InternalName, interpreter: Interpreter[V] = new BasicInterpreter) { |