diff options
3 files changed, 19 insertions, 5 deletions
diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala index 68c4ac03f6..4f3b0bf951 100644 --- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala +++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala @@ -386,10 +386,16 @@ trait BasicBlocks { def close() { assert(!closed || ignore, this) assert(instructionList.nonEmpty, "Empty block: " + this) - closed = true - setFlag(DIRTYSUCCS) - instructionList = instructionList.reverse - instrs = instructionList.toArray + if (ignore && closed) { // redundant `ignore &&` for clarity -- we should never be in state `!ignore && closed` + // not doing anything to this block is important... + // because the else branch reverses innocent blocks, which is wrong when they're in ignore mode (and closed) + // reversing the instructions when (closed && ignore) wreaks havoc for nested label jumps (see comments in genLoad) + } else { + closed = true + setFlag(DIRTYSUCCS) + instructionList = instructionList.reverse + instrs = instructionList.toArray + } } def open() { diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala index 9e801e3ea8..41d9d93e7a 100644 --- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala +++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala @@ -868,6 +868,13 @@ abstract class GenICode extends SubComponent { abort("Unknown label target: " + sym + " at: " + (fun.pos) + ": ctx: " + ctx) } }) + // note: when one of the args to genLoadLabelArguments is a jump to a label, + // it will call back into genLoad and arrive at this case, which will then set ctx1.bb.ignore to true, + // this is okay, since we're jumping unconditionally, so the loads and jumps emitted by the outer + // call to genLoad (by calling genLoadLabelArguments and emitOnly) can safely be ignored, + // however, as emitOnly will close the block, which reverses its instructions (when it's still open), + // we better not reverse when the block has already been closed but is in ignore mode + // (if it's not in ignore mode, double-closing is an error) val ctx1 = genLoadLabelArguments(args, label, ctx) ctx1.bb.emitOnly(if (label.anchored) JUMP(label.block) else PJUMP(label)) ctx1.bb.enterIgnoreMode diff --git a/test/files/run/virtpatmat_tailcalls_verifyerror.scala b/test/files/run/virtpatmat_tailcalls_verifyerror.scala index 1ee613f09e..5ce91e8dce 100644 --- a/test/files/run/virtpatmat_tailcalls_verifyerror.scala +++ b/test/files/run/virtpatmat_tailcalls_verifyerror.scala @@ -5,7 +5,8 @@ object Test extends App { Some("a") match { case x => x match { - case _ => if(meh) test(false) else false + case Some(_) => if(meh) test(false) else false + case _ => test(false) } } } |