diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala index 917fe8b292..d772dcb6c4 100644 --- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala +++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala @@ -17,7 +17,7 @@ trait BasicBlocks { self: ICodes => import opcodes._ - import global.{ settings, log, nme } + import global.{ settings, debuglog, log, nme } import nme.isExceptionResultName /** Override Array creation for efficiency (to not go through reflection). */ @@ -383,7 +383,6 @@ trait BasicBlocks { /** Close the block */ def close() { assert(!closed || ignore, this) - assert(instructionList.nonEmpty, "Empty block: " + this) 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) @@ -393,9 +392,38 @@ trait BasicBlocks { setFlag(DIRTYSUCCS) instructionList = instructionList.reverse instrs = instructionList.toArray + if (instructionList.isEmpty) { + debuglog(s"Removing empty block $this") + code removeBlock this + } } } + /** + * if cond is true, closes this block, entersIgnoreMode, and removes the block from + * its list of blocks. Used to allow a block to be started and then cancelled when it + * is discovered to be unreachable. + */ + def killIf(cond: Boolean) { + if (!settings.YdisableUnreachablePrevention.value && cond) { + debuglog(s"Killing block $this") + assert(instructionList.isEmpty, s"Killing a non empty block $this") + // only checked under debug because fetching predecessor list is moderately expensive + if (settings.debug.value) + assert(predecessors.isEmpty, s"Killing block $this which is referred to from ${predecessors.mkString}") + + close() + enterIgnoreMode() + } + } + + /** + * Same as killIf but with the logic of the condition reversed + */ + def killUnless(cond: Boolean) { + this killIf !cond + } + def open() { assert(closed, this) closed = false |