opt

Type Members

1. class LocalOpt extends AnyRef

   

   Optimizations within a single method.

   Optimizations within a single method.

   unreachable code

   • removes instrucions of basic blocks to which no branch instruction points + enables eliminating some exception handlers and local variable descriptors > eliminating them is required for correctness, as explained in removeUnreachableCode

   empty exception handlers

   • removes exception handlers whose try block is empty + eliminating a handler where the try block is empty and reachable will turn the catch block unreachble. in this case "unreachable code" is invoked recursively until reaching a fixpiont. > for try blocks that are unreachable, "unreachable code" removes also the instructions of the catch block, and the recrusive invocation is not necessary.

   simplify jumps

   • various simplifications, see doc domments of individual optimizations + changing or eliminating jumps may render some code unreachable, therefore "simplify jumps" is executed in a loop with "unreachable code"

   empty local variable descriptors

   • removes entries from the local variable table where the variable is not actually used + enables eliminating labels that the entry points to (if they are not otherwise referenced)

   empty line numbers

   • eliminates line number nodes that describe no executable instructions + enables eliminating the label of the line number node (if it's not otherwise referenced)

   stale labels

   • eliminate labels that are not referenced, merge sequences of label definitions.