[refinement] implement getBlock block lookup function.

refinement/src/Data/Macaw/Refinement/FuncBlockUtils.hs

@@ -62,10 +62,15 @@ funIncludesBlock :: BlockIdentifier arch
 funIncludesBlock blkID (Some fi) =
   isJust ((fi ^. parsedBlocks) Map.!? blkID)
 
+-- | Returns the actual block (if it exists) from the Discovery State
+-- (in the first function for which it exists).
 getBlock :: DiscoveryState arch
          -> BlockIdentifier arch
-         -> Some (ParsedBlock arch)
-getBlock ds blkID = undefined
+         -> Maybe (Some (ParsedBlock arch))
+getBlock ds blkID =
+  case filter (funIncludesBlock blkID) (ds ^. funInfo ^.. folded) of
+    ((Some fi):_) -> Some <$> (fi ^. parsedBlocks) Map.!? blkID
+    [] -> Nothing
 
 -- | This function identifies the possible target addresses (of other
 -- blocks within this function) from the terminal statement in the

refinement/src/Data/Macaw/Refinement/UnknownTransfer.hs

@@ -284,8 +284,11 @@ type Solution arch = [ArchSegmentOff arch]  -- identified transfers
 equationFor :: DiscoveryState arch -> FuncBlockPath arch -> Equation arch
 equationFor inpDS (Path bid anc _loop) =
   let curBlk = getBlock inpDS bid
-  in if null anc
-     then Equation inpDS curBlk
+  in case curBlk of
+       Nothing -> error "did not find requested block in discovery results!" -- internal
+       Just b ->
+         if null anc
+         then Equation inpDS b
          else undefined
               -- Should linearly combine the anc statements with the
               -- current block's statements and asserts that state that