Make module membership on ModuleGraph faster

When loading/reloading with a large number of modules
(>5000) the cost of linear lookups becomes significant.

The changes here made `:reload` go from 6s to 1s on my
test case.

The bottlenecks were `needsLinker` in `DriverPipeline` and
`getModLoop` in `GhcMake`.

Test Plan: ./validate

Reviewers: simonmar, austin, bgamari

Subscribers: thomie, rwbarton

Differential Revision: https://phabricator.haskell.org/D3703

3 files changed, 9 insertions, 9 deletions

diff --git a/utils/check-api-annotations/Main.hs b/utils/check-api-annotations/Main.hs
index 1d577421fb..6b973e12e8 100644
--- a/utils/check-api-annotations/Main.hs
+++ b/utils/check-api-annotations/Main.hs
@@ -32,11 +32,11 @@ testOneFile libdir fileName = do
                                          , targetContents = Nothing }
                         _ <- load LoadAllTargets
                         graph <- getModuleGraph
-                        let
-                          modSum = case filter modByFile graph of
-                                    [x] -> x
-                                    xs -> error $ "Can't find module, got:"
-                                             ++ show (map (ml_hs_file . ms_location) xs)
+                        let modSum =
+                              case filter modByFile (mgModSummaries graph) of
+                                [x] -> x
+                                xs -> error $ "Can't find module, got:"
+                                  ++ show (map (ml_hs_file . ms_location) xs)
                         p <- parseModule modSum
                         return (pm_annotations p,p)
 
diff --git a/utils/check-ppr/Main.hs b/utils/check-ppr/Main.hs
index 47a95659ff..2fd44b2be0 100644
--- a/utils/check-ppr/Main.hs
+++ b/utils/check-ppr/Main.hs
@@ -77,7 +77,7 @@ parseOneFile libdir fileName = do
          _ <- load LoadAllTargets
          graph <- getModuleGraph
          let
-           modSum = case filter modByFile graph of
+           modSum = case filter modByFile (mgModSummaries graph) of
                      [x] -> x
                      xs -> error $ "Can't find module, got:"
                               ++ show (map (ml_hs_file . ms_location) xs)
diff --git a/utils/ghctags/Main.hs b/utils/ghctags/Main.hs
index 4842a0cbfb..c4db3ca212 100644
--- a/utils/ghctags/Main.hs
+++ b/utils/ghctags/Main.hs
@@ -222,9 +222,9 @@ fileTarget filename = Target (TargetFile filename Nothing) True Nothing
 ---------------------------------------------------------------
 ----- CRAWLING ABSTRACT SYNTAX TO SNAFFLE THE DEFINITIONS -----
 
-graphData :: ModuleGraph -> (Maybe Handle, Maybe Handle) -> Ghc ()
-graphData graph handles = do
-    mapM_ foundthings graph
+graphData :: [ModSummary] -> (Maybe Handle, Maybe Handle) -> Ghc ()
+graphData mss handles = do
+    mapM_ foundthings mss
     where foundthings ms =
               let filename = msHsFilePath ms
                   modname = moduleName $ ms_mod ms