FinderCache: Also cache file hashing in interface file checkswip/hash-file-cache

Now that we hash object files to decide when to recompile due to TH,
this can make a big difference as each interface file in a project will
contain reference to the object files of all package dependencies.
Especially when these are statically linked, hashing them can add up.

The cache is invalidated when `depanalPartial` is called, like the
normal finder cache.

1 files changed, 10 insertions, 11 deletions

diff --git a/compiler/GHC/Iface/Recomp.hs b/compiler/GHC/Iface/Recomp.hs
index 68ca5bfdbe..7759aea72d 100644
--- a/compiler/GHC/Iface/Recomp.hs
+++ b/compiler/GHC/Iface/Recomp.hs
@@ -271,7 +271,7 @@ checkVersions hsc_env mod_summary iface
        when (isOneShot (ghcMode (hsc_dflags hsc_env))) $ do {
           ; updateEps_ $ \eps  -> eps { eps_is_boot = mkModDeps $ (dep_boot_mods (mi_deps iface)) }
        }
-       ; recomp <- checkList [checkModUsage (homeUnitAsUnit home_unit) u
+       ; recomp <- checkList [checkModUsage (hsc_FC hsc_env) (homeUnitAsUnit home_unit) u
                              | u <- mi_usages iface]
        ; return (recomp, Just iface)
     }}}}}}}}}}}
@@ -550,8 +550,8 @@ getFromModIface doc_msg mod getter
 -- | Given the usage information extracted from the old
 -- M.hi file for the module being compiled, figure out
 -- whether M needs to be recompiled.
-checkModUsage :: Unit -> Usage -> IfG RecompileRequired
-checkModUsage _this_pkg UsagePackageModule{
+checkModUsage :: FinderCache -> Unit -> Usage -> IfG RecompileRequired
+checkModUsage _ _this_pkg UsagePackageModule{
                                 usg_mod = mod,
                                 usg_mod_hash = old_mod_hash } = do
   logger <- getLogger
@@ -563,19 +563,19 @@ checkModUsage _this_pkg UsagePackageModule{
         -- recompile.  This is safe but may entail more recompilation when
         -- a dependent package has changed.
 
-checkModUsage _ UsageMergedRequirement{ usg_mod = mod, usg_mod_hash = old_mod_hash } = do
+checkModUsage _ _ UsageMergedRequirement{ usg_mod = mod, usg_mod_hash = old_mod_hash } = do
   logger <- getLogger
   needInterface mod $ \iface -> do
     let reason = moduleNameString (moduleName mod) ++ " changed (raw)"
     checkModuleFingerprint logger reason old_mod_hash (mi_mod_hash (mi_final_exts iface))
-checkModUsage this_pkg UsageHomeModuleInterface{ usg_mod_name = mod_name, usg_iface_hash = old_mod_hash } = do
+checkModUsage _ this_pkg UsageHomeModuleInterface{ usg_mod_name = mod_name, usg_iface_hash = old_mod_hash } = do
   let mod = mkModule this_pkg mod_name
   logger <- getLogger
   needInterface mod $ \iface -> do
     let reason = moduleNameString (moduleName mod) ++ " changed (interface)"
     checkIfaceFingerprint logger reason old_mod_hash (mi_iface_hash (mi_final_exts iface))
 
-checkModUsage this_pkg UsageHomeModule{
+checkModUsage _ this_pkg UsageHomeModule{
                                 usg_mod_name = mod_name,
                                 usg_mod_hash = old_mod_hash,
                                 usg_exports = maybe_old_export_hash,
@@ -602,19 +602,18 @@ checkModUsage this_pkg UsageHomeModule{
                (text "  Export list changed") $ do
 
                  -- CHECK ITEMS ONE BY ONE
-                 recompile <- checkList [ checkEntityUsage logger reason new_decl_hash u
-                                        | u <- old_decl_hash]
+                 !recompile <- checkList [ checkEntityUsage logger reason new_decl_hash u
+                                          | u <- old_decl_hash]
                  if recompileRequired recompile
                    then return recompile     -- This one failed, so just bail out now
                    else up_to_date logger (text "  Great!  The bits I use are up to date")
 
-
-checkModUsage _this_pkg UsageFile{ usg_file_path = file,
+checkModUsage fc _this_pkg UsageFile{ usg_file_path = file,
                                    usg_file_hash = old_hash,
                                    usg_file_label = mlabel } =
   liftIO $
     handleIO handler $ do
-      new_hash <- getFileHash file
+      new_hash <- lookupFileCache fc file
       if (old_hash /= new_hash)
          then return recomp
          else return UpToDate