[project @ 2005-05-13 09:39:00 by simonmar]

summariseFile: use a cached summary if one is available.  Previously
we always preprocessed modules named by filename on each reload.

diff --git a/ghc/compiler/main/GHC.hs b/ghc/compiler/main/GHC.hs
index 67dd723..bcd1fa8 100644 (file)
--- a/ghc/compiler/main/GHC.hs
+++ b/ghc/compiler/main/GHC.hs
@@ -1212,10 +1212,12 @@ downsweep hsc_env old_summaries excl_mods
        getRootSummary :: Target -> IO ModSummary
        getRootSummary (Target (TargetFile file) maybe_buf)
           = do exists <- doesFileExist file
-               if exists then summariseFile hsc_env file maybe_buf else do
+               if exists 
+                       then summariseFile hsc_env old_summaries file maybe_buf
+                       else do
                throwDyn (CmdLineError ("can't find file: " ++ file))   
        getRootSummary (Target (TargetModule modl) maybe_buf)
-          = do maybe_summary <- summarise hsc_env emptyNodeMap Nothing False 
+          = do maybe_summary <- summariseModule hsc_env emptyNodeMap Nothing False 
                                           modl maybe_buf excl_mods
                case maybe_summary of
                   Nothing -> packageModErr modl
@@ -1247,7 +1249,7 @@ downsweep hsc_env old_summaries excl_mods
        loop [] done      = return (nodeMapElts done)
        loop ((cur_path, wanted_mod, is_boot) : ss) done 
          | key `elemFM` done = loop ss done
-         | otherwise         = do { mb_s <- summarise hsc_env old_summary_map 
+         | otherwise         = do { mb_s <- summariseModule hsc_env old_summary_map 
                                                 (Just cur_path) is_boot 
                                                 wanted_mod Nothing excl_mods
                                   ; case mb_s of
@@ -1287,14 +1289,38 @@ msDeps s =  concat [ [(f, m, True), (f,m,False)] | m <- ms_srcimps s]
 --     a summary.  The finder is used to locate the file in which the module
 --     resides.
 
-summariseFile :: HscEnv -> FilePath
-   -> Maybe (StringBuffer,ClockTime)
-   -> IO ModSummary
--- Used for Haskell source only, I think
--- We know the file name, and we know it exists,
--- but we don't necessarily know the module name (might differ)
-summariseFile hsc_env file maybe_buf
-   = do let dflags = hsc_dflags hsc_env
+summariseFile
+       :: HscEnv
+       -> [ModSummary]                 -- old summaries
+       -> FilePath                     -- source file name
+       -> Maybe (StringBuffer,ClockTime)
+       -> IO ModSummary
+
+summariseFile hsc_env old_summaries file maybe_buf
+       -- we can use a cached summary if one is available and the
+       -- source file hasn't changed,  But we have to look up the summary
+       -- by source file, rather than module name as we do in summarise.
+   | Just old_summary <- findSummaryBySourceFile old_summaries file
+   = do
+       let location = ms_location old_summary
+
+               -- return the cached summary if the source didn't change
+       src_timestamp <- case maybe_buf of
+                          Just (_,t) -> return t
+                          Nothing    -> getModificationTime file
+
+       if ms_hs_date old_summary == src_timestamp 
+          then do -- update the object-file timestamp
+                 obj_timestamp <- getObjTimestamp location False
+                 return old_summary{ ms_obj_date = obj_timestamp }
+          else
+               new_summary
+
+   | otherwise
+   = new_summary
+  where
+    new_summary = do
+       let dflags = hsc_dflags hsc_env
 
        (dflags', hspp_fn, buf)
            <- preprocessFile dflags file maybe_buf
@@ -1322,8 +1348,16 @@ summariseFile hsc_env file maybe_buf
                             ms_hs_date = src_timestamp,
                             ms_obj_date = obj_timestamp })
 
+findSummaryBySourceFile :: [ModSummary] -> FilePath -> Maybe ModSummary
+findSummaryBySourceFile summaries file
+  = case [ ms | ms <- summaries, HsSrcFile <- [ms_hsc_src ms],
+                                fromJust (ml_hs_file (ms_location ms)) == file ] of
+       [] -> Nothing
+       (x:xs) -> Just x
+
 -- Summarise a module, and pick up source and timestamp.
-summarise :: HscEnv
+summariseModule
+         :: HscEnv
          -> NodeMap ModSummary -- Map of old summaries
          -> Maybe FilePath     -- Importing module (for error messages)
          -> IsBootInterface    -- True <=> a {-# SOURCE #-} import
@@ -1332,7 +1366,7 @@ summarise :: HscEnv
          -> [Module]           -- Modules to exclude
          -> IO (Maybe ModSummary)      -- Its new summary
 
-summarise hsc_env old_summary_map cur_mod is_boot wanted_mod maybe_buf excl_mods
+summariseModule hsc_env old_summary_map cur_mod is_boot wanted_mod maybe_buf excl_mods
   | wanted_mod `elem` excl_mods
   = return Nothing
 
@@ -1340,7 +1374,7 @@ summarise hsc_env old_summary_map cur_mod is_boot wanted_mod maybe_buf excl_mods
   = do         -- Find its new timestamp; all the 
                -- ModSummaries in the old map have valid ml_hs_files
        let location = ms_location old_summary
-           src_fn = expectJust "summarise" (ml_hs_file location)
+           src_fn = expectJust "summariseModule" (ml_hs_file location)
 
                -- return the cached summary if the source didn't change
        src_timestamp <- case maybe_buf of