[project @ 2002-07-30 11:49:17 by simonpj]

[ghc-hetmet.git] / ghc / compiler / main / TidyPgm.lhs

diff --git a/ghc/compiler/main/TidyPgm.lhs b/ghc/compiler/main/TidyPgm.lhs
index 38c6745..bacbee4 100644 (file)
--- a/ghc/compiler/main/TidyPgm.lhs
+++ b/ghc/compiler/main/TidyPgm.lhs
@@ -20,8 +20,8 @@ import VarEnv
 import VarSet
 import Var             ( Id, Var )
 import Id              ( idType, idInfo, idName, idCoreRules, 
-                         isExportedId, idUnique, mkVanillaGlobal, isLocalId, 
-                         isImplicitId, mkUserLocal, setIdInfo
+                         isExportedId, mkVanillaGlobal, isLocalId, 
+                         isImplicitId 
                        ) 
 import IdInfo          {- loads of stuff -}
 import NewDemand       ( isBottomingSig, topSig )
@@ -42,7 +42,6 @@ import HscTypes               ( PersistentCompilerState( pcs_PRS ),
 import FiniteMap       ( lookupFM, addToFM )
 import Maybes          ( orElse )
 import ErrUtils                ( showPass, dumpIfSet_core )
-import SrcLoc          ( noSrcLoc )
 import UniqFM          ( mapUFM )
 import UniqSupply      ( splitUniqSupply, uniqFromSupply )
 import List            ( partition )
@@ -493,24 +492,38 @@ tidyTopBinder mod ext_ids cg_info_env rec_tidy_env rhs tidy_rhs
 --     of Ids, and rules, right at the top, but that would be a pain.
 
 tidyTopIdInfo tidy_env is_external idinfo unfold_info arity cg_info
-  | opt_OmitInterfacePragmas || not is_external
-       -- Only basic info if the Id isn't external, or if we don't have -O
-  = basic_info
-
-  | otherwise  -- Add extra optimisation info
-  = basic_info
+  | opt_OmitInterfacePragmas   -- If the interface file has no pragma info
+  = hasCafIdInfo               -- then discard all info right here
+       -- This is not so important for *this* module, but it's
+       -- vital for ghc --make:
+       --   subsequent compilations must not see (e.g.) the arity if
+       --   the interface file does not contain arity
+       -- If they do, they'll exploit the arity; then the arity might
+       -- change, but the iface file doesn't change => recompilation
+       -- does not happen => disaster
+       --
+       -- This IdInfo will live long-term in the Id => need to make
+       -- conservative assumption about Caf-hood
+
+  | not is_external    -- For internal Ids (not externally visible)
+  = vanillaIdInfo      -- we only need enough info for code generation
+                       -- Arity and strictness info are enough;
+                       --      c.f. CoreTidy.tidyLetBndr
+       -- Use vanillaIdInfo (whose CafInfo is a panic) because we 
+       -- should not need the CafInfo
+       `setArityInfo`         arity
+       `setAllStrictnessInfo` newStrictnessInfo idinfo
+
+  | otherwise          -- Externally-visible Ids get the whole lot
+  = vanillaIdInfo
+       `setCgInfo`            cg_info
+       `setArityInfo`         arity
+       `setAllStrictnessInfo` newStrictnessInfo idinfo
        `setInlinePragInfo`    inlinePragInfo idinfo
        `setUnfoldingInfo`     unfold_info
        `setWorkerInfo`        tidyWorker tidy_env (workerInfo idinfo)
                -- NB: we throw away the Rules
                -- They have already been extracted by findExternalRules
-  
-  where
-       -- baasic_info is attached to every top-level binder
-    basic_info = vanillaIdInfo 
-                       `setCgInfo`            cg_info
-                       `setArityInfo`         arity
-                       `setAllStrictnessInfo` newStrictnessInfo idinfo
 
 -- This is where we set names to local/global based on whether they really are 
 -- externally visible (see comment at the top of this module).  If the name