X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FdeSugar%2FDsGRHSs.lhs;h=4daab975ecbe28d85fdd5aae5a748a3c1a7de604;hb=6a05ec5ef5373f61b7f9f5bdc344483417fa801b;hp=55b4f572f07dcd2887ed34816b9ca70f2faa5584;hpb=ccaf28d80e40cc2944bdaea3b46b245194cb90ab;p=ghc-hetmet.git

diff --git a/compiler/deSugar/DsGRHSs.lhs b/compiler/deSugar/DsGRHSs.lhs
index 55b4f57..4daab97 100644
--- a/compiler/deSugar/DsGRHSs.lhs
+++ b/compiler/deSugar/DsGRHSs.lhs
@@ -6,6 +6,13 @@
 Matching guarded right-hand-sides (GRHSs)
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module DsGRHSs ( dsGuarded, dsGRHSs ) where
 
 #include "HsVersions.h"
@@ -14,14 +21,12 @@ import {-# SOURCE #-} DsExpr  ( dsLExpr, dsLocalBinds )
 import {-# SOURCE #-} Match   ( matchSinglePat )
 
 import HsSyn
-import HsUtils
 import CoreSyn
 import Var
 import Type
 
 import DsMonad
 import DsUtils
-import Unique
 import PrelInfo
 import TysWiredIn
 import PrelNames
@@ -57,21 +62,16 @@ dsGRHSs :: HsMatchContext Name -> [Pat Id]	-- These are to build a MatchContext
 	-> GRHSs Id				-- Guarded RHSs
 	-> Type					-- Type of RHS
 	-> DsM MatchResult
-dsGRHSs hs_ctx pats grhssa@(GRHSs grhss binds) rhs_ty =
-   bindLocalsDs binders $ do
+dsGRHSs hs_ctx pats grhssa@(GRHSs grhss binds) rhs_ty = do
     match_results <- mappM (dsGRHS hs_ctx pats rhs_ty) grhss
     let 
 	match_result1 = foldr1 combineMatchResults match_results
 	match_result2 = adjustMatchResultDs 
-                                 (\e -> bindLocalsDs binders $ 
-                                        dsLocalBinds binds e) 
+                                 (\e -> dsLocalBinds binds e) 
                                  match_result1
 		-- NB: nested dsLet inside matchResult
     --
     returnDs match_result2
-        where bindsBinders = map unLoc (collectLocalBinders binds)
-              patsBinders  = collectPatsBinders (map (L undefined) pats) 
-              binders = bindsBinders ++ patsBinders
 
 dsGRHS hs_ctx pats rhs_ty (L loc (GRHS guards rhs))
   = matchGuards (map unLoc guards) hs_ctx rhs rhs_ty
@@ -105,20 +105,17 @@ matchGuards [] ctx rhs rhs_ty
 	-- NB:	The success of this clause depends on the typechecker not
 	-- 	wrapping the 'otherwise' in empty HsTyApp or HsWrap constructors
 	--	If it does, you'll get bogus overlap warnings
-matchGuards (ExprStmt (L _ (HsVar v)) _ _ : stmts) ctx rhs rhs_ty
-  |  v `hasKey` otherwiseIdKey
-  || v `hasKey` getUnique trueDataConId	
-	-- trueDataConId doesn't have the same unique as trueDataCon
-  = matchGuards stmts ctx rhs rhs_ty
-
+matchGuards (ExprStmt e _ _ : stmts) ctx rhs rhs_ty
+  | Just addTicks <- isTrueLHsExpr e
+  = matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
+    returnDs (adjustMatchResultDs addTicks match_result)
 matchGuards (ExprStmt expr _ _ : stmts) ctx rhs rhs_ty
   = matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
     dsLExpr expr			`thenDs` \ pred_expr ->
     returnDs (mkGuardedMatchResult pred_expr match_result)
 
 matchGuards (LetStmt binds : stmts) ctx rhs rhs_ty
-  = bindLocalsDs (map unLoc $ collectLocalBinders binds) $
-    matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
+  = matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
     returnDs (adjustMatchResultDs (dsLocalBinds binds) match_result)
 	-- NB the dsLet occurs inside the match_result
 	-- Reason: dsLet takes the body expression as its argument
@@ -126,10 +123,34 @@ matchGuards (LetStmt binds : stmts) ctx rhs rhs_ty
 	--	   body expression in hand
 
 matchGuards (BindStmt pat bind_rhs _ _ : stmts) ctx rhs rhs_ty
-  = bindLocalsDs (collectPatBinders pat) $
-    matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
+  = matchGuards stmts ctx rhs rhs_ty	`thenDs` \ match_result ->
     dsLExpr bind_rhs			`thenDs` \ core_rhs ->
     matchSinglePat core_rhs ctx pat rhs_ty match_result
+
+isTrueLHsExpr :: LHsExpr Id -> Maybe (CoreExpr -> DsM CoreExpr)
+
+-- Returns Just {..} if we're sure that the expression is True
+-- I.e.   * 'True' datacon
+--	  * 'otherwise' Id
+--	  * Trivial wappings of these
+-- The arguments to Just are any HsTicks that we have found,
+-- because we still want to tick then, even it they are aways evaluted.
+isTrueLHsExpr (L _ (HsVar v)) |  v `hasKey` otherwiseIdKey
+			      || v `hasKey` getUnique trueDataConId	
+                                      = Just returnDs
+	-- trueDataConId doesn't have the same unique as trueDataCon
+isTrueLHsExpr (L loc (HsTick    ix frees e)) 
+    | Just ticks <- isTrueLHsExpr e   = Just (\ e1 -> 
+			     ticks e1 `thenDs` \ e2 -> 
+			     mkTickBox ix frees e2)
+   -- This encodes that the result is constant True for Hpc tick purposes;
+   -- which is specifically what isTrueLHsExpr is trying to find out.
+isTrueLHsExpr (L loc (HsBinTick ixT _ e))
+    | Just ticks <- isTrueLHsExpr e   = Just (\ e1 -> 
+			     ticks e1 `thenDs` \ e2 -> 
+			     mkTickBox ixT [] e2)
+isTrueLHsExpr (L _ (HsPar e))         = isTrueLHsExpr e
+isTrueLHsExpr other = Nothing
 \end{code}
 
 Should {\em fail} if @e@ returns @D@