[commit: ghc] wip/T10137: CmmSwitch: Actually do nothing when targetting C or LLVM (92452b3)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/T10137
Link       : http://ghc.haskell.org/trac/ghc/changeset/92452b36417da684de9b81d8b0731731b632605d/ghc

>---------------------------------------------------------------

commit 92452b36417da684de9b81d8b0731731b632605d
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Thu Mar 19 10:12:00 2015 +0100

    CmmSwitch: Actually do nothing when targetting C or LLVM


>---------------------------------------------------------------

92452b36417da684de9b81d8b0731731b632605d
 compiler/cmm/CmmCreateSwitchPlans.hs | 4 +++-
 compiler/cmm/CmmSwitch.hs            | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/compiler/cmm/CmmCreateSwitchPlans.hs b/compiler/cmm/CmmCreateSwitchPlans.hs
index 0fac30c..1ca0cd4 100644
--- a/compiler/cmm/CmmCreateSwitchPlans.hs
+++ b/compiler/cmm/CmmCreateSwitchPlans.hs
@@ -29,7 +29,9 @@ import DynFlags
 -- | Traverses the 'CmmGraph', making sure that 'CmmSwitch' are suitable for
 -- code generation.
 cmmCreateSwitchPlans :: DynFlags -> CmmGraph -> UniqSM CmmGraph
-cmmCreateSwitchPlans dflags g = do
+cmmCreateSwitchPlans dflags g
+    | targetSupportsSwitch (hscTarget dflags) = return g
+    | otherwise = do
     blocks' <- concat `fmap` mapM (visitSwitches dflags) (toBlockList g)
     return $ ofBlockList (g_entry g) blocks'
 
diff --git a/compiler/cmm/CmmSwitch.hs b/compiler/cmm/CmmSwitch.hs
index 7190d6e..edb2087 100644
--- a/compiler/cmm/CmmSwitch.hs
+++ b/compiler/cmm/CmmSwitch.hs
@@ -7,10 +7,12 @@ module CmmSwitch (
      switchTargetsToList, eqSwitchTargetWith,
 
      SwitchPlan(..),
+     targetSupportsSwitch,
      createSwitchPlan,
   ) where
 
 import Outputable
+import DynFlags
 import Compiler.Hoopl (Label)
 
 import Data.Maybe
@@ -243,6 +245,13 @@ data SwitchPlan
 
 type FlatSwitchPlan = SeparatedList Integer SwitchPlan
 
+-- | Does the target support switch out of the box? Then leave this to the
+-- target!
+targetSupportsSwitch :: HscTarget -> Bool
+targetSupportsSwitch HscC = True
+targetSupportsSwitch HscLlvm = True
+targetSupportsSwitch _ = False
+
 -- | This function creates a SwitchPlan from a SwitchTargets value, breaking it
 -- down into smaller pieces suitable for code generation.
 createSwitchPlan :: SwitchTargets -> SwitchPlan