When generating C, don't pretend functions are data

We used to generated things like:
    extern StgWordArray (newCAF) __attribute__((aligned (8)));
    ((void (*)(void *))(W_)&newCAF)((void *)R1.w);
(which is to say, pretend that newCAF is some data, then cast it to a
function and call it).
This goes wrong on at least IA64, where:
    A function pointer on the ia64 does not point to the first byte of
    code. Intsead, it points to a structure that describes the function.
    The first quadword in the structure is the address of the first byte
    of code
so we end up dereferencing function pointers one time too many, and
segfaulting.

1 files changed, 22 insertions, 17 deletions

diff --git a/compiler/cmm/CLabel.hs b/compiler/cmm/CLabel.hs
index aa72b65243..2501b6ebed 100644
--- a/compiler/cmm/CLabel.hs
+++ b/compiler/cmm/CLabel.hs
@@ -119,6 +119,8 @@ module CLabel (
 
 import IdInfo
 import StaticFlags
+import BasicTypes
+import Literal
 import Packages
 import DataCon
 import PackageConfig
@@ -193,11 +195,12 @@ data CLabel
 
   | RtsLabel RtsLabelInfo
 
-  | ForeignLabel FastString	-- a 'C' (or otherwise foreign) label
-	(Maybe Int) 		-- possible '@n' suffix for stdcall functions
-		-- When generating C, the '@n' suffix is omitted, but when
-		-- generating assembler we must add it to the label.
-	Bool			-- True <=> is dynamic
+  | ForeignLabel FastString     -- a 'C' (or otherwise foreign) label
+        (Maybe Int)             -- possible '@n' suffix for stdcall functions
+                -- When generating C, the '@n' suffix is omitted, but when
+                -- generating assembler we must add it to the label.
+        Bool                    -- True <=> is dynamic
+        FunctionOrData
 
   | CC_Label  CostCentre
   | CCS_Label CostCentreStack
@@ -373,17 +376,18 @@ mkApEntryLabel upd off		= RtsLabel (RtsApEntry   upd off)
 
 	-- Foreign labels
 
-mkForeignLabel :: FastString -> Maybe Int -> Bool -> CLabel
-mkForeignLabel str mb_sz  is_dynamic = ForeignLabel str mb_sz is_dynamic
+mkForeignLabel :: FastString -> Maybe Int -> Bool -> FunctionOrData -> CLabel
+mkForeignLabel str mb_sz is_dynamic fod
+    = ForeignLabel str mb_sz is_dynamic fod
 
 addLabelSize :: CLabel -> Int -> CLabel
-addLabelSize (ForeignLabel str _ is_dynamic) sz
-  = ForeignLabel str (Just sz) is_dynamic
+addLabelSize (ForeignLabel str _ is_dynamic fod) sz
+  = ForeignLabel str (Just sz) is_dynamic fod
 addLabelSize label _
   = label
 
 foreignLabelStdcallInfo :: CLabel -> Maybe Int
-foreignLabelStdcallInfo (ForeignLabel _ info _) = info
+foreignLabelStdcallInfo (ForeignLabel _ info _ _) = info
 foreignLabelStdcallInfo _lbl = Nothing
 
 	-- Cost centres etc.
@@ -498,7 +502,7 @@ needsCDecl ModuleRegdLabel		= False
 needsCDecl (StringLitLabel _)		= False
 needsCDecl (AsmTempLabel _)		= False
 needsCDecl (RtsLabel _)			= False
-needsCDecl l@(ForeignLabel _ _ _)	= not (isMathFun l)
+needsCDecl l@(ForeignLabel _ _ _ _)	= not (isMathFun l)
 needsCDecl (CC_Label _)			= True
 needsCDecl (CCS_Label _)		= True
 needsCDecl (HpcTicksLabel _)            = True
@@ -518,7 +522,7 @@ maybeAsmTemp _ 	    	       = Nothing
 -- they are builtin to the C compiler.  For these labels we avoid
 -- generating our own C prototypes.
 isMathFun :: CLabel -> Bool
-isMathFun (ForeignLabel fs _ _) = fs `elem` math_funs
+isMathFun (ForeignLabel fs _ _ _) = fs `elem` math_funs
   where
   math_funs = [
         (fsLit "pow"),    (fsLit "sin"),   (fsLit "cos"),
@@ -557,7 +561,7 @@ externallyVisibleCLabel (PlainModuleInitLabel _)= True
 externallyVisibleCLabel (ModuleInitTableLabel _)= False
 externallyVisibleCLabel ModuleRegdLabel    = False
 externallyVisibleCLabel (RtsLabel _)	   = True
-externallyVisibleCLabel (ForeignLabel _ _ _) = True
+externallyVisibleCLabel (ForeignLabel _ _ _ _) = True
 externallyVisibleCLabel (IdLabel name _ _)     = isExternalName name
 externallyVisibleCLabel (CC_Label _)	   = True
 externallyVisibleCLabel (CCS_Label _)	   = True
@@ -611,6 +615,7 @@ labelType (PlainModuleInitLabel _)            = CodeLabel
 labelType (ModuleInitTableLabel _)            = DataLabel
 labelType (LargeSRTLabel _)                   = DataLabel
 labelType (LargeBitmapLabel _)                = DataLabel
+labelType (ForeignLabel _ _ _ IsFunction) = CodeLabel
 labelType (IdLabel _ _ info) = idInfoLabelType info
 labelType _                = DataLabel
 
@@ -639,11 +644,11 @@ labelDynamic this_pkg lbl =
    RtsLabel _  	     -> not opt_Static && (this_pkg /= rtsPackageId) -- i.e., is the RTS in a DLL or not?
    IdLabel n _ k       -> isDllName this_pkg n
 #if mingw32_TARGET_OS
-   ForeignLabel _ _ d  -> d
+   ForeignLabel _ _ d _ -> d
 #else
    -- On Mac OS X and on ELF platforms, false positives are OK,
    -- so we claim that all foreign imports come from dynamic libraries
-   ForeignLabel _ _ _ -> True
+   ForeignLabel _ _ _ _ -> True
 #endif
    ModuleInitLabel m _    -> not opt_Static && this_pkg /= (modulePackageId m)
    PlainModuleInitLabel m -> not opt_Static && this_pkg /= (modulePackageId m)
@@ -738,7 +743,7 @@ maybe_underscore doc
 #ifdef mingw32_TARGET_OS
 -- In asm mode, we need to put the suffix on a stdcall ForeignLabel.
 -- (The C compiler does this itself).
-pprAsmCLbl (ForeignLabel fs (Just sz) _)
+pprAsmCLbl (ForeignLabel fs (Just sz) _ _)
    = ftext fs <> char '@' <> int sz
 #endif
 pprAsmCLbl lbl
@@ -832,7 +837,7 @@ pprCLbl (RtsLabel (RtsSlowTickyCtr pat))
 pprCLbl ModuleRegdLabel
   = ptext (sLit "_module_registered")
 
-pprCLbl (ForeignLabel str _ _)
+pprCLbl (ForeignLabel str _ _ _)
   = ftext str
 
 pprCLbl (IdLabel name cafs flavor) = ppr name <> ppIdFlavor flavor