Refactoring: explicitly mark whether we have an info table in RawCmm

I introduced this to support explicitly recording the info table label
in RawCmm for another patch I am working on, but it turned out to lead
to significant simplification in those parts of the compiler that
consume RawCmm.

Now, instead of lots of tests for null [CmmStatic] we have a simple
test of a Maybe, and have reduced the number of guys that need to know
how to convert entry->info labels by a TON. There are only 3 callers
of that function now!

14 files changed, 90 insertions, 82 deletions

diff --git a/compiler/cmm/CmmDecl.hs b/compiler/cmm/CmmDecl.hs
index a663b8483f..b154e5094b 100644
--- a/compiler/cmm/CmmDecl.hs
+++ b/compiler/cmm/CmmDecl.hs
@@ -55,7 +55,7 @@ newtype GenCmm d h g = Cmm [GenCmmTop d h g]
 data GenCmmTop d h g
   = CmmProc     -- A procedure
      h                 -- Extra header such as the info table
-     CLabel            -- Used to generate both info & entry labels
+     CLabel            -- Used to generate both info & entry labels (though the info table label is in 'h' in RawCmmTop)
      g                 -- Control-flow graph for the procedure's code
 
   | CmmData     -- Static data
diff --git a/compiler/cmm/CmmInfo.hs b/compiler/cmm/CmmInfo.hs
index a606da2aec..107e64f2d4 100644
--- a/compiler/cmm/CmmInfo.hs
+++ b/compiler/cmm/CmmInfo.hs
@@ -78,7 +78,7 @@ mkInfoTable _    (CmmData sec dat) = [CmmData sec dat]
 mkInfoTable uniq (CmmProc (CmmInfo _ _ info) entry_label blocks) =
     case info of
       -- Code without an info table.  Easy.
-      CmmNonInfoTable -> [CmmProc [] entry_label blocks]
+      CmmNonInfoTable -> [CmmProc Nothing entry_label blocks]
 
       CmmInfoTable _ (ProfilingInfo ty_prof cl_prof) type_tag type_info ->
           let info_label = entryLblToInfoLbl entry_label
@@ -153,7 +153,7 @@ mkInfoTableAndCode :: CLabel
                    -> [RawCmmTop]
 mkInfoTableAndCode info_lbl std_info extra_bits entry_lbl blocks
   | tablesNextToCode 	-- Reverse the extra_bits; and emit the top-level proc
-  = [CmmProc (map CmmStaticLit (reverse extra_bits ++ std_info))
+  = [CmmProc (Just (Statics info_lbl $ map CmmStaticLit (reverse extra_bits ++ std_info)))
              entry_lbl blocks]
 
   | ListGraph [] <- blocks -- No code; only the info table is significant
@@ -163,7 +163,7 @@ mkInfoTableAndCode info_lbl std_info extra_bits entry_lbl blocks
 
   | otherwise	-- Separately emit info table (with the function entry 
   =		-- point as first entry) and the entry code 
-    [CmmProc [] entry_lbl blocks,
+    [CmmProc Nothing entry_lbl blocks,
      mkDataLits info_lbl (CmmLabel entry_lbl : std_info ++ extra_bits)]
 
 mkSRTLit :: CLabel
diff --git a/compiler/cmm/CmmOpt.hs b/compiler/cmm/CmmOpt.hs
index 28f21e21f3..5480d9c597 100644
--- a/compiler/cmm/CmmOpt.hs
+++ b/compiler/cmm/CmmOpt.hs
@@ -673,12 +673,11 @@ exactLog2 x_
 -}
 
 cmmLoopifyForC :: RawCmmTop -> RawCmmTop
-cmmLoopifyForC p@(CmmProc info entry_lbl
-                 (ListGraph blocks@(BasicBlock top_id _ : _)))
-  | null info = p  -- only if there's an info table, ignore case alts
-  | otherwise =  
+cmmLoopifyForC p@(CmmProc Nothing _ _) = p  -- only if there's an info table, ignore case alts
+cmmLoopifyForC p@(CmmProc (Just info@(Statics info_lbl _)) entry_lbl
+                 (ListGraph blocks@(BasicBlock top_id _ : _))) =
 --  pprTrace "jump_lbl" (ppr jump_lbl <+> ppr entry_lbl) $
-  CmmProc info entry_lbl (ListGraph blocks')
+  CmmProc (Just info) entry_lbl (ListGraph blocks')
   where blocks' = [ BasicBlock id (map do_stmt stmts)
 		  | BasicBlock id stmts <- blocks ]
 
@@ -686,7 +685,7 @@ cmmLoopifyForC p@(CmmProc info entry_lbl
 		= CmmBranch top_id
 	do_stmt stmt = stmt
 
-	jump_lbl | tablesNextToCode = entryLblToInfoLbl entry_lbl
+	jump_lbl | tablesNextToCode = info_lbl
 		 | otherwise        = entry_lbl
 
 cmmLoopifyForC top = top
diff --git a/compiler/cmm/OldCmm.hs b/compiler/cmm/OldCmm.hs
index 5ba78dcc7e..f691183038 100644
--- a/compiler/cmm/OldCmm.hs
+++ b/compiler/cmm/OldCmm.hs
@@ -76,9 +76,12 @@ newtype ListGraph i = ListGraph [GenBasicBlock i]
 type Cmm    = GenCmm    CmmStatics CmmInfo (ListGraph CmmStmt)
 type CmmTop = GenCmmTop CmmStatics CmmInfo (ListGraph CmmStmt)
 
--- | Cmm with the info tables converted to a list of 'CmmStatic'
-type RawCmm    = GenCmm    CmmStatics [CmmStatic] (ListGraph CmmStmt)
-type RawCmmTop = GenCmmTop CmmStatics [CmmStatic] (ListGraph CmmStmt)
+-- | Cmm with the info tables converted to a list of 'CmmStatic' along with the info
+-- table label. If we are building without tables-next-to-code there will be no statics
+--
+-- INVARIANT: if there is an info table, it has at least one CmmStatic
+type RawCmm    = GenCmm    CmmStatics (Maybe CmmStatics) (ListGraph CmmStmt)
+type RawCmmTop = GenCmmTop CmmStatics (Maybe CmmStatics) (ListGraph CmmStmt)
 
 
 -- A basic block containing a single label, at the beginning.
diff --git a/compiler/cmm/PprC.hs b/compiler/cmm/PprC.hs
index fe29bc604d..b48d2de3c8 100644
--- a/compiler/cmm/PprC.hs
+++ b/compiler/cmm/PprC.hs
@@ -83,11 +83,11 @@ pprC (Cmm tops) = vcat $ intersperse blankLine $ map pprTop tops
 -- top level procs
 -- 
 pprTop :: RawCmmTop -> SDoc
-pprTop (CmmProc info clbl (ListGraph blocks)) =
-    (if not (null info)
-        then pprDataExterns info $$
-             pprWordArray (entryLblToInfoLbl clbl) info
-        else empty) $$
+pprTop (CmmProc mb_info clbl (ListGraph blocks)) =
+    (case mb_info of
+       Nothing -> empty
+       Just (Statics info_clbl info_dat) -> pprDataExterns info_dat $$
+                                            pprWordArray info_clbl info_dat) $$
     (vcat [
            blankLine,
            extern_decls,
diff --git a/compiler/llvmGen/LlvmCodeGen.hs b/compiler/llvmGen/LlvmCodeGen.hs
index 46f3f268a3..340a313561 100644
--- a/compiler/llvmGen/LlvmCodeGen.hs
+++ b/compiler/llvmGen/LlvmCodeGen.hs
@@ -13,7 +13,6 @@ import LlvmCodeGen.Data
 import LlvmCodeGen.Ppr
 import LlvmMangler
 
-import CLabel
 import CgUtils ( fixStgRegisters )
 import OldCmm
 import OldPprCmm
@@ -40,9 +39,9 @@ llvmCodeGen dflags h us cmms
         (cdata,env) = foldr split ([],initLlvmEnv) cmm
         split (CmmData s d' ) (d,e) = ((s,d'):d,e)
         split (CmmProc i l _) (d,e) =
-            let lbl = strCLabel_llvm $ if not (null i)
-                   then entryLblToInfoLbl l
-                   else l
+            let lbl = strCLabel_llvm $ case i of
+                        Nothing                   -> l
+                        Just (Statics info_lbl _) -> info_lbl
                 env' = funInsert lbl llvmFunTy e
             in (d,env')
     in do
diff --git a/compiler/llvmGen/LlvmCodeGen/Base.hs b/compiler/llvmGen/LlvmCodeGen/Base.hs
index e73f41cde1..1c7592ad2d 100644
--- a/compiler/llvmGen/LlvmCodeGen/Base.hs
+++ b/compiler/llvmGen/LlvmCodeGen/Base.hs
@@ -41,7 +41,7 @@ import Unique
 -- * Some Data Types
 --
 
-type LlvmCmmTop = GenCmmTop [LlvmData] [CmmStatic] (ListGraph LlvmStatement)
+type LlvmCmmTop = GenCmmTop [LlvmData] (Maybe CmmStatics) (ListGraph LlvmStatement)
 type LlvmBasicBlock = GenBasicBlock LlvmStatement
 
 -- | Unresolved code.
diff --git a/compiler/llvmGen/LlvmCodeGen/Ppr.hs b/compiler/llvmGen/LlvmCodeGen/Ppr.hs
index 48a0d6967c..40f7ce05f1 100644
--- a/compiler/llvmGen/LlvmCodeGen/Ppr.hs
+++ b/compiler/llvmGen/LlvmCodeGen/Ppr.hs
@@ -82,16 +82,16 @@ pprLlvmCmmTop :: LlvmEnv -> Int -> LlvmCmmTop -> (Doc, [LlvmVar])
 pprLlvmCmmTop _ _ (CmmData _ lmdata)
   = (vcat $ map pprLlvmData lmdata, [])
 
-pprLlvmCmmTop env count (CmmProc info lbl (ListGraph blks))
-  = let static = Statics lbl info
-        (idoc, ivar) = if not (null info)
-                          then pprInfoTable env count lbl static
-                          else (empty, [])
+pprLlvmCmmTop env count (CmmProc mb_info entry_lbl (ListGraph blks))
+  = let (idoc, ivar) = case mb_info of
+                        Nothing -> (empty, [])
+                        Just (Statics info_lbl dat)
+                         -> pprInfoTable env count info_lbl (Statics entry_lbl dat)
     in (idoc $+$ (
         let sec = mkLayoutSection (count + 1)
-            (lbl',sec') = if not (null info)
-                            then (entryLblToInfoLbl lbl, sec)
-                            else (lbl, Nothing)
+            (lbl',sec') = case mb_info of
+                           Nothing                   -> (entry_lbl, Nothing)
+                           Just (Statics info_lbl _) -> (info_lbl,  sec)
             link = if externallyVisibleCLabel lbl'
                       then ExternallyVisible
                       else Internal
@@ -104,13 +104,13 @@ pprLlvmCmmTop env count (CmmProc info lbl (ListGraph blks))
 
 -- | Pretty print CmmStatic
 pprInfoTable :: LlvmEnv -> Int -> CLabel -> CmmStatics -> (Doc, [LlvmVar])
-pprInfoTable env count lbl stat
+pprInfoTable env count info_lbl stat
   = let unres = genLlvmData (Text, stat)
         (_, (ldata, ltypes)) = resolveLlvmData env unres
 
         setSection ((LMGlobalVar _ ty l _ _ c), d)
             = let sec = mkLayoutSection count
-                  ilabel = strCLabel_llvm (entryLblToInfoLbl lbl)
+                  ilabel = strCLabel_llvm info_lbl
                               `appendFS` fsLit iTableSuf
                   gv = LMGlobalVar ilabel ty l sec llvmInfAlign c
                   v = if l == Internal then [gv] else []
diff --git a/compiler/nativeGen/AsmCodeGen.lhs b/compiler/nativeGen/AsmCodeGen.lhs
index bfeaf9e8e3..83082eaab8 100644
--- a/compiler/nativeGen/AsmCodeGen.lhs
+++ b/compiler/nativeGen/AsmCodeGen.lhs
@@ -267,7 +267,7 @@ nativeCodeGen' dflags ncgImpl h us cmms
 		| dopt Opt_SplitObjs dflags = split_marker : tops
 		| otherwise		    = tops
 
-	split_marker = CmmProc [] mkSplitMarkerLabel (ListGraph [])
+	split_marker = CmmProc Nothing mkSplitMarkerLabel (ListGraph [])
 
 
 -- | Do native code generation on all these cmms.
diff --git a/compiler/nativeGen/Instruction.hs b/compiler/nativeGen/Instruction.hs
index 5c85101e8e..7bcaa2b2a9 100644
--- a/compiler/nativeGen/Instruction.hs
+++ b/compiler/nativeGen/Instruction.hs
@@ -38,13 +38,13 @@ noUsage  = RU [] []
 type NatCmm instr
 	= GenCmm
 		CmmStatics
-		[CmmStatic]
+		(Maybe CmmStatics)
 		(ListGraph instr)
 
 type NatCmmTop statics instr
 	= GenCmmTop
 		statics
-		[CmmStatic]
+		(Maybe CmmStatics)
 		(ListGraph instr)
 
 
diff --git a/compiler/nativeGen/PPC/Ppr.hs b/compiler/nativeGen/PPC/Ppr.hs
index 7d85b4c66b..3209e9981c 100644
--- a/compiler/nativeGen/PPC/Ppr.hs
+++ b/compiler/nativeGen/PPC/Ppr.hs
@@ -54,19 +54,23 @@ pprNatCmmTop (CmmData section dats) =
   pprSectionHeader section $$ pprDatas dats
 
  -- special case for split markers:
-pprNatCmmTop (CmmProc [] lbl (ListGraph [])) = pprLabel lbl
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph [])) = pprLabel lbl
 
-pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) = 
+ -- special case for code without an info table:
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph blocks)) = 
   pprSectionHeader Text $$
-  (if null info then -- blocks guaranteed not null, so label needed
-       pprLabel lbl
-   else
+  pprLabel lbl $$ -- blocks guaranteed not null, so label needed
+  vcat (map pprBasicBlock blocks)
+
+pprNatCmmTop (CmmProc (Just (Statics info_lbl info)) _entry_lbl (ListGraph blocks)) = 
+  pprSectionHeader Text $$
+  (
 #if HAVE_SUBSECTIONS_VIA_SYMBOLS
-            pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-                <> char ':' $$
+       pprCLabel_asm (mkDeadStripPreventer info_lbl)
+           <> char ':' $$
 #endif
        vcat (map pprData info) $$
-       pprLabel (entryLblToInfoLbl lbl)
+       pprLabel info_lbl
   ) $$
   vcat (map pprBasicBlock blocks)
      -- above: Even the first block gets a label, because with branch-chain
@@ -78,12 +82,10 @@ pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) =
         -- from the entry code to a label on the _top_ of of the info table,
         -- so that the linker will not think it is unreferenced and dead-strip
         -- it. That's why the label is called a DeadStripPreventer (_dsp).
-  $$ if not (null info)
-		    then text "\t.long "
-		      <+> pprCLabel_asm (entryLblToInfoLbl lbl)
-		      <+> char '-'
-		      <+> pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-		    else empty
+  $$ text "\t.long "
+	<+> pprCLabel_asm info_lbl
+	<+> char '-'
+	<+> pprCLabel_asm (mkDeadStripPreventer info_lbl)
 #endif
 
 
diff --git a/compiler/nativeGen/RegAlloc/Liveness.hs b/compiler/nativeGen/RegAlloc/Liveness.hs
index a6a3724bfa..0f9220de8f 100644
--- a/compiler/nativeGen/RegAlloc/Liveness.hs
+++ b/compiler/nativeGen/RegAlloc/Liveness.hs
@@ -158,7 +158,7 @@ data Liveness
 -- | Stash regs live on entry to each basic block in the info part of the cmm code.
 data LiveInfo
 	= LiveInfo
-		[CmmStatic]				-- cmm static stuff
+		(Maybe CmmStatics)			-- cmm info table static stuff
 		(Maybe BlockId)				-- id of the first block
 		(Maybe (BlockMap RegSet))		-- argument locals live on entry to this block
 		(Map BlockId (Set Int))			-- stack slots live on entry to this block
@@ -212,8 +212,8 @@ instance Outputable instr
 		 | otherwise		= name <> (hcat $ punctuate space $ map ppr $ uniqSetToList regs)
 
 instance Outputable LiveInfo where
-	ppr (LiveInfo static firstId liveVRegsOnEntry liveSlotsOnEntry)
-		=  (vcat $ map ppr static)
+	ppr (LiveInfo mb_static firstId liveVRegsOnEntry liveSlotsOnEntry)
+		=  (maybe empty ppr mb_static)
 		$$ text "# firstId          = " <> ppr firstId
 		$$ text "# liveVRegsOnEntry = " <> ppr liveVRegsOnEntry
 		$$ text "# liveSlotsOnEntry = " <> text (show liveSlotsOnEntry)
diff --git a/compiler/nativeGen/SPARC/Ppr.hs b/compiler/nativeGen/SPARC/Ppr.hs
index 7f3583f26c..aab700acc3 100644
--- a/compiler/nativeGen/SPARC/Ppr.hs
+++ b/compiler/nativeGen/SPARC/Ppr.hs
@@ -52,19 +52,23 @@ pprNatCmmTop (CmmData section dats) =
   pprSectionHeader section $$ pprDatas dats
 
  -- special case for split markers:
-pprNatCmmTop (CmmProc [] lbl (ListGraph [])) = pprLabel lbl
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph [])) = pprLabel lbl
 
-pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) = 
+ -- special case for code without info table:
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph blocks)) = 
   pprSectionHeader Text $$
-  (if null info then -- blocks guaranteed not null, so label needed
-       pprLabel lbl
-   else
+  pprLabel lbl $$ -- blocks guaranteed not null, so label needed
+  vcat (map pprBasicBlock blocks)
+
+pprNatCmmTop (CmmProc (Just (Statics info_lbl info)) _entry_lbl (ListGraph blocks)) = 
+  pprSectionHeader Text $$
+  (
 #if HAVE_SUBSECTIONS_VIA_SYMBOLS
-            pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-                <> char ':' $$
+       pprCLabel_asm (mkDeadStripPreventer info_lbl)
+           <> char ':' $$
 #endif
        vcat (map pprData info) $$
-       pprLabel (entryLblToInfoLbl lbl)
+       pprLabel info_lbl
   ) $$
   vcat (map pprBasicBlock blocks)
      -- above: Even the first block gets a label, because with branch-chain
@@ -76,12 +80,10 @@ pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) =
         -- from the entry code to a label on the _top_ of of the info table,
         -- so that the linker will not think it is unreferenced and dead-strip
         -- it. That's why the label is called a DeadStripPreventer (_dsp).
-  $$ if not (null info)
-		    then text "\t.long "
-		      <+> pprCLabel_asm (entryLblToInfoLbl lbl)
-		      <+> char '-'
-		      <+> pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-		    else empty
+  $$ text "\t.long "
+	<+> pprCLabel_asm info_lbl
+	<+> char '-'
+	<+> pprCLabel_asm (mkDeadStripPreventer info_lbl)
 #endif
 
 
diff --git a/compiler/nativeGen/X86/Ppr.hs b/compiler/nativeGen/X86/Ppr.hs
index 10af5ef8c1..5762cd93d5 100644
--- a/compiler/nativeGen/X86/Ppr.hs
+++ b/compiler/nativeGen/X86/Ppr.hs
@@ -54,19 +54,24 @@ pprNatCmmTop (CmmData section dats) =
   pprSectionHeader section $$ pprDatas dats
 
  -- special case for split markers:
-pprNatCmmTop (CmmProc [] lbl (ListGraph [])) = pprLabel lbl
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph [])) = pprLabel lbl
 
-pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) =
+ -- special case for code without info table:
+pprNatCmmTop (CmmProc Nothing lbl (ListGraph blocks)) =
   pprSectionHeader Text $$
-  (if null info then -- blocks guaranteed not null, so label needed
-       pprLabel lbl
-   else
+  pprLabel lbl $$ -- blocks guaranteed not null, so label needed
+  vcat (map pprBasicBlock blocks) $$
+  pprSizeDecl lbl
+
+pprNatCmmTop (CmmProc (Just (Statics info_lbl info)) _entry_lbl (ListGraph blocks)) =
+  pprSectionHeader Text $$
+  (
 #if HAVE_SUBSECTIONS_VIA_SYMBOLS
-            pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-                <> char ':' $$
+       pprCLabel_asm (mkDeadStripPreventer info_lbl)
+           <> char ':' $$
 #endif
        vcat (map pprData info) $$
-       pprLabel (entryLblToInfoLbl lbl)
+       pprLabel info_lbl
   ) $$
   vcat (map pprBasicBlock blocks)
      -- above: Even the first block gets a label, because with branch-chain
@@ -78,14 +83,12 @@ pprNatCmmTop (CmmProc info lbl (ListGraph blocks)) =
         -- from the entry code to a label on the _top_ of of the info table,
         -- so that the linker will not think it is unreferenced and dead-strip
         -- it. That's why the label is called a DeadStripPreventer (_dsp).
-  $$ if not (null info)
-                    then text "\t.long "
-                      <+> pprCLabel_asm (entryLblToInfoLbl lbl)
-                      <+> char '-'
-                      <+> pprCLabel_asm (mkDeadStripPreventer $ entryLblToInfoLbl lbl)
-                    else empty
+  $$ text "\t.long "
+       <+> pprCLabel_asm info_lbl
+       <+> char '-'
+       <+> pprCLabel_asm (mkDeadStripPreventer info_lbl)
 #endif
-   $$ pprSizeDecl (if null info then lbl else entryLblToInfoLbl lbl)
+   $$ pprSizeDecl info_lbl
 
 -- | Output the ELF .size directive.
 pprSizeDecl :: CLabel -> Doc