Add Outputable.blankLine and use it

[ghc-hetmet.git] / compiler / cmm / ZipCfgCmmRep.hs

diff --git a/compiler/cmm/ZipCfgCmmRep.hs b/compiler/cmm/ZipCfgCmmRep.hs
index 27191f3..451450e 100644 (file)
--- a/compiler/cmm/ZipCfgCmmRep.hs
+++ b/compiler/cmm/ZipCfgCmmRep.hs
@@ -103,12 +103,15 @@ data Last
            -- This is really needed at the *return* point rather than here
            -- at the call, but in practice it's convenient to record it here.
 
-        cml_ret_off :: Maybe UpdFrameOffset
-          -- Stack offset for return (update frames);
-          -- The return offset should be Nothing only if we have to create
-          -- a new call, e.g. for a procpoint, in which case it's an invariant
-          -- that the call does not stand for a return or a tail call,
-          -- and the successor does not need an info table.
+        cml_ret_off :: Maybe ByteOff
+          -- For calls *only*, the byte offset of the base of the frame that
+         -- must be described by the info table for the return point.  
+         -- The older words are an update frames, which have their own
+         -- info-table and layout information
+
+         -- From a liveness point of view, the stack words older than
+         -- cml_ret_off are treated as live, even if the sequel of
+         -- the call goes into a loop.
        }
 
 data MidCallTarget     -- The target of a MidUnsafeCall
@@ -456,10 +459,9 @@ pprMiddle stmt = pp_stmt <+> pp_debug
        -- call "ccall" foo(x, y)[r1, r2];
        -- ToDo ppr volatile
        MidForeignCall safety target results args ->
-           hsep [ if null results
-                     then empty
-                     else parens (commafy $ map ppr results) <+> equals,
-                      ppr_safety safety,
+           hsep [ ppUnless (null results) $
+                     parens (commafy $ map ppr results) <+> equals,
+                   ppr_safety safety,
                   ptext $ sLit "call", 
                   ppr_call_target target <> parens (commafy $ map ppr args) <> semi]