small debugging output cleanup

[ghc-hetmet.git] / compiler / codeGen / CgUtils.hs

diff --git a/compiler/codeGen/CgUtils.hs b/compiler/codeGen/CgUtils.hs
index ab39080..804aeab 100644 (file)
--- a/compiler/codeGen/CgUtils.hs
+++ b/compiler/codeGen/CgUtils.hs
@@ -474,15 +474,18 @@ mk_switch tag_expr branches mb_deflt lo_tag hi_tag via_C
   where
     use_switch          = {- pprTrace "mk_switch" (
                        ppr tag_expr <+> text "n_tags:" <+> int n_tags <+>
+                        text "branches:" <+> ppr (map fst branches) <+>
                        text "n_branches:" <+> int n_branches <+>
-                       text "lo_tag: " <+> int lo_tag <+>
-                       text "hi_tag: " <+> int hi_tag <+>
-                       text "real_lo_tag: " <+> int real_lo_tag <+>
-                       text "real_hi_tag: " <+> int real_hi_tag) $ -}
+                       text "lo_tag:" <+> int lo_tag <+>
+                       text "hi_tag:" <+> int hi_tag <+>
+                       text "real_lo_tag:" <+> int real_lo_tag <+>
+                       text "real_hi_tag:" <+> int real_hi_tag) $ -}
                   ASSERT( n_branches > 1 && n_tags > 1 ) 
-                  n_tags > 2 && (small || dense || via_C)
-                -- a 2-branch switch always turns into an if.
-    small               = n_tags <= 4
+                  n_tags > 2 && (via_C || (dense && big_enough))
+                -- up to 4 branches we use a decision tree, otherwise
+                 -- a switch (== jump table in the NCG).  This seems to be
+                 -- optimal, and corresponds with what gcc does.
+    big_enough          = n_branches > 4
     dense               = n_branches > (n_tags `div` 2)
     n_branches   = length branches