[project @ 2005-08-04 11:23:42 by simonmar]

callSiteInline: consider inlining even the once-in-one-branch
occurrences.  See comment for details.

diff --git a/ghc/compiler/coreSyn/CoreUnfold.lhs b/ghc/compiler/coreSyn/CoreUnfold.lhs
index 774ee6e..d840f45 100644 (file)
--- a/ghc/compiler/coreSyn/CoreUnfold.lhs
+++ b/ghc/compiler/coreSyn/CoreUnfold.lhs
@@ -520,13 +520,15 @@ callSiteInline dflags active_inline inline_call occ id arg_infos interesting_con
          | otherwise = case occ of
                                IAmDead              -> pprTrace "callSiteInline: dead" (ppr id) False
                                IAmALoopBreaker      -> False
-
-                               -- Occurs once in one branch.  These are deal with by
-                               -- preInlineUnconditionally, so we ignore them here:
-                               OneOcc _ True _      -> False
-
-                               OneOcc in_lam False _ -> (not in_lam || is_cheap) && consider_safe True
+                               OneOcc in_lam _ _    -> (not in_lam || is_cheap) && consider_safe True
                                other                -> is_cheap && consider_safe False
+               -- we consider even the once-in-one-branch
+               -- occurrences, because they won't all have been
+               -- caught by preInlineUnconditionally.  In particular,
+               -- if the occurrence is once inside a lambda, and the
+               -- rhs is cheap but not a manifest lambda, then
+               -- pre-inline will not have inlined it for fear of
+               -- invalidating the occurrence info in the rhs.
 
        consider_safe once
                -- consider_safe decides whether it's a good idea to