[project @ 2001-03-19 16:20:44 by simonpj]

------------------------------------
	Be more gung-ho about INLINE pragmas
	------------------------------------

When we see

	{-# INLINE f #-}
	f = g $ h

should we inline f inside a lambda?  Previously we said 'no'
because f looks like a redex, but that's a great mistake sometimes.
So this commit is more gung-ho: if you say INLINE that's what you get.

The changes are to exprIsDupable and exprIsCheap.

diff --git a/ghc/compiler/coreSyn/CoreUtils.lhs b/ghc/compiler/coreSyn/CoreUtils.lhs
index 6905cb7..00d5723 100644 (file)
--- a/ghc/compiler/coreSyn/CoreUtils.lhs
+++ b/ghc/compiler/coreSyn/CoreUtils.lhs
@@ -333,10 +333,11 @@ exprIsAtom other      = False
 
 
 \begin{code}
-exprIsDupable (Type _)      = True
-exprIsDupable (Var v)       = True
-exprIsDupable (Lit lit)      = litIsDupable lit
-exprIsDupable (Note _ e)     = exprIsDupable e
+exprIsDupable (Type _)         = True
+exprIsDupable (Var v)          = True
+exprIsDupable (Lit lit)        = litIsDupable lit
+exprIsDupable (Note InlineMe e) = True
+exprIsDupable (Note _ e)        = exprIsDupable e
 exprIsDupable expr          
   = go expr 0
   where
@@ -383,6 +384,7 @@ exprIsCheap :: CoreExpr -> Bool
 exprIsCheap (Lit lit)            = True
 exprIsCheap (Type _)             = True
 exprIsCheap (Var _)              = True
+exprIsCheap (Note InlineMe e)            = True
 exprIsCheap (Note _ e)           = exprIsCheap e
 exprIsCheap (Lam x e)            = if isId x then True else exprIsCheap e
 exprIsCheap (Case e _ alts)       = exprIsCheap e && 
@@ -518,9 +520,11 @@ as values, even if their arguments are non-trivial;
              map (...redex...)         is a value
 Because `seq` on such things completes immediately
 
-A worry: constructors with unboxed args:
+A possible worry: constructors with unboxed args:
                C (f x :: Int#)
-Suppose (f x) diverges; then C (f x) is not a value.
+Suppose (f x) diverges; then C (f x) is not a value.  True, but
+this form is illegal (see the invariants in CoreSyn).  Args of unboxed
+type must be ok-for-speculation (or trivial).
 
 \begin{code}
 exprIsValue :: CoreExpr -> Bool                -- True => Value-lambda, constructor, PAP