Commit 33406b8c authored by simonpj@microsoft.com's avatar simonpj@microsoft.com
Browse files

Add an IAmDead case to postInlineUnconditionally, and comments

parent c43e5edf
......@@ -748,6 +748,11 @@ postInlineUnconditionally env top_lvl bndr occ_info rhs unfolding
-- int_cxt to prevent us inlining inside a lambda without some
-- good reason. See the notes on int_cxt in preInlineUnconditionally
IAmDead -> True -- This happens; for example, the case_bndr during case of
-- known constructor: case (a,b) of x { (p,q) -> ... }
-- Here x isn't mentioned in the RHS, so we don't want to
-- create the (dead) let-binding let x = (a,b) in ...
other -> False
-- Here's an example that we don't handle well:
......
......@@ -365,7 +365,9 @@ simplNonRecX env bndr new_rhs thing_inside
returnSmpl (emptyFloats env, Case new_rhs bndr' (exprType body') [(DEFAULT, [], body')])
{- No, no, no! Do not try preInlineUnconditionally
| preInlineUnconditionally env NotTopLevel bndr new_rhs
Doing so risks exponential behaviour, because new_rhs has been simplified once already
In the cases described by the folowing commment, postInlineUnconditionally will
catch many of the relevant cases.
-- This happens; for example, the case_bndr during case of
-- known constructor: case (a,b) of x { (p,q) -> ... }
-- Here x isn't mentioned in the RHS, so we don't want to
......@@ -374,6 +376,7 @@ simplNonRecX env bndr new_rhs thing_inside
-- Similarly, single occurrences can be inlined vigourously
-- e.g. case (f x, g y) of (a,b) -> ....
-- If a,b occur once we can avoid constructing the let binding for them.
| preInlineUnconditionally env NotTopLevel bndr new_rhs
= thing_inside (extendIdSubst env bndr (DoneEx new_rhs))
-}
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment