#14737: Improve performance of Simplify.simplCast -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #11735 #14683 | Differential Rev(s): Phab:D4385 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Interestingly, the coercion optimizer will '''not''' work on `InstCo ... (Refl ...)`. Other points of interest here: - The first line of the `opt_co4` case for `InstCo` looks plain wrong, extending the substitution with a use of `kind_co`, where `kind_co` has not, itself, been substituted. - `opt_co4` uses `splitForAllCo_maybe`, which doesn't look for `Refl`s. Perhaps it should. - The ''only'' way `InstCo`s can come into being is in the coercion optimizer. There is no call to `mkInstCo` beyond it. So perhaps we can take that into account when designing these functions. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14737#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler