#8326: Place heap checks common in case alternatives before the case -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: jstolarek Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: #1498 Test Case: | Blocking: 8317 | Differential Revisions: Phab:D343 | -------------------------------------+------------------------------------- Comment (by jstolarek): Status update: [https://github.com/jstolarek/ghc/blob/T8326-heap-checks-alternative- plan/compiler/codeGen/StgCmmExpr.hs#L398 I tried knot-tying] but it doesn't work - `cgAlts` is strict in `gc_plan` and changing that doesn't look trivial. The only alternative I see at the moment is to: a) compile the alternatives without heap checks; b) examine heap usage of compiled alternatives c) create a GC plan d) add heap checks to compiled alternatives, if necessary That sounds simple but I have no idea how to leverage FCode monadery to add heap checks to compiled `CmmAGraph`. Am I right to think that currently there is no plumbing for compiling more code on top of already existing `CmmAGraph`? So far I was only able to came up with a prototype that [https://github.com/jstolarek/ghc/commit/266b1295abfc807f6aab2d6b3578f8d52e92... #diff-6f97a583ff892976f6b49509aec5ab28R403 implements point a-c above but instead of d) it re-compiles the alternatives from scratch]. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8326#comment:17 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler