#9476: Implement late lambda-lifting -------------------------------------+------------------------------------- Reporter: simonpj | Owner: nfrisby Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #8763 | Differential Rev(s): Wiki Page: LateLamLift | -------------------------------------+------------------------------------- Comment (by sgraf): I reimplemented this as an STG pass and just rebased it onto a recent 8.6 alpha commit. You can track the progress on my [https://github.com/sgraf812/ghc/tree/22ce14be00f73b63c24e584dda1ad5e1252e57b... `lift-lambda` branch, of which this is the current HEAD]. It passes `./validate`, but due to nofib's `lambda` benchmark not made fit for the next step of the MonadFail proposal, we can't run benchmarks. I ran some benchmarks before the rebase, which was relative to [https://github.com/ghc/ghc/tree/bb539cfe335e this commit]. Here are the numbers, eliding some uninteresting ones: {{{ -------------------------------------------------------------------------------- Program Allocs Instrs -------------------------------------------------------------------------------- VSD -0.3% +0.0% VSM 0.0% -0.1% atom -0.8% -1.2% binary-trees -0.0% -1.5% circsim -1.0% -0.6% clausify -1.9% -0.2% constraints -0.9% -0.7% cryptarithm1 -2.8% -8.0% cryptarithm2 -4.0% -2.9% exact-reals -2.1% -0.1% fft2 -1.0% -0.4% fluid -0.9% -0.6% hidden -1.0% -0.6% k-nucleotide -0.0% +2.4% lcss -0.1% -1.3% mate -3.2% -0.6% mkhprog -1.3% +1.0% power -0.7% -1.0% puzzle -0.0% +0.0% queens -17.7% -0.9% reptile -0.3% -17.1% rewrite -1.7% -0.1% typecheck -2.7% -1.9% -------------------------------------------------------------------------------- Min -17.7% -17.1% Max 0.0% +4.2% Geometric Mean -0.5% -0.3% }}} So, no regressions in allocation (which I'd consider a bug) and some small gains in general. Note that because of ticket:15333#comment:2 I'm not really trusting many of the regressions in counted instructions. I'd test with the proposed `-fllvm -optlo -Os` configuration, but that will have to wait until nofib is fixed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9476#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler