#9476: Implement late lambda-lifting -------------------------------------+------------------------------------- Reporter: simonpj | Owner: sgraf Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: LateLamLift Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #8763 #13286 | Differential Rev(s): Wiki Page: LateLamLift | -------------------------------------+------------------------------------- Comment (by sgraf): Over the last week, I polished this some more and played around with heuristics regarding known and unknown calls. I'm pretty confident the transformation can handle every idea outlined in Wiki:LateLamLift. Here are is an excerpt from a benchmarks run: {{{ -------------------------------------------------------------------------------- Program Allocs Instrs -------------------------------------------------------------------------------- cryptarithm1 -2.8% -7.9% cryptarithm2 -4.0% -2.4% exact-reals -2.1% -0.0% k-nucleotide -0.0% +2.4% kahan -0.4% -2.0% lcss -0.1% -5.8% mate -8.4% -3.5% n-body -20.2% -0.0% queens -17.7% -0.8% typecheck -2.7% -1.8% -------------------------------------------------------------------------------- Min -20.2% -7.9% Max +0.0% +2.4% Geometric Mean -0.8% -0.3% }}} I had to fight with a surprising amount of benchmark wibbles (+-12% in instructions, c.f. #15333) related to GC parameters and code layout (probably), although I was using cachegrind for measurements. The above numbers are from running NoFib with `make EXTRA_RUNTEST_OPTS='-cachegrind +RTS -V0 -A128M -H1G -RTS' NoFibRuns=1`. I looked at the regression in `k-nucleotide` (+2.4% counted instructions), but couldn't reproduce so far. I'll probably refactor the one huge module into 2 or 3 smaller ones and then prepare a patch. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9476#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler