#13379: Space leak / quadratic behavior when inlining -------------------------------------+------------------------------------- Reporter: jberryman | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by jberryman): Still looking into this slowly when I have time. It looks like this is a regression between ghc-7.10 and 8.0.1 at least. Here e.g. `# 50 lines` etc refers to 50 lines of {{{ f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> f bs >> }}} With ghc 7.10 this looks slow but linear: {{{ jberryman /tmp/again » time ghc-7.10.3 -fforce-recomp -O2 Main.hs # 25 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc-7.10.3 -fforce-recomp -O2 Main.hs 0.90s user 0.09s system 97% cpu 1.018 total jberryman /tmp/again » time ghc-7.10.3 -fforce-recomp -O2 Main.hs # 50 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc-7.10.3 -fforce-recomp -O2 Main.hs 1.59s user 0.13s system 98% cpu 1.744 total jberryman /tmp/again » time ghc-7.10.3 -fforce-recomp -O2 Main.hs # 100 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc-7.10.3 -fforce-recomp -O2 Main.hs 3.87s user 0.25s system 99% cpu 4.146 total }}} And in 8.0 we have a regression and what looks like worse asymptotics: {{{ jberryman /tmp/again » time ghc -fforce-recomp -O2 Main.hs # 25 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc -fforce-recomp -O2 Main.hs 2.41s user 0.15s system 99% cpu 2.583 total jberryman /tmp/again » time ghc -fforce-recomp -O2 Main.hs # 50 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc -fforce-recomp -O2 Main.hs 7.36s user 0.21s system 99% cpu 7.586 total jberryman /tmp/again » time ghc -fforce-recomp -O2 Main.hs # 100 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc -fforce-recomp -O2 Main.hs 27.99s user 0.45s system 99% cpu 28.463 total jberryman /tmp/again » time ghc -fforce-recomp -O2 Main.hs # 200 lines [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... ghc -fforce-recomp -O2 Main.hs 122.58s user 6.40s system 84% cpu 2:33.50 total }}} Also attached profiles using the ghc library via https://gist.github.com/nominolo/d18efaabf3e074d03969 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13379#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler