#16190: Speed up handling of large String literals -------------------------------------+------------------------------------- Reporter: hsyl20 | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by hsyl20): I have experimented with this in the following branch: https://gitlab.haskell.org/hsyl20/ghc/tree/hsyl20-T16190 It adds a GHC command-line flag to choose the threshold (in bytes) above which the strings are dumped in a binary file (e.g. `./inplace/bin/ghc- stage2 -fbinary-string-threshold=200`). The current implementation performs the transformation in the tidy pass. I'm not sure if it is the best place to do it. The included `bench_literal.sh` script generates an Haskell source file which prints a string literal and then benches the time required to compile it. Below are the results for different string lengths. With this test, the optimization starts to be really noticeable for string literals
500K.
|| Size || No optimization || Threshold 100 || Gain || || 128 || 0.730 || 0.770 || -5% || || 3K || 0.731 || 0.829 || -13% || || 30K || 0.736 || 0.805 || -9% || || 100K || 0.804 || 0.856 || -6% || || 500K || 1.038 || 0.912 || +12% || || 1M || 1.342 || 1.101 || +18% || || 2M || 1.926 || 1.446 || +25% || || 3M || 2.539 || 1.805 || +29% || || 30M || 20.182 || 10.244 || +49% || I couldn't test with TH generated string literals as it crashes the compiler because some names become garbage with the optimization enabled. We should probably only enable the optimization if we generate an actual linked object file. It isn't done yet. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16190#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler