#13360: Add a flag to enable inferring HasCallStack constraints -------------------------------------+------------------------------------- Reporter: gridaphobe | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.0.1 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 saurabhnanda): Does this seem like a sensible benchmark for a pure function that throws an Exception: https://github.com/vacationlabs/hascallstack- benchmarks/blob/f055b16db7bf42e069daf25e126bd04a3c8b65bc/app/Main.hs Here are the numbers, which seem to be suggesting a 6-7x perf penalty for using `HasCallstack`, which seems to be getting worse as the depth of the callstack increases: * factorial/20: 4x penalty * factorial/30: 4.8x penalty * factorial/50: 5.9x penalty * factorial/100: 6.9x penalty * factorial/200: 7.7x penalty * factorial/300: 7.8x penalty Can someone confirm this pattern on their machine as well? {{{ benchmarking factorial/regular/20 time 1.757 μs (1.734 μs .. 1.782 μs) 0.999 R² (0.998 R² .. 1.000 R²) mean 1.732 μs (1.722 μs .. 1.753 μs) std dev 41.67 ns (26.25 ns .. 72.27 ns) variance introduced by outliers: 30% (moderately inflated) benchmarking factorial/callstack/20 time 7.080 μs (7.041 μs .. 7.138 μs) 1.000 R² (0.999 R² .. 1.000 R²) mean 7.087 μs (7.058 μs .. 7.135 μs) std dev 128.1 ns (88.70 ns .. 183.6 ns) variance introduced by outliers: 17% (moderately inflated) benchmarking factorial/regular/30 time 2.142 μs (2.129 μs .. 2.161 μs) 0.999 R² (0.998 R² .. 1.000 R²) mean 2.155 μs (2.140 μs .. 2.192 μs) std dev 76.73 ns (47.29 ns .. 132.5 ns) variance introduced by outliers: 48% (moderately inflated) benchmarking factorial/callstack/30 time 10.42 μs (10.34 μs .. 10.53 μs) 0.999 R² (0.998 R² .. 1.000 R²) mean 10.65 μs (10.53 μs .. 10.84 μs) std dev 527.4 ns (362.1 ns .. 827.1 ns) variance introduced by outliers: 60% (severely inflated) benchmarking factorial/regular/50 time 2.962 μs (2.933 μs .. 3.007 μs) 0.998 R² (0.997 R² .. 1.000 R²) mean 2.972 μs (2.947 μs .. 3.021 μs) std dev 119.0 ns (80.88 ns .. 181.1 ns) variance introduced by outliers: 53% (severely inflated) benchmarking factorial/callstack/50 time 17.56 μs (17.26 μs .. 18.13 μs) 0.993 R² (0.979 R² .. 0.999 R²) mean 17.62 μs (17.34 μs .. 18.34 μs) std dev 1.365 μs (588.7 ns .. 2.620 μs) variance introduced by outliers: 77% (severely inflated) benchmarking factorial/regular/100 time 4.920 μs (4.883 μs .. 4.973 μs) 0.999 R² (0.998 R² .. 1.000 R²) mean 4.969 μs (4.915 μs .. 5.037 μs) std dev 200.2 ns (144.0 ns .. 264.3 ns) variance introduced by outliers: 52% (severely inflated) benchmarking factorial/callstack/100 time 33.78 μs (33.63 μs .. 33.99 μs) 0.999 R² (0.999 R² .. 1.000 R²) mean 34.36 μs (34.04 μs .. 34.98 μs) std dev 1.493 μs (1.015 μs .. 2.390 μs) variance introduced by outliers: 50% (moderately inflated) benchmarking factorial/regular/200 time 9.002 μs (8.921 μs .. 9.131 μs) 0.999 R² (0.998 R² .. 1.000 R²) mean 9.132 μs (9.052 μs .. 9.229 μs) std dev 299.3 ns (238.2 ns .. 375.3 ns) variance introduced by outliers: 39% (moderately inflated) benchmarking factorial/callstack/200 time 69.26 μs (67.10 μs .. 71.77 μs) 0.995 R² (0.992 R² .. 1.000 R²) mean 68.59 μs (67.86 μs .. 69.60 μs) std dev 2.830 μs (1.919 μs .. 3.858 μs) variance introduced by outliers: 44% (moderately inflated) benchmarking factorial/regular/300 time 12.93 μs (12.90 μs .. 12.97 μs) 0.999 R² (0.999 R² .. 1.000 R²) mean 13.27 μs (13.11 μs .. 13.51 μs) std dev 597.3 ns (422.6 ns .. 842.9 ns) variance introduced by outliers: 54% (severely inflated) benchmarking factorial/callstack/300 time 101.2 μs (100.7 μs .. 101.7 μs) 0.999 R² (0.999 R² .. 1.000 R²) mean 103.9 μs (102.5 μs .. 105.9 μs) std dev 5.361 μs (3.981 μs .. 6.618 μs) variance introduced by outliers: 54% (severely inflated) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13360#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler