#14257: Heap profiling with ghc and hp2ps and strict function application ($!) gives samples out of sequence (regression) -------------------------------------+------------------------------------- Reporter: carlostome | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.2.1 System | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #14006 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following program generates an invalid .hp file when compiled with ghc 8.2.1 but it does not when using ghc 8.0.2. {{{#!hs {-# LANGUAGE ScopedTypeVariables #-} module Main where eval :: forall a b. (a -> b -> b) -> b -> [a] -> b eval f b xs = load xs [] where load :: [a] -> [a] -> b load [] stk = unload b stk load (x:xs) stk = load xs (x : stk) unload :: b -> [a] -> b unload v [] = v unload v (x : stk) = unload ((f $! x) $! v) stk main :: IO () main = print (eval (||) False (True : replicate 10000000 False)) }}} If strict application ($!) is substituted for normal application ($) or removed then the .hp generated file is correct. For reproducing the error: {{{ ghc -O2 --make -prof -fprof-auto Example.hs -fforce-recomp ./Example +RTS -hc hp2ps -e8in -c Example.hp }}} It outputs: {{{ hp2ps: Example.hp, line 43, samples out of sequence }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14257 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler