#11822: Pattern match checker exceeded (2000000) iterations -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: gkaracha Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc3 Resolution: | Keywords: | PatternMatchWarnings Operating System: Unknown/Multiple | Architecture: x86_64 Type of failure: Compile-time | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by niteria): I don't have an optimized `HEAD` at hand, so I tried it with `ghc-8.0` branch: {{{ $ for i in 1 10 100 1000 2000 4000 10000 20000; do echo $i; ./A.gen.sh $i
A.hs && time ghc8.0 -dno-debug-output -fmax-pmcheck-iterations=200000000 A.hs; done 1 [1 of 1] Compiling A ( A.hs, A.o )
real 0m0.289s user 0m0.178s sys 0m0.032s 10 [1 of 1] Compiling A ( A.hs, A.o ) real 0m0.228s user 0m0.135s sys 0m0.031s 100 [1 of 1] Compiling A ( A.hs, A.o ) real 0m0.299s user 0m0.225s sys 0m0.038s 1000 [1 of 1] Compiling A ( A.hs, A.o ) real 0m2.087s user 0m1.941s sys 0m0.112s 2000 [1 of 1] Compiling A ( A.hs, A.o ) real 0m5.885s user 0m5.126s sys 0m0.127s 4000 [1 of 1] Compiling A ( A.hs, A.o ) real 0m15.612s user 0m15.094s sys 0m0.472s 10000 [1 of 1] Compiling A ( A.hs, A.o ) real 1m31.634s user 1m29.615s sys 0m1.873s 20000 [1 of 1] Compiling A ( A.hs, A.o ) A.hs:40006:3: warning: Pattern match checker exceeded (200000000) iterations in an equation for ‘fromEnum’. (Use -fmax-pmcheck-iterations=n to set the maximun number of iterations to n) }}} I will measure again after I build `HEAD`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11822#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler