20x slow down with -O or -O2
This program:
http://www.cse.unsw.edu.au/~dons/code/nobench/spectral/calendar/
Suffers a misoptimisation when compiled with -O or -O2. When compiled with -Onot:
serenity$ ghc -Onot --make -o calendar calendar.hs -no-recomp
[1 of 1] Compiling Main ( calendar.hs, calendar.o )
Linking calendar ...
serenity$ time ./calendar 1993 10000 > /dev/null
./calendar 1993 10000 > /dev/null 0.02s user 0.00s system 99% cpu 0.021 total
When compiled with -O:
serenity$ ghc -O --make -o calendar calendar.hs -no-recomp
[1 of 1] Compiling Main ( calendar.hs, calendar.o )
Linking calendar ...
serenity$ time ./calendar 1993 10000 > /dev/null
./calendar 1993 10000 > /dev/null 5.00s user 0.01s system 99% cpu 5.011 total
And with -O2:
serenity$ time ./calendar 1993 10000 > /dev/null
./calendar 1993 10000 > /dev/null 4.95s user 0.01s system 100% cpu 4.953 total
Reproduced in amd64 and x86 linux.
Trac metadata
Trac field | Value |
---|---|
Version | 6.6 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture | Multiple |