#4838: LLVM mangler takes too long at runtime
---------------------------------+------------------------------------------
Reporter: benl | Owner: davidte...@…
Type: bug | Status: new
Priority: normal | Component: Compiler (LLVM)
Version: 7.0.1 | Keywords:
Testcase: | Blockedby:
Os: MacOS X | Blocking:
Architecture: Unknown/Multiple | Failure: Compile-time performance bug
---------------------------------+------------------------------------------
Compiling the !BarnesHut example from DPH takes 30 min with -fllvm, but
only 2 min with -fasm. The Words benchmark has similar problems. Running
GHC with -v and using 'top' shows that the llvm compiler finishes in <
1min, so the problem is in GHC and not LLVM. Suspect complexity issues in
LLVM mangler, which is only needed on OSX. #4211 is related.
{{{
limitingfactor:dph-examples benl$ pwd
/Users/benl/devel/ghc/build/nightly/ghc-head/libraries/dph/dph-examples
# Compiling with the NCG
/usr/bin/time ../../../inplace/bin/ghc-stage2 -fasm -Odph \
--make imaginary/Words/Main.hs -package dph-prim-par -package dph-par \
-iimaginary/Words -fforce-recomp
[1 of 2] Compiling WordsVect ( imaginary/Words/WordsVect.hs,
imaginary/Words/WordsVect.o )
[2 of 2] Compiling Main ( imaginary/Words/Main.hs,
imaginary/Words/Main.o )
Linking imaginary/Words/Main ...
93.21 real 91.30 user 1.68 sys
# Compiling with LLVM
/usr/bin/time ../../../inplace/bin/ghc-stage2 -fllvm -Odph \
--make imaginary/Words/Main.hs -package dph-prim-par \
-package dph-par -iimaginary/Words -fforce-recomp
[1 of 2] Compiling WordsVect ( imaginary/Words/WordsVect.hs,
imaginary/Words/WordsVect.o )
# ... 10 mins later I'm getting bored so Control-C it, though it's
completed in the past.
^C 677.91 real 673.53 user 3.59 sys
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4838>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
