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| author | simonpj@microsoft.com <unknown> | 2008-06-05 12:44:23 +0000 |
|---|---|---|
| committer | simonpj@microsoft.com <unknown> | 2008-06-05 12:44:23 +0000 |
| commit | a3f24157839605f19e869fdde8cd73266fecf4ac (patch) | |
| tree | 3a5794e3b447df97b446e1361843cf3f5185b078 /compiler/main/StaticFlags.hs | |
| parent | 1b1190e01d0c65043628d2532988d9b1b4a78384 (diff) | |
| download | haskell-a3f24157839605f19e869fdde8cd73266fecf4ac.tar.gz | |
Desugar multiple polymorphic bindings more intelligently
Occasionally people write very large recursive groups of definitions.
In general we desugar these to a single definition that binds tuple,
plus lots of tuple selectors. But that code has quadratic size, which
can be bad.
This patch adds a new case to the desugaring of bindings, for the
situation where there are lots of polymorphic variables, but no
dictionaries. (Dictionaries force us into the general case.)
See Note [Abstracting over tyvars only].
The extra behaviour can be disabled with the (static) flag
-fno-ds-multi-tyvar
in case we want to experiment with switching it on or off. There is
essentially-zero effect on the nofib suite though.
I was provoked into doing this by Trac #1136. In fact I'm not sure
it's the real cause of the problem there, but it's a good idea anyway.
Diffstat (limited to 'compiler/main/StaticFlags.hs')
| -rw-r--r-- | compiler/main/StaticFlags.hs | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/compiler/main/StaticFlags.hs b/compiler/main/StaticFlags.hs index 6fa6032bb0..6d826cb72b 100644 --- a/compiler/main/StaticFlags.hs +++ b/compiler/main/StaticFlags.hs @@ -39,6 +39,7 @@ module StaticFlags ( opt_Parallel, -- optimisation opts + opt_DsMultiTyVar, opt_NoStateHack, opt_SpecInlineJoinPoints, opt_CprOff, @@ -320,8 +321,13 @@ opt_Parallel :: Bool opt_Parallel = lookUp (fsLit "-fparallel") -- optimisation opts +opt_DsMultiTyVar :: Bool +opt_DsMultiTyVar = not (lookUp (fsLit "-fno-ds-multi-tyvar")) + -- On by default + opt_SpecInlineJoinPoints :: Bool opt_SpecInlineJoinPoints = lookUp (fsLit "-fspec-inline-join-points") + opt_NoStateHack :: Bool opt_NoStateHack = lookUp (fsLit "-fno-state-hack") opt_CprOff :: Bool @@ -410,6 +416,7 @@ isStaticFlag f = "dno-black-holing", "fno-method-sharing", "fno-state-hack", + "fno-ds-multi-tyvar", "fruntime-types", "fno-pre-inlining", "fexcess-precision", |