Rollback INLINE patches
rolling back:
Fri Dec 5 16:54:00 GMT 2008 simonpj@microsoft.com
* Completely new treatment of INLINE pragmas (big patch)
This is a major patch, which changes the way INLINE pragmas work.
Although lots of files are touched, the net is only +21 lines of
code -- and I bet that most of those are comments!
HEADS UP: interface file format has changed, so you'll need to
recompile everything.
There is not much effect on overall performance for nofib,
probably because those programs don't make heavy use of INLINE pragmas.
Program Size Allocs Runtime Elapsed
Min -11.3% -6.9% -9.2% -8.2%
Max -0.1% +4.6% +7.5% +8.9%
Geometric Mean -2.2% -0.2% -1.0% -0.8%
(The +4.6% for on allocs is cichelli; see other patch relating to
-fpass-case-bndr-to-join-points.)
The old INLINE system
~~~~~~~~~~~~~~~~~~~~~
The old system worked like this. A function with an INLINE pragam
got a right-hand side which looked like
f = __inline_me__ (\xy. e)
The __inline_me__ part was an InlineNote, and was treated specially
in various ways. Notably, the simplifier didn't inline inside an
__inline_me__ note.
As a result, the code for f itself was pretty crappy. That matters
if you say (map f xs), because then you execute the code for f,
rather than inlining a copy at the call site.
The new story: InlineRules
~~~~~~~~~~~~~~~~~~~~~~~~~~
The new system removes the InlineMe Note altogether. Instead there
is a new constructor InlineRule in CoreSyn.Unfolding. This is a
bit like a RULE, in that it remembers the template to be inlined inside
the InlineRule. No simplification or inlining is done on an InlineRule,
just like RULEs.
An Id can have an InlineRule *or* a CoreUnfolding (since these are two
constructors from Unfolding). The simplifier treats them differently:
- An InlineRule is has the substitution applied (like RULES) but
is otherwise left undisturbed.
- A CoreUnfolding is updated with the new RHS of the definition,
on each iteration of the simplifier.
An InlineRule fires regardless of size, but *only* when the function
is applied to enough arguments. The "arity" of the rule is specified
(by the programmer) as the number of args on the LHS of the "=". So
it makes a difference whether you say
{-# INLINE f #-}
f x = \y -> e or f x y = e
This is one of the big new features that InlineRule gives us, and it
is one that Roman really wanted.
In contrast, a CoreUnfolding can fire when it is applied to fewer
args than than the function has lambdas, provided the result is small
enough.
Consequential stuff
~~~~~~~~~~~~~~~~~~~
* A 'wrapper' no longer has a WrapperInfo in the IdInfo. Instead,
the InlineRule has a field identifying wrappers.
* Of course, IfaceSyn and interface serialisation changes appropriately.
* Making implication constraints inline nicely was a bit fiddly. In
the end I added a var_inline field to HsBInd.VarBind, which is why
this patch affects the type checker slightly
* I made some changes to the way in which eta expansion happens in
CorePrep, mainly to ensure that *arguments* that become let-bound
are also eta-expanded. I'm still not too happy with the clarity
and robustness fo the result.
* We now complain if the programmer gives an INLINE pragma for
a recursive function (prevsiously we just ignored it). Reason for
change: we don't want an InlineRule on a LoopBreaker, because then
we'd have to check for loop-breaker-hood at occurrence sites (which
isn't currenlty done). Some tests need changing as a result.
This patch has been in my tree for quite a while, so there are
probably some other minor changes.
M ./compiler/basicTypes/Id.lhs -11
M ./compiler/basicTypes/IdInfo.lhs -82
M ./compiler/basicTypes/MkId.lhs -2 +2
M ./compiler/coreSyn/CoreFVs.lhs -2 +25
M ./compiler/coreSyn/CoreLint.lhs -5 +1
M ./compiler/coreSyn/CorePrep.lhs -59 +53
M ./compiler/coreSyn/CoreSubst.lhs -22 +31
M ./compiler/coreSyn/CoreSyn.lhs -66 +92
M ./compiler/coreSyn/CoreUnfold.lhs -112 +112
M ./compiler/coreSyn/CoreUtils.lhs -185 +184
M ./compiler/coreSyn/MkExternalCore.lhs -1
M ./compiler/coreSyn/PprCore.lhs -4 +40
M ./compiler/deSugar/DsBinds.lhs -70 +118
M ./compiler/deSugar/DsForeign.lhs -2 +4
M ./compiler/deSugar/DsMeta.hs -4 +3
M ./compiler/hsSyn/HsBinds.lhs -3 +3
M ./compiler/hsSyn/HsUtils.lhs -2 +7
M ./compiler/iface/BinIface.hs -11 +25
M ./compiler/iface/IfaceSyn.lhs -13 +21
M ./compiler/iface/MkIface.lhs -24 +19
M ./compiler/iface/TcIface.lhs -29 +23
M ./compiler/main/TidyPgm.lhs -55 +49
M ./compiler/parser/ParserCore.y -5 +6
M ./compiler/simplCore/CSE.lhs -2 +1
M ./compiler/simplCore/FloatIn.lhs -6 +1
M ./compiler/simplCore/FloatOut.lhs -23
M ./compiler/simplCore/OccurAnal.lhs -36 +5
M ./compiler/simplCore/SetLevels.lhs -59 +54
M ./compiler/simplCore/SimplCore.lhs -48 +52
M ./compiler/simplCore/SimplEnv.lhs -26 +22
M ./compiler/simplCore/SimplUtils.lhs -28 +4
M ./compiler/simplCore/Simplify.lhs -91 +109
M ./compiler/specialise/Specialise.lhs -15 +18
M ./compiler/stranal/WorkWrap.lhs -14 +11
M ./compiler/stranal/WwLib.lhs -2 +2
M ./compiler/typecheck/Inst.lhs -1 +3
M ./compiler/typecheck/TcBinds.lhs -17 +27
M ./compiler/typecheck/TcClassDcl.lhs -1 +2
M ./compiler/typecheck/TcExpr.lhs -4 +6
M ./compiler/typecheck/TcForeign.lhs -1 +1
M ./compiler/typecheck/TcGenDeriv.lhs -14 +13
M ./compiler/typecheck/TcHsSyn.lhs -3 +2
M ./compiler/typecheck/TcInstDcls.lhs -5 +4
M ./compiler/typecheck/TcRnDriver.lhs -2 +11
M ./compiler/typecheck/TcSimplify.lhs -10 +17
M ./compiler/vectorise/VectType.hs +7
Mon Dec 8 12:43:10 GMT 2008 simonpj@microsoft.com
* White space only
M ./compiler/simplCore/Simplify.lhs -2
Mon Dec 8 12:48:40 GMT 2008 simonpj@microsoft.com
* Move simpleOptExpr from CoreUnfold to CoreSubst
M ./compiler/coreSyn/CoreSubst.lhs -1 +87
M ./compiler/coreSyn/CoreUnfold.lhs -72 +1
Mon Dec 8 17:30:18 GMT 2008 simonpj@microsoft.com
* Use CoreSubst.simpleOptExpr in place of the ad-hoc simpleSubst (reduces code too)
M ./compiler/deSugar/DsBinds.lhs -50 +16
Tue Dec 9 17:03:02 GMT 2008 simonpj@microsoft.com
* Fix Trac #2861: bogus eta expansion
Urghlhl! I "tided up" the treatment of the "state hack" in CoreUtils, but
missed an unexpected interaction with the way that a bottoming function
simply swallows excess arguments. There's a long
Note [State hack and bottoming functions]
to explain (which accounts for most of the new lines of code).
M ./compiler/coreSyn/CoreUtils.lhs -16 +53
Mon Dec 15 10:02:21 GMT 2008 Simon Marlow <marlowsd@gmail.com>
* Revert CorePrep part of "Completely new treatment of INLINE pragmas..."
The original patch said:
* I made some changes to the way in which eta expansion happens in
CorePrep, mainly to ensure that *arguments* that become let-bound
are also eta-expanded. I'm still not too happy with the clarity
and robustness fo the result.
Unfortunately this change apparently broke some invariants that were
relied on elsewhere, and in particular lead to panics when compiling
with profiling on.
Will re-investigate in the new year.
M ./compiler/coreSyn/CorePrep.lhs -53 +58
M ./configure.ac -1 +1
Mon Dec 15 12:28:51 GMT 2008 Simon Marlow <marlowsd@gmail.com>
* revert accidental change to configure.ac
M ./configure.ac -1 +1
46 files changed: