#4299: a less forceful INLINE pragma
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Reporter: simonmar | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.3
Keywords: | Testcase:
Blockedby: | Difficulty: Moderate (less than a day)
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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The `INLINE` pragmas currently does two things:
1. it saves an unoptimised definition of the function in the interface
file, and
2. it unfolds the definition at (almost) every call site, before
optimising it further in situ.
I'm proposing that we have a variant of the `INLINE` pragma that does (1)
without necessarily unfolding the definition at every call site. GHC's
simplifier already has some well-tuned heuristics for deciding whether to
inline something or not based on information about the context, and when
we use `INLINE` we bypass all this and potentially end up with unnecessary
code bloat and maybe even a loss of performance in some cases.
If we had an `INLINEABLE` pragma that did (1) without forcing (2), then
the decision about whether to inline or not is deferred to the call site,
where the user can decide how they want to trade off code size against
speed. Right now the user doesn't get to decide - the library writer
does.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4299>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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