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author | Takano Akio <tak@anoak.io> | 2017-01-18 18:26:47 -0500 |
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committer | Ben Gamari <ben@smart-cactus.org> | 2017-01-20 14:36:29 -0500 |
commit | d49b2bb21691892ca6ac8f2403e31f2a5e53feb3 (patch) | |
tree | cc8488acf59467899e4d3279a340577eec95310f /docs/core-spec | |
parent | a2a67b77c3048713541d1ed96ec0b95fb2542f9a (diff) | |
download | haskell-d49b2bb21691892ca6ac8f2403e31f2a5e53feb3.tar.gz |
Allow top-level string literals in Core (#8472)
This commits relaxes the invariants of the Core syntax so that a
top-level variable can be bound to a primitive string literal of type
Addr#.
This commit:
* Relaxes the invatiants of the Core, and allows top-level bindings whose
type is Addr# as long as their RHS is either a primitive string literal or
another variable.
* Allows the simplifier and the full-laziness transformer to float out
primitive string literals to the top leve.
* Introduces the new StgGenTopBinding type to accomodate top-level Addr#
bindings.
* Introduces a new type of labels in the object code, with the suffix "_bytes",
for exported top-level Addr# bindings.
* Makes some built-in rules more robust. This was necessary to keep them
functional after the above changes.
This is a continuation of D2554.
Rebasing notes:
This had two slightly suspicious performance regressions:
* T12425: bytes allocated regressed by roughly 5%
* T4029: bytes allocated regressed by a bit over 1%
* T13035: bytes allocated regressed by a bit over 5%
These deserve additional investigation.
Rebased by: bgamari.
Test Plan: ./validate --slow
Reviewers: goldfire, trofi, simonmar, simonpj, austin, hvr, bgamari
Reviewed By: trofi, simonpj, bgamari
Subscribers: trofi, simonpj, gridaphobe, thomie
Differential Revision: https://phabricator.haskell.org/D2605
GHC Trac Issues: #8472
Diffstat (limited to 'docs/core-spec')
-rw-r--r-- | docs/core-spec/core-spec.mng | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/docs/core-spec/core-spec.mng b/docs/core-spec/core-spec.mng index f9db420857..623ba0e596 100644 --- a/docs/core-spec/core-spec.mng +++ b/docs/core-spec/core-spec.mng @@ -100,7 +100,9 @@ The datatype that represents expressions: There are a few key invariants about expressions: \begin{itemize} \item The right-hand sides of all top-level and recursive $[[let]]$s -must be of lifted type. +must be of lifted type, with one exception: the right-hand side of a top-level +$[[let]]$ may be of type \texttt{Addr#} if it's a primitive string literal. +See \verb|#top_level_invariant#| in \ghcfile{coreSyn/CoreSyn.hs}. \item The right-hand side of a non-recursive $[[let]]$ and the argument of an application may be of unlifted type, but only if the expression is ok-for-speculation. See \verb|#let_app_invariant#| in \ghcfile{coreSyn/CoreSyn.lhs}. |