Commit 301f1535 authored by simonpj's avatar simonpj
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[project @ 2003-03-21 09:22:28 by simonpj]

Notes about constructor info tables
parent aae3d827
......@@ -220,7 +220,23 @@ that type, and that in turn depends on whether module <tt>M</tt> was
compiled with <tt>-funbox-strict-fields</tt>. So when writing an
interface file, GHC therefore records with each data type whether its
strict fields (if any) should be unboxed.
<h2> Labels and info tables </h2>
<em>Quick rough notes: SLPJ March 2003</em>.
Every data constructor <tt>C</tt>has two info tables:
<li> The static info table (label <tt>C_static_info</tt>), used for statically-allocated constructors.
<li> The dynamic info table (label <tt>C_con_info</tt>), used for dynamically-allocated constructors.
Statically-allocated constructors are not moved by the garbage collector, and therefore have a different closure
type from dynamically-allocated constructors; hence they need
a distinct info table.
Both info tables share the same entry code, but since the entry code is phyiscally juxtaposed with the
info table, it must be duplicated (<tt>C_static_entry</tt> and <tt>C_con_entry</tt> respectively).
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