Optimizing Dynamically-Typed Object-Oriented Programming Languages
with Polymorphic Inline Caches
Urs Hölzle,
Craig Chambers,
and
David Ungar
Abstract:
Polymorphic inline caches (PICs) provide a new way to reduce the
overhead of polymorphic message sends by extending inline caches to
include more than one cached lookup result per call site. For a set of
typical object-oriented SELF programs, PICs achieve a median speedup
of 11%.
As an important side effect, PICs collect type information by
recording all of the receiver types actually used at a given call
site. The compiler can exploit this type infor\-mation to generate
better code when recompiling a method. An experimental version of such
a system achieves a median speedup of 27% for our set of SELF
programs, reducing the number of non-inlined message sends by a factor
of two.
Implementations of dynamically-typed object-oriented languages have
been limited by the paucity of type information available to the
compiler. The abundance of the type information provided by PICs
suggests a new compilation approach for these languages, adaptive
compilation. Such compilers may succeed in generating very efficient
code for the time-critical parts of a program without incurring
distracting compilation pauses.
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