Author: Hakan Ardo <[email protected]>
Branch: extradoc
Changeset: r3671:d7363ca28f5d
Date: 2011-06-13 20:23 +0200
http://bitbucket.org/pypy/extradoc/changeset/d7363ca28f5d/
Log: pure operations
diff --git a/talk/iwtc11/paper.tex b/talk/iwtc11/paper.tex
--- a/talk/iwtc11/paper.tex
+++ b/talk/iwtc11/paper.tex
@@ -109,7 +109,7 @@
%\subtitle{Subtitle Text, if any}
\authorinfo{Hakan Ardo XXX}
- {Affiliation1}
+ {Centre for Mathematical Sciences, Lund University}
{[email protected]}
\authorinfo{Carl Friedrich Bolz}
{Heinrich-Heine-Universität Düsseldorf}
@@ -487,13 +487,16 @@
In general what is needed is for the heap optimizer is to keep track of
which variables from the preamble it reuses in the peeled loop.
It has to construct a vector of such variables $H$ which
-can be used to update the input and jump arguments,
+can be used to update the input and jump arguments using
\begin{equation}
\hat J = \left(J_1, J_2, \cdots, J_{|J|}, H_1, H_2, \cdots, H_{|H}\right)
+ \label{eq:heap-inputargs}
\end{equation}
+and
\begin{equation}
\hat K = \left(K_1, K_2, \cdots, K_{|J|}, m(H_1), m(H_2), \cdots,
m(H_{|H})\right)
.
+ \label{eq:heap-jumpargs}
\end{equation}
In the optimized trace $I$ is replaced by $\hat I$ and $K$ by $\hat
K$. The trace from Figure~\ref{fig:unopt-trace} will be optimized to:
@@ -525,7 +528,16 @@
\end{lstlisting}
\subsection{Pure operation reusage}
-XXX
+If a pure operation appears more than once in the trace with same input
+arguments, it only needs be executed the first time and then the result
+can be reused for all other appearances. When that is combined with loop
+peeling, the single execution of the operation is placed in the
+preamble. That is, loop invariant pure operations are moved out of the
+loop. The interactions here are the same as in the previous
+section. That is, a vector, $H$, of variables produced in the preamble
+and used in the peeled loop needs to be constructed. Then the jump and
+input arguments are updated according to
+Equation~\ref{eq:heap-inputargs} and Equation~\ref{eq:heap-jumpargs}.
\subsection{Allocation Removals}
By using escape analysis it is possible to identify objects that are
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