deletions | additions       diff --git a/overview.tex b/overview.tex  index 490ec69..cb66288 100644  --- a/overview.tex  +++ b/overview.tex 
...
Consider the generic OSR scenario shown in \myfigure\ref{fi:osr-dynamics}. A base function \fbase\ is executed and it can either terminate normally (dashed lines), or an OSR event may transfer control to a variant \fvariant, which acts as a continuation function. The decision of whether an OSR should be fired at a given point \osrpoint\ of \fbase\ is based on an {\em OSR condition}. A typical example in JIT-based virtual machines is a profile counter reaching a certain hotness threshold, which indicates that \fbase\ is taking longer than expected and is worth optimizing. Another example is a guard testing whether \fbase\ has become unsafe and execution needs to fall back to a safe version \fvariant. This scenario includes deoptimization of functions generated with aggressive speculative optimizations.   Classic Serveral  OSR implementations adjust the stack so that execution can continue in \fvariant\ with the current frame \cite{chambers1992design}. \cite{chambers1992design, suganuma2006region}.  This requires manipulating the program state at machine code level and is highly ABI- and compiler-dependent. A simpler approach, which we follow in this article, consists of creating a new frame every time an OSR is fired, essentially regarding an OSR transition as a function call~\cite{Lameed_2013,webkit14}. Our implementation targets two general scenarios: 1) {\em resolved OSR}: \fvariant\ is known before executing \fbase\ as in the deoptimization example discussed above; 2) {\em open OSR}: \fvariant\ is generated when the OSR is fired, supporting deferred and profile-guided compilation strategies. In both cases, \fbase\ is instrumented before its execution to incorporate the OSR machinery. We call such OSR-instrumented version \fosrfrom.  In the resolved OSR scenario (see \myfigure\ref{fi:overview-osr-final}), instrumentation consists of adding a check of the OSR condition and, if it is satisfied, a tail call that fires the OSR. The called function is an instrumented version of \fvariant, which we call \fosrto. The assumption is that \fosrto\ produces the same side-effects and return value that one would obtain by \fbase\ if no OSR was performed. Differently from \fvariant, \fosrto\ takes as input all live variables of \fbase\ at \osrpoint, executes an optional compensation code to fix the computation state ({\tt comp\_code}), and then jumps to a point \textsf{L'} from which execution can continue. The OSR practice often makes the conservative assumption that execution can always continue with the very same program state as the base function. However, this assumption may reduce the number of points where sound OSR transitions can be fired. Supporting compensation code in our framework adds flexibility, allowing OSR transitions to happen at arbitrary places in the base function.  \ifdefined\noauthorea  \begin{figure}[t]  \begin{center} 
...
\end{figure}  \fi  In the resolved OSR scenario (see \myfigure\ref{fi:overview-osr-final}), instrumentation consists of adding a check of the OSR condition and, if it is satisfied, a tail call that fires the OSR. The called function is an instrumented version of \fvariant, which we call \fosrto. The assumption is that \fosrto\ produces the same side-effects and return value that one would obtain by \fbase\ if no OSR was performed. Differently from \fvariant, \fosrto\ takes as input all live variables of \fbase\ at \osrpoint, executes an optional compensation code to fix the computation state ({\tt comp\_code}), and then jumps to a point \textsf{L'} from which execution can continue. The OSR practice often makes the conservative assumption that execution can always continue with the very same program state as the base function. However, this assumption may reduce the number of points where sound OSR transitions can be fired. Supporting compensation code in our framework adds flexibility, allowing OSR transitions to happen at arbitrary places in the base function.  \ifdefined\noauthorea  \begin{figure}[t] \begin{figure}[h!]  \begin{center}  \includegraphics[width=1.0\columnwidth]{figures/overview-osr-open/overview-osr-open.eps}  \caption{\protect\input{figures/overview-osr-open/caption}} 
...
\end{figure}  \fi  \noindent The open OSR scenario is similar, with one main difference (see \myfigure\ref{fi:overview-osr-open}): instead of calling \fosrto\ directly, \fosrfrom\ calls a stub function \fstub, which first creates \fosrto\ and then calls it. Function \fosrto\ is generated by a function {\tt gen} that takes the base function \fbase\ and the OSR point \osrpoint\ as input. The reason for having a stub in the open OSR scenario, rather than directly instrumenting \fbase\ with the code generation machinery, is to minimize the extra code injected into \fbase. Indeed, instrumentation may interfere with optimizations, e.g., by increasing register pressure and altering code layout and instruction cache behavior. \paragraph{Discussion.}