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Staticdeps intro: partial writeup

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Théophile Bastian 2024-11-29 13:32:50 +01:00
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slides/50_staticdeps/main.tex
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@ -1,10 +1,61 @@
\section{\staticdeps: static extraction of memory-carried dependencies}
\begin{frame}
\begin{frame}[fragile]{Dependencies, through registers}
\begin{minipage}[c]{0.35\textwidth}
\begin{lstlisting}[language={[x86masm]Assembler}, numbers=none]
0: mov (%rax), %rcx
...
3: add %rcx, %rdx
\end{lstlisting}
\end{minipage}\hfill
\begin{minipage}[c]{0.5\textwidth}
\begin{itemize}
\item Track register writes
\item Generate dependency upon read
\end{itemize}
\end{minipage}
\begin{center}
3 $\rightarrow$ 0 through \reg{rcx}
\end{center}
\end{frame}
\begin{frame}[fragile]{Dependencies, loop-carried}
\begin{minipage}[c]{0.40\textwidth}
\begin{lstlisting}[language={[x86masm]Assembler}, numbers=none]
loop:
0: add %rcx, %rdx
...
3: mov (%rax), %rcx
6: jmp loop
\end{lstlisting}
\end{minipage}\hfill
\begin{minipage}[c]{0.1\textwidth}
$\longrightarrow$
\end{minipage}\hfill
\begin{minipage}[c]{0.40\textwidth}
\begin{lstlisting}[language={[x86masm]Assembler}, numbers=none]
0,0: add %rcx, %rdx
...
0,3: mov (%rax), %rcx
1,0: add %rcx, %rdx
...
1,3: mov (%rax), %rcx
\end{lstlisting}
\end{minipage}
\begin{center}
0,3 $\rightarrow$ 1,0 through \reg{rcx}\\
\ie{} \alert{loop-carried 3 $\rightarrow$ 1}
\end{center}
\end{frame}
\begin{frame}{Dependencies, through memory}
\todo{}
\begin{itemize}
\item Dependency through registers: easy
\item Loop-carried: still fine
\item Through memory: indirections, arithmetics, …
\item Loop-carried: ROB is finite and small-ish
\item Requires comparison of arbitrary formal expressions
@ -12,6 +63,7 @@
\end{itemize}
\end{frame}
\begin{frame}{The \staticdeps{} algorithm}
\begin{itemize}
\item \alert{Unroll} kernel until $\card{\kerK} \geq \card{\text{ROB}} +