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talk-2019-10-OOPSLA19
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Refactor "complex & slow"

This commit is contained in:
Théophile Bastian 2019-10-17 16:18:08 +02:00
parent 2870f6a51d
commit 3b9768c76a
1 changed files with 56 additions and 6 deletions
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slides.tex
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@ -56,6 +56,10 @@
morekeywords={gdb},
sensitive=false,
}
\lstdefinelanguage{cfiasm}{
morekeywords={cfi_startproc,cfi_def_cfa_offset,cfi_offset,cfi_def_cfa_register},
sensitive=false,
}
\setbeamertemplate{footline}
{
@ -237,14 +241,58 @@ Segmentation fault.
\end{lstlisting}
\pause{}
\vfill
\begin{itemize}
\item[\textbf{$\longrightarrow$}] \textbf{\alert{constructed} on-demand
by a \alert{Turing-complete stack machine}!}
\end{itemize}
\end{frame}
\begin{frame}{What does this imply?}
Your compiler actually generates codes for \alert{two machines}: your
processor and the DWARF VM\@.
\vfill{}
\begin{columns}
\begin{column}{0.5\textwidth}
\begin{center}
\begin{tikzpicture}
\begin{scope}[every node/.style={rectangle,thick,draw,scale=0.95}]
\node (cmd) at (0, 2.5) {
\lstbash{\$ gcc -S foo.c}
};
\node (asm) at (0, 0) {
\lstinputlisting[numbers=none, language=cfiasm]{src/main_cfi.s}
};
\end{scope}
\begin{scope}[>={Stealth[black]},
every path/.style={draw=black,very thick}]
\path [->] (cmd) -- (asm);
\end{scope}
\end{tikzpicture}
\medskip{}
\textbf{The \lstc{.cfi_*} is inline DWARF!}
\end{center}
\end{column}
\begin{column}{0.5\textwidth}
\begin{center}
\bf
$\implies$ if you write inline asm, you must write inline DWARF!
\end{center}
In \prog{glibc}, \prog{lowlevellock.h}:
\alert{off by one error in unwinding data}. Result:
\lstinputlisting[language=gdb,numbers=none]{src/lowlevellock_backtrace}
\end{column}
\end{columns}
\only<2->{
\begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.17\paperheight)%
\begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.10\paperheight)%
\begin{tcolorbox}[halign=center, colframe=red, colback=Lavender]
\bf \huge
Complex \,\& \,slow
@ -253,13 +301,15 @@ Segmentation fault.
}
\only<3->{
\begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.35\paperheight)%
\begin{textblock*}{0.90\textwidth}[0.5,0](0.5\paperwidth,0.30\paperheight)%
\begin{tcolorbox}[halign=center, colframe=red, colback=Lavender]
\huge
\textbf{Pervasive:}\\ relied upon by debuggers, profilers, C++
exceptions \\
\medskip{}
\textbf{$\leadsto$ not only for debuggers!}
\textbf{Pervasive:}\\ relied upon by debuggers, profilers,
aaand\ldots{}
\onslide<4->{
C++ exceptions. \\
\medskip{}
\textbf{$\leadsto$ not only for debuggers!}}
\end{tcolorbox}
\end{textblock*}
}