stuff

src/slides.tex

@@ -78,6 +78,19 @@
   Some primitives such as \mintinline{c}{malloc} need to be rewritten in Wasm and provided by the compiler.
 \end{frame}
 
+\begin{frame}[fragile]
+  How does a GC work ?
+  \begin{itemize}
+    \item \emph{Tracing}: we start from \emph{roots} and we find live objects recursively (OCaml, Java)
+    \item \emph{Reference counting}: we start from dying objects and we kill objects recursively (Python)
+  \end{itemize}
+  We need to discriminate pointers:
+  \begin{itemize}
+    \item \emph{Conservative (Boehm)}: we make a guess and accept memory leaks (Crystal, Guile, Inkscape).
+    \item \emph{Precise}: we have the right information (almost everybody).
+  \end{itemize}
+  We must have the information somewhere at runtime: quite similar to polymorphism!
+\end{frame}
 % TODO: how do GC work
 
 % GC languages to Wasm1
@@ -98,11 +111,24 @@
   \begin{itemize}
     \item safe and fast
     \item do not make Wasm1 code slower
-    \item fit with many existing value representation strategies
+    \item can represent values from any language
   \end{itemize}
 \end{frame}
 
-% Flambda1
+% Compiling Flambda1 to WasmGC
+
+\begin{frame}
+  A type system to represent values from any kind of source language is too complex.\\
+  Instead, WasmGC introduces reference types and a subtyping hierarchy:
+  \begin{center}
+    \includegraphics[width=20em]{figure_type_hierarchy.mps}
+  \end{center}
+  The hierarchy tells which casts are allowed.\\
+  Upcasts are implicit.\\
+  Downcasts are explicit and lead to runtime errors if incorrect.\\
+  Casts are cheap.\\
+  Possible to dynamically test for compatibility.
+\end{frame}
 
 \begin{frame}
   \includegraphics[width=25em]{ocaml_chain.png}
@@ -143,6 +169,7 @@
 \end{frame}
 
 \begin{frame}[fragile]
+\fontsize{5pt}{5pt}\selectfont
 \begin{minted}{ocaml}
 let f =
   let s =
@@ -193,8 +220,6 @@ iter_print ltwo
 \end{minted}
 \end{frame}
 
-% Compiling Flambda1 to WasmGC
-
 \begin{frame}
   Value representation strategies:
   \begin{itemize}
@@ -225,19 +250,6 @@ iter_print ltwo
   small scalars: \ocaml{bool}, \ocaml{char}, \ocaml{int}, constant constructors of ADTs
 \end{frame}
 
-\begin{frame}
-  A type system to represent values from any kind of source language is too complex.\\
-  Instead, WasmGC introduces reference types and a subtyping hierarchy:
-  \begin{center}
-    \includegraphics[width=20em]{figure_type_hierarchy.mps}
-  \end{center}
-  The hierarchy tells which casts are allowed.\\
-  Upcasts are implicit.\\
-  Downcasts are explicit and lead to runtime errors if incorrect.\\
-  Casts are cheap.\\
-  Possible to dynamically test for compatibility.
-\end{frame}
-
 \begin{frame}
   \begin{center}
     \includegraphics[width=20em]{figure_type_hierarchy.mps}
@@ -330,6 +342,19 @@ iter_print ltwo
 
 % TODO: exceptions
 
+\begin{frame}
+  \begin{description}
+    \item[monomorphisation] works with Wasm1
+    \item[boxing everything] works with WasmGC + our strategies
+    \item[polymorphic boxing] works with WasmGC + our strategies
+    \item[pointer-tagging] works with WasmGC + our strategies
+    \item[tagged union] works with WasmGC + our strategies
+    % TODO: add it back ?
+    %\item[type-passing] ?
+    \item[runtime monomorphisation] doesn't work easily
+  \end{description}
+\end{frame}
+
 % Formalized compilation
 
 \begin{frame}
@@ -352,7 +377,9 @@ iter_print ltwo
   \\
   Meant as a way to demonstrate the usefulness of \wasm{i31ref} and convinced the WasmGC working group (along with the Guile implementation that came a few months later).\\
   \\
-  Only a fraction of the stdlib externals are provided and the object fragments of the language has not yet been implemented.
+  Only a fraction of the stdlib externals are provided and the object fragments of the language has not yet been implemented.\\
+  \\
+  The first compiler for a functional language targeting WasmGC.
 
 \end{frame}
 
@@ -364,12 +391,13 @@ iter_print ltwo
   \\
   No real sized programs for now.\\
   \\
-  Classical functional microbenchmarks are two times slower than native OCaml. Jsoo is slower in an unpredictable fashion.\\
+  Classical functional microbenchmarks are two times slower than native OCaml..\\
   \\
   Knuth-Bendix: exceptions are slow (100 times slower than native for a raise) and we need to discuss this with the V8 team (in SpiderMonkey they're fast but other extensions are missing).\\
   \\
   With casts as no-ops we have a 10\% gain.\\
-  With optimisations and Flambda2 it should be much better.
+  With optimisations and Flambda2 it should be much better.\\
+  Jsoo is slower in an unpredictable fashion (up to 40 times)
   % TODO: ^ split in many slides ?
 \end{frame}
 
@@ -420,3 +448,16 @@ iter_print ltwo
 % Symbolic execution
 
 % TODO: ?
+
+\begin{frame}
+  Contributions:
+  \begin{itemize}
+    \item a Wasm backend for OCaml
+    \item the first compiler for a functional language to WasmGC
+    \item impact on the GC proposal for Wasm
+    \item the first Flambda1 semantics
+    \item a formalized compilation scheme from Flambda1 to WasmGC
+    \item compilation strategies usable by others compilers (Guile, Wasm\_of\_ocaml)
+  \end{itemize}
+  Thanks !
+\end{frame}