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@@ -14,8 +14,11 @@
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\usepackage{xypic}
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\usepackage{semantic}
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\usepackage{wrapfig}
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+
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+%% For pictures
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\usepackage{tikz}
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-\usetikzlibrary{arrows}
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+\usetikzlibrary{arrows.meta}
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+\tikzset{baseline=(current bounding box.center), >/.tip={Triangle[scale=1.4]}}
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% Computer Modern is already the default. -Jeremy
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%\renewcommand{\ttdefault}{cmtt}
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@@ -155,7 +158,6 @@ programs is the \emph{abstract syntax tree} (AST). When considering
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some part of a program, a compiler needs to ask what kind of part it
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is and what sub-parts it has. For example, the program on the left is
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represented by the AST on the right.
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-\marginpar{\scriptsize The arrow heads need to be bigger. -JGS}
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\begin{center}
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\begin{minipage}{0.4\textwidth}
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\begin{lstlisting}
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@@ -164,7 +166,7 @@ represented by the AST on the right.
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\end{minipage}
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\begin{minipage}{0.4\textwidth}
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\begin{equation}
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-\begin{tikzpicture}[baseline=(current bounding box.center)]
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+\begin{tikzpicture}
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\node[draw, circle] (plus) at (0 , 0) {$+$};
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\node[draw, circle] (read) at (-1, -1.5) {$\tt read$};
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\node[draw, circle] (minus) at (1 , -1.5) {$\text{--}$};
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@@ -243,7 +245,7 @@ an $\itm{arith}$.
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\end{minipage}
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\begin{minipage}{0.25\textwidth}
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\begin{equation}
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-\begin{tikzpicture}[baseline=(current bounding box.center)]
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+\begin{tikzpicture}
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\node[draw, circle] (minus) at (0, 0) {$\text{--}$};
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\node[draw, circle] (8) at (0, -1.2) {$8$};
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@@ -1255,6 +1257,11 @@ Chapter~\ref{ch:register-allocation} is implementing a smarter
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approach in which we make a best-effort to map variables to registers,
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resorting to the stack only when necessary.
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+\marginpar{\scriptsize I'm confused: shouldn't `select instructions' do this?
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+After all, that selects the x86-64 instructions. Even if it is separate,
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+if we perform `patching' before register allocation, we aren't forced to rely on
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+\key{rax} as much. This can ultimately make a more-performant result. --
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+Cam}
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The final pass in our journey to x86 handles an indiosycracy of x86
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assembly. Many x86 instructions have two arguments but only one of the
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arguments may be a memory reference. Because we are mapping variables
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@@ -1838,7 +1845,6 @@ while @$W \neq \emptyset$@ do
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\label{fig:satur-algo}
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\end{figure}
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-
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With this algorithm in hand, let us return to the running example and
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consider how to color the interference graph in
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Figure~\ref{fig:interfere}. Initially, all of the nodes are not yet
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@@ -1973,7 +1979,8 @@ The last iteration of the coloring algorithm assigns color $0$ to $v$.
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With the coloring complete, we can finalize assignment of variables to
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registers and stack locations. Recall that if we have $k$ registers,
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we map the first $k$ colors to registers and the rest to stack
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-locations. Suppose for the moment that we just have one extra register
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+locations.
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+Suppose for the moment that we just have one extra register
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to use for register allocation, just \key{rbx}. Then the following is
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the mapping of colors to registers and stack allocations.
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\[
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@@ -2021,18 +2028,18 @@ shown in Figure~\ref{fig:reg-alloc-passes}.
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\begin{figure}[tbp]
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\[
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\begin{tikzpicture}[baseline=(current bounding box.center)]
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-\node (1) at (-2,0) {$C_0$};
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+\node (1) at (-3.5,0) {$C_0$};
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\node (2) at (0,0) {$\text{x86-64}^{*}$};
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\node (3) at (0,-1.5) {$\text{x86-64}^{*}$};
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\node (4) at (0,-3) {$\text{x86-64}^{*}$};
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\node (5) at (0,-4.5) {$\text{x86-64}^{*}$};
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-\node (6) at (2,-4.5) {$\text{x86-64}$};
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+\node (6) at (3.5,-4.5) {$\text{x86-64}$};
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-\path[->,bend left=15] (1) edge [above] node {\ttfamily\scriptsize select-instr.} (2);
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-\path[->, ] (2) edge [right] node {\ttfamily\scriptsize uncover-live} (3);
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-\path[->, ] (3) edge [right] node {\ttfamily\scriptsize build-interference} (4);
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-\path[->, ] (4) edge [left] node {\ttfamily\scriptsize allocate-registers} (5);
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-\path[->,bend left=15] (5) edge [above] node {\ttfamily\scriptsize patch-instr.} (6);
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+\path[->] (1) edge [above] node {\ttfamily\scriptsize select-instr.} (2);
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+\path[->] (2) edge [right] node {\ttfamily\scriptsize uncover-live} (3);
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+\path[->] (3) edge [right] node {\ttfamily\scriptsize build-interference} (4);
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+\path[->] (4) edge [left] node {\ttfamily\scriptsize allocate-registers} (5);
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+\path[->] (5) edge [above] node {\ttfamily\scriptsize patch-instr.} (6);
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\end{tikzpicture}
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\]
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\caption{Diagram of the passes for register allocation.}
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@@ -2066,6 +2073,7 @@ shown in Figure~\ref{fig:reg-alloc-passes}.
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\section{Type Checking $S_1$ Programs}
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+\marginpar{\scriptsize Type checking is a difficult thing to cover, I think, without having 522 as a prerequisite for this course. -- Cam}
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% T ::= Integer | Boolean
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It is common practice to specify a type system by writing rules for
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jsiek