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@@ -13168,10 +13168,20 @@ an array:
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In the following subsections we provide hints regarding how to update
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the passes to handle arrays.
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+\subsection{Shrink}
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+
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+Translate calls to \racket{\code{vector-length}}\python{\code{len}}
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+into a primitive specific to arrays, \racket{\code{vectorof-length}}\python{\code{array\_len}},
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+when the argument's type is \CARRAYTY{T}.
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+%
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+\python{The type checker for \LangArray{} adds a \code{has\_type}
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+ field to the argument of \code{len} for this purpose.}
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+
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+
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\subsection{Bounds Checking}
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We recommend inserting a new pass named \code{check\_bounds} that
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-inserts code around each the \racket{\code{vector-ref} and \code{vector-set!}}
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+inserts code around each \racket{\code{vector-ref} and \code{vector-set!}}
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\python{subscript} operation to ensure that the index is greater than or equal to zero
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and less than the array's length.
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@@ -13209,16 +13219,13 @@ and less than the array's length.
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\subsection{Expose Allocation}
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-This pass should translate the \code{make-vector} operator into
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-lower-level operations. In particular, the new AST node
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-$\LP\key{AllocateArray}~\Exp~\Type\RP$ is analogous to the
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-\code{Allocate} AST node for tuples. It allocates an array of the
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-length specified by the $\Exp$, but does not initialize the elements
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-of the array. The $\Type$ argument must be $\LP\key{Vectorof}~T\RP$
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-where $T$ is the element type for the array. Regarding the
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-initialization of the array, we recommend generated a \code{while}
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-loop that uses \code{vector-set!} to put the initializing value into
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-every element of the array.
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+This pass should translate array creation into lower-level
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+operations. In particular, the new AST node \ALLOCARRAY{\Exp}{\Type}
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+is analogous to the \code{Allocate} AST node for tuples. The $\Type$
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+argument must be \ARRAYTY{T} where $T$ is the element type for the
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+array. The \code{AllocateArray} AST node allocates an array of the
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+length specified by the $\Exp$ but does not initialize the elements of
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+the array. Generate code in this pass to initialize the elements.
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\subsection{Remove Complex Operands}
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@@ -13238,16 +13245,16 @@ Generate instructions for \code{AllocateArray} similar to those for
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that the tag at the front of the array should instead use the
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representation discussed in Section~\ref{sec:array-rep}.
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-Regarding \code{vectorof-length}, extract the length from the tag
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-according to the representation discussed in
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+Regarding \racket{\code{vectorof-length}}\python{\code{array\_len}},
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+extract the length from the tag according to the representation discussed in
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Section~\ref{sec:array-rep}.
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-The instructions generated for \code{vectorof-ref} differ from those
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-for \code{vector-ref} (Section~\ref{sec:select-instructions-gc}) in
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+The instructions generated for accessing an element of an array differ
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+from those for a tuple (Section~\ref{sec:select-instructions-gc}) in
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that the index is not a constant so the offset must be computed at
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-runtime. The same is true for \code{vectorof-set!}. Also, the
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-\code{vectorof-set!} may appear in an assignment and as a stand-alone
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-statement, so make sure to handle both situations in this pass.
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+runtime. Also, note that assignment to an array element may appear in
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+as a stand-alone statement, so make sure to handle that situation in
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+this pass.
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%% Finally, the instructions for \code{any-vectorof-length} should be
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%% similar to those for \code{vectorof-length}, except that one must
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Jeremy Siek