table.fill: Bounds check before mutating the table

[fitzgen]

Fixes #105

@rossberg please take a look. Thanks!

[binji]

The formal notation needs to be fixed too -- this will still partially fill.

[fitzgen]

Perhaps someone else could fix that part? I'm not super familiar with latex / our conventions for the formal notation.

[rossberg]

Thanks for looking into this. The corresponding formal rules should look something like this:

.. math::
   \begin{array}{l}
   S; F; (\I32.\CONST~i)~\val~(\I32.\CONST~n)~(\TABLEFILL~x)
     \quad\stepto\quad S; F; \TRAP
     \\ \qquad
     \begin{array}[t]{@{}r@{~}l@{}}
     (\iff & i + n > |S.\STABLES[F.\AMODULE.\MITABLES[x]].\TIELEM|) \\
     \end{array}
   \\[1ex]
   S; F; (\I32.\CONST~i)~\val~(\I32.\CONST~0)~(\TABLEFILL~x)
     \quad\stepto\quad S; F; \epsilon
     \\ \qquad
     (\otherwise)
   \\[1ex]
   S; F; (\I32.\CONST~i)~\val~(\I32.\CONST~n+1)~(\TABLEFILL~x)
     \quad\stepto\quad S; F;
       \begin{array}[t]{@{}l@{}}
       (\I32.\CONST~i)~\val~(\TABLESET~x) \\
       (\I32.\CONST~i+1)~\val~(\I32.\CONST~n)~(\TABLEFILL~x) \\
       \end{array}
     \\ \qquad
     (\otherwise) \\
   \end{array}

[fitzgen]

The corresponding formal rules should look something like this:

Thanks! I've added that to the commit.

[fitzgen]

(Note: I don't have merge permissions myself)