COMPILER TECHNIQUES FOR MATLAB PROGRAMS ... - CiteSeerX

for all M-les in the list. Notice that if the same M-le is called multiple times in the whole
program, only one parse tree and corresponding symbol table are generated. As described
below, however, this same parse tree will be inlined in the main program's parse tree multiple
times.
The second step is the actual inlining. In this step, the main program's parse tree is read
in lexicographic order and, for each call to an M-le, a copy of its corresponding parse tree
is inserted in the main program's parse tree, replacing the M-le call. At this point, nodes
are inserted in the parse tree to copy the actual parameters of the M-le call into the formal
parameters of the M-le denition, and to copy the output parameters of the M-le into
their corresponding variables in the program.
In contrast to regular Fortran or C functions, MATLAB functions can return more than
one output variable and, although the number of output parameters in the function denition
is xed, the actual number of parameters returned by the function is dependent onthe
function call. Thus, the copy of the output parameters is performed only for the actual
variables used by the M-le caller.
Finally, the M-le's symbol table is integrated into the program's symbol table, with all
the M-le's local variables renamed to receive unique names. The reason for these unique
variable names, as well as the multiple instances of the same M-le and copies of the M-le's
input and output parameters, is that M-les are polymorphic, and their variables have local
scope. Therefore, the same variable in an M-le may have dierent properties in dierent
activations of the M-le, depending on the properties of the actual input parameters.
3.2.4 The Intermediate Representation
After the inline of the M-les, the parse tree is transformed into an abstract syntax tree
(AST) [McK76], which hasanintermediate representation more suitable for the generation
of the output code.
Our inference algorithms are applied to a Static Single Assignment (SSA) [CFR + 91]
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