MATLAB Compiler

Optimizing Loops

Simple Indexing

(array_indexing) This optimization improves the performance of simple one- and two-dimensional array index expressions. Without this optimization, all array indexing uses the fully general array indexing function, which is not optimized for one- and two-dimensional indexing. With this optimization enabled, indexing uses faster routines that are optimized for simple indexing. For example:

• function y = test(x,i1,i2);
  y = x(i1,i2);
  

If you compile this with the -O none option, you get

• ...
  mlfAssign(
    &y,
    mlfIndexRef(mclVa(x, "x"), "(?,?)", mclVa(i1, "i1"),
                mclVa(i2, "i2")));
  ...
  

Compiling with -O none -O array_indexing:on gives

• ...
  mlfAssign(
    &y, mclArrayRef2(mclVa(x, "x"), mclVa(i1, "i1"),
                     mclVa(i2,"i2")));
  ...
  

The mclArrayRef2 function is optimized for two-dimensional indexing. mclArrayRef1 is used for one-dimensional indexing.

Scalars

Loop Simplification