Execution Speed

Improve execution speed of generated C/C++ code

Before you take steps to improve code generation, read about your options in Optimization Strategies.

Functions

parfor Parallel for-loop
coder.varsize Declare variable-size array
coder.const Fold expressions into constants in generated code
coder.inline Control inlining in generated code
coder.unroll Copy body of for-loop in generated code for each iteration
coder.ceval Call external C/C++ function

Classes

coder.CodeConfig codegen configuration object
coder.ExternalDependency Interface to external code
coder.LAPACKCallback Abstract class for specifying the LAPACK library and LAPACKE header file for LAPACK calls in generated code

Examples and How To

Variable-Size Arrays

Minimize Dynamic Memory Allocation

Improve execution time by minimizing dynamic memory allocation.

Provide Maximum Size for Variable-Size Arrays

Use techniques to help the code generator determine the upper bound for a variable-size array.

Disable Dynamic Memory Allocation During Code Generation

Disable dynamic memory allocation in the app or at the command line.

Set Dynamic Memory Allocation Threshold

Disable dynamic memory allocation for arrays less than a certain size.

Loops

Generate Code with Parallel for-Loops (parfor)

Generate a loop that runs in parallel on shared-memory multicore platforms.

Specify Maximum Number of Threads in parfor-Loops

Generate a MEX function that executes loop iterations in parallel on specific number of available cores.

Control Compilation of parfor-Loops

Treat parfor-loops as parfor-loops that run on a single thread.

Minimize Redundant Operations in Loops

Move operations outside of loop when possible.

Unroll for-Loops

Generate a copy of for-loop body for each loop iteration.

Function Calls

Eliminate Redundant Copies of Function Inputs

Use the same variable as a function input and output.

Inline Code

Inlining eliminates the overhead of a function call by replacing the function call with the body of the function.

Control Inlining

Restrict inlining to reduce the size of generated code and memory usage.

Fold Function Calls into Constants

Reduce execution time by replacing expression with constant in the generated code.

Numerical Edge Cases

Disable Support for Integer Overflow or Non-Finites

Improve performance by suppressing generation of supporting code for integer overflow or non-finites.

External Code Integration

Integrate External/Custom Code

Improve performance by integrating your own optimized code.

Speed Up Linear Algebra in Generated Standalone Code by Using LAPACK Calls

Generate LAPACK calls for certain linear algebra functions. Specify LAPACK library to use.

Concepts

Optimization Strategies

Optimize the execution speed or memory usage of generated code.

Dynamic Memory Allocation and Performance

Dynamic memory allocation can slow down execution speeds.

Algorithm Acceleration Using Parallel for-Loops (parfor)

Generate MEX functions for parfor-loops.

Classification of Variables in parfor-Loops

Variables inside parfor-loops are classified as loop, sliced, broadcast, reduction, or temporary.

Reduction Assignments in parfor-Loops

A reduction variable accumulates a value that depends on all the loop iterations together.

MATLAB Coder Optimizations in Generated Code

To improve the performance of generated code, the code generator uses optimizations.

memcpy Optimization

The code generator optimizes generated code by using memcpy.

memset Optimization

The code generator optimizes generated code by using memset.

LAPACK Calls in Generated Code

LAPACK function calls improve the execution speed of code generated for certain linear algebra functions.

Troubleshooting

Troubleshooting parfor-Loops

Diagnose errors for code generation of parfor-loops.

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