SPRUJG0B December   2024  – November 2025 F29H850TU , F29H859TU-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Performance Optimization
    1. 2.1 Compiler Settings
      1. 2.1.1 Enabling Debug and Source Inter-Listing
      2. 2.1.2 Optimization Control
      3. 2.1.3 Floating-Point Math
      4. 2.1.4 Fixed-Point Division
      5. 2.1.5 Single vs Double Precision Floating-Point
      6. 2.1.6 Link-Time Optimization (LTO)
    2. 2.2 Memory Settings
      1. 2.2.1 Executing Code From RAM
      2. 2.2.2 Executing Code From Flash
      3. 2.2.3 Data Placement
    3. 2.3 Code Construction and Configuration
      1. 2.3.1 Inlining
      2. 2.3.2 Intrinsics
      3. 2.3.3 Volatile Variables
      4. 2.3.4 Function Arguments
      5. 2.3.5 Enabling Wider Data Accesses
      6. 2.3.6 Auto Code-Generation Tools
      7. 2.3.7 Accurately Profiling Code
    4. 2.4 Application Code Optimization
      1. 2.4.1 Optimized SDK Libraries
      2. 2.4.2 Optimizing Code-Size With Libraries
      3. 2.4.3 C29 Special Instructions
      4. 2.4.4 C29 Parallelism
      5. 2.4.5 32-Bit Variables and Writes Preferred
      6. 2.4.6 Coding Style and Impact on Performance
  6. 3References
  7. 4Revision History

2.3.7 Accurately Profiling Code

The user can use different profiling techniques to benchmark their application code. With optimization enabled, the compiler can re-order operations and perform inlining, and so forth. This can sometimes make it difficult to understand exactly what was profiled, and whether what was profiled was indeed what the user wanted to profile.

"__builtin_instrumentation_label()" is a helpful label to use before and after the code that needs to be profiled (see code block below). However, it is not a perfect code barrier when optimization is enabled. The C29 compiler has no true code movement barrier other than to outline the code block into its own function, mark it noinline to disable inlining, and call that function.

// Example 1
__builtin_instrumentation_label("profiling_start");
function1();
__builtin_instrumentation_label("profiling_stop");

// Example 2
__builtin_instrumentation_label("profiling_start");
// code being profiled
..
..
__builtin_instrumentation_label("profiling_stop");