ARM Compiler 6 optimization level

table of Contents

ARM Compiler 6 optimization level introduction

ARM Compiler 5 optimization level introduction

Comparison test:

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ARM Compiler 6 optimization level introduction

 

 

 

 

-O0: No optimization. Not recommended for use in ARM Compiler 6.6

-O1: Limited optimization. This is the current recommended level of source code level debugging.

-O2: Optimize speed. Due to many loop unrolling and function inlining, the code size will increase.

-O3: Optimize speed. Faster than -O2 generated code, but larger

-Os: Balanced optimization. The speed of optimization and the increase in code size are reasonable.

-Oz: purely optimize code size

For detailed understanding, please refer to Migrate from ARM C/C++ Compiler 5 to ARM Compiler 6 https://www.keil.com/appnotes/docs/apnt_298.asp

 

ARM Compiler 5 optimization level introduction

Reference: https://blog.csdn.net/zhuimeng_ruili/article/details/108208012

 

Comparison test:

ARM Compiler 5 provides 4 different optimization levels 0 to 3 . Their behavior is related to the optimization level, the higher the optimization level, the smaller the code.

There is no direct relationship between the optimization levels of ARM Compiler 6. You can compile the project under each optimization level and select the optimal optimization level.

 

Code size comparison after compilation

ARM Compiler 5 in -O3 optimized compiled class code size

ARM Compiler 6 in -Oz optimized compiled code size, found in the Level ARM Compiler 6 the compiler -Oz Optimization level, minimum compiled code.

It can be seen that only from the size of generated code, ARM Compiler 5 has more advantages