µVISION: Dynamic Syntax Checking Shows Errors for Embedded Assembler

Information in this knowledgebase article applies to:

• Keil MDK version 4.70 and later
• Arm Compiler 5 all versions

QUESTION

I'm using the embedded assembler in one of my C-function. In the µVision editor, the Dynamic Syntax Checking shows me some errors for this function. Here is an example:

When I hover the mouse over these red error symbols, I see the following error messages:

error: expected '(' after 'asm'
error: expected ';' after top-level asm block

and

error: use of undeclared identifier 'mov'

However, when I build my project, the compiler does not report any errors. 

Why does the Dynamic Syntax Checking report these errors and how can I avoid them?

ANSWER

In this example, the embedded assembler of the Arm compiler 5 is used. The Dynamic Syntax Checking uses the same compiler-frontend as our Arm compiler 6. Since the syntax for the embedded assembler of Arm compiler 5 is different to the inline assembler of Arm compiler 6, this syntax is not recognized and errors are generated.

It is not planned to change this behavior. If you stay with Arm compiler 5, you need to ignore these errors or turn off Dynamic Syntax Checking. You might consider to use the Arm compiler 6 in the future to avoid this effect.

MORE INFORMATION

• Refer to Dynamic Syntax Checking in the µVision User's Guide.
• Refer to Embedded assembler syntax in C and C++ in the Compiler User Guide.
• Refer to Inline Assembly in the Compiler Reference Guide.

Last Reviewed: Thursday, January 7, 2021