Keil Logo

Instruction width diagnostics

6.12 Instruction width diagnostics

The assembler can issue a warning when it assembles a Thumb branch instruction to a 32-bit encoding when it could have used a 16-bit encoding.

If you use the .W specifier, the instruction is encoded in 32 bits even if it can be encoded in 16 bits. You can use a diagnostic warning to detect when a branch instruction could have been encoded in 16 bits, but has been encoded in 32 bits. To do this, use the following command-line option when invoking the assembler:
armasm --diag_warning 1607

Note

This diagnostic does not produce a warning for relocated branch instructions, because the final address is not known. The linker might even insert a veneer, if the branch is out of range for a 32-bit instruction.
Related concepts
Non-ConfidentialPDF file icon PDF versionARM DUI0379H
Copyright © 2007, 2008, 2011, 2012, 2014-2016 ARM. All rights reserved. 
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.