6.11 ARM and Thumb instruction portability diagnostics

The assembler can issue warnings about instructions that cannot assemble to both ARM and Thumb code.

There are a few UAL instructions that can assemble as either ARM code or Thumb code, but not both. You can identify these instructions in the source code using the following command-line option when invoking the assembler:
armasm --diag_warning 1812
It warns for any instruction that cannot be assembled in the other instruction set. This is only a hint, and other factors, like relocation availability or target distance might affect the accuracy of the message.
Related concepts
2.2 ARM, Thumb, and ThumbEE instruction sets
6.6 Diagnostic messages
Related reference
9.22 --diag_warning=tag[,tag,…]
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