6.10 Thumb code size diagnostics

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

In Thumb code, some instructions, for example a branch or LDR (PC-relative), can be encoded as a 32-bit or 16-bit instruction. The assembler chooses the size of the encoded instruction.
To enable this warning, use the following command-line option when invoking the assembler:
armasm --diag_warning 1813
Related concepts
6.17 Instruction width selection in Thumb
2.2 ARM, Thumb, and ThumbEE instruction sets
6.6 Diagnostic messages
Related reference
9.22 --diag_warning=tag[,tag,…]
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