13.2 Instruction width specifiers

The instruction width specifiers .W and .N control the size of T32 instruction encodings.

In T32 code the .W width specifier forces the assembler to generate a 32-bit encoding, even if a 16-bit encoding is available. The .W specifier has no effect when assembling to A32 code.

In T32 code the .N width specifier forces the assembler to generate a 16-bit encoding. In this case, if the instruction cannot be encoded in 16 bits or if .N is used in A32 code, the assembler generates an error.

If you use an instruction width specifier, you must place it immediately after the instruction mnemonic and any condition code, for example:

BCS.W   label   ; forces 32-bit instruction even for a short branch
B.N     label   ; faults if label out of range for 16-bit instruction
Non-ConfidentialPDF file icon PDF versionDUI0801J
Copyright © 2014–2017, 2019 Arm Limited or its affiliates. All rights reserved.