ARM Instruction Reference
ARM DUI 0068B Copyright © 2000, 2001 ARM Limited. All r ights reserved. 4-33
Use of r15
If you use r15 as
Rn
, the value used is the address of the instruction plus 8.
If you use r15 as
Rd
:
•Execution branches to the address corresponding to the result.
•If you use the
S
suffix, the SPSR of the current mode is copied to the CPSR. You
can use this to return from exceptions (see the Handling Processor Exceptions
chapter in ADS Developer Guide).
Caution
Do not use the
S
suffix when using r15 as
Rd
in User mode or System mod e. The effect
of such an instruction is unpredictable, but the assembler cannot warn you at assembly
time.
You cannot use r15 for
Rd
or any operand in any data processing instruction that has a
register-controlled shift (see Flexible second operand on page4-24).
Architectures
These instructions are availabl e in all versions of the ARM architec ture.
Examples
MOV r5,r2
MVNNE r11,#0xF000000B
MOVS r0,r0,ASR r3
Incorrect examples
MVN r15,r3,ASR r0 ; r15 not allowed with register
; controlled shift