4.1.3. Program Counter

One feature of the original ARMv7 instruction set was the use of R15, the Program Counter (PC) as a general-purpose register. The PC enabled some clever programming tricks, but it introduced complications for compilers and the design of complex pipelines. Removing direct access to the PC in ARMv8 makes return prediction easier and simplifies the ABI specification.

The PC is never accessible as a named register. Its use is implicit in certain instructions such as PC-relative load and address generation. The PC cannot be specified as the destination of a data processing instruction or load instruction.

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