4.9.1. ADR ARM pseudo-instruction

Load a program-relative or register-relative address into a register.

Syntax

ADR{cond} register,expr

where:

cond

is an optional condition code.

register

is the register to load.

expr

is a program-relative or register-relative expressionthat evaluates to:

  • a non word-aligned address within ±255 bytes

  • a word-aligned address within ±1020 bytes.

More distant addresses can be used if the alignment is 16 bytes or more.

The address can be either before or after the address of the instruction or the base register (see Register-relative and program-relative expressions).

Note

For program-relative expressions, the given range is relative to a point two words after the address of the current instruction.

Usage

ADR always assembles to one instruction. The assembler attempts to produce a single ADD or SUB instruction to load the address. If the address cannot be constructed in a single instruction, an error is generated and the assembly fails.

ADR produces position-independent code, because the address is program-relative or register-relative.

Use the ADRL pseudo-instruction to assemble a wider range of effective addresses.

If expr is program-relative, it must evaluate to an address in the same code section as the ADR pseudo-instruction.

Example

start   MOV     r0,#10
        ADR     r4,start    ; => SUB r4,pc,#0xc
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