b

Branch

b target_addr (AA=0 LK=0)

Unconditionally branches to a target address relative to the current instruction pointer.

Encoding

Binary Layout

18

0:5

LI

6:29

AA

30

LK

31

 

Format I-form

Opcode 0x48000000

Extension Base

Operands

• LI
  24-bit Signed Immediate (Displacement / 4)
• target_addr
  Branch Target Address

Example

b label

// Jump to 'label'.

Registers Altered

LR

Related

More in Base

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

The branch target address is the sum of LI || 0b00 sign-extended and the address of this instruction, with the high-order 32 bits of the branch target address set to 0 in 32-bit mode.

Operation

if AA then
    NIA ←iea EXTS(LI || 0b00)
else
    NIA ←iea CIA + EXTS(LI || 0b00)
if LK then
    LR ←iea CIA + 4

Programming Note

The b instruction is used for unconditional branching. The AA and LK fields control whether the address is absolute or relative and whether to link back to the current instruction.