or

OR Logical Operation

or RT,RA,RB

Performs a bitwise OR operation on the contents of two registers and places the result in a third register.

Encoding

Binary Layout

31

0:5

RS

6:10

RA

11:15

RB

16:20

444

21:30

Rc

31

 

Format X-form

Opcode 0x7C000378

Extension Base

Operands

• RA
  Target Register
• RS
  Source Register 1
• RB
  Source Register 2
• RT
  Target General Purpose Register

Example

or r3, r4, r5

// r3 = r4 | r5

Registers Altered

CR0, XER

Related

More in Base

Reference

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

Description

Performs a bitwise OR operation on two general-purpose registers and stores the result in a third register. This is a base category instruction that operates on the full 64-bit register width. If Rc=1, the instruction updates CR0 based on the result.

Operation

RA ← RS | RB
if Rc = 1 then CR0 ← (RA = 0, RA < 0, RA > 0, SO)

Extended Mnemonics

Extended Mnemonic	Equivalent Instruction
miso	or 26,26,26

Programming Note

Warning: Other forms of or Rx,Rx,Rx that are not described in this section and in Section 4.3.3 may also cause program priority to change. Use of these forms should be avoided except when software explicitly intends to alter program priority. If a no-op is needed, the preferred no-op (ori 0,0,0) should be used.