mfbhrbe

Move From Branch History Rolling Buffer Entry

mfbhrbe RT, BHRBE

Reads a specific entry from the BHRB.

Details

Move the contents of a Branch History Rolling Buffer (BHRB) entry, indexed by BHRBE, into GPR RT. The BHRB records branch addresses and is used for performance monitoring. This is a hypervisor-privileged or performance-monitoring register operation. No architected status fields are affected.

Pseudocode Operation

RT ← BHRB[BHRBE]

Programming Note

The mfbhrbe instruction is used to access entries in the Branch History Rolling Buffer (BHRB). Ensure that the specified entry index is within the range of implemented entries to avoid placing zero in the target register. This instruction operates at user privilege level and does not generate exceptions under normal conditions.

Example

mfbhrbe r3, 0

Encoding

Binary Layout
31
0
RT
6
BHRBE
11
/
16
302
21
/
31
 
Format X-form
Opcode 0x7C00025C
Extension Base
Registers Altered BHRBE0:9

Operands

  • RT
    Target
  • BHRBE
    Entry Index