tcheck

Transaction Check

tcheck BF

Checks transaction status and updates CR.

Encoding

Binary Layout

31

0:5

BF

6:10

/

11:15

/

16:20

716

21:30

/

31

 

Format X-form

Opcode 0x7C00059C

Extension Transactional Memory

Operands

• BF
  CR Field

Example

tcheck cr0

Registers Altered

CR

Related

More in Transactional Memory

Reference

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

Description

Transaction Check. Tests the state of the current transaction and sets CR field BF based on whether a transaction is active, suspended, or whether a failure has been recorded. No effect outside a transaction.

Operation

if Transactional_or_Suspended() then
  CR[4*BF:4*BF+3] ← transaction_state_bits()
else
  CR[4*BF:4*BF+3] ← 0b0000

Programming Note

The tcheck instruction is used to determine the state of the current transaction, setting the condition register field BF accordingly. It should be used within a transactional context; outside transactions, it will clear the specified CR field. Ensure proper alignment and ordering relative to other transactional instructions for accurate state checks.