Consumption of Speculative Data Barrier is a memory barrier that controls speculative execution and data value prediction.
No instruction other than branch instructions and instructions that write to the PC appearing in program order after the CSDB can be speculatively executed using the results of any:
For purposes of the definition of CSDB, PSTATE.{N,Z,C,V} is not considered a data value. This definition permits:
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
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!= 1111 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | (1) | (1) | (1) | (1) | (0) | (0) | (0) | (0) | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | |||
cond |
if cond != '1110' then UNPREDICTABLE; // CSDB must be encoded with AL condition
If cond != '1110', then one of the following behaviors must occur:
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1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | (1) | (1) | (1) | (1) | 1 | 0 | (0) | 0 | (0) | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 |
if InITBlock() then UNPREDICTABLE;
If InITBlock(), then one of the following behaviors must occur:
For more information about the constrained unpredictable behavior, see Architectural Constraints on UNPREDICTABLE behaviors.
if ConditionPassed() then EncodingSpecificOperations(); ConsumptionOfSpeculativeDataBarrier();
Internal version only: isa v01_31, pseudocode v2023-06_rel, sve v2023-06_rel ; Build timestamp: 2023-07-04T18:06
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