pto.mte_ub_ub

pto.mte_ub_ub is part of the DMA Copy instruction set.

PTO ISA v0.6 surface

The v0.6 PTO micro-instruction surface replaces the earlier pto.copy_ubuf_to_ubuf with the grouped pto.mte_ub_ub instruction, expressed with an inline nburst(...) clause. Burst length, source gap, and destination gap are all encoded in units of 32 bytes.

Summary

Execute a grouped intra-UB copy. nburst(...) defines the repeated burst transfer between two UB regions.

Mechanism

The MTE engine reads %n_burst blocks of %len_burst * 32 bytes from %ub_src and writes them to %ub_dst. Between bursts, the source advances by (len_burst + src_gap) * 32 bytes and the destination advances by (len_burst + dst_gap) * 32 bytes. src_gap and dst_gap are the inter-burst gap fields (in 32-byte units) that follow each copied block.

Syntax

pto.mte_ub_ub %ub_src, %ub_dst, %len_burst
  nburst(%n_burst, %src_gap, %dst_gap)
  : !pto.ptr<T, ub>, !pto.ptr<T, ub>, i64, i64, i64, i64

Inputs

Parameter Width Description
%ub_src ptr UB source pointer (!pto.ptr<T, ub>, 32B-aligned)
%ub_dst ptr UB destination pointer (!pto.ptr<T, ub>, 32B-aligned)
%len_burst 16 bits Burst length in units of 32 bytes
nburst(%n_burst, %src_gap, %dst_gap) 16 bits / 16 bits / 16 bits Required copy burst group: count, source gap, destination gap

Expected Outputs

Result Type Description
None — This form does not return SSA values; it writes data into the Unified Buffer destination region.

Side Effects

Reads UB-visible storage and writes UB-visible storage. The MTE pipe is engaged for the duration of the transfer; downstream consumers must synchronize through the appropriate pipeline-sync primitives.

Constraints

Constraints

  • UB source and destination addresses must be 32-byte aligned.
  • %len_burst, %src_gap, and %dst_gap are encoded in units of 32 bytes.

Exceptions

Exceptions

  • The verifier rejects illegal operand shapes and clause groups not valid for the selected target profile.
  • Any additional illegality stated in the constraints section is also part of the contract.

Target-Profile Restrictions

Target-Profile Restrictions
  • CPU simulation preserves the visible copy contract but may not expose all DMA overlap hazards.
  • A2/A3 and A5 may narrow supported element sizes, burst lengths, or gap encodings.

Examples

pto.mte_ub_ub %ub_src, %ub_dst, %len32b
  nburst(%rows, %src_gap, %dst_gap)
  : !pto.ptr<i16, ub>, !pto.ptr<i16, ub>, i64, i64, i64, i64