pto.tfillpad_expand

pto.tfillpad_expand is part of the Layout And Rearrangement instruction set.

Summary

Fill/pad while allowing dst to be larger than src.

Mechanism

Expand fill/pad variant of TFILLPAD — allows dst to be larger than src, copying the valid region from src and filling the remainder with PadVal. On A2/A3: the operation iterates over dst's valid region via GetValidRow/GetValidCol, copying the src valid region into the corresponding top-left portion of dst and filling all other elements with PadVal; if src is smaller than dst in either dimension, the padded portion receives PadVal. On A5: behavior is identical — the valid region copy and pad fill follow the same semantics; the hardware enforces 32-byte alignment on the major dimension which may affect the effective valid region boundaries for some tile shapes. On the CPU simulator: the operation is emulated by iterating over the destination shape and performing elementwise copies or fills, matching the A2/A3/A5 semantics exactly.

Unless otherwise specified, semantics are defined over the valid region. On A2/A3 and A5: TFILLPAD_EXPAND iterates over the destination valid region (defined by GetValidRow/GetValidCol on the destination tile), copying elements from the corresponding source positions and filling any positions that fall outside the source's valid region with PadVal. On the CPU simulator: the operation is emulated element-by-element, following the same valid-region iteration semantics as the hardware targets.

Syntax

Textual spelling is defined by the PTO ISA syntax-and-operands pages.

AS Level 1 (SSA)

%dst = pto.tfillpad_expand %src : !pto.tile<...> -> !pto.tile<...>

AS Level 2 (DPS)

pto.tfillpad_expand ins(%src : !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

IR Level 1 (SSA)

%dst = pto.tfillpad_expand %src : !pto.tile<...> -> !pto.tile<...>

IR Level 2 (DPS)

pto.tfillpad_expand ins(%src : !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

C++ Intrinsic

Declared in include/pto/common/pto_instr.hpp:

template <typename DstTileData, typename SrcTileData, typename... WaitEvents>
PTO_INST RecordEvent TFILLPAD_EXPAND(DstTileData &dst, SrcTileData &src, WaitEvents &... events);

Inputs

  • src is the source tile.
  • dst names the destination tile. May be larger than src.
  • PadVal is the compile-time pad value for elements outside the valid region.

Expected Outputs

dst holds a copy of src with valid region copied and padded region filled with the specified pad value.

Side Effects

No architectural side effects beyond producing the destination tile. Does not implicitly fence unrelated traffic.

Constraints

Constraints

Type/layout/location/shape legality is backend-dependent; treat implementation-specific notes as normative for that backend.

Exceptions

Exceptions

  • Illegal operand tuples, unsupported types, invalid layout combinations, or unsupported target-profile modes are rejected by the verifier or by the selected backend instruction set.
  • Programs must not rely on behavior outside the documented legal domain of this operation, even if one backend currently accepts it.

Target-Profile Restrictions

Target-Profile Restrictions

  • pto.tfillpad_expand preserves PTO-visible semantics across CPU simulation, A2/A3-class targets, and A5-class targets, but concrete support subsets may differ by profile.

  • Portable code must rely only on the documented type, layout, shape, and mode combinations that the selected target profile guarantees.

Examples

See related examples in docs/isa/ and docs/coding/tutorials/.

Auto Mode

# Auto mode: compiler/runtime-managed placement and scheduling.
%dst = pto.tfillpad_expand %src : !pto.tile<...> -> !pto.tile<...>

Manual Mode

# Manual mode: bind resources explicitly before issuing the instruction.
# Optional for tile operands:
# pto.tassign %arg0, @tile(0x1000)
# pto.tassign %arg1, @tile(0x2000)
%dst = pto.tfillpad_expand %src : !pto.tile<...> -> !pto.tile<...>

PTO Assembly Form

%dst = pto.tfillpad_expand %src : !pto.tile<...> -> !pto.tile<...>
# AS Level 2 (DPS)
pto.tfillpad_expand ins(%src : !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)