pto.tfillpad

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

Summary

Copy+pad a tile outside the valid region with a compile-time pad value.

Mechanism

Copy a source tile into a destination tile and fill the remaining (padded) elements with a compile-time pad value selected by TileDataDst::PadVal (e.g., PadValue::Min/PadValue::Max).

This is commonly used to materialize deterministic values outside the runtime valid region so that subsequent ops can operate on a full static tile shape. It belongs to the tile instructions and carries architecture-visible behavior that is not reducible to a plain elementwise compute pattern.

Let VR = src.GetValidRow() and VC = src.GetValidCol(). For each destination element (i, j):

\[ \mathrm{dst}_{i,j} = \begin{cases} \mathrm{src}_{i,j} & \text{if } i < VR \text{ and } j < VC \\ \mathrm{pad} & \text{otherwise} \end{cases} \]

pad is determined by TileDataDst::PadVal and the element type (e.g., +inf/-inf for floating types when available, otherwise std::numeric_limits<T>::max()/min()).

Syntax

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

Synchronous form (conceptual):

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

AS Level 1 (SSA)

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

AS Level 2 (DPS)

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

IR Level 1 (SSA)

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

IR Level 2 (DPS)

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

C++ Intrinsic

Implemented in the backend headers pulled in by include/pto/common/pto_instr_impl.hpp:

template <typename TileData, PadValue PadVal = PadValue::Zero, typename... WaitEvents>
PTO_INST RecordEvent TFILLPAD(TileData &dst, TileData &src, WaitEvents &... events);

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

Inputs

  • src is the source tile.
  • dst names the destination tile. Must have same shape as 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

  • TileDataDst::PadVal != PadValue::Null.

  • sizeof(TileDataDst::DType) == sizeof(TileDataSrc::DType) and element size must be 1, 2, or 4 bytes.

  • TFILLPAD: TileDataDst::Rows/Cols must match TileDataSrc::Rows/Cols.

  • TFILLPAD_EXPAND: TileDataDst::Rows >= TileDataSrc::Rows and TileDataDst::Cols >= TileDataSrc::Cols.

  • TFILLPAD(TileData &dst, TileData &src):if TileData::TileType is Mat, layout only support (!TileData::isRowMajor && TileData::Slayout::RowMajor), and PadVal only support PadValue::Zero

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 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

#include <pto/pto-inst.hpp>

using namespace pto;

void example1() {
  using SrcT = Tile<TileType::Vec, float, 16, 16>;
  using DstT = Tile<TileType::Vec, float, 16, 16, BLayout::RowMajor, 16, 16, SLayout::NoneBox, TileConfig::fractalABSize, PadValue::Min>;

  SrcT src;
  DstT dst;
  TFILLPAD(dst, src);
}

void example2() {
  using TileMatData = Tile<TileType::Mat, float, 16, 256, BLayout::ColMajor, 1, 224, SLayout::RowMajor, 512>;

  TileMatData matTile;
  TFILLPAD(matTile, matTile);
}

Auto Mode

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

PTO Assembly Form

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