pto.subview¶

pto.subview is part of the Sync And Config instruction set.

Summary¶

Reinterpret a tile as a subtile of another tile. This establishes a view relationship without copying data.

Mechanism¶

rowIdx and colIdx are zero-based offsets into the valid region of src for the top-left corner of dst.

For each element (i, j) in the valid region of dst:

\[ \mathrm{dst}_{i,j} = \mathrm{src}_{\mathrm{rowIdx} + i,\mathrm{colIdx} + j} \]

On A2/A3 and A5, this operation is purely a metadata operation that establishes a view relationship between dst and src within the tile register file; no data movement occurs. On the CPU simulator, the operation similarly records the offset in the tile descriptor.

No synchronization edges are created.

Syntax¶

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

Synchronous form:

%dst = pto.subview %src, %row_idx, %col_idx : !pto.tile<...>, i16, i16

AS Level 1 (SSA)¶

%dst = pto.subview %src, %row_idx, %col_idx : (!pto.tile<...>, i16, i16) -> !pto.tile<...>

AS Level 2 (DPS)¶

pto.subview ins(%src, %row_idx, %col_idx : !pto.tile_buf<...>, i16, i16) outs(%dst : !pto.tile_buf<...>)

C++ Intrinsic¶

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

template <typename TileDataDst, typename TileDataSrc, typename... WaitEvents>
PTO_INST RecordEvent SUBVIEW(TileDataDst &dst, TileDataSrc &src, uint16_t rowIdx, uint16_t colIdx, WaitEvents&... events);

Inputs¶

Operand	Description
`src`	Source tile
`rowIdx`	Zero-based row offset into the valid region of `src` for `dst`'s top-left corner
`colIdx`	Zero-based column offset into the valid region of `src` for `dst`'s top-left corner
`dst`	Destination tile that views a sub-rectangle of `src`

Expected Outputs¶

dst carries the result tile or updated tile payload produced by the operation.

Constraints¶

Constraints

Enforced by SUBVIEW_IMPL:

Tile type must match: TileDataSrc::Loc == TileDataDst::Loc
Both tiles must have the same static capacity: TileDataSrc::Rows == TileDataDst::Rows and TileDataSrc::Cols == TileDataDst::Cols
Both tiles must have the same BLayout: TileDataSrc::BFractal == TileDataDst::BFractal
Source valid region must contain destination: The source tile's validRow (validCol) must be at least as big as the destination tile's validRow (validCol)

Cases That Are Not Allowed¶

Cases That Are Not Allowed

Creating a subview where rowIdx + dst.validRow > src.validRow or colIdx + dst.validCol > src.validCol.
Mismatched tile types or layouts between src and dst.

Examples¶

#include <pto/pto-inst.hpp>
using namespace pto;

void example() {
  using Src = Tile<TileType::Vec, float, 4, 64, BLayout::RowMajor, 4, 64>;
  using Dst = Tile<TileType::Vec, float, 4, 64, BLayout::RowMajor, 2, 32>;

  Src src;
  Dst dst0, dst1, dst2, dst3;

  // Split into four 2x32 subtiles
  SUBVIEW(dst0, src, 0, 0);
  SUBVIEW(dst1, src, 0, 32);
  SUBVIEW(dst2, src, 2, 0);
  SUBVIEW(dst3, src, 2, 32);
}