TROWMAX¶

Tile Operation Diagram¶

Introduction¶

Reduce each row by taking the maximum across columns.

Math Interpretation¶

Let R = src.GetValidRow() and C = src.GetValidCol(). For 0 <= i < R:

Assembly Syntax¶

Synchronous form:

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

Lowering may introduce internal scratch tiles; the C++ intrinsic requires an explicit tmp operand.

AS Level 1 (SSA)¶

%dst = pto.trowmax %src, %tmp : (!pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

AS Level 2 (DPS)¶

pto.trowmax ins(%src, %tmp : !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

C++ Intrinsic¶

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

template <typename TileDataOut, typename TileDataIn, typename TileDataTmp, typename... WaitEvents>
PTO_INST RecordEvent TROWMAX(TileDataOut &dst, TileDataIn &src, TileDataTmp &tmp, WaitEvents &... events);

Constraints¶

General constraints / checks¶

• dst and src must both be TileType::Vec.
• src must use standard ND layout: row-major and non-fractal (BLayout::RowMajor, SLayout::NoneBox).
• dst must use one of the following non-fractal layouts:
  • ND layout (BLayout::RowMajor, SLayout::NoneBox), or
  • DN layout with exactly one column (BLayout::ColMajor, SLayout::NoneBox, Cols == 1).
• dst and src must use the same element type.
• Runtime valid-region checks:
  • src.GetValidRow() != 0
  • src.GetValidCol() != 0
  • src.GetValidRow() == dst.GetValidRow()
• The intrinsic signature requires an explicit tmp operand.

A2A3 implementation checks¶

• Supported element types (A2A3): half, float, int32_t, int16_t.
• Supported element types (A5): half, float, int32_t, int16_t, int8_t, uint8_t.
• The implementation accepts both ND output and DN output with Cols == 1.
• Runtime checks follow the shared row-reduce check path:
  • src.GetValidRow() != 0
  • src.GetValidCol() != 0
  • src.GetValidRow() == dst.GetValidRow()

Temporary Space¶

A2A3¶

tmp is used as scratch storage for row-wise max reduction.

• For integer types (int32_t, int16_t): tmp is used as a per-row accumulator buffer (1 block). For each row, tmp is initialized to the minimum representable value, then blocks of src are accumulated via vmax. The final max is read from tmp in scalar mode.
• tmp size: at least 1 row and BLOCK_BYTE_SIZE / sizeof(T) columns (8 for int32_t, 16 for int16_t).
• For floating-point types (float, half): tmp is used for binary-tree reduction via vcmax/vcgmax.
• A safe default: set tmp to the same shape as src.

A5¶

tmp is accepted by the interface but not used by the A5 implementation. The A5 backend uses vector register-based reduction (vcmax instruction) and does not require scratch tile storage. tmp is retained in the C++ intrinsic signature solely for API compatibility with A2A3.

Examples¶

Auto¶

#include <pto/pto-inst.hpp>

using namespace pto;

void example_auto() {
  using SrcT = Tile<TileType::Vec, float, 16, 16>;
  using DstT = Tile<TileType::Vec, float, 16, 1, BLayout::ColMajor>;
  using TmpT = Tile<TileType::Vec, float, 16, 16>;
  SrcT src;
  DstT dst;
  TmpT tmp;
  TROWMAX(dst, src, tmp);
}

Manual¶

#include <pto/pto-inst.hpp>

using namespace pto;

void example_manual() {
  using SrcT = Tile<TileType::Vec, float, 16, 16>;
  using DstT = Tile<TileType::Vec, float, 16, 1, BLayout::ColMajor>;
  using TmpT = Tile<TileType::Vec, float, 16, 16>;
  SrcT src;
  DstT dst;
  TmpT tmp;
  TASSIGN(src, 0x1000);
  TASSIGN(dst, 0x2000);
  TASSIGN(tmp, 0x3000);
  TROWMAX(dst, src, tmp);
}

ASM Form Examples¶

Auto Mode¶

# Auto mode: compiler/runtime-managed placement and scheduling.
%dst = pto.trowmax %src, %tmp : (!pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

Manual Mode¶

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

PTO Assembly Form¶

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