pto.trowexpandexpdif¶

pto.trowexpandexpdif is part of the Reduce And Expand instruction set.

Summary¶

Row-wise exp-diff: compute exp(src0 - src1) with per-row scalars.

Mechanism¶

Row-wise exp-diff: compute exp(src0 - src1) where src1 provides one scalar per row.

Let R = dst.GetValidRow() and C = dst.GetValidCol(). Let s_i be the per-row scalar taken from src1 (one value per row).

For 0 <= i < R and 0 <= j < C:

Syntax¶

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

Synchronous form:

%dst = trowexpandexpdif %src0, %src1 : !pto.tile<...>, !pto.tile<...> -> !pto.tile<...>

AS Level 1 (SSA)¶

%dst = pto.trowexpandexpdif %src0, %src1 : !pto.tile<...>, !pto.tile<...> -> !pto.tile<...>

AS Level 2 (DPS)¶

pto.trowexpandexpdif ins(%src0, %src1 : !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

C++ Intrinsic¶

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

template <typename TileDataDst, typename TileDataSrc0, typename TileDataSrc1, typename... WaitEvents>
PTO_INST RecordEvent TROWEXPANDEXPDIF(TileDataDst &dst, TileDataSrc0 &src0, TileDataSrc1 &src1, WaitEvents &... events);

template <typename TileDataDst, typename TileDataSrc0, typename TileDataSrc1, typename TileDataTmp,
          typename... WaitEvents>
PTO_INST RecordEvent TROWEXPANDEXPDIF(TileDataDst &dst, TileDataSrc0 &src0, TileDataSrc1 &src1, TileDataTmp &tmp, WaitEvents &... events);

Inputs¶

• src0 is the first source tile (the tile to be modified).
• src1 is the second source tile providing per-row scalar values.
• tmp (optional): temporary tile for intermediate storage.
• dst names the destination tile. The operation iterates over dst's valid region.

Expected Outputs¶

dst[i,j] = exp(src0[i,j] - src1[i,0]) (row-wise exp-diff of per-row scalar).

Side Effects¶

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

Constraints¶

Temporary tile¶

The C++ API provides an overload with an explicit TileDataTmp &tmp. This overload only supports Mode 1 (ColMajor expanded operand, scalar per row). Internally, TROWEXPANDEXPDIF is implemented as TROWEXPANDSUB followed by TEXP, so the tmp tile is used for the SUB step broadcast buffer.

• A2A3: The tmp tile is used as a broadcast buffer. The per-row scalar values from the ColMajor expanded operand are broadcast via the vbrcb instruction into the tmp buffer, creating a 32-byte block per row, which is then used as the expanded operand in the subtraction. The vbrcb instruction uses a repeat stride of 8 blocks (256 bytes) between repeat groups, processing 8 rows per repeat. Minimum tmp size calculation:
  • Common parameters: R = dst.GetValidRow(), T = TileDataDst::DType.
  • For R < 256: $$ \text{tmpSize} = \left\lceil\frac{R}{8}\right\rceil \times 256 \text{ bytes} $$
  • For R >= 256, the operation is looped with at most 30 repeats (240 rows) per loop iteration. The tmp buffer is reused across loops, so the per-loop requirement is: $$ \text{tmpSize} = 30 \times 256 = 7680 \text{ bytes} $$
  • A compact shape-independent upper bound for any Mode 1 invocation is 8 KB (8192 bytes).
  • The 3-arg overload without tmp supports both Mode 1 and Mode 2. For Mode 1, it uses an internal 8 KB buffer (TMP_UB_OFFSET). For Mode 2, no broadcast buffer is needed.
• A5: The tmp tile is accepted and ignored ([[maybe_unused]]). A5 hardware supports row-broadcast natively via the vlds instruction's broadcast modes, so no scratch buffer is required.

Exceptions¶

Target-Profile Restrictions¶

Target-Profile Restrictions

• pto.trowexpandexpdif 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¶

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, 16>;
  using RowVecT = Tile<TileType::Vec, float, 16, 1, BLayout::ColMajor>;
  SrcT src0;
  DstT dst;
  RowVecT src1;
  // Row-expand-expdif: each row of dst = exp(src0.row - src1.row_scalar)
  TROWEXPANDEXPDIF(dst, src0, src1);
}

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, 16>;
  using RowVecT = Tile<TileType::Vec, float, 16, 1, BLayout::ColMajor>;
  SrcT src0;
  DstT dst;
  RowVecT src1;
  TASSIGN(src0, 0x1000);
  TASSIGN(dst, 0x2000);
  TASSIGN(src1, 0x3000);
  // Row-expand-expdif in manual mode
  TROWEXPANDEXPDIF(dst, src0, src1);
}

Auto Mode¶

# Auto mode: compiler/runtime-managed placement and scheduling.
%dst = pto.trowexpandexpdif %src0, %src1 : !pto.tile<...>, !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.trowexpandexpdif %src0, %src1 : !pto.tile<...>, !pto.tile<...> -> !pto.tile<...>

PTO Assembly Form¶

%dst = trowexpandexpdif %src0, %src1 : !pto.tile<...>, !pto.tile<...> -> !pto.tile<...>
# AS Level 2 (DPS)
pto.trowexpandexpdif ins(%src0, %src1 : !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

Related Ops / Instruction Set Links¶

• Instruction set overview: Reduce And Expand
• Previous op in instruction set: pto.trowexpandmin
• Next op in instruction set: pto.tcolmin