TGEMV_ACC

Instruction Diagram

Introduction

GEMV with an explicit accumulator input tile (cInMatrix) and output tile (cOutMatrix).

See Also

• Basic GEMV instruction: docs/isa/TGEMV.md.

• Bias variant: docs/isa/TGEMV_BIAS.md.

C++ Built-in APIs

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

The public include header is <pto/pto-inst.hpp>, and the internal declaration is located in pto/common/pto_instr.hpp.

template <typename TileRes, typename TileLeft, typename TileRight, typename... WaitEvents>
PTO_INST RecordEvent TGEMV_ACC(TileRes &cOutMatrix, TileRes &cInMatrix, TileLeft &aMatrix, TileRight &bMatrix, WaitEvents &... events);

template <AccPhase Phase, typename TileRes, typename TileLeft, typename TileRight, typename... WaitEvents>
PTO_INST RecordEvent TGEMV_ACC(TileRes &cOutMatrix, TileRes &cInMatrix, TileLeft &aMatrix, TileRight &bMatrix, WaitEvents &... events);

Mathematical Semantics

Assume:

• M = 1

• K = bMatrix.GetValidRow()

• N = bMatrix.GetValidCol()

For 0 <= j < N (accumulate into the existing output tile):

$$\mathrm{C}_{0,j} \gets \mathrm{C}_{0,j} + \sum_{k=0}^{K-1} \mathrm{A}_{0,k} \cdot \mathrm{B}_{k,j}$$

Note: The exact accumulator behavior and data type promotion are target/implementation-defined.

Assembly Syntax

Synchronous form:

%acc1 = tgemv.acc %acc0, %a, %b : (!pto.tile<...>, !pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

AS Level 1 (SSA)

%c_out = pto.tgemv.acc %c_in, %a, %b : (!pto.tile<...>, !pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

AS Level 2 (DPS)

pto.tgemv.acc ins(%c_in, %a, %b : !pto.tile_buf<...>, !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%c_out : !pto.tile_buf<...>)

Constraints

General Shape and Position Constraints

• Static shape constraints:

  • TileLeft::Rows == TileRes::Rows

  • TileLeft::Cols == TileRight::Rows

  • TileRight::Cols == TileRes::Cols

• Tile position constraints:

  • TileLeft::Loc == Left

  • TileRight::Loc == Right

  • TileRes::Loc == Acc

• Runtime valid size constraints:

  • m must be 1

  • k and n (taken from bMatrix.GetValidRow() and bMatrix.GetValidCol()) must be within [1, 4095]

Data Type Constraints

• Implementation check (Atlas A2/A3 training products/Atlas A2/A3 inference products):

  • Supported (CType, AType, BType) triplets:

    • (int32_t, int8_t, int8_t)

    • (float, half, half)

    • (float, float, float)

    • (float, bfloat16_t, bfloat16_t)

• Implementation check (Ascend 950PR/Ascend 950DT):

  • The accumulator type must be int32_t or float.

  • If it is int32_t: AType == int8_t and BType == int8_t.

  • If it is float: supports half, bfloat16_t, float, selected fp8 combinations, and hifloat8_t/hifloat8_t (destination-defined).

  • The following fractal/layout constraints are enforced:

    • Left: Loc == Left, !isRowMajor, SFractal == RowMajor

    • Right: Loc == Right, isRowMajor, SFractal == ColMajor

    • Acc: Loc == Acc, !isRowMajor, SFractal == RowMajor

  • In addition to the GEMV conventions above, the underlying Ascend 950PR/Ascend 950DT matmul implementation does not add a separate set of explicit m/k/n runtime assertions.

Examples

Automatic

#include <pto/pto-inst.hpp>

using namespace pto;

void example_auto() {
  using A = TileLeft<half, 1, 16>;
  using B = TileRight<half, 16, 16>;
  using C = TileAcc<float, 1, 16>;
  A a;
  B b;
  C c0, c1;
  TGEMV_ACC(c1, c0, a, b);
}

Manual

#include <pto/pto-inst.hpp>

using namespace pto;

void example_manual() {
  using A = TileLeft<half, 1, 16>;
  using B = TileRight<half, 16, 16>;
  using C = TileAcc<float, 1, 16>;
  A a;
  B b;
  C c0, c1;
  TASSIGN(a, 0x1000);
  TASSIGN(b, 0x2000);
  TASSIGN(c0, 0x3000);
  TASSIGN(c1, 0x4000);
  TGEMV_ACC(c1, c0, a, b);
}

ASM Examples

Automatic Mode

# Automatic mode: the compiler/runtime handles resource placement and scheduling.
%c_out = pto.tgemv.acc %c_in, %a, %b : (!pto.tile<...>, !pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

Manual Mode

# Manual mode: explicitly bind resources first, then issue the instruction.
# Optional (when the instruction contains tile operands):
# pto.tassign %arg0, @tile(0x1000)
# pto.tassign %arg1, @tile(0x2000)
%c_out = pto.tgemv.acc %c_in, %a, %b : (!pto.tile<...>, !pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

PTO Assembly Form

%acc1 = tgemv.acc %acc0, %a, %b : (!pto.tile<...>, !pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>
# AS Level 2 (DPS)
pto.tgemv.acc ins(%c_in, %a, %b : !pto.tile_buf<...>, !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%c_out : !pto.tile_buf<...>)