TGATHERB

Instruction Diagram

Introduction

Gathers elements using byte offsets.

Mathematical Semantics

For each element in the valid region:

$$\mathrm{dst}_{i,j} = *\left(\mathrm{srcBase} + \mathrm{offset}_{i,j}\right)$$

The exact boundary behavior is implementation-defined.

Assembly Syntax

Synchronous form:

%dst = tgatherb %src, %offsets : !pto.tile<...> -> !pto.tile<...>

AS Level 1 (SSA)

%dst = pto.tgatherb %src, %offsets : (!pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

AS Level 2 (DPS)

pto.tgatherb ins(%src, %offsets : !pto.tile_buf<...>, !pto.tile_buf<...>) outs(%dst : !pto.tile_buf<...>)

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 TileDataDst, typename TileDataSrc, typename TileDataOffset, typename... WaitEvents>
PTO_INST RecordEvent TGATHERB(TileDataDst &dst, TileDataSrc &src, TileDataOffset &offset, WaitEvents &... events);

Constraints

• Implementation check (Atlas A2/A3 training products/Atlas A2/A3 inference products):
  • The destination layout must be row-major (TileDataDst::isRowMajor).
  • The destination element size must be 1, 2, or 4 bytes (enforced by static_assert in the helper function).
  • TileDataSrc::DType/TileDataDst::DType must be int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, half, bfloat16_t, or float.
• Implementation check (Ascend 950PR/Ascend 950DT):
  • The destination element size must be 1, 2, or 4 bytes.
  • TileDataSrc::DType/TileDataDst::DType must be int8_t, uint8_t, int16_t, uint16_t, int32_t, uint32_t, half, bfloat16_t, or float.
• Offset interpretation:
  • Offsets are interpreted by the implementation as uint32_t values (byte offsets).
  • Offset bounds are not validated through explicit runtime assertions; out-of-range offsets are destination-defined.

Examples

Automatic

#include <pto/pto-inst.hpp>

using namespace pto;

void example_auto() {
  using SrcT = Tile<TileType::Vec, uint8_t, 1, 256>;
  using OffT = Tile<TileType::Vec, uint32_t, 1, 256>;
  using DstT = Tile<TileType::Vec, uint8_t, 1, 256>;
  SrcT src;
  OffT off;
  DstT dst;
  TGATHERB(dst, src, off);
}

Manual

#include <pto/pto-inst.hpp>

using namespace pto;

void example_manual() {
  using SrcT = Tile<TileType::Vec, uint8_t, 1, 256>;
  using OffT = Tile<TileType::Vec, uint32_t, 1, 256>;
  using DstT = Tile<TileType::Vec, uint8_t, 1, 256>;
  SrcT src;
  OffT off;
  DstT dst;
  TASSIGN(src, 0x1000);
  TASSIGN(off, 0x2000);
  TASSIGN(dst, 0x3000);
  TGATHERB(dst, src, off);
}

ASM Examples

Automatic Mode

# Automatic mode: the compiler/runtime handles resource placement and scheduling.
%dst = pto.tgatherb %src, %offsets : (!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)
%dst = pto.tgatherb %src, %offsets : (!pto.tile<...>, !pto.tile<...>) -> !pto.tile<...>

PTO Assembly Form

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