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AstrAI/csrc/kernels/fp8/common.h
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ViperEkura 057c0d33df refactor: split quantize into multi-type primitive
- split quantize into quantize.cuh, templated on input type (bf16/fp16/fp32)
- rename pybind entry quantize_bf16 to quantize; validate the fmt enum
- fix fp8x2 packing: one 32-bit word packs two pairs (halves were dropped)
- drop the dead OutFp8 template param; GEMM output is always bf16
- fp8_state.reset() restores recipe/format defaults too (test state leak)
- rewrite tests for the two-primitive API with fp32-domain amax references
2026-08-25 20:07:40 +08:00

114 lines
4.5 KiB
C++

#pragma once
#include <cuda_bf16.h>
#include <cuda_fp8.h>
#include <cuda_runtime.h>
#include <cstdint>
// Pure POD/traits header — no .cuh/CUDA-kernel includes; raw __nv_* type
// spellings only.
namespace astrai {
namespace fp8 {
// Compile-time FP8 format: E4M3 (forward / high precision, max 448) or
// E5M2 (gradient / large dynamic range, max 57344).
enum class FP8Format : int {
E4M3 = 0,
E5M2 = 1,
};
// Operand memory layouts as types (CUTLASS-style tags). The tag names the
// storage order of the raw buffer relative to the operand's canonical GEMM
// matrix — A is [M][K], B is [K][N]:
// A RowMajor = [M][K] storage (K-contiguous rows; the default)
// A ColMajor = [K][M] storage (M-contiguous; A^T)
// B RowMajor = [K][N] storage (N-contiguous; the plain a @ b operand)
// B ColMajor = [N][K] storage (K-contiguous; the nn.Linear weight layout)
// Empty tags: selection happens by type at compile time (see load_operand_tile).
struct RowMajor {};
struct ColMajor {};
// Transpose of a layout tag: the same buffer with the rows and contract dims
// swapped. B's tag is relative to the canonical [K][N] GEMM matrix, so the
// stage-load (which views any operand as [rows][contract]) sees the transposed
// tag — this trait makes that inversion explicit.
template <typename Layout>
struct transpose_layout;
template <>
struct transpose_layout<RowMajor> {
using type = ColMajor;
};
template <>
struct transpose_layout<ColMajor> {
using type = RowMajor;
};
template <typename Layout>
using transpose_layout_t = typename transpose_layout<Layout>::type;
// Compile-time tile configuration, mirroring KernelTraits<HEAD_DIM, BC,
// WARPS, STAGES> in the attention kernels. `Fmt` selects the FP8 conversion
// and the MMA PTX mnemonic; the remaining parameters shape the CTA tile and
// the cp.async pipeline depth.
template <FP8Format Fmt, int BlockM, int BlockN, int K, int Stages>
struct Fp8GemmTraits {
static constexpr FP8Format kFormat = Fmt;
static constexpr int kBlockM = BlockM;
static constexpr int kBlockN = BlockN;
static constexpr int kK = K;
static constexpr int kStages = Stages;
static constexpr bool kIsE5M2 = (Fmt == FP8Format::E5M2);
static constexpr __nv_fp8_interpretation_t kNvFormat =
kIsE5M2 ? __NV_E5M2 : __NV_E4M3;
static constexpr float kFp8Max = kIsE5M2 ? 57344.0f : 448.0f;
// Derived launch geometry: 64x32 warp tiles give the CTA thread count.
// The shared-memory budget is layout-aware (crosswise operands add K-
// major staging + a canonical buffer), so it lives in Fp8GemmSmem in
// gemm.cuh together with the resident-CTA hint for __launch_bounds__.
static constexpr int kCtaThreads = (BlockM / 64) * (BlockN / 32) * 32;
};
// Quantize-kernel parameter POD: float input (bf16 / fp16 / fp32) -> FP8
// with fused amax.
struct FP8QuantizeParams {
// Float input and FP8 output buffers; scale is the quantization
// multiplier (device scalar). amax (may be null) is zero-initialized by
// the binding and receives the raw-domain absolute maximum.
const void* __restrict__ input_ptr = nullptr;
void* __restrict__ output_ptr = nullptr;
const float* __restrict__ scale = nullptr;
float* __restrict__ amax = nullptr;
// Element count (only the elementwise quantize kernel uses it).
int total = 0;
};
// Unified GEMM parameter POD, mirroring AttentionParams: one struct flows
// through the pre-quantized GEMM kernels. Each kernel touches only the
// fields it needs; buffers are raw pointers packed by the torch binding.
// Pointer members default to null so optional paths cannot hold garbage.
struct FP8Params {
// Inputs: a/b are FP8 for the pre-quantized path. Scales are
// quantization steps (device scalars).
const void* __restrict__ a_ptr = nullptr;
const void* __restrict__ b_ptr = nullptr;
void* __restrict__ out_ptr = nullptr;
const float* __restrict__ scale = nullptr;
// Shapes. `int` covers every realistic LLM shape; the kernels promote
// to int64 for all pointer arithmetic.
int m, n, k;
// Physical leading dimensions (column count, i.e. row stride) of A and
// B. For a non-transposed operand the stride equals the contract dim;
// for a transposed operand it is the operand's own column count. The
// binding packs these so the kernel reads both buffers either naturally
// or transposed depending on the LayoutA/LayoutB tags (see gemm.cuh).
int a_ld, b_ld;
};
} // namespace fp8
} // namespace astrai