triton-ascend-api-rules

name	triton-ascend-api-rules
description	Triton Ascend hard API restrictions and forbidden syntax. MUST-follow rules that apply to every kernel: forbidden control flow (return/break/continue/lambda/while), tensor slice/index restrictions, scalar conversion rules, BLOCK_SIZE upper bound. Violating any of these produces a compile or runtime error on Ascend.
category	fundamental
version	1.0.0
metadata	{"backend":"ascend","dsl":"triton_ascend","hardware":"Atlas A2, Atlas A3"}

Triton Ascend API Hard Rules (MUST follow)

This file lists rules whose violation causes a compile or runtime error on Ascend. They apply to every kernel in this DSL — no exceptions.

禁止使用的语法

• return / break / continue → 使用 mask 控制
• lambda → 内联函数或 tl.where
• 链式布尔运算 → 分步计算 mask
• 张量直接索引 → tl.load / tl.store
• if-else 中负偏移 → tl.maximum(offset, 0)
• Ascend: 复杂 tl.where → if-else
• Ascend: while 循环 → for 替代
• Ascend: range() 的 start/stop 混用运行时变量和 constexpr → 用全 constexpr 的 range + 循环体内运行时 if 跳过

While 循环替代（Ascend）

静态上限（编译时常量）: 直接 for i in range(N_ITERS)

动态上限（运行时参数）:

@triton.jit
def kernel(ptr, n_iters, TILE: tl.constexpr, MAX_ITERS: tl.constexpr):
    for i in range(MAX_ITERS):
        if i < n_iters:
            offset = i * TILE + tl.arange(0, TILE)
            data = tl.load(ptr + offset)
            tl.store(ptr + offset, data * 2)

切片操作

• 禁止 Python 切片 b[0] b[i:j]
• 单元素: tl.get_element(tensor, (index,))
• 切片: tl.extract_slice(tensor, offsets, sizes, strides)
• 插入: tl.insert_slice(full, sub, offsets, sizes, strides)
• 禁止对 tl.arange 张量用 get_element

其他限制

• tl.constexpr 仅在内核参数中使用，host 侧不可用
• 输出张量用 torch.empty / empty_like（避免 zeros/ones 初始化开销）
• 标量转换仅 scalar.to(type)，禁止 tl.float16(scalar)
• BLOCK_SIZE 必须小于 65536