bench: ignore the switch's own annotations when fingerprinting the IR

FlagTree's _apply_musa_rlc_policy(mod) stamps the whole RLC policy onto the
module as ttg.rlc-* attributes whenever the switch is on, regardless of whether
the pass then changes anything. Hashing the raw text therefore carried a
constant offset: every operator that compiles a kernel differed on that one
line and screened as IR_CHANGED. A filter that excludes nothing is not
filtering.

The null control could not catch it. Both of its sides run with the switch off,
so both carry the same attributes and the fingerprints match — it proved the
dump is deterministic, which was true, and said nothing about this.

Stripping ttg.rlc-* before hashing turns the screen back into a filter. Over
the same 24 operators, recomputed from the artifacts already on disk: 23
IR_CHANGED becomes 16, with 7 falling back to NO_IR_DIFF — tanh, gelu, mul,
softmax, mm, bmm, replication_pad3d, each byte-identical apart from that line.
replication_pad3d is the PR's largest NVIDIA win at +124.6%; on MUSA this pass
does not touch it.

The counts also show why the convert_layout count fails as a criterion in both
directions: addmm keeps cvt at 15 -> 15 while all 15 of its ttgir files differ
in substance, and tanh has no conversions and no change.

README.md

@@ -164,7 +164,14 @@ SWITCH=FLAGTREE_MUSA_RLC_ENHANCE ROUNDS=6 OPS="topk:topk" bash ab_repeat.sh
 两件容易做错的：
 
 - **判据是 ttgir 指纹，不是 `convert_layout` 计数。** cvt 数相同不等于生成代码
-  相同，而要测的是"生成代码变了没有"。cvt 数照样记，它解释的是变化的性质。
+  相同，而要测的是"生成代码变了没有"。两个方向都会骗人：`addmm` 的 cvt 是 15→15
+  没变，15 个 ttgir 文件却实质全不同；`tanh`/`softmax` 的 cvt 是 0→0，生成代码也
+  真的没动。cvt 数照样记，它解释的是变化的性质。
+- **指纹先抹掉开关自己盖的注解。** FlagTree 的 `_apply_musa_rlc_policy(mod)` 在开关
+  打开时把整套 RLC 策略旋钮盖成 module 属性（`ttg.rlc-*`），跟这个 pass 后面有没有
+  真的改动什么无关。不抹的话判据有个常量偏移——**凡是能编出 kernel 的算子都必然判成
+  "变了"，筛选器谁都不排除**。24 个算子实测：抹之前 23 个 `IR_CHANGED`，抹之后 7 个
+  落回 `NO_IR_DIFF`。零对照抓不到这个，因为两侧同值时属性也相同。
 - **不要全局写死一个 `DTYPES`。** `OPS` 元素支持 `OP:OP_FILE:DTYPES`，留空表示用
   该算子自己的全套。`fft` 只吃 complex64，被一刀切的 `DTYPES=float16` 判死过一次
   ——那是 harness 的问题，被记成了算子的问题。