[AMD][Bugfix][Quantization] Honor fused-name match in is_layer_skipped

tests/quantization/test_quark.py

@@ -25,6 +25,9 @@
 from vllm.model_executor.layers.quantization.quark.quark_moe import (  # noqa: E501
     QuarkW8A8Int8MoEMethod,
 )
+from vllm.model_executor.layers.quantization.utils.quant_utils import (
+    is_layer_skipped,
+)
 from vllm.platforms import current_platform
 
 from .reference_mxfp4 import dq_mxfp4_torch, qdq_mxfp4_torch
@@ -437,3 +440,88 @@ def test_mxfp4_dequant_kernel_match_quark(
     out_torch = dq_mxfp4_torch(w_mxfp4, scale, float_dtype)
 
     assert torch.equal(out_hip, out_torch)
+
+
+# Unit tests for ``is_layer_skipped`` fused-name handling.
+
+FUSED_MAPPING = {
+    "qkv_proj": ["q_proj", "k_proj", "v_proj"],
+    "gate_up_proj": ["gate_proj", "up_proj"],
+}
+
+
+def test_fused_name_listed_directly_is_skipped():
+    # Regression for Step-3.5-Flash-FP8: the checkpoint lists the fused
+    # name (``qkv_proj``) directly in ``modules_to_not_convert``. When a
+    # ``packed_modules_mapping`` is registered on the model, the fused
+    # match must still win over per-shard expansion.
+    ignored = ["model.layers.0.self_attn.qkv_proj"]
+    assert is_layer_skipped(
+        prefix="model.layers.0.self_attn.qkv_proj",
+        ignored_layers=ignored,
+        fused_mapping=FUSED_MAPPING,
+    )
+    assert is_layer_skipped(
+        prefix="model.layers.0.mlp.gate_up_proj",
+        ignored_layers=["model.layers.0.mlp.gate_up_proj"],
+        fused_mapping=FUSED_MAPPING,
+    )
+
+
+def test_unfused_shards_listed_is_skipped():
+    # Quark INT8 style: per-shard names listed; all shards present means
+    # the fused layer is skipped via expansion.
+    ignored = [
+        "model.layers.0.self_attn.q_proj",
+        "model.layers.0.self_attn.k_proj",
+        "model.layers.0.self_attn.v_proj",
+    ]
+    assert is_layer_skipped(
+        prefix="model.layers.0.self_attn.qkv_proj",
+        ignored_layers=ignored,
+        fused_mapping=FUSED_MAPPING,
+    )
+
+
+def test_partial_shards_raises():
+    # Only some shards listed -> ambiguous, must raise. Fused name is
+    # not in ignored_layers, so we fall through to per-shard expansion.
+    ignored = ["model.layers.0.self_attn.q_proj"]
+    with pytest.raises(ValueError):
+        is_layer_skipped(
+            prefix="model.layers.0.self_attn.qkv_proj",
+            ignored_layers=ignored,
+            fused_mapping=FUSED_MAPPING,
+        )
+
+
+def test_not_skipped_when_nothing_listed():
+    assert not is_layer_skipped(
+        prefix="model.layers.0.self_attn.qkv_proj",
+        ignored_layers=["model.layers.0.mlp.gate_up_proj"],
+        fused_mapping=FUSED_MAPPING,
+    )
+
+
+def test_non_fused_layer_unaffected():
+    assert is_layer_skipped(
+        prefix="model.layers.0.self_attn.o_proj",
+        ignored_layers=["model.layers.0.self_attn.o_proj"],
+        fused_mapping=FUSED_MAPPING,
+    )
+    assert not is_layer_skipped(
+        prefix="model.layers.0.self_attn.o_proj",
+        ignored_layers=["model.layers.1.self_attn.o_proj"],
+        fused_mapping=FUSED_MAPPING,
+    )
+
+
+def test_substr_match_on_fused_name():
+    # skip_with_substr=True path: fused-name substring match should also
+    # short-circuit before shard expansion.
+    assert is_layer_skipped(
+        prefix="model.layers.0.self_attn.qkv_proj",
+        ignored_layers=["self_attn.qkv_proj"],
+        fused_mapping=FUSED_MAPPING,
+        skip_with_substr=True,
+    )

vllm/model_executor/layers/quantization/utils/quant_utils.py

@@ -520,7 +520,15 @@ def substr_match(prefix: str, ignored_layers: list[str]) -> bool:
     # in the safetensors checkpoint. So, we convert the name
     # from the fused version to unfused + check to make sure that
     # each shard of the fused layer has the same scheme.
-    if proj_name in fused_mapping:
+    #
+    # Some checkpoints (e.g. block-FP8 Step-3.5-Flash) already list the
+    # fused name (e.g. ``self_attn.qkv_proj``) directly in
+    # ``modules_to_not_convert``. Honor that fused-name match first so
+    # those layers are still correctly skipped even when a
+    # ``packed_modules_mapping`` is registered on the model.
+    if proj_name in fused_mapping and match_func(prefix, ignored_layers):
+        is_skipped = True
+    elif proj_name in fused_mapping:
         shard_prefixes = [
             prefix.replace(proj_name, shard_proj_name)
             for shard_proj_name in fused_mapping[proj_name]