[ExecuTorch][XNNPACK] Don't partition per_tensor weights with qd8

This is not supported, so we shouldn't partition it.

Add an expectedFailure test to indicate that this is not supported.

Differential Revision: [D70343584](https://our.internmc.facebook.com/intern/diff/D70343584/)

[ghstack-poisoned]

Author: digantdesai

backends/xnnpack/partition/config/gemm_configs.py

@@ -21,6 +21,7 @@
     is_dynamic_qdq,
     is_per_channel,
     is_per_channel_group,
+    is_per_tensor,
     is_qparam,
     is_quant,
 )
@@ -66,8 +67,6 @@ def check_constraints(self, node: torch.fx.Node, ep: ExportedProgram) -> bool:
             return False
 
         is_valid, _ = self.get_deps(node, ep)
-        if not is_valid:
-            why(node, "Failed to get valid dependent nodes.")
         return is_valid
 
     def get_node_and_deps(
@@ -123,6 +122,7 @@ def get_deps(
         precision = self._detect_precision(node)
         if precision not in self.supported_precision_types():
             # detected precision but it is either disabled or not supported
+            why(node, f"Unsupported precision type {precision}")
             return (False, [])
         _, precision = self._overwrite_precision(node)
         valid_bias, bias_deps = self._get_bias_deps(node, ep, precision)
@@ -143,26 +143,34 @@ def _get_weight_deps(
             # First find the weight
             weight_node = get_input_node(node, self.weight_idx)
             if not is_param_node(ep, weight_node):
-                return (False, [])  # weight must be a static param
+                why(node, "Expected weight to be a static param")
+                return (False, [])
             gemm_deps.append(weight_node)
 
             return (True, gemm_deps)
         else:
             # Quantized Weight deps
             dequant_node = get_input_node(node, self.weight_idx)
             if not is_dequant(dequant_node):
+                why(node, "Expected  weight to have a dequantized node")
                 return False, []
             gemm_deps.append(dequant_node)
             weight = get_input_node(dequant_node, 0)
             if not is_param_node(ep, weight):
+                why(node, "Expected weight to be a static param")
                 return False, []
             gemm_deps.append(weight)
 
             if is_per_channel(dequant_node) or is_per_channel_group(dequant_node):
                 if len(dequant_node.all_input_nodes) < 2:
                     # Expected channel quantized to have scale/zp nodes
+                    why(node, "Expected channel quantized to have scale/zp nodes")
                     return False, []
 
+            if is_per_tensor(dequant_node) and precision == ConfigPrecisionType.DYNAMIC_QUANT:
+                why(node, "XNNPACK does not support per tensor quantized weights for dynamic quantization of activations")
+                return False, []
+
                 gemm_deps.extend(dequant_node.all_input_nodes[1:3])
             return (True, gemm_deps)
 
@@ -174,7 +182,7 @@ def _get_output_deps(
             # Look for fused activations and tail end quant node
             node_users = list(node.users.keys())
             if len(node_users) != 1:
-                # Expect quantized node to have a single output (fused act or dequant)
+                why(node, "Expected quantized node to have a single output")
                 return False, []
 
             # Check if the quantized pattern has a fused activation
@@ -190,6 +198,7 @@ def _get_output_deps(
 
             if not is_quant(n_output):
                 # Expected gemm_node --> fused_act (optional) --> dequant
+                why(node, "Expected output node to have a dequantized node")
                 return (False, [])
             gemm_deps.append(n_output)
         elif precision == ConfigPrecisionType.FP32:
@@ -219,7 +228,8 @@ def _get_bias_deps(
             bias_node = get_input_node(node, self.bias_idx)
             if bias_node:
                 if not is_param_node(ep, bias_node):
-                    return (False, [])  # bias node must be a static param
+                    why(node, "Expected bias to be a static param")
+                    return (False, [])
                 gemm_deps.append(bias_node)
 
         return (True, gemm_deps)
@@ -233,7 +243,7 @@ def _get_act_deps(
         else:
             dq_input = get_input_node(node, self.act_idx)
             if not is_dequant(dq_input):
-                # Expected static quant input to be dequant node
+                why(node, "Expected act input to be dequant node")
                 return False, []
             gemm_deps.append(dq_input)
             if precision == ConfigPrecisionType.STATIC_QUANT:
@@ -243,27 +253,28 @@ def _get_act_deps(
             # q input node
             q_input = get_input_node(dq_input, 0)
             if not is_quant(q_input):
+                why(node, "Expected  dequant input to be quant node")
                 return (False, [])
 
             gemm_deps.append(q_input)
             q_input_args = q_input.args
             if is_affine_qdq(q_input):
                 q_input_args = extract_qdq_affine_op_args_for_decomposed_ops(q_input)
             if not (is_node(q_input_args[1]) and is_node(q_input_args[2])):
-                # expected to find getitem node from choose qparam
+                why(node, "expected to find getitem node from choose qparam")
                 return (False, [])
 
             getitem1 = q_input_args[1]
             getitem2 = q_input_args[2]
 
             if not (is_getitem(getitem1) and is_getitem(getitem2)):
-                # expected getitem node from choose qparam
+                why(node, "expected getitem node from choose qparam")
                 return (False, [])
 
             gemm_deps.extend([getitem1, getitem2])
             choose_qparam = get_input_node(getitem1, 0)
             if not is_qparam(choose_qparam):
-                # expected to find choose_qparam node
+                why(node, "expected to find choose_qparam node")
                 return (False, [])
             gemm_deps.append(choose_qparam)
             return (True, gemm_deps)
@@ -471,6 +482,7 @@ def find_partition_args(input_node):
             # there can only be a single output node in partition
             or len(src_partition.output_nodes) != 1
         ):
+            why(node, "invalid source partition")
             return (False, [])
 
         # map addmm's args to the source partition linear's inputs and users

backends/xnnpack/test/ops/test_linear.py

@@ -520,7 +520,7 @@ def get_qnode_checks(quant_node_checks, dialect):
                 #     qtol=bool(quant_config), atol=atol
                 # )
 
-    def _test_qd8_per_channel_linear(self, dtype: torch.dtype = torch.float):
+    def _test_qd8_linear(self, dtype: torch.dtype = torch.float, is_per_channel:bool=True):
         for uses_bias in (False, True):
             module = BaseLinear(
                 in_size=8,
@@ -535,7 +535,7 @@ def _test_qd8_per_channel_linear(self, dtype: torch.dtype = torch.float):
                 module,
                 inputs,
                 dynamic_shapes=({1: torch.export.Dim("batch", max=100)},),
-                is_per_channel=True,
+                is_per_channel=is_per_channel,
                 uses_bias=uses_bias,
             )
 
@@ -695,11 +695,29 @@ def test_qs8_linear(self):
 
     # Tests for q[dp]8-f16-qc8w
     def test_qd8_f16_per_channel_linear(self):
-        self._test_qd8_per_channel_linear(dtype=torch.half)
+        self._test_qd8_linear(dtype=torch.half)
+
+    @unittest.expectedFailure
+    def test_qd8_f16_per_tensor_linear(self):
+        """
+        XNNPACK doesn't support per_tensor quantized weights for dynamic quantized linear op.
+        This test is to verify that we can't lower per_tensor quantized weights to per_channel quantized weights.
+        """
+        self._test_qd8_linear(dtype=torch.half, is_per_channel=False)
+
+
 
     # Tests for q[dp]8-f32-qc8w
     def test_qd8_f32_per_channel_linear(self):
-        self._test_qd8_per_channel_linear(dtype=torch.float)
+        self._test_qd8_linear(dtype=torch.float)
+
+    @unittest.expectedFailure
+    def test_qd8_f32_per_tensor_linear(self):
+        """
+        XNNPACK doesn't support per_tensor quantized weights for dynamic quantized linear op.
+        This test is to verify that we can't lower per_tensor quantized weights to per_channel quantized weights.
+        """ 
+        self._test_qd8_linear(dtype=torch.half, is_per_channel=False)
 
     # Tests for q[dp]8-f16-qc4w
     def test_linear_qd8_f16_per_channel_int4(self):

backends/xnnpack/utils/quant_utils.py

@@ -88,6 +88,13 @@ def is_per_channel(node: torch.fx.Node) -> bool:
 
     return is_per_channel or is_affine_per_channel_group
 
+def is_per_tensor(node: torch.fx.Node) -> bool:
+    if not (is_quant(node) or is_dequant(node)):
+        return False
+    
+    is_per_tensor = "per_tensor" in node.target.__name__  # pyre-ignore
+
+    return is_per_tensor and not (is_per_channel(node))
 
 def is_affine_qdq(node: torch.fx.Node) -> bool:
     if not (is_quant(node) or is_dequant(node)):