Fix xnnpack quantization discrepancy for non-fp32

Differential Revision: D70184325

Pull Request resolved: #8488

Author: jackzhxng

examples/models/checkpoint.py

@@ -9,6 +9,8 @@
 from pathlib import Path
 from typing import Any, Dict, Optional
 
+import torch
+
 
 def get_default_model_resource_dir(model_file_path: str) -> Path:
     """
@@ -52,7 +54,7 @@ def get_default_model_resource_dir(model_file_path: str) -> Path:
     return resource_dir
 
 
-def get_checkpoint_dtype(checkpoint: Dict[str, Any]) -> Optional[str]:
+def get_checkpoint_dtype(checkpoint: Dict[str, Any]) -> Optional[torch.dtype]:
     """
     Get the dtype of the checkpoint, returning "None" if the checkpoint is empty.
     """

examples/models/llama/export_llama_lib.py

@@ -16,6 +16,7 @@
 import re
 import shlex
 from enum import Enum
+from functools import partial
 from json import JSONDecodeError
 from pathlib import Path
 from typing import Callable, List, Optional, Union
@@ -594,9 +595,36 @@ def _prepare_for_llama_export(args) -> LLMEdgeManager:
     )
 
     # At this point, the model is loaded in the default fp32.
+
+    # Checkpoint dtype should be lower or equal precision to the dtype override.
+    checkpoint_dtype = edge_manager.model.checkpoint_dtype
+    if not (
+        checkpoint_dtype == dtype_override.to_torch_dtype()
+        or (
+            checkpoint_dtype == torch.float16
+            and dtype_override.to_torch_dtype() == torch.float32
+        )
+        or (
+            checkpoint_dtype == torch.bfloat16
+            and dtype_override.to_torch_dtype() == torch.float32
+        )
+    ):
+        logging.warning(
+            f"Checkpoint dtype {checkpoint_dtype} precision is higher than dtype override {dtype_override.to_torch_dtype()}."
+        )
+
     edge_manager.model = edge_manager.model.to(dtype=dtype_override.to_torch_dtype())
-    edge_manager.set_output_dir(output_dir_path).source_transform(
-        _get_source_transforms(args.model, dtype_override, args)
+
+    # We want to quantize (in the source transforms) the weights of the model
+    # in the checkpoint dtype.
+    logging.info(f"Checkpoint dtype: {edge_manager.model.checkpoint_dtype}")
+    edge_manager = edge_manager.set_output_dir(output_dir_path).source_transform(
+        _get_source_transforms(
+            modelname=args.model,
+            dtype_override=dtype_override,
+            checkpoint_dtype=DType.from_torch_dtype(checkpoint_dtype),
+            args=args,
+        )
     )
 
     return edge_manager
@@ -784,8 +812,6 @@ def _to_edge_and_lower_llama(  # noqa: C901
                 shares=args.num_sharding,
             )
 
-        from functools import partial
-
         # pyre-ignore
         from executorch.backends.qualcomm.quantizer.custom_annotation import (
             get_custom_quant_ios_dtype,
@@ -1069,8 +1095,31 @@ def _load_llama_model(
 
 
 def _get_source_transforms(  # noqa
-    modelname: str, dtype_override: Optional[DType], args
+    modelname: str,
+    dtype_override: DType,
+    *,
+    checkpoint_dtype: Optional[DType] = None,
+    args,
 ) -> List[Callable[[torch.nn.Module], torch.nn.Module]]:
+    """
+    Return a list of functions that transform a graph.
+
+    Args:
+        modelname: The name of the model.
+        dtype_override: The dtype to use for the model.
+        checkpoint_dtype: The dtype of the checkpoint. At the moment, if this is specified,
+            it means that you want to run quantize transformations on the weights represented
+            in their original dtype, while the overall dtype of the model maybe something
+            different. If not specified, defaults to dtype_override.
+        args: The arguments passed to the script.
+
+    Returns:
+        A list of transformation functions.
+    """
+
+    if not checkpoint_dtype:
+        checkpoint_dtype = dtype_override
+
     transforms = []
 
     if args.use_spin_quant:
@@ -1103,7 +1152,11 @@ def _get_source_transforms(  # noqa
         """
         modelname = f"{modelname}_q"
         transforms.append(
-            get_quant_weight_transform(args, dtype_override, verbose_export())
+            get_quant_weight_transform(
+                args=args,
+                computation_dtype=dtype_override,
+                checkpoint_dtype=checkpoint_dtype,
+            )
         )
 
     if args.embedding_quantize:
@@ -1117,7 +1170,7 @@ def _get_source_transforms(  # noqa
         this wil be a no-op.
         """
         modelname = f"{modelname}_e"
-        transforms.append(get_quant_embedding_transform(args))
+        transforms.append(get_quant_embedding_transform(args, checkpoint_dtype))
 
     if args.expand_rope_table:
         transforms.append(materialze_broadcast_of_rope_freq_cis)

examples/models/llama/source_transformation/quantize.py

@@ -18,6 +18,7 @@
 
 from sentencepiece import SentencePieceProcessor
 
+
 try:
     from fairseq2.nn.embedding import (
         Embedding as fsEmbedding,
@@ -36,7 +37,8 @@
 def quantize(  # noqa C901
     model: torch.nn.Module,
     qmode: str,
-    activation_dtype: Optional[DType],
+    computation_dtype: Optional[DType] = None,
+    checkpoint_dtype: Optional[DType] = None,
     checkpoint_path: Optional[Path] = None,
     # following arguments only available when setting int4 or gptq quantization.
     group_size: Optional[int] = 128,
@@ -52,20 +54,33 @@ def quantize(  # noqa C901
 ) -> torch.nn.Module:
     """
     Quantizes a model by converting all weights to int8.
+
     Args:
-        model: A model to quantize.
-        qmode: quantization mode, e.g. int8, 8da4w, 8da4w-gptq
+        model: The model to quantize.
+        qmode: The quantization mode, e.g. int8, 8da4w, 8da4w-gptq.
+        computation_dtype: The dtype that ops are performed in (the resulting dtype of dequantization).
+            Also the dtype of the rest of the non-quantized compoents of the model.
+        checkpoint_dtype: The dtype of the checkpoint, this arg exists since it is more accurate to
+            quantize the weight in its original dtype.
+
     Returns:
         A quantized model.
     """
-    if activation_dtype is not None:
-        torch_dtype = activation_dtype.to_torch_dtype()
+    if computation_dtype:
+        computation_torch_dtype = computation_dtype.to_torch_dtype()
     else:
-        torch_dtype = torch.float16
+        computation_torch_dtype = torch.float32
+
+    if not checkpoint_dtype:
+        checkpoint_torch_dtype = computation_torch_dtype
+    else:
+        checkpoint_torch_dtype = checkpoint_dtype.to_torch_dtype()
 
     if qmode == "int8":
         # Add quantization mode options here: group size, bit width, etc.
-        return WeightOnlyInt8QuantHandler(model).quantized_model()
+        return WeightOnlyInt8QuantHandler(
+            model, precision=checkpoint_torch_dtype
+        ).quantized_model()
     elif qmode.startswith("torchao:fpa"):
         pattern = r"torchao:fpa(\d+)w"
         matches = re.findall(pattern, qmode)
@@ -75,10 +90,12 @@ def quantize(  # noqa C901
         from torchao.experimental.quant_api import UIntxWeightOnlyLinearQuantizer
 
         with torch.no_grad():
+            # This quantize() is currently doing a model.to(self.precision) so cannot
+            # decouple computation and checkpoint dtypes.
             model = (
                 UIntxWeightOnlyLinearQuantizer(
                     device="mps",
-                    precision=torch.float32,
+                    precision=computation_torch_dtype,
                     groupsize=group_size,
                     bitwidth=bitwidth,
                 )
@@ -101,6 +118,8 @@ def quantize(  # noqa C901
         from torchao.utils import unwrap_tensor_subclass
 
         with torch.no_grad():
+            # Computation dtype is fixed to fp32 in the implementation of quantize_, so
+            # no way to decouple checkpoint and computation dtype.
             quantize_(
                 model,
                 Int8DynamicActivationIntxWeightConfig(
@@ -121,9 +140,12 @@ def quantize(  # noqa C901
             raise Exception("For 8da4w quantization, group size must be specified.")
         from torchao.quantization.quant_api import Int8DynActInt4WeightQuantizer
 
+        # 1. Quantize in checkpoint dtype.
         model = Int8DynActInt4WeightQuantizer(
-            precision=torch_dtype, groupsize=group_size
+            precision=checkpoint_torch_dtype, groupsize=group_size
         ).quantize(model)
+        # 2. Set the computation dtype (what weights/acts dequantize to).
+        model = set_8da4w_computation_dtype(model, computation_torch_dtype)
 
         if verbose:
             print("quantized model:", model)
@@ -177,7 +199,7 @@ def quantize(  # noqa C901
             blocksize,
             percdamp,
             group_size,
-        )
+        )  # TODO: separate computation and checkpoint dtype for GPTQ.
         model = gptq_quantizer.quantize(model, inputs)
         return model
     elif qmode == "vulkan_4w":
@@ -190,9 +212,12 @@ def quantize(  # noqa C901
         # at the moment
         from torchao.quantization.quant_api import Int8DynActInt4WeightQuantizer
 
+        # 1. Quantize in checkpoint dtype.
         model = Int8DynActInt4WeightQuantizer(
-            precision=torch_dtype, groupsize=q_group_size
+            precision=checkpoint_torch_dtype, groupsize=q_group_size
         ).quantize(model)
+        # 2. Set the computation dtype (what weights/acts dequantize to).
+        model = set_8da4w_computation_dtype(model, computation_torch_dtype)
 
         return model
     else:
@@ -348,6 +373,7 @@ def __init__(
         node_type: str = "*",
         bitwidth: Optional[int] = None,
         group_size: Optional[int] = None,
+        precision: torch.dtype = torch.float32,
     ):
         self.mod = mod
         self.group_size = group_size
@@ -356,6 +382,7 @@ def __init__(
             self.bitwidth = 8
         else:
             self.bitwidth = bitwidth
+        self.precision = precision
 
     @torch.no_grad()
     def create_quantized_state_dict(self) -> Dict:
@@ -391,7 +418,7 @@ def create_quantized_state_dict(self) -> Dict:
 
                     # print(f"expanded weight shape {input_weight.shape}")
                     weight, scales, _ = dynamically_quantize_per_channel(
-                        input_weight,
+                        input_weight.to(dtype=self.precision),
                         range_min,
                         range_max,
                         torch.int8,
@@ -576,6 +603,7 @@ def __init__(
         bitwidth: int = 8,
         group_size: Optional[int] = None,
         packed=False,
+        precision: Optional[torch.dtype] = None,
     ):
         if isinstance(packed, str):
             packed = packed == "True"
@@ -584,6 +612,8 @@ def __init__(
         self.group_size = group_size
         self.bitwidth = bitwidth
         self.packed = packed
+        # Dtype of the weights right before quantization.
+        self.precision = precision
         if (bitwidth not in [2, 4]) and packed:
             raise RuntimeError("pack only works with bitsize 2, 4")
 
@@ -614,7 +644,11 @@ def create_quantized_state_dict(self, packed=False) -> Dict:
                     f"quantize {fqn, mod} with group_size {self.group_size}, bitwidth {self.bitwidth}"
                 )
                 weight, scales, _ = dynamically_quantize_per_channel(
-                    mod.weight.float(),
+                    (
+                        mod.weight.to(dtype=self.precision)
+                        if self.precision
+                        else mod.weight
+                    ),
                     range_min,
                     range_max,
                     torch.int8,
@@ -750,7 +784,7 @@ def forward(self, indices: torch.Tensor) -> torch.Tensor:
 ############################ Source Transform Start #######################
 
 
-def get_quant_embedding_transform(args):
+def get_quant_embedding_transform(args, dtype_override: Optional[DType] = None):
     if args.embedding_quantize.startswith("torchao:"):
         bitwidth, group_size = args.embedding_quantize.split(":")[1].split(",")
         group_size = int(group_size)
@@ -775,16 +809,22 @@ def _torchao_embedding_quantizer(model):
     else:
         group_size = int(group_size)
     bitwidth = int(bitwidth)
+    torch_dtype = dtype_override.to_torch_dtype() if dtype_override else None
     return lambda model: EmbeddingQuantHandler(
         model,
         bitwidth=bitwidth,
         group_size=group_size,
         packed=(bitwidth in [2, 4]),
+        precision=torch_dtype,
     ).quantized_model()
 
 
-def get_quant_weight_transform(args, dtype_override, verbose):
-    # If these optional args are None, don't provide them to quantize()
+def get_quant_weight_transform(
+    args,
+    computation_dtype: Optional[DType] = None,
+    checkpoint_dtype: Optional[DType] = None,
+):
+    # If these optional args are None, don't provide them to quantize().
     quant_args_str = [
         "group_size",
         "calibration_tasks",
@@ -802,7 +842,8 @@ def get_quant_weight_transform(args, dtype_override, verbose):
         quantize,
         **quant_args,
         qmode=args.quantization_mode,
-        activation_dtype=dtype_override,
+        computation_dtype=computation_dtype,
+        checkpoint_dtype=checkpoint_dtype,
         checkpoint_path=(Path(path) if (path := args.checkpoint) is not None else None),
         tokenizer_path=(
             Path(path) if (path := args.tokenizer_path) is not None else None
@@ -829,4 +870,28 @@ def _load_torchao_aten_lib(libname):
     torch.ops.load_library(libs[0])
 
 
+# We want to do compute the actual ops in the computation dtype, since the precision of the
+# quantized linear will initially be the dtype of the checkpoint.
+def set_8da4w_computation_dtype(
+    module: nn.Module, computation_dtype: torch.dtype
+) -> nn.Module:
+
+    from torchao.quantization.GPTQ import Int8DynActInt4WeightLinear
+
+    def _set_8da4w_computation_dtype(module: nn.Module, dtype: torch.dtype) -> None:
+        """
+        Recursively iterate through the module and set the precision attributes
+        of all Int8DynActInt4WeightLinears.
+        """
+        for _name, child in module.named_children():
+            if isinstance(child, Int8DynActInt4WeightLinear):
+                child.precision = dtype
+            else:
+                # Recursively apply to child modules
+                _set_8da4w_computation_dtype(child, dtype)
+
+    _set_8da4w_computation_dtype(module, computation_dtype)
+    return module
+
+
 ############################ Source Transform End #######################

examples/models/llava/export_llava.py

@@ -100,7 +100,7 @@ def forward(self, input_pos, embeddings):
     args = parser.parse_args(
         ["-X", "-qmode", "8da4w", "--group_size", "128", "--embedding-quantize", "4,32"]
     )
-    quant_transform = get_quant_weight_transform(args, dtype_override, False)
+    quant_transform = get_quant_weight_transform(args, dtype_override)
     _, quantizers, _ = get_quantizer_and_quant_params(args)
     source_transforms = []
     if llava.use_sdpa_with_kv_cache_op:

exir/tests/test_memory_planning.py

@@ -708,10 +708,10 @@ def call(self, graph_module: torch.fx.GraphModule) -> PassResult:
         et_program = et.executorch_program
         inputs = et_program.execution_plan[0].inputs
         self.assertNotEqual(
-            et_program.execution_plan[0]  # pyre-ignore
+            et_program.execution_plan[0]
             .values[inputs[0]]
             .val.allocation_info.memory_offset_low,
-            et_program.execution_plan[0]  # pyre-ignore
+            et_program.execution_plan[0]
             .values[inputs[1]]
             .val.allocation_info.memory_offset_low,
         )