diff --git a/backends/arm/_passes/__init__.py b/backends/arm/_passes/__init__.py
index ddca8ea4a06..09b5b50e8c5 100644
--- a/backends/arm/_passes/__init__.py
+++ b/backends/arm/_passes/__init__.py
@@ -38,6 +38,7 @@
)
from .fuse_batchnorm2d_pass import FuseBatchnorm2DPass # noqa
from .fuse_constant_ops_pass import ComputeConstantOpsAOT, FuseConstantArgsPass # noqa
+from .fuse_equal_placeholders_pass import FuseEqualPlaceholdersPass # noqa
from .fuse_quantized_activation_pass import FuseQuantizedActivationPass # noqa
from .insert_rescales_pass import InsertRescalePass # noqa
from .insert_table_ops import InsertTableOpsPass # noqa
diff --git a/backends/arm/_passes/arm_pass_manager.py b/backends/arm/_passes/arm_pass_manager.py
index dd4ca7ad7bd..0dd4f67cf7c 100644
--- a/backends/arm/_passes/arm_pass_manager.py
+++ b/backends/arm/_passes/arm_pass_manager.py
@@ -39,6 +39,7 @@
FoldAndAnnotateQParamsPass,
FuseBatchnorm2DPass,
FuseConstantArgsPass,
+ FuseEqualPlaceholdersPass,
FuseQuantizedActivationPass,
InsertRescalePass,
InsertTableOpsPass,
@@ -112,6 +113,7 @@ def _tosa_080_BI_pipeline(self, exported_program: ExportedProgram) -> GraphModul
self.add_pass(FuseConstantArgsPass(exported_program))
self.add_pass(InsertTableOpsPass(exported_program))
+ self.add_pass(FuseEqualPlaceholdersPass(exported_program))
self.add_pass(AnnotateChannelsLastDimOrder())
self.add_pass(InsertRescalePass())
@@ -162,6 +164,7 @@ def _tosa_080_MI_pipeline(self, exported_program: ExportedProgram) -> GraphModul
self.add_pass(FuseViewCopyTransform())
self.add_pass(FuseConstantArgsPass(exported_program))
self.add_pass(InsertTableOpsPass(exported_program))
+ self.add_pass(FuseEqualPlaceholdersPass(exported_program))
self.add_pass(AnnotateChannelsLastDimOrder())
self.add_pass(InsertRescalePass())
diff --git a/backends/arm/_passes/fuse_equal_placeholders_pass.py b/backends/arm/_passes/fuse_equal_placeholders_pass.py
new file mode 100644
index 00000000000..cd8cce1b3ea
--- /dev/null
+++ b/backends/arm/_passes/fuse_equal_placeholders_pass.py
@@ -0,0 +1,83 @@
+# Copyright 2025 Arm Limited and/or its affiliates.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+import torch
+from executorch.backends.arm._passes.arm_pass_utils import (
+ get_constant_placeholder_kind,
+ get_param_tensor,
+ is_param_node,
+)
+from executorch.backends.transforms.utils import (
+ create_constant_placeholder,
+ delete_constant_placeholder,
+)
+from executorch.exir import ExportedProgram
+from executorch.exir.pass_base import ExportPass, PassResult
+
+
+class FuseEqualPlaceholdersPass(ExportPass):
+ """
+ This pass optimizes memory usage by finding constant placeholders
+ pointing to identical tensors and fusing them to one single placeholder
+ with multiple users.
+ """
+
+ def __init__(self, exported_program: ExportedProgram):
+ self.exported_program = exported_program
+ super().__init__()
+
+ def call(self, graph_module: torch.fx.GraphModule) -> PassResult:
+ modified = False
+ const_placeholder_nodes = []
+ for node in graph_module.graph.nodes:
+ if is_param_node(self.exported_program, node):
+ const_placeholder_nodes.append(node)
+
+ while const_placeholder_nodes:
+
+ # Find equal tensors
+ node1 = const_placeholder_nodes.pop()
+ eq_nodes = [node1]
+ tensor1 = get_param_tensor(self.exported_program, node1)
+ if tensor1 is None:
+ continue
+
+ for node2 in const_placeholder_nodes:
+ tensor2 = get_param_tensor(self.exported_program, node2)
+ if tensor2 is None:
+ continue
+
+ if torch.equal(tensor1, tensor2):
+ eq_nodes.append(node2)
+
+ if len(eq_nodes) > 1:
+ common_name = node1.name + "_common"
+ common_kind = get_constant_placeholder_kind(
+ self.exported_program, node1
+ )
+ common_persisten_buffer = True
+
+ with graph_module.graph.inserting_before(node1):
+ common_node = create_constant_placeholder(
+ self.exported_program,
+ graph_module.graph,
+ common_name,
+ common_kind,
+ tensor1,
+ common_persisten_buffer,
+ )
+
+ for eq_node in eq_nodes:
+ eq_node.replace_all_uses_with(common_node)
+ delete_constant_placeholder(self.exported_program, eq_node)
+ if eq_node != node1:
+ const_placeholder_nodes.remove(eq_node)
+
+ modified = True
+
+ if modified:
+ graph_module.recompile()
+ graph_module = super().call(graph_module).graph_module
+ return PassResult(graph_module=graph_module, modified=modified)
diff --git a/backends/arm/test/passes/test_fuse_equal_placeholders_ops_pass.py b/backends/arm/test/passes/test_fuse_equal_placeholders_ops_pass.py
new file mode 100644
index 00000000000..2674f45cf6a
--- /dev/null
+++ b/backends/arm/test/passes/test_fuse_equal_placeholders_ops_pass.py
@@ -0,0 +1,96 @@
+# Copyright 2025 Arm Limited and/or its affiliates.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+from copy import deepcopy
+from typing import Tuple
+
+import torch
+from executorch.backends.arm._passes.fuse_equal_placeholders_pass import (
+ FuseEqualPlaceholdersPass,
+)
+from executorch.backends.arm.test.tester.test_pipeline import PassPipeline
+
+input_t = Tuple[torch.Tensor] # Input x
+
+
+class FuseWeightsConstants(torch.nn.Module):
+ ops_before_pass = {}
+ ops_after_pass = {}
+ ops_not_after_pass = []
+
+ def __init__(
+ self,
+ ):
+ super().__init__()
+ self.weights1 = torch.rand(1, 2, 1)
+ self.weights2 = deepcopy(self.weights1)
+ self.bias1 = torch.rand(1)
+ self.bias2 = deepcopy(self.bias1)
+ self.bias3 = deepcopy(self.bias1)
+
+ def forward(self, x):
+ return (
+ torch.conv1d(x, self.weights1, self.bias1)
+ + torch.conv1d(x, self.weights2, self.bias2)
+ + self.bias3
+ )
+
+
+class FuseWeightsStateDict(torch.nn.Module):
+ ops_before_pass = {}
+ ops_after_pass = {}
+ ops_not_after_pass = []
+
+ def __init__(
+ self,
+ ):
+ super().__init__()
+ self.fc1 = torch.nn.Linear(in_features=8, out_features=2, bias=True)
+ self.fc2 = deepcopy(self.fc1)
+
+ def forward(self, x):
+ return self.fc1(x) + self.fc2(x)
+
+
+def test_fuse_equal_placeholders_constants_tosa_MI():
+ module = FuseWeightsConstants()
+ data = (torch.rand(1, 2, 8),)
+ pipeline = PassPipeline[input_t](
+ module,
+ data,
+ tosa_version="TOSA-0.80+MI",
+ ops_before_pass=module.ops_before_pass,
+ ops_after_pass=module.ops_after_pass,
+ passes_with_exported_program=[FuseEqualPlaceholdersPass],
+ )
+ pipeline.run()
+
+ # Check that weights and bias has been merged.
+ exp_program = pipeline.tester.get_artifact().exported_program()
+ constant_keys = list(exp_program.constants.keys())
+ assert len(constant_keys) == 2, "FuseEqualPlaceholders constants failed"
+ assert "_common" in constant_keys[0], "FuseEqualPlaceholders constants failed"
+ assert "_common" in constant_keys[1], "FuseEqualPlaceholders constants failed"
+
+
+def test_fuse_equal_placeholders_state_dict_tosa_MI():
+ module = FuseWeightsStateDict()
+ data = (torch.rand(1, 2, 8),)
+ pipeline = PassPipeline[input_t](
+ module,
+ data,
+ tosa_version="TOSA-0.80+MI",
+ ops_before_pass=module.ops_before_pass,
+ ops_after_pass=module.ops_after_pass,
+ passes_with_exported_program=[FuseEqualPlaceholdersPass],
+ )
+ pipeline.run()
+
+ # Check that weights and bias has been merged.
+ exp_program = pipeline.tester.get_artifact().exported_program()
+ state_dict_keys = list(exp_program.state_dict.keys())
+ assert len(state_dict_keys) == 2, "FuseEqualPlaceholders state_dict failed"
+ assert "_common" in state_dict_keys[0], "FuseEqualPlaceholders state_dict failed"
+ assert "_common" in state_dict_keys[1], "FuseEqualPlaceholders state_dict failed"
diff --git a/examples/arm/setup.sh b/examples/arm/setup.sh
index 8d77eabce0f..44f09f211b5 100755
--- a/examples/arm/setup.sh
+++ b/examples/arm/setup.sh
@@ -57,7 +57,7 @@ fi
# vela
vela_repo_url="https://gitlab.arm.com/artificial-intelligence/ethos-u/ethos-u-vela"
-vela_rev="425541302c7e4b6fbeca7c0061286b131ee507c3"
+vela_rev="859cc066178a87ff28230c1ce9bd370f1e98aa5a"
########
### Optional user args