Revert "Arm backend: Refactor compile spec handling (#14111)" (#14175)

This reverts commit 29cec35. This broke
our internal Buck builds and I think revert/reapply will allow us to
ingest changes faster overall. (Have plans to get some Buck coverage in
GitHub CI that will prevent problems like this going forward soon.)

Author: swolchok

backends/arm/arm_backend.py

@@ -0,0 +1,245 @@
+# Copyright 2023-2025 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.
+
+# pyre-unsafe
+
+#
+# Main implementation of AoT flow to partition and preprocess for Arm target
+# backends. Converts via TOSA as an intermediate form supported by AoT and
+# JIT compiler flows.
+#
+from enum import Enum
+from typing import List, Optional
+
+from executorch.backends.arm.tosa import TosaSpecification
+
+from executorch.exir.backend.compile_spec_schema import (  # type: ignore[import-not-found]
+    CompileSpec,
+)
+
+
+class ArmCompileSpecBuilder:
+    class DebugMode(Enum):
+        JSON = 1
+        TOSA = 2
+
+    def __init__(self):
+        self.compile_spec: List[CompileSpec] = []
+        self.compiler_flags = []
+        self.output_format = None
+        self.path_for_intermediates = None
+        self.tosa_spec = None
+        self.tosa_debug_mode = None
+
+    def vgf_compile_spec(
+        self,
+        tosa_spec: TosaSpecification = None,  # type: ignore[assignment]
+        compiler_flags: Optional[str] = "",
+    ) -> "ArmCompileSpecBuilder":
+        """
+        Generate compile spec for VGF compatible targets
+
+        Args:
+            compiler_flags: Extra compiler flags for converter_backend
+        """
+        self.output_format = "vgf"
+        self.compiler_flags = [
+            compiler_flags,
+        ]
+
+        if tosa_spec is None:
+            tosa_spec = TosaSpecification.create_from_string("TOSA-1.0+FP")
+
+        tosa_version = tosa_spec.version  # type: ignore[attr-defined]
+        tosa_profiles = tosa_spec.profiles  # type: ignore[attr-defined]
+
+        if tosa_version.major != 1:
+            raise ValueError(
+                "Arm backend only supports converter-backend for TOSA version 1. "
+                f"Invalid TOSA version: {tosa_version}"
+            )
+
+        if "FP" not in tosa_profiles and "INT" not in tosa_profiles:
+            raise ValueError(
+                "Arm backend only supports converter-backend for FP or INT. "
+                f"Invalid TOSA profile: {tosa_profiles}"
+            )
+
+        if len(tosa_profiles) != 1:
+            raise ValueError(
+                "For now Arm backend only supports converter-backend for either FP or INT. "
+                f"Invalid TOSA profile: {tosa_profiles}"
+            )
+
+        self.tosa_spec = tosa_spec
+
+        return self
+
+    def ethosu_compile_spec(
+        self,
+        target: str,
+        system_config: Optional[str] = None,
+        memory_mode: Optional[str] = None,
+        extra_flags: Optional[str] = None,
+        config_ini: Optional[str] = "Arm/vela.ini",
+    ) -> "ArmCompileSpecBuilder":
+        """
+        Generate compile spec for Ethos-U NPU
+
+        Args:
+            target: Ethos-U accelerator configuration, e.g. ethos-u55-128
+            system_config: System configuration to select from the Vel
+                configuration file
+            memory_mode: Memory mode to select from the Vela configuration file
+            extra_flags: Extra flags for the Vela compiler
+            config_ini: Vela configuration file(s) in Python ConfigParser .ini
+                file format
+        """
+        assert (
+            self.output_format is None
+        ), f"Output format already set to f{self.output_format}"
+        self.output_format = "vela"
+        self.compiler_flags = [
+            f"--accelerator-config={target}",
+            f"--config={config_ini}",
+        ]
+
+        # default system config and memory mode
+        if "ethos-u55" in target:
+            if system_config is None:
+                system_config = "Ethos_U55_High_End_Embedded"
+            if memory_mode is None:
+                memory_mode = "Shared_Sram"
+        elif "ethos-u85" in target:
+            if system_config is None:
+                system_config = "Ethos_U85_SYS_DRAM_Mid"
+            if memory_mode is None:
+                memory_mode = "Sram_Only"
+        else:
+            raise RuntimeError(f"Unknown ethos target: {target}")
+
+        if system_config is not None:
+            self.compiler_flags.append(f"--system-config={system_config}")
+        if memory_mode is not None:
+            self.compiler_flags.append(f"--memory-mode={memory_mode}")
+        if extra_flags is not None:
+            self.compiler_flags.append(extra_flags)
+
+        # We require raw output and regor, so add these flags if absent. This
+        # overrides any other output setting.
+        self.compiler_flags.append("--output-format=raw")
+        self.compiler_flags.append("--debug-force-regor")
+
+        base_tosa_version = "TOSA-1.0+INT+int16"
+        if "u55" in target:
+            # Add the Ethos-U55 extension marker
+            base_tosa_version += "+u55"
+        self.tosa_spec = TosaSpecification.create_from_string(base_tosa_version)
+
+        return self
+
+    def tosa_compile_spec(
+        self, tosa_spec: str | TosaSpecification
+    ) -> "ArmCompileSpecBuilder":
+        """
+        Generate compile spec for TOSA flatbuffer output
+        """
+        assert (
+            self.output_format is None
+        ), f"Output format already set: {self.output_format}"
+        self.output_format = "tosa"
+        if isinstance(tosa_spec, TosaSpecification):
+            self.tosa_spec = tosa_spec
+        elif isinstance(tosa_spec, str):
+            self.tosa_spec = TosaSpecification.create_from_string(tosa_spec)
+        else:
+            raise RuntimeError(f"Invalid type for {tosa_spec}!")
+        return self
+
+    def dump_intermediate_artifacts_to(
+        self, output_path: str
+    ) -> "ArmCompileSpecBuilder":
+        """
+        Sets a path for dumping intermediate results during such as tosa and pte.
+        """
+        self.path_for_intermediates = output_path
+        return self
+
+    def dump_debug_info(self, debug_mode: DebugMode) -> "ArmCompileSpecBuilder":
+        """
+        Dump debugging information into the intermediates path
+        """
+        self.tosa_debug_mode = debug_mode.name
+        return self
+
+    def build(self) -> List[CompileSpec]:
+        """
+        Generate a list of compile spec objects from the builder
+        """
+        assert self.tosa_spec
+
+        # Always supply a TOSA version
+        self.compile_spec = [CompileSpec("tosa_spec", str(self.tosa_spec).encode())]
+
+        # Add compile flags, these are backend specific, refer to the backend
+        # documentation.
+        self.compile_spec += [
+            CompileSpec("compile_flags", " ".join(self.compiler_flags).encode()),
+        ]
+
+        # encode output format
+        self.compile_spec.append(
+            CompileSpec("output_format", self.output_format.encode())
+        )
+
+        if self.path_for_intermediates is not None:
+            self.compile_spec.append(
+                CompileSpec("debug_artifact_path", self.path_for_intermediates.encode())
+            )
+
+        if self.tosa_debug_mode is not None:
+            if not self.path_for_intermediates:
+                raise ValueError(
+                    "dump_debug_info() must be used in conjunction with dump_intermediate_artifacts_to()"
+                )
+
+            self.compile_spec.append(
+                CompileSpec("dump_debug_info", self.tosa_debug_mode.encode())
+            )
+
+        return self.compile_spec
+
+
+def is_tosa(compile_spec: List[CompileSpec]) -> bool:
+    has_tosa_output = False
+    has_tosa_spec = False
+    for spec in compile_spec:
+        if spec.key == "output_format":
+            has_tosa_output = spec.value.decode() == "tosa"
+        if spec.key == "tosa_spec":
+            has_tosa_spec = True
+
+    return has_tosa_output and has_tosa_spec
+
+
+def is_ethosu(compile_spec: List[CompileSpec]) -> bool:
+    for spec in compile_spec:
+        if spec.key == "output_format":
+            return spec.value.decode() == "vela"
+    return False
+
+
+def is_vgf(compile_spec: List[CompileSpec]) -> bool:
+    for spec in compile_spec:
+        if spec.key == "output_format":
+            return spec.value.decode() == "vgf"
+    return False
+
+
+def get_intermediate_path(compile_spec: List[CompileSpec]) -> Optional[str]:
+    for spec in compile_spec:
+        if spec.key == "debug_artifact_path":
+            return spec.value.decode()
+    return None