Move backend deps to extras_require, not install_requires

AIR supports multiple backends (AIE, GPU, VCK5000); making mlir_aie a
hard `Requires-Dist` would force it on users targeting other backends.
Use the standard pip extras pattern instead — the AIE backend deps live
under the `[aie]` extra and pip's METADATA records them via
`Provides-Extra: aie` + `Requires-Dist: mlir_aie==X; extra == "aie"`.

Same effect for AIE users (`pip install 'mlir_air[aie]' -f ... -f ...`
resolves the pinned mlir_aie automatically) but `pip install mlir_air`
on its own remains backend-agnostic.

- setup.py: replace get_install_requires() with get_extras_require();
  put mlir_aie + llvm-aie under extras["aie"].
- buildAIRWheels.yml + buildingRyzenLin.md: install command becomes
  `pip install 'mlir_air[aie]' ...`. Mention the extra explicitly so
  users know how to skip it for non-AIE backends.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: erwei-xilinx

.github/workflows/buildAIRWheels.yml

@@ -282,15 +282,17 @@ jobs:
 
             ### Installation
 
-            The `mlir_air` wheel declares `mlir_aie` (pinned) and `llvm-aie` as runtime dependencies, so a single `pip install` with the right `--find-links` pages resolves the whole stack:
+            AIR supports multiple backends (AIE, GPU, VCK5000); backend dependencies are exposed as pip extras. For the AIE backend, the `[aie]` extra pulls the matching pinned `mlir_aie` and `llvm-aie` from the additional `--find-links` pages:
 
             ```bash
-            pip install mlir_air \
+            pip install 'mlir_air[aie]' \
               -f https://github.com/Xilinx/mlir-air/releases/expanded_assets/${{ matrix.ENABLE_RTTI == 'ON' && 'latest-air-wheels' || 'latest-air-wheels-no-rtti' }} \
               -f https://github.com/Xilinx/mlir-aie/releases/expanded_assets/${{ matrix.ENABLE_RTTI == 'ON' && 'latest-wheels-3' || 'latest-wheels-no-rtti' }} \
               -f https://github.com/Xilinx/llvm-aie/releases/expanded_assets/nightly
             ```
 
+            Drop the `[aie]` extra to install AIR core only (e.g. when bringing your own backend).
+
             ### RTTI / no-RTTI Variants
 
             Both RTTI-enabled and RTTI-disabled wheels are released for downstream integration convenience:
@@ -471,15 +473,17 @@ jobs:
 
             ### Installation
 
-            The `mlir_air` wheel declares `mlir_aie` (pinned) and `llvm-aie` as runtime dependencies, so a single `pip install` with the right `--find-links` pages resolves the whole stack:
+            AIR supports multiple backends (AIE, GPU, VCK5000); backend dependencies are exposed as pip extras. For the AIE backend, the `[aie]` extra pulls the matching pinned `mlir_aie` and `llvm-aie` from the additional `--find-links` pages:
 
             ```bash
-            pip install mlir_air \
+            pip install 'mlir_air[aie]' \
               -f https://github.com/Xilinx/mlir-air/releases/expanded_assets/${{ matrix.ENABLE_RTTI == 'ON' && 'latest-air-wheels' || 'latest-air-wheels-no-rtti' }} \
               -f https://github.com/Xilinx/mlir-aie/releases/expanded_assets/${{ matrix.ENABLE_RTTI == 'ON' && 'latest-wheels-3' || 'latest-wheels-no-rtti' }} \
               -f https://github.com/Xilinx/llvm-aie/releases/expanded_assets/nightly
             ```
 
+            Drop the `[aie]` extra to install AIR core only (e.g. when bringing your own backend).
+
             ### RTTI / no-RTTI Variants
 
             Both RTTI-enabled and RTTI-disabled wheels are released for downstream integration convenience:

docs/buildingRyzenLin.md

@@ -14,7 +14,7 @@ The fastest way to get MLIR-AIR is to install the prebuilt wheel — no source b
 
 ### Steps
 
-MLIR-AIR depends on **MLIR-AIE** and **Peano (`llvm-aie`)** at compile/run time. The `mlir_air` wheel declares both as runtime dependencies (`mlir_aie` is pinned to the exact version AIR was built and tested against), so a single `pip install` with the right `--find-links` pages installs the whole stack — no clone, no helper script.
+AIR supports multiple backends — AIE (NPU / Versal AI Engines), [GPU](buildingGPU.md), and [VCK5000](buildingVCK5000.md). Backend dependencies are exposed as pip **extras** so you only install what you need. For the AIE backend on Ryzen™ AI, use the `[aie]` extra; pip reads the pinned `mlir_aie==<version>` and `llvm-aie` from the wheel's metadata and resolves them from the additional `--find-links` pages.
 
 1. **Create a virtual environment:**
    ```bash
@@ -23,15 +23,17 @@ MLIR-AIR depends on **MLIR-AIE** and **Peano (`llvm-aie`)** at compile/run time.
    pip install --upgrade pip
    ```
 
-2. **Install MLIR-AIR and its pinned dependencies:**
+2. **Install MLIR-AIR with the AIE backend:**
    ```bash
-   pip install mlir_air \
+   pip install 'mlir_air[aie]' \
      -f https://github.com/Xilinx/mlir-air/releases/expanded_assets/latest-air-wheels \
      -f https://github.com/Xilinx/mlir-aie/releases/expanded_assets/latest-wheels-3 \
      -f https://github.com/Xilinx/llvm-aie/releases/expanded_assets/nightly
    ```
 
-   Pip reads the `mlir_aie==<pinned>` and `llvm-aie` requirements from `mlir_air`'s wheel metadata and resolves them from the additional `--find-links` pages. The exact pinned `mlir_aie` version this AIR wheel was tested against is shown on the [release page](https://github.com/Xilinx/mlir-air/releases/tag/latest-air-wheels).
+   The `[aie]` extra pulls `mlir_aie` (pinned to the exact version this AIR wheel was tested against) and `llvm-aie` (the Peano backend compiler — nightly). The pinned `mlir_aie` version is shown on the [release page](https://github.com/Xilinx/mlir-air/releases/tag/latest-air-wheels).
+
+   To install AIR core only (e.g. when bringing your own backend), drop the `[aie]` extra and the last two `-f` flags.
 
 3. **Set up environment variables** (paths derived from `pip show`):
    ```bash
@@ -67,7 +69,7 @@ We release **both RTTI and no-RTTI variants** so downstream projects can match t
 For the no-RTTI variant, point both find-links at the no-RTTI pages so pip resolves the matching `mlir_aie`:
 
 ```bash
-pip install mlir_air \
+pip install 'mlir_air[aie]' \
   -f https://github.com/Xilinx/mlir-air/releases/expanded_assets/latest-air-wheels-no-rtti \
   -f https://github.com/Xilinx/mlir-aie/releases/expanded_assets/latest-wheels-no-rtti \
   -f https://github.com/Xilinx/llvm-aie/releases/expanded_assets/nightly

utils/mlir_air_wheels/setup.py

@@ -304,21 +304,22 @@ def parse_requirements(filename):
         ]
 
 
-def get_install_requires():
-    reqs = parse_requirements(Path(__file__).parent / "requirements.txt")
-    # Pin mlir_aie to the version this AIR wheel was built and tested
-    # against, so users only need a single `pip install mlir_air -f ... -f
-    # ...` and pip resolves the matching mlir_aie wheel automatically.
-    # Falls back to no pin when MLIR_AIE_VERSION isn't set (e.g. local dev
-    # builds outside CI).
+def get_extras_require():
+    # AIR supports multiple backends (AIE, GPU, VCK5000), so backend
+    # dependencies live in `extras_require` rather than `install_requires`.
+    # `pip install mlir_air[aie]` pulls the matching mlir_aie + Peano;
+    # users targeting other backends skip the extra.
+    extras = {}
     mlir_aie_version = os.getenv("MLIR_AIE_VERSION", "")
     if mlir_aie_version:
         no_rtti_dot = "" if check_env("ENABLE_RTTI", 1) else ".no.rtti"
-        reqs.append(f"mlir_aie=={mlir_aie_version}{no_rtti_dot}")
-    # Peano (Xilinx llvm-aie) is the AIE backend compiler. No version pin
-    # — AIR tracks the nightly build.
-    reqs.append("llvm-aie")
-    return reqs
+        # mlir_aie is pinned to the version this AIR wheel was built and
+        # tested against. llvm-aie (Peano) tracks nightly — no pin.
+        extras["aie"] = [
+            f"mlir_aie=={mlir_aie_version}{no_rtti_dot}",
+            "llvm-aie",
+        ]
+    return extras
 
 
 setup(
@@ -334,5 +335,6 @@ def get_install_requires():
     zip_safe=False,
     packages=find_packages(exclude=["wheelhouse", "mlir-air"]),
     python_requires=">=3.10",
-    install_requires=get_install_requires(),
+    install_requires=parse_requirements(Path(__file__).parent / "requirements.txt"),
+    extras_require=get_extras_require(),
 )