Update build instruction about how to leverage the customize flags

LiteRT-PiperOrigin-RevId: 835357060

g3doc/instructions/CMAKE_BUILD_INSTRUCTIONS.md

@@ -1,8 +1,8 @@
 # LiteRT CMake Build Instructions
 
-Use this guide to configure and build the LiteRT runtime with CMake on macOS
-The instructions cover both Android cross-compilation targets
-(built from Linux and Mac OS) machine and native macOS and Linux builds.
+Use this guide to configure and build the LiteRT runtime with CMake on macOS The
+instructions cover both Android cross-compilation targets (built from Linux and
+Mac OS) machine and native macOS and Linux builds.
 
 ## Common Build Steps
 
@@ -19,48 +19,90 @@ controlled via `-j` with the desired core count.
 
 ## Android (arm64) Cross-Compilation
 
-1.  Install the Android NDK and export the path so CMake can find it:
+1. Install the Android NDK and export the path so CMake can find it:
 
-    ```bash
-    export ANDROID_NDK_HOME=/absolute/path/to/android-ndk-r27
-    ```
+   ```bash
+   export ANDROID_NDK_HOME=/absolute/path/to/android-ndk-r27
+   ```
 
-2.  Configure host-side flatbuffer tools
+1. Configure host-side flatbuffer tools
 
-    ```bash
-    cmake --preset android-arm64;
-    ```
+   ```bash
+   cmake --preset android-arm64;
+   ```
 
-3.  Configure the LiteRT Android build using the provided preset and point to
-    the generated FlatBuffers tools:
+1. Configure the LiteRT Android build using the provided preset and point to the
+   generated FlatBuffers tools:
 
-    ```bash
-    cmake --preset android-arm64 \
-      -DTFLITE_HOST_TOOLS_DIR="$(cd ../host_flatc_build/_deps/flatbuffers-build && pwd)"
-    ```
+   ```bash
+   cmake --preset android-arm64 \
+     -DTFLITE_HOST_TOOLS_DIR="$(cd ../host_flatc_build/_deps/flatbuffers-build && pwd)"
+   ```
 
-4.  Build LiteRT for Android:
+1. Build LiteRT for Android:
 
-    ```bash
-    cmake --build cmake_build_android_arm64 -j
-    ```
+   ```bash
+   cmake --build cmake_build_android_arm64 -j
+   ```
 
 Artifacts such as static libraries will be emitted under
 `cmake_build_android_arm64`.
 
 ## Host Build from Mac OS and Linux
 
-1.  Configure the default host preset:
+1. Configure the default host preset:
 
-    ```bash
-    cmake --preset default
-    ```
+   ```bash
+   cmake --preset default
+   ```
 
-2.  Build LiteRT:
+1. Build LiteRT:
 
-    ```bash
-    cmake --build cmake_build -j
-    ```
+   ```bash
+   cmake --build cmake_build -j
+   ```
+
+## Customize your build target
+
+## Customizing CMake Builds
+
+Use CMake options to control which toolchains and features are compiled into
+your targets. E.g.:
+
+```bash
+cmake -S . -B build-release \
+      -DCMAKE_BUILD_TYPE=Release \
+      -DLITERT_AUTO_BUILD_TFLITE=ON \
+      -DLITERT_ENABLE_GPU=OFF \
+      -DLITERT_ENABLE_NPU=OFF \
+      -DLITERT_DISABLE_KLEIDIAI=ON \
+      -DLITERT_HOST_C_COMPILER=/usr/bin/clang \
+      -DLITERT_HOST_CXX_COMPILER=/usr/bin/clang++
+cmake --build build-release --target dispatch_api_Qualcomm_so -j8
+```
+
+- `LITERT_HOST_C_COMPILER` / `LITERT_HOST_CXX_COMPILER` let you point the helper
+  host tools at any Clang/GCC installation without editing `CMakeLists.txt`.
+- `LITERT_DISABLE_KLEIDIAI` keeps x86 host builds reproducible by skipping
+  KleidiAI; set it to `OFF` whenever you want to bundle the delegate.
+- Always pass `-DCMAKE_BUILD_TYPE=Release` (or the equivalent preset) when you
+  need the optimized artifact. This makes CMake use `-O3 -DNDEBUG` for you.
+
+### Producing Minimum-Size Vendor Libraries
+
+At link time enable dead-stripping so dispatch libraries match Bazel’s size:
+
+- macOS: add
+  `-DCMAKE_SHARED_LINKER_FLAGS_RELEASE="-Wl,-dead_strip -dead_strip_dylibs"`
+  (and the same for `CMAKE_EXE_LINKER_FLAGS_RELEASE` if you want the
+  executeables stripped). After building, run
+  `strip -x path/to/libLiteRtDispatch_Qualcomm.dylib`.
+- Linux: add `-DCMAKE_SHARED_LINKER_FLAGS_RELEASE="-Wl,--gc-sections"` and run
+  `strip --strip-unneeded path/to/libLiteRtDispatch_Qualcomm.so` (or make it a
+  `POST_BUILD` command).
+
+These flags can live directly in `cmake --preset …` entries in
+`CMakePresets.json` so every developer in your team gets the same configuration.
 
 ## Troubleshooting Tips