NFC: Add MLIR-TensorRT 'CMakePresets.json' and update build documenta…

…tion (#312)

This change adds a CMake presets file to MLIR-TensorRT, which helps to
simplify the initial CMake setup considerably.

The build documentation is updated to use this feature, and some
additional
notes are added to describe how to control the TensorRT version that
is used for build & test.

mlir-tensorrt/CMakeLists.txt

@@ -17,9 +17,9 @@ endif()
 if(MLIR_TRT_PACKAGE_CACHE_DIR)
   set(CPM_SOURCE_CACHE "${MLIR_TRT_PACKAGE_CACHE_DIR}" CACHE STRING "" FORCE)
   set(CPM_USE_NAMED_CACHE_DIRECTORIES ON CACHE BOOL "" FORCE)
-else()
-  message(WARNING "MLIR_TRT_PACKAGE_CACHE_DIR is not set. Downloaded packages will be \
-  stored in your build directory. It is highly recommended to specify a package cache directory outside of \
+elseif(NOT CPM_SOURCE_CACHE)
+  message(WARNING "CPM_SOURCE_CACHE is not set. Source code for third party C++ packages will be \
+  stored in your build directory. It is highly recommended to specify a CPM source cache directory outside of \
   your build directory (for example '$PWD/.cache.cpm')")
 endif()
 
@@ -55,7 +55,7 @@ mtrt_option(MLIR_TRT_ENABLE_EXECUTOR "Build the Executor dialect and MLIR-Tensor
 mtrt_option(MLIR_TRT_ENABLE_NCCL "Enable the NCCL runtime module" ON)
 
 set(MLIR_TRT_TENSORRT_DIR "" CACHE STRING "Path to TensorRT install directory")
-set(MLIR_TRT_DOWNLOAD_TENSORRT_VERSION "10.0" CACHE STRING
+set(MLIR_TRT_DOWNLOAD_TENSORRT_VERSION "10.2" CACHE STRING
    "Version of TensorRT to download and use. It overrides MLIR_TRT_TENSORRT_DIR.")
 set(MLIR_TRT_PACKAGE_CACHE_DIR "" CACHE STRING "Directory where to cache downloaded C++ packages")
 set(MLIR_TRT_USE_LINKER "" CACHE STRING "Specify a linker to use (e.g. LLD); this is just an alias for LLVM_USE_LINKER")

mlir-tensorrt/CMakePresets.json

@@ -0,0 +1,56 @@
+{
+  "version": 6,
+  "include": [],
+  "configurePresets": [
+    {
+      "name": "base",
+      "generator": "Ninja",
+      "binaryDir": "build",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "RelWithDebInfo",
+        "LLVM_ENABLE_ASSERTIONS": "ON",
+        "CPM_SOURCE_CACHE": "${sourceDir}/.cache.cpm",
+        "CPM_USE_NAMED_CACHE_DIRECTORIES": "ON"
+      }
+    },
+    {
+      "name": "ninja-llvm",
+      "displayName": "Ninja RelWithDebInfo LLVM",
+      "generator": "Ninja",
+      "binaryDir": "build",
+      "inherits": "base",
+      "cacheVariables": {
+        "CMAKE_C_COMPILER": "clang",
+        "CMAKE_CXX_COMPILER": "clang++",
+        "LLVM_USE_LINKER": "lld"
+      }
+    },
+    {
+      "name": "ninja-llvm-release",
+      "inherits": "ninja-llvm",
+      "displayName": "Ninja Release LLVM",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Release"
+      }
+    },
+    {
+      "name": "ninja-llvm-debug",
+      "inherits": "ninja-llvm",
+      "displayName": "Ninja Release LLVM",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug"
+      }
+    },
+    {
+      "name": "ninja-gcc",
+      "displayName": "Ninja RelWithDebInfo GCC",
+      "generator": "Ninja",
+      "binaryDir": "build-gcc",
+      "inherits": "base",
+      "cacheVariables": {
+        "CMAKE_C_COMPILER": "gcc",
+        "CMAKE_CXX_COMPILER": "g++"
+      }
+    }
+  ]
+}

mlir-tensorrt/README.md

@@ -42,16 +42,14 @@ since we download LLVM-Project as a zip archive directly from GitHub
 at our pinned commit.
 
 ```sh
-# Note: we use clang and lld here. These are recommended.
-# However, GNU toolchains will also work,
-# clang toolchain is optional.
-cmake -B ./build -S . -G Ninja \
-    -DCMAKE_BUILD_TYPE=RelWithDebInfo \
-    -DMLIR_TRT_PACKAGE_CACHE_DIR=${PWD}/.cache.cpm \
-    -DMLIR_TRT_ENABLE_ASSERTIONS=ON \
-    -DMLIR_TRT_DOWNLOAD_TENSORRT_VERSION=10.2 \
-    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
-    -DMLIR_TRT_USE_LINKER=lld
+# See CMakePresets.json for convenient CMake presets.
+# Preset 'ninja-llvm' uses the Ninja generator, clang, and
+# LLD, but GNU GCC toolchain is also supported (use preset
+# ninja-gcc).
+#
+# By default, the CMake build system will download a version
+# of TensorRT for you.
+cmake --preset ninja-llvm
 
 # Example build commands:
 
@@ -116,6 +114,39 @@ This will produce wheels under `build/mlir-tensorrt/wheels`:
 ninja -C build/mlir-tensorrt mlir-tensorrt-all-wheels
 ```
 
+## Configuring What TensorRT Version is Used
+
+Our CMake-based build system will by default attempt to download a
+version of TensorRT to use during building and testing. This is controlled
+by the CMake cache variable [`MLIR_TRT_DOWNLOAD_TENSORRT_VERSION`](./CMakeLists.txt#L58).
+
+To instead use a local TensorRT version, simply set the CMake
+cache variable [`MLIR_TRT_TENSORRT_DIR`](./CMakeLists.txt#L200) to the
+path to the TensorRT installation directory (containing directories `include`, `lib64`, and
+so on), and set `MLIR_TRT_DOWNLOAD_TENSORRT_VERSION` to the empty string.
+
+These variables are fed into the CMake function `find_tesnsorrt` which is invoked
+[here](./CMakeLists.txt#L199). Options `INSTALL_DIR` and `DOWNLOAD_VERSION` are
+mutually exclusive.
+
+All executables built by the project will link TensorRT dynamically and load it
+dynamically at runtime using the runtime environment's default dynamic library
+search mechanism. The LIT testing configurations used in the project set the
+dynamic library search path (e.g. the environment variable `LD_LIBRARY_PATH` on
+Linux systems) to ensure that the TensorRT version used during compilation is
+also used during testing.
+
+When invoking an executable (e.g. `mlir-tensorrt-opt`) directly outside of the
+LIT test runner, one should set the appropriate environment variables (e.g.
+`LD_LIBRARY_PATH`) to point to the TensorRT library which should be loaded at runtime.
+In general, if the project is compiled with TensorRT `X.Y` but version
+`X.Z` is loaded at runtime, with `Z > Y`, the software is expected to work, but
+no guarantees are currently made.
+
+
+
+
+