[llvm] [MLGO] Model selection for models lowered through EmitC (PR #212650)

[Paul Kirth via llvm-commits]

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@@ -0,0 +1,123 @@
+# Compile MLGO models expressed as MLIR to C++ headers via the EmitC pipeline.
+#
+# Each entry of ${models} has the form
+# "cli-flag,path/to/model.mlir,type". Entries whose type matches
+# ${target_type} are lowered with ${mlir_opt} and translated with
+# ${mlir_translate} to a C++ header defining Model<N>, placed in
+# ${LLVM_INCLUDE_DIR}/${include_subdir}. In the same directory, generate
+# ${def_file}, with one MLGO_MODEL(ClassName, "cli-flag") entry per model, and
+# ${umbrella_header}, including all the generated model headers.
+# Append the target driving generation to MLDeps in the caller's scope, and
+# define LLVM_HAVE_EMITC_COMPILE_<TARGET_TYPE>.
+function(mlgo_compile_models models mlir_opt mlir_translate target_type
+         include_subdir def_file umbrella_header)
+  if ("${mlir_opt}" MATCHES "/")
+    get_filename_component(mlir_opt "${mlir_opt}" ABSOLUTE BASE_DIR "${CMAKE_BINARY_DIR}")
+  endif()
+  if ("${mlir_translate}" MATCHES "/")
+    get_filename_component(mlir_translate "${mlir_translate}" ABSOLUTE BASE_DIR "${CMAKE_BINARY_DIR}")
----------------
ilovepi wrote:

wont this break on windows?

I'd think this would be equivalent w/o any regex.
```cmake
get_filename_component(mlir_opt "${mlir_opt}" ABSOLUTE BASE_DIR "${CMAKE_BINARY_DIR}")
get_filename_component(mlir_translate "${mlir_translate}" ABSOLUTE BASE_DIR "${CMAKE_BINARY_DIR}")
```

I think a more modern spelling is the following.

```cmake
if(NOT IS_ABSOLUTE "${mlir_opt}")
  cmake_path(ABSOLUTE_PATH mlir_opt BASE_DIRECTORY "${CMAKE_BINARY_DIR}")
endif()

if(NOT IS_ABSOLUTE "${mlir_translate}")
  cmake_path(ABSOLUTE_PATH mlir_translate BASE_DIRECTORY "${CMAKE_BINARY_DIR}")
endif()
```


https://github.com/llvm/llvm-project/pull/212650