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

[Paul Kirth via llvm-commits]

================
@@ -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 "${CMAKE_BINARY_DIR}")
+  endif()
+
+  set(DEF_CONTENT "/* Auto-generated by CMake */\n")
+  set(DEF_CONTENT "${DEF_CONTENT}#ifndef MLGO_MODEL\n#define MLGO_MODEL(CLASS_NAME, CLI_FLAG)\n#endif\n\n")
+
+  set(HEADERS_CONTENT "/* Auto-generated by CMake */\nnamespace llvm {\n")
+  set(MLGO_GEN_TARGETS "")
+  set(MODEL_INDEX 1)
+
+  foreach(MODEL_INFO IN LISTS models)
+    # Parse comma-separated fields: cli-flag,path/to/model.mlir,type
+    string(REPLACE "," ";" MODEL_FIELDS "${MODEL_INFO}")
+    list(GET MODEL_FIELDS 0 CLI_FLAG)
+    list(GET MODEL_FIELDS 1 MODEL_PATH)
+    list(GET MODEL_FIELDS 2 MODEL_TYPE)
+
+    # Only process models matching target_type
+    if (NOT MODEL_TYPE STREQUAL target_type)
+      continue()
+    endif()
+
+    set(CLASS_NAME "Model${MODEL_INDEX}")
+    math(EXPR MODEL_INDEX "${MODEL_INDEX} + 1")
+
+    if (NOT IS_ABSOLUTE "${MODEL_PATH}")
+      get_filename_component(MODEL_PATH "${MODEL_PATH}" ABSOLUTE BASE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+    endif()
+
+    set(EMITC_MLIR "${CMAKE_CURRENT_BINARY_DIR}/${CLASS_NAME}_emitc.mlir")
+    set(HEADER_FILE "${LLVM_INCLUDE_DIR}/${include_subdir}/${CLASS_NAME}.h")
+
+    # Pass pipeline to lower MLIR models to EmitC dialect
+    set(EMITC_PASSES
----------------
ilovepi wrote:

```suggestion
    # Pass pipeline to lower MLIR models to EmitC dialect.
    # TODO: Simplify with builtin pipeline for translation.
    set(EMITC_PASSES
```

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