Fail gracefully if no inlining model is available to download.

[mtrofin]

llvm/lib/Analysis/CMakeLists.txt

17

should this be handled in TensorflowCompile.cmake? Likely common behavior.

[jacobhegna]

Move the relevant code to TensorflowCompile.cmake.

When removing a model, the default url should be set to the string literal
"none".

We cannot simply set it to "", as cmake will then think that the call to
tf_find_and_compile is missing and argument.

[jacobhegna]

Change "none" -> "TO_BE_UPDATED".

llvm/lib/Analysis/CMakeLists.txt

 if (DEFINED LLVM_HAVE_TF_AOT OR DEFINED LLVM_HAVE_TF_API)
   include(TensorFlowCompile)
   set(LLVM_INLINER_MODEL_PATH_DEFAULT "models/inliner-Oz")
 
   # This url points to the most recent most which is known to be compatible with
   # LLVM. When better models are published, this url should be updated to aid
   # discoverability.
   set(LLVM_INLINER_MODEL_CURRENT_URL "https://github.com/google/ml-compiler-opt/releases/download/inlining-Oz-v0.1/inlining-Oz-acabaf6-v0.1.tar.gz")
 
   if (DEFINED LLVM_HAVE_TF_AOT)
     # If the path is empty, autogenerate the model
     if (NOT DEFINED LLVM_INLINER_MODEL_PATH OR "${LLVM_INLINER_MODEL_PATH}" STREQUAL "")
       set(LLVM_INLINER_MODEL_PATH "autogenerate")
       message(WARNING "LLVM_INLINER_MODEL_PATH was not set: autogenerating a model to finish the build.")
     endif()
 
+    # Crash if the user wants to download a model but a URL is not specified
+    if ("${LLVM_INLINER_MODEL_PATH}" STREQUAL "download" AND "${LLVM_INLINER_MODEL_CURRENT_URL}" STREQUAL "")
+        message(FATAL_ERROR "LLVM_INLINER_MODEL_PATH was set to 'download' but there is no model url currently specified in cmake - likely, the model interface recently changed, and so there is not a released model available.")
+    endif()
+
     tf_find_and_compile(
       ${LLVM_INLINER_MODEL_PATH}
       ${LLVM_INLINER_MODEL_CURRENT_URL}
       ${LLVM_INLINER_MODEL_PATH_DEFAULT}
       "models/inlining/config.py"
       serve
       action
       InlinerSizeModel