[PATCH] D118186: [cmake] Allow optionally to build `tablegen` in `Release` and use it in `Debug` for the `Ninja Multi-Config` generator

[Argyrios Kyrtzidis via Phabricator via llvm-commits]

akyrtzi created this revision.
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If `Ninja Multi-Config` is used and LLVM_OPTIMIZED_TABLEGEN=YES is set
tablegen binaries will be built in `Release`, even when building for `Debug` configuration,
without needing a separate configured build directory just for tablegen binaries.
To get such a setup you'd configure like this:

  cmake -G 'Ninja Multi-Config' /path/to/llvm-project/llvm \
       -DCMAKE_CONFIGURATION_TYPES="Debug;Release" -DCMAKE_CROSS_CONFIGS="Release" \
       -DLLVM_OPTIMIZED_TABLEGEN=YES                       \
     ....

Also note the other benefit of `Ninja Multi-Config` is saving configure time, particularly when
switching between `Debug` and `Release` during development.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118186

Files:
  llvm/CMakeLists.txt
  llvm/cmake/modules/TableGen.cmake


Index: llvm/cmake/modules/TableGen.cmake
===================================================================
--- llvm/cmake/modules/TableGen.cmake
+++ llvm/cmake/modules/TableGen.cmake
@@ -96,6 +96,13 @@
   set(tablegen_exe ${${project}_TABLEGEN_EXE})
   set(tablegen_depends ${${project}_TABLEGEN_TARGET} ${tablegen_exe})
 
+  if (LLVM_OPTIMIZED_TABLEGEN_VIA_NINJA_MULTI_CONFIG)
+    set(tablegen_exe "${CMAKE_BINARY_DIR}/Release/bin/${${project}_TABLEGEN_EXE}")
+    # Only depend on the release executable; if we also depend on the target
+    # we'll build for both release and debug.
+    set(tablegen_depends ${tablegen_exe})
+  endif()
+
   add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${ofn}
     COMMAND ${tablegen_exe} ${ARGN} -I ${CMAKE_CURRENT_SOURCE_DIR}
     ${tblgen_includes}
Index: llvm/CMakeLists.txt
===================================================================
--- llvm/CMakeLists.txt
+++ llvm/CMakeLists.txt
@@ -661,7 +661,12 @@
 endif()
 
 option(LLVM_OPTIMIZED_TABLEGEN "Force TableGen to be built with optimization" OFF)
-if(CMAKE_CROSSCOMPILING OR (LLVM_OPTIMIZED_TABLEGEN AND (LLVM_ENABLE_ASSERTIONS OR CMAKE_CONFIGURATION_TYPES)))
+if (LLVM_OPTIMIZED_TABLEGEN AND NOT CMAKE_CROSSCOMPILING AND CMAKE_GENERATOR STREQUAL "Ninja Multi-Config" AND "Release" IN_LIST CMAKE_CROSS_CONFIGS)
+  # "Ninja Multi-Config" generator allows using release tablegen binaries
+  # without needing a separate configured build directory for them.
+  set(LLVM_OPTIMIZED_TABLEGEN_VIA_NINJA_MULTI_CONFIG TRUE)
+endif()
+if(CMAKE_CROSSCOMPILING OR (LLVM_OPTIMIZED_TABLEGEN AND NOT LLVM_OPTIMIZED_TABLEGEN_VIA_NINJA_MULTI_CONFIG AND (LLVM_ENABLE_ASSERTIONS OR CMAKE_CONFIGURATION_TYPES)))
   set(LLVM_USE_HOST_TOOLS ON)
 endif()
 


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