[PATCH] D61346: [CMake] Do not use libtool on Apple platforms when building LLVM with (full) LTO.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: kubamracek, aprantl, ab.
Herald added subscribers: dexonsmith, inglorion, mehdi_amini, mgorny.
Herald added a project: LLVM.

libtool does not support bitcode files generated by upstream LLVM in the latest
toolchains. When building LLVM with full LTO, we should use llvm-ranlib/llvm-ar.

I am not sure if this is the best way to solve the underlying problem:
being able to do a stage2 bootstrap build of LLVM master with LTO on
Darwin. Unfortunately, CMAKE_AR/CMAKE_RANLIB are automatically populated
if they are not provided. Otherwise we could limit avoiding using
libtool only when the user specified CMAKE_AR/CMAKE_RANLIB manually with LTO.

Any thoughts very appreciated!


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D61346

Files:
  llvm/CMakeLists.txt


Index: llvm/CMakeLists.txt
===================================================================
--- llvm/CMakeLists.txt
+++ llvm/CMakeLists.txt
@@ -47,43 +47,50 @@
 
 # This should only apply if you are both on an Apple host, and targeting Apple.
 if(CMAKE_HOST_APPLE AND APPLE)
-  # if CMAKE_LIBTOOL is not set, try and find it with xcrun or find_program
-  if(NOT CMAKE_LIBTOOL)
-    if(NOT CMAKE_XCRUN)
-      find_program(CMAKE_XCRUN NAMES xcrun)
-    endif()
-    if(CMAKE_XCRUN)
-      execute_process(COMMAND ${CMAKE_XCRUN} -find libtool
-        OUTPUT_VARIABLE CMAKE_LIBTOOL
-        OUTPUT_STRIP_TRAILING_WHITESPACE)
-    endif()
-
-    if(NOT CMAKE_LIBTOOL OR NOT EXISTS CMAKE_LIBTOOL)
-      find_program(CMAKE_LIBTOOL NAMES libtool)
-    endif()
-  endif()
 
-  get_property(languages GLOBAL PROPERTY ENABLED_LANGUAGES)
-  if(CMAKE_LIBTOOL)
-    set(CMAKE_LIBTOOL ${CMAKE_LIBTOOL} CACHE PATH "libtool executable")
-    message(STATUS "Found libtool - ${CMAKE_LIBTOOL}")
-
-    execute_process(COMMAND ${CMAKE_LIBTOOL} -V
-      OUTPUT_VARIABLE LIBTOOL_V_OUTPUT
-      OUTPUT_STRIP_TRAILING_WHITESPACE)
-    if("${LIBTOOL_V_OUTPUT}" MATCHES ".*cctools-([0-9.]+).*")
-      string(REGEX REPLACE ".*cctools-([0-9.]+).*" "\\1" LIBTOOL_VERSION
-        ${LIBTOOL_V_OUTPUT})
-      if(NOT LIBTOOL_VERSION VERSION_LESS "862")
-        set(LIBTOOL_NO_WARNING_FLAG "-no_warning_for_no_symbols")
+  # Only use libtool when not doing full LTO. When bootstrapping LLVM master
+  # with LTO, we have to use llvm-ranlib/llvm-ar, as libtool may not support
+  # the newest LLVM bitcode version.
+  string(TOUPPER "${LLVM_ENABLE_LTO}" uppercase_LLVM_ENABLE_LTO)
+  if(NOT uppercase_LLVM_ENABLE_LTO STREQUAL "FULL" OR CMAKE_AR_val)
+      # if CMAKE_LIBTOOL is not set, try and find it with xcrun or find_program
+      if(NOT CMAKE_LIBTOOL)
+        if(NOT CMAKE_XCRUN)
+          find_program(CMAKE_XCRUN NAMES xcrun)
+        endif()
+        if(CMAKE_XCRUN)
+          execute_process(COMMAND ${CMAKE_XCRUN} -find libtool
+            OUTPUT_VARIABLE CMAKE_LIBTOOL
+            OUTPUT_STRIP_TRAILING_WHITESPACE)
+        endif()
+
+        if(NOT CMAKE_LIBTOOL OR NOT EXISTS CMAKE_LIBTOOL)
+          find_program(CMAKE_LIBTOOL NAMES libtool)
+        endif()
       endif()
-    endif()
 
-    foreach(lang ${languages})
-      set(CMAKE_${lang}_CREATE_STATIC_LIBRARY
-        "\"${CMAKE_LIBTOOL}\" -static ${LIBTOOL_NO_WARNING_FLAG} -o <TARGET> \
-        <LINK_FLAGS> <OBJECTS> ")
-    endforeach()
+      get_property(languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+      if(CMAKE_LIBTOOL)
+        set(CMAKE_LIBTOOL ${CMAKE_LIBTOOL} CACHE PATH "libtool executable")
+        message(STATUS "Found libtool - ${CMAKE_LIBTOOL}")
+
+        execute_process(COMMAND ${CMAKE_LIBTOOL} -V
+          OUTPUT_VARIABLE LIBTOOL_V_OUTPUT
+          OUTPUT_STRIP_TRAILING_WHITESPACE)
+        if("${LIBTOOL_V_OUTPUT}" MATCHES ".*cctools-([0-9.]+).*")
+          string(REGEX REPLACE ".*cctools-([0-9.]+).*" "\\1" LIBTOOL_VERSION
+            ${LIBTOOL_V_OUTPUT})
+          if(NOT LIBTOOL_VERSION VERSION_LESS "862")
+            set(LIBTOOL_NO_WARNING_FLAG "-no_warning_for_no_symbols")
+          endif()
+        endif()
+
+        foreach(lang ${languages})
+          set(CMAKE_${lang}_CREATE_STATIC_LIBRARY
+            "\"${CMAKE_LIBTOOL}\" -static ${LIBTOOL_NO_WARNING_FLAG} -o <TARGET> \
+            <LINK_FLAGS> <OBJECTS> ")
+        endforeach()
+      endif()
   endif()
 
   # If DYLD_LIBRARY_PATH is set we need to set it on archiver commands


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