From 974dab4e8f3885f70642cb4fad76b7109cafe6d1 Mon Sep 17 00:00:00 2001
From: Justin Bogner <mail@justinbogner.com>
Date: Mon, 8 Feb 2016 21:01:24 +0000
Subject: [PATCH] cmake: Accept "thin" or "full" as arguments to
 -DLLVM_ENABLE_LTO

Mehdi suggested in a review of r259766 that it's also useful to easily
set the type of LTO. Augment the cmake variable to support that.

llvm-svn: 260143
---
 cmake/modules/HandleLLVMOptions.cmake | 18 ++++++++++++------
 docs/CMake.rst                        |  7 ++++---
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 99b23180bbb..8156e8c83ae 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -656,12 +656,18 @@ append_if(LLVM_BUILD_INSTRUMENTED "-fprofile-instr-generate"
   CMAKE_EXE_LINKER_FLAGS
   CMAKE_SHARED_LINKER_FLAGS)
 
-option(LLVM_ENABLE_LTO "Enable link-time optimization" OFF)
-append_if(LLVM_ENABLE_LTO "-flto"
-  CMAKE_CXX_FLAGS
-  CMAKE_C_FLAGS
-  CMAKE_EXE_LINKER_FLAGS
-  CMAKE_SHARED_LINKER_FLAGS)
+option(LLVM_ENABLE_LTO "Build LLVM with LTO. May be specified as Thin or Full to use a particular kind of LTO" OFF)
+string(TOUPPER "${LLVM_ENABLE_LTO}" uppercase_LLVM_ENABLE_LTO)
+if(uppercase_LLVM_ENABLE_LTO STREQUAL "THIN")
+  append("-flto=thin" CMAKE_CXX_FLAGS CMAKE_C_FLAGS
+                      CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+elseif(uppercase_LLVM_ENABLE_LTO STREQUAL "FULL")
+  append("-flto=full" CMAKE_CXX_FLAGS CMAKE_C_FLAGS
+                 CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+elseif(LLVM_ENABLE_LTO)
+  append("-flto" CMAKE_CXX_FLAGS CMAKE_C_FLAGS
+                 CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+endif()
 
 # Plugin support
 # FIXME: Make this configurable.
diff --git a/docs/CMake.rst b/docs/CMake.rst
index 12d74ace161..879e4627e41 100644
--- a/docs/CMake.rst
+++ b/docs/CMake.rst
@@ -351,9 +351,10 @@ LLVM-specific variables
   are ``Address``, ``Memory``, ``MemoryWithOrigins``, ``Undefined``, ``Thread``,
   and ``Address;Undefined``. Defaults to empty string.
 
-**LLVM_ENABLE_LTO**:BOOL
-  Add the ``-flto`` flag to the compile and link command lines,
-  enabling link-time optimization. Defaults to OFF.
+**LLVM_ENABLE_LTO**:STRING
+  Add ``-flto`` or ``-flto=`` flags to the compile and link command
+  lines, enabling link-time optimization. Possible values are ``Off``,
+  ``On``, ``Thin`` and ``Full``. Defaults to OFF.
 
 **LLVM_PARALLEL_COMPILE_JOBS**:STRING
   Define the maximum number of concurrent compilation jobs.