From 39ec1549af7a281f8f431a057a4c860f7b2cfb80 Mon Sep 17 00:00:00 2001
From: Evan Klitzke <evan@eklitzke.org>
Date: Wed, 10 Jun 2020 09:21:13 -0700
Subject: [PATCH] Build using LTO if compiler supports it (requires Cmake 3.9)

---
 CMakeLists.txt | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 471f4a63..990c484b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.9)
 project(ccls LANGUAGES CXX)
 
 option(USE_SYSTEM_RAPIDJSON "Use system RapidJSON instead of the git submodule if exists" ON)
@@ -30,6 +30,13 @@ set_property(TARGET ccls PROPERTY CXX_STANDARD 17)
 set_property(TARGET ccls PROPERTY CXX_STANDARD_REQUIRED ON)
 set_property(TARGET ccls PROPERTY CXX_EXTENSIONS OFF)
 
+# Build using LTO if the compiler supports it
+include(CheckIPOSupported)
+check_ipo_supported(RESULT ipo OUTPUT error)
+if (ipo)
+  set_property(TARGET ccls PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
+endif()
+
 # CMake sets MSVC for both MSVC and Clang(Windows)
 if(MSVC)
   # Common MSVC/Clang(Windows) options