From 9aa749f76f6da1291835859eac0673384dcccd94 Mon Sep 17 00:00:00 2001
From: Octavian Soldea <octavian.soldea@intel.com>
Date: Thu, 5 Jul 2018 11:19:22 -0700
Subject: [PATCH 1/2] build: enabling lto at configure

This modification allows for compiling with link time optimization (lto)
using the flag --enable-lto.

Refs: https://github.com/nodejs/node/issues/7400
---
 common.gypi | 11 +++++++++++
 configure   | 22 ++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/common.gypi b/common.gypi
index d25a434b03d433..023e4f84cfcd5c 100644
--- a/common.gypi
+++ b/common.gypi
@@ -176,6 +176,17 @@
           ['OS!="mac" and OS!="win"', {
             'cflags': [ '-fno-omit-frame-pointer' ],
           }],
+          ['OS=="linux"', {
+            'variables': {
+              'lto': ' -flto=4 -fuse-linker-plugin -ffat-lto-objects ',
+            },
+            'conditions': [
+              ['enable_lto=="true"', {
+                'cflags': ['<(lto)'],
+                'ldflags': ['<(lto)'],
+              },],
+            ],
+          },],
           ['OS == "android"', {
             'cflags': [ '-fPIE' ],
             'ldflags': [ '-fPIE', '-pie' ]
diff --git a/configure b/configure
index 3a9ab42414569e..db27ef0b807456 100755
--- a/configure
+++ b/configure
@@ -157,6 +157,11 @@ parser.add_option("--enable-vtune-profiling",
          "JavaScript code executed in nodejs. This feature is only available "
          "for x32, x86, and x64 architectures.")
 
+parser.add_option("--enable-lto",
+    action="store_true",
+    dest="enable_lto",
+    help="Enable compiling with lto of a binary. This feature is only available "
+         "on linux with gcc and g++.")
 
 parser.add_option("--link-module",
     action="append",
@@ -932,6 +937,23 @@ def configure_node(o):
   else:
     o['variables']['node_enable_v8_vtunejit'] = 'false'
 
+  if flavor != 'linux' and (options.enable_lto):
+    raise Exception(
+      'The lto option is supported only on linux.')
+
+  if flavor == 'linux':
+    if options.enable_lto:
+      version_checked = '5.4.1'
+      for compiler in [(CC, 'c'), (CXX, 'c++')]:
+        ok, is_clang, clang_version, compiler_version = \
+          try_check_compiler(compiler[0], compiler[1])
+        if is_clang or compiler_version < version_checked:
+          raise Exception(
+            'The option --enable-lto is supported for '
+            'gcc and gxx 5.4.1 or newer only.')
+
+  o['variables']['enable_lto'] = b(options.enable_lto)
+
   if flavor in ('solaris', 'mac', 'linux', 'freebsd'):
     use_dtrace = not options.without_dtrace
     # Don't enable by default on linux and freebsd

From f2f7dba82ef72b9a1b8abec0cd666342fa2a6585 Mon Sep 17 00:00:00 2001
From: Octavian Soldea <octavian.soldea@intel.com>
Date: Fri, 6 Jul 2018 16:45:46 -0700
Subject: [PATCH 2/2] build: enabling lto at configure

This commit is a refactoring for testing that the compilers used
for lto are gcc and g++ only.
---
 configure | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/configure b/configure
index db27ef0b807456..2f57dcaa2f73a0 100755
--- a/configure
+++ b/configure
@@ -943,14 +943,16 @@ def configure_node(o):
 
   if flavor == 'linux':
     if options.enable_lto:
-      version_checked = '5.4.1'
+      version_checked = (5, 4, 1)
       for compiler in [(CC, 'c'), (CXX, 'c++')]:
         ok, is_clang, clang_version, compiler_version = \
           try_check_compiler(compiler[0], compiler[1])
-        if is_clang or compiler_version < version_checked:
+        compiler_version_num = tuple(map(int, compiler_version))
+        if is_clang or compiler_version_num < version_checked:
+          version_checked_str = ".".join(map(str, version_checked))
           raise Exception(
-            'The option --enable-lto is supported for '
-            'gcc and gxx 5.4.1 or newer only.')
+            'The option --enable-lto is supported for gcc and gxx %s'
+            ' or newer only.' % (version_checked_str))
 
   o['variables']['enable_lto'] = b(options.enable_lto)