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

PR-URL: https://github.com/nodejs/node/pull/21677
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 24 insertions, 0 deletions

diff --git a/configure b/configure
index 094d8e09f7..068fb8a769 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 +937,25 @@ 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])
+        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 %s'
+            ' or newer only.' % (version_checked_str))
+
+  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