# HG changeset patch
# User David Major <dmajor@mozilla.com>
# Date 1531778389 14400
# Node ID e09ba0bb848afe8b66c4cdd56794301b790c6c34
# Parent  cf51b2ad1549fd0a5f858bc6a9041a37e7e63f41
Bug 1475660: Make clang-cl PGO enable LTO (enables ThinLTO in official builds) r=froydnj,glandium

diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -1572,23 +1572,27 @@ include('windows.configure', when=is_win
 # ==============================================================
 
 js_option('--enable-lto',
           nargs='?',
           choices=('full', 'thin'),
           help='Enable LTO')
 
 
-@depends('--enable-lto', c_compiler)
+@depends('--enable-lto', 'MOZ_PGO', c_compiler)
 @imports('multiprocessing')
-def lto(value, c_compiler):
+def lto(value, pgo, c_compiler):
     cflags = []
     ldflags = []
     enabled = None
 
+    # MSVC's implementation of PGO implies LTO. Make clang-cl match this.
+    if c_compiler.type == 'clang-cl' and pgo and value.origin == 'default':
+        value = ['thin']
+
     if value:
         enabled = True
         if c_compiler.type == 'clang':
             if len(value) and value[0].lower() == 'full':
                 cflags.append("-flto")
                 ldflags.append("-flto")
             else:
                 cflags.append("-flto=thin")