clang: Compiler tweaks to make android build for x64

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
 if (current_cpu == "mipsel" || current_cpu == "mips64el") {
@@ skipping 517 matching lines @@
   }
 
   # Android-specific flags setup.
   # -----------------------------
   if (is_android) {
     cflags += [
       "-ffunction-sections",
       "-funwind-tables",
       "-fno-short-enums",
     ]
+    if (!is_clang) {
+      # Clang doesn't support these flags.
+      cflags += [ "-finline-limit=64" ]
+    }
     if (is_clang) {
       rebased_android_toolchain_root =
           rebase_path(android_toolchain_root, root_build_dir)
-      cflags += [
-        # TODO(hans) Enable integrated-as (crbug.com/124610).
-        "-no-integrated-as",
-        "-B${rebased_android_toolchain_root}/bin",  # Else /usr/bin/as gets picked up.
-      ]
-    } else {
-      # Clang doesn't support these flags.
-      cflags += [ "-finline-limit=64" ]
+      if (current_cpu == "arm") {
+        cflags += [
+          # TODO(hans) Enable integrated-as (crbug.com/124610).
+          "-no-integrated-as",
+          "-B${rebased_android_toolchain_root}/bin",  # Else /usr/bin/as gets picked up.
+        ]
+      }
     }
     if (is_asan) {
       # Android build relies on -Wl,--gc-sections removing unreachable code.
       # ASan instrumentation for globals inhibits this and results in a library
       # with unresolvable relocations.
       # TODO(eugenis): find a way to reenable this.
       cflags += [ "-mllvm -asan-globals=0" ]
     }
 
     defines += [ "ANDROID" ]
+    if (is_clang) {
+      # GCC provides this as a built-in macro, but clang does not.

[Nico, 2015/08/11 21:06:14]

Under which circumstances? Based on the triple? Is there a clang bug filed for
this? This seems something we should be able to fix very quickly.

+      defines += [ "__ANDROID__" ]
+    }
 
     # The NDK has these things, but doesn't define the constants
     # to say that it does. Define them here instead.
     defines += [ "HAVE_SYS_UIO_H" ]
 
     # Use gold for Android for most CPU architectures.
     if (current_cpu == "x86" || current_cpu == "x64" || current_cpu == "arm") {
       ldflags += [ "-fuse-ld=gold" ]
       if (is_clang) {
         # Let clang find the ld.gold in the NDK.
@@ skipping 16 matching lines @@
     ]
     if (current_cpu == "arm") {
       ldflags += [
         # Enable identical code folding to reduce size.
         "-Wl,--icf=safe",
       ]
     }
 
     if (is_clang) {
       if (current_cpu == "arm") {
-        cflags += [
-          "-target",
-          "arm-linux-androideabi",
-        ]
-        ldflags += [
-          "-target",
-          "arm-linux-androideabi",
-        ]
+        _abi_target = "arm-linux-androideabi"
       } else if (current_cpu == "x86") {
-        cflags += [
-          "-target",
-          "i686-linux-androideabi",
-        ]
-        ldflags += [
-          "-target",
-          "i686-linux-androideabi",
-        ]
+        _abi_target = "i686-linux-androideabi"
+      } else if (current_cpu == "arm64") {
+        # Place holder for arm64 support, not tested.
+        _abi_target = "aarch64-linux-androideabi"
+      } else if (current_cpu == "x64") {
+        # Place holder for x64 support, not tested.
+        # TODO: Enable clang support for Android x64. http://crbug.com/346626
+        _abi_target = "x86_64-linux-androideabi"
+      } else if (current_cpu == "mipsel") {
+        # Place holder for mips support, not tested.
+        _abi_target = "mipsel-linux-androideabi"
+      } else if (current_cpu == "mips64el") {
+        # Place holder for mips64 support, not tested.
+        _abi_target = "mips64el-linux-androideabi"
+      } else {
+        assert(false, "Architecture not supported")
       }
+      cflags += [
+        "-target",
+        _abi_target,
+      ]
+      ldflags += [
+        "-target",
+        _abi_target,
+      ]
     }
   }
 
   # Pass the same C/C++ flags to the objective C/C++ compiler.
   cflags_objc += cflags_c
   cflags_objcc += cflags_cc
 }
 
 config("compiler_arm_fpu") {
   if (current_cpu == "arm" && !is_ios) {
@@ skipping 364 matching lines @@
       "-Wsign-compare",
     ]
 
     # In Chromium code, we define __STDC_foo_MACROS in order to get the
     # C99 macros on Mac and Linux.
     defines = [
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
     ]
 
-    if (!using_sanitizer && (!is_linux || !is_clang || is_official_build)) {
+    if (!is_debug && !using_sanitizer &&
+        (!is_linux || !is_clang || is_official_build)) {
       # _FORTIFY_SOURCE isn't really supported by Clang now, see
       # http://llvm.org/bugs/show_bug.cgi?id=16821.
       # It seems to work fine with Ubuntu 12 headers though, so use it in
       # official builds.
       #
       # Non-chromium code is not guaranteed to compile cleanly with
       # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
       # disabled, so only do that for Release build.
       defines += [ "_FORTIFY_SOURCE=2" ]
     }
@@ skipping 311 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }