From 4f598c584d7e4f34162efa5b179af62cd201f554 Mon Sep 17 00:00:00 2001
From: Ryan Macnak <rmacnak@google.com>
Date: Fri, 20 Jan 2017 15:44:24 -0800
Subject: [PATCH] GN: Fix cross ARM64 and cross MIPS builds.

R=zra@google.com

Review-Url: https://codereview.chromium.org/2643583002 .
---
 build/config/compiler/BUILD.gn |  4 ++++
 runtime/platform/globals.h     |  3 +++
 tools/gn.py                    | 19 +++++++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 346059763e2..ab45443d08c 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -226,6 +226,10 @@ config("compiler") {
         ]
       }
     } else if (current_cpu == "mipsel") {
+      # Some toolchains default to big-endian.
+      cflags += [ "-EL" ]
+      ldflags += [ "-EL" ]
+
       # We have to explicitly request exceptions to get good heap profiles from
       # tcmalloc.
       if (is_debug || is_release) {
diff --git a/runtime/platform/globals.h b/runtime/platform/globals.h
index 101200bec5f..d862a9edaf8 100644
--- a/runtime/platform/globals.h
+++ b/runtime/platform/globals.h
@@ -248,6 +248,9 @@ typedef simd_value_t fpu_register_t;
 #define ARCH_IS_32_BIT 1
 #define kFpuRegisterSize 8
 typedef double fpu_register_t;
+#elif defined(__MIPSEB__)
+#error Big-endian MIPS is not supported by Dart. Try passing -EL to your      \
+ compiler.
 #elif defined(__aarch64__)
 #define HOST_ARCH_ARM64 1
 #define ARCH_IS_64_BIT 1
diff --git a/tools/gn.py b/tools/gn.py
index 1e5120b927b..df6e36ec058 100755
--- a/tools/gn.py
+++ b/tools/gn.py
@@ -140,14 +140,17 @@ def to_gn_args(args, mode, arch, target_os):
                                   and not args.msan
                                   and not args.tsan)
 
-  # Force -mfloat-abi=hard and -mfpu=neon on Linux as we're specifying
-  # a gnueabihf compiler in //build/toolchain/linux BUILD.gn.
-  # TODO(zra): This will likely need some adjustment to build for armv6 etc.
-  hard_float = (gn_args['target_cpu'].startswith('arm') and
-                (gn_args['target_os'] == 'linux'))
-  if hard_float:
-    gn_args['arm_float_abi'] = 'hard'
-    gn_args['arm_use_neon'] = True
+  if gn_args['target_os'] == 'linux':
+    if gn_args['target_cpu'] == 'arm':
+      # Force -mfloat-abi=hard and -mfpu=neon for arm on Linux as we're
+      # specifying a gnueabihf compiler in //build/toolchain/linux BUILD.gn.
+      gn_args['arm_arch'] = 'armv7'
+      gn_args['arm_float_abi'] = 'hard'
+      gn_args['arm_use_neon'] = True
+    elif gn_args['target_cpu'] == 'armv6':
+      raise Exception("GN support for armv6 unimplemented")
+    elif gn_args['target_cpu'] == 'armv5te':
+      raise Exception("GN support for armv5te unimplemented")
 
   gn_args['is_debug'] = mode == 'debug'
   gn_args['is_release'] = mode == 'release'