Fix ARMv6 Linux cross-build

related #29676

R=rmacnak@google.com

Review-Url: https://codereview.chromium.org/2892413002 .

build/config/compiler/BUILD.gn

@@ -556,6 +556,12 @@ if (is_win) {
     default_warning_flags += [ "-Wno-psabi" ]
   }
 
+  # The Raspberry Pi 1 toolchain enables this warning, but Dart doesn't build
+  # cleanly with it.
+  if (is_linux && !is_clang && current_cpu == "arm" && arm_version == 6) {
+    default_warning_flags += [ "-Wno-type-limits" ]
+  }
+
   if (is_android) {
     # Disable any additional warnings enabled by the Android build system but
     # which chromium does not build cleanly with (when treating warning as

build/toolchain/linux/BUILD.gn

@@ -10,6 +10,7 @@ import("//build/toolchain/goma.gni")
 
 declare_args() {
   toolchain_prefix = ""
+  # TODO(zra): Add an argument for overriding the host toolchain.
 }
 
 if (use_goma) {
@@ -64,9 +65,6 @@ gcc_toolchain("arm64") {
 gcc_toolchain("clang_x86") {
   prefix = rebase_path("//buildtools/toolchain/clang+llvm-x86_64-linux/bin",
                        root_build_dir)
-  if (toolchain_prefix != "") {
-    prefix = toolchain_prefix
-  }
   cc = "${compiler_prefix}${prefix}/clang"
   cxx = "${compiler_prefix}${prefix}/clang++"
   readelf = "readelf"
@@ -82,9 +80,6 @@ gcc_toolchain("clang_x86") {
 
 gcc_toolchain("x86") {
   prefix = ""
-  if (toolchain_prefix != "") {
-    prefix = toolchain_prefix
-  }
   cc = "${compiler_prefix}${prefix}gcc"
   cxx = "${compiler_prefix}${prefix}g++"
 
@@ -102,9 +97,6 @@ gcc_toolchain("x86") {
 gcc_toolchain("clang_x64") {
   prefix = rebase_path("//buildtools/toolchain/clang+llvm-x86_64-linux/bin",
                        root_build_dir)
-  if (toolchain_prefix != "") {
-    prefix = toolchain_prefix
-  }
   cc = "${compiler_prefix}${prefix}/clang"
   cxx = "${compiler_prefix}${prefix}/clang++"
 
@@ -121,9 +113,6 @@ gcc_toolchain("clang_x64") {
 
 gcc_toolchain("x64") {
   prefix = ""
-  if (toolchain_prefix != "") {
-    prefix = toolchain_prefix
-  }
   cc = "${compiler_prefix}${prefix}gcc"
   cxx = "${compiler_prefix}${prefix}g++"
 

runtime/vm/compiler.cc

@@ -474,7 +474,8 @@ RawError* Compiler::CompileClass(const Class& cls) {
         parse_class.reset_is_marked_for_parsing();
       }
     }
-    Error& error = Error::Handle(zone.GetZone());
+    Thread* thread = Thread::Current();
+    Error& error = Error::Handle(thread->zone());
     error = thread->sticky_error();
     thread->clear_sticky_error();
     return error.raw();

runtime/vm/intermediate_language.cc

@@ -380,7 +380,7 @@ intptr_t CheckClassInstr::ComputeCidMask() const {
   for (intptr_t i = 0; i < cids_.length(); ++i) {
     intptr_t run;
     uintptr_t range = 1ul + cids_[i].Extent();
-    if (range >= kBitsPerWord) {
+    if (range >= static_cast<uintptr_t>(kBitsPerWord)) {
       run = -1;
     } else {
       run = (1 << range) - 1;

third_party/tcmalloc/BUILD.gn

@@ -32,6 +32,9 @@ config("internal_config") {
   if (is_clang) {
     cflags += [ "-Wno-unused-const-variable" ]
   }
+  if (current_cpu == "arm" && !is_clang) {
+    cflags += [ "-Wno-psabi" ]
+  }
 }
 
 config("link_config") {

tools/gn.py

@@ -68,6 +68,8 @@ def ToCommandLine(gn_args):
   def merge(key, value):
     if type(value) is bool:
       return '%s=%s' % (key, 'true' if value else 'false')
+    elif type(value) is int:
+      return '%s=%d' % (key, value)
     return '%s="%s"' % (key, value)
   return [merge(x, y) for x, y in gn_args.iteritems()]
 
@@ -174,13 +176,17 @@ def ToGnArgs(args, mode, arch, target_os):
 
   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'
+      # Default to -mfloat-abi=hard and -mfpu=neon for arm on Linux as we're
+      # specifying a gnueabihf compiler in //build/toolchain/linux/BUILD.gn.
+      floatabi = 'hard' if args.arm_float_abi == '' else args.arm_float_abi
+      gn_args['arm_version'] = 7
+      gn_args['arm_float_abi'] = floatabi
       gn_args['arm_use_neon'] = True
     elif gn_args['target_cpu'] == 'armv6':
-      raise Exception("GN support for armv6 unimplemented")
+      floatabi = 'softfp' if args.arm_float_abi == '' else args.arm_float_abi
+      gn_args['target_cpu'] = 'arm'
+      gn_args['arm_version'] = 6
+      gn_args['arm_float_abi'] = floatabi
     elif gn_args['target_cpu'] == 'armv5te':
       raise Exception("GN support for armv5te unimplemented")
 
@@ -323,8 +329,14 @@ def parse_args(args):
       default='host')
   common_group.add_argument("-v", "--verbose",
       help='Verbose output.',
-      default=False, action="store_true")
+      default=False,
+      action="store_true")
 
+  other_group.add_argument('--arm-float-abi',
+      type=str,
+      help='The ARM float ABI (soft, softfp, hard)',
+      metavar='[soft,softfp,hard]',
+      default='')
   other_group.add_argument('--asan',
       help='Build with ASAN',
       default=UseASAN(),