Add compiler and linker flags for MIPS.

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")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 if (is_posix) {
   import("//build/config/gcc/gcc_version.gni")
@@ skipping 253 matching lines @@
             # compiler (r5-r7). This can be verified using
             # webkit_unit_tests' WTF.Checked_int8_t test.
             "-fno-tree-sra",
 
             # The following option is disabled to improve binary
             # size and performance in gcc 4.9.
             "-fno-caller-saves",
           ]
         }
       }
+    } else if (cpu_arch == "mipsel") {
+      # Don't set the compiler flags for the WebView build. These will come
+      # from the Android build system.

[wtc, 2015/01/07 21:40:00]

I copied this comment from the cpu_arch == "arm" case on lines 242-243 above.

+      if (!is_android_webview_build) {
+        # TODO(wtc): check mips_arch_variant (possible values are "r1", "r2",

[Ben Chan, 2015/01/07 21:48:40]

should it be done in the same CL?

[wtc, 2015/01/07 23:00:22]

Done.

+        # "r6") and use -mips32, -mips32r2 or -mips32r6 in cflags accordingly.
+        cflags += [
+          "-mips32",
+          "-Wa,-mips32",
+        ]
+      }
+      ldflags += [ "-Wl,--no-keep-memory" ]
+      cflags_cc += [ "-Wno-uninitialized" ]

[Ben Chan, 2015/01/07 21:48:40]

are these ldflags and cflags_cc really needed?

[wtc, 2015/01/07 23:00:22]

I ported the GYP code faithfully without thinking. Now that you asked,
I think -Wno-uninitialized is actually harmful. I will remove it from
this CL and probably from build/common.gypi as well.

-Wl,--no-keep-memory seems to be a linker flag that affects the performance
of ld:

       --no-keep-memory
           ld normally optimizes for speed over memory usage by caching the
           symbol tables of input files in memory.  This option tells ld to
           instead optimize for memory usage, by rereading the symbol tables
           as necessary.  This may be required if ld runs out of memory space
           while linking a large executable.

I'll remove it until we see ld run out of memory.

+    } else if (cpu_arch == "mips64el") {
+      # Don't set the compiler flags for the WebView build. These will come
+      # from the Android build system.
+      if (!is_android_webview_build) {
+        # TODO(wtc): check mips_arch_variant (possible values are "r2", "r6")
+        # and use -mips32r2 or -mips32r6 in cflags and ldflags accordingly.
+        cflags += [
+          "-mips64r2",
+          "-Wa,-mips64r2",
+        ]
+        ldflags += [ "-mips64r2" ]
+      }
+      cflags_cc += [ "-Wno-uninitialized" ]
     }
 
     defines += [ "_FILE_OFFSET_BITS=64" ]
 
     # Omit unwind support in official builds to save space. We can use breakpad
     # for these builds.
     if (is_chrome_branded && is_official_build) {
       cflags += [
         "-fno-unwind-tables",
         "-fno-asynchronous-unwind-tables",
@@ skipping 703 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }