For building v8 using gn on aix_ppc64, linux_s390x and linux_ppc64.

BUILD.gn

 # Copyright 2014 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/arm.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
@@ skipping 89 matching lines @@
 
   # Like v8_extra_library_files but for experimental features.
   #
   # This default is used by cctests. Projects using V8 will want to override.
   v8_experimental_extra_library_files =
       [ "//test/cctest/test-experimental-extra.js" ]
 
   v8_enable_gdbjit = ((v8_current_cpu == "x86" || v8_current_cpu == "x64" ||
                        v8_current_cpu == "x87") && (is_linux || is_mac)) ||
                      (v8_current_cpu == "ppc64" && is_linux)
-
-  # Set v8_host_byteorder
-  v8_host_byteorder = "little"
-
-  # ppc64 can be either BE or LE
-  if (host_cpu == "ppc64") {
-    v8_host_byteorder =
-        exec_script("//tools/get_byteorder.py", [], "trim string")
-  }
-  if (host_cpu == "ppc" || host_cpu == "s390" || host_cpu == "s390x" ||
-      host_cpu == "mips" || host_cpu == "mips64") {
-    v8_host_byteorder = "big"
-  }

[Dirk Pranke, 2017/04/18 20:31:35]

I think we should leave this here, at least until we have a need for
host_byteorder somewhere outside of v8.

If we have that need at that time, we should start by creating a separate
host_byteorder.gni file, rather than setting it in BUILDCONFIG. We should avoid
changes to BUILDCONFIG if at all possible.

[rayb, 2017/04/25 00:39:06]

As per the discussion on the other CL, we now use host_byteorder.gni to get the
host_byteorder. 

 }
 
 # Derived defaults.
 if (v8_enable_verify_heap == "") {
   v8_enable_verify_heap = is_debug
 }
 if (v8_enable_object_print == "") {
   v8_enable_object_print = is_debug
 }
 if (v8_enable_disassembler == "") {
@@ skipping 239 matching lines @@
       defines += [ "_MIPS_ARCH_MIPS64R6" ]
     } else if (mips_arch_variant == "r2") {
       defines += [ "_MIPS_ARCH_MIPS64R2" ]
     }
   }
   if (v8_current_cpu == "s390" || v8_current_cpu == "s390x") {
     defines += [ "V8_TARGET_ARCH_S390" ]
     if (v8_current_cpu == "s390x") {
       defines += [ "V8_TARGET_ARCH_S390X" ]
     }
-    if (v8_host_byteorder == "little") {
+    if (host_byteorder == "little") {
       defines += [ "V8_TARGET_ARCH_S390_LE_SIM" ]
     } else {
       cflags += [ "-march=z196" ]
     }
   }
   if (v8_current_cpu == "ppc" || v8_current_cpu == "ppc64") {
     defines += [ "V8_TARGET_ARCH_PPC" ]
     if (v8_current_cpu == "ppc64") {
       defines += [ "V8_TARGET_ARCH_PPC64" ]
     }
-    if (v8_host_byteorder == "little") {
+    if (host_byteorder == "little") {
       defines += [ "V8_TARGET_ARCH_PPC_LE" ]
-    } else if (v8_host_byteorder == "big") {
+    } else if (host_byteorder == "big") {
       defines += [ "V8_TARGET_ARCH_PPC_BE" ]
       if (current_os == "aix") {
         cflags += [
           # Work around AIX ceil, trunc and round oddities.
           "-mcpu=power5+",
           "-mfprnd",
 
           # Work around AIX assembler popcntb bug.
           "-mno-popcntb",
         ]
       }
     }
   }
+
   if (v8_current_cpu == "x86") {
     defines += [ "V8_TARGET_ARCH_IA32" ]
     if (is_win) {
       # Ensure no surprising artifacts from 80bit double math with x86.
       cflags += [ "/arch:SSE2" ]
     }
   }
   if (v8_current_cpu == "x64") {
     defines += [ "V8_TARGET_ARCH_X64" ]
     if (is_win) {
@@ skipping 2039 matching lines @@
   if (is_linux) {
     sources += [
       "src/base/debug/stack_trace_posix.cc",
       "src/base/platform/platform-linux.cc",
     ]
 
     libs = [
       "dl",
       "rt",
     ]
+  } else if (current_os == "aix") {
+    sources += [
+      "src/base/debug/stack_trace_posix.cc",
+      "src/base/platform/platform-aix.cc",
+    ]
+
+    libs = [
+      "dl",
+      "rt",
+    ]
   } else if (is_android) {
     if (current_toolchain == host_toolchain) {
       libs = [
         "dl",
         "rt",
       ]
       if (host_os == "mac") {
         sources += [
           "src/base/debug/stack_trace_posix.cc",
           "src/base/platform/platform-macos.cc",
@@ skipping 715 matching lines @@
   ]
 
   configs = [
     ":external_config",
     ":internal_config_base",
   ]
 }
 
 v8_fuzzer("wasm_compile_fuzzer") {
 }