[build] Add v8gen support for PPC/s390 architecture

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 83 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"
+  }
 }
 
 # 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 234 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 (host_cpu == "x64" || host_cpu == "x86") {
+    if (v8_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") {
+      defines += [ "V8_TARGET_ARCH_PPC_LE" ]
+    } else if (v8_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") {
@@ skipping 2756 matching lines @@
   ]
 
   configs = [
     ":external_config",
     ":internal_config_base",
   ]
 }
 
 v8_fuzzer("wasm_compile_fuzzer") {
 }