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

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index 441bd21026adbd9c7ca7327b06bef56aa656ea5c..1ac602ad6cb80e0cd13faf9e645ca48acbb52ca0 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -24,8 +24,13 @@ declare_args() {
   # Enables Native Client support.
   # Temporarily disable nacl on arm64 linux to get rid of compilation errors.
   # TODO(mcgrathr): When mipsel-nacl-clang is available, drop the exclusion.
-  enable_nacl = !is_ios && !is_android && !is_chromecast &&
-                current_cpu != "mipsel" && !(is_linux && target_cpu == "arm64")
+  enable_nacl =
+      !is_ios && !is_android && !is_chromecast && current_os != "aix" &&
+      current_cpu != "mipsel" && !(is_linux && target_cpu == "arm64") &&
+      (current_cpu != "s390" && current_cpu != "s390x" &&

[Michael Achenbach, 2017/04/18 13:46:04]

nit: Why parentheses?

[rayb, 2017/04/25 00:41:04]

Done.

+       target_cpu != "s390" && target_cpu != "s390x") &&
+      (current_cpu != "ppc" && current_cpu != "ppc64" && target_cpu != "ppc" &&
+       target_cpu != "ppc64")

[Dirk Pranke, 2017/04/14 01:29:02]

Are you planning to port NaCl to these architectures? I'm guessing not, and
maybe we can just simplify this logic to only look at the target_cpus?

[rayb, 2017/04/25 00:41:04]

Not that I know of. Also simplified the logic a little.

 
   # Non-SFI is not yet supported on mipsel
   enable_nacl_nonsfi = current_cpu != "mipsel"