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

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 6a495cc2a82b8b2500a5c7c0c5398b7389c8f0a3..166bc817c6fc77af1def91afbcd28f92cb36038b 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -165,6 +165,8 @@ config("compiler") {
     configs += [ "//build/config/nacl:compiler" ]
   } else if (is_ios || is_mac) {
     configs += [ "//build/config/mac:compiler" ]
+  } else if (current_os == "aix") {
+    configs += [ "//build/config/aix:compiler" ]
   }
 
   # See the definitions below.
@@ -178,13 +180,15 @@ config("compiler") {
   if (!is_win) {
     # Common GCC compiler flags setup.
     # --------------------------------
-    cflags += [ "-fno-strict-aliasing" ]  # See http://crbug.com/32204
-    cflags_cc += [
-      # Not exporting C++ inline functions can generally be applied anywhere
-      # so we do so here. Normal function visibility is controlled by
-      # //build/config/gcc:symbol_visibility_hidden.
-      "-fvisibility-inlines-hidden",
-    ]
+    if (!is_power_or_z) {

[brettw, 2017/04/26 20:07:42]

Why does this condition exist?

[Dirk Pranke, 2017/04/26 23:32:13]

I believe these flags don't work on the IBM versions of gcc. Perhaps add some
comment to that effect?

[rayb, 2017/04/27 19:29:45]

So for the -fno-strict-aliasing one, I wasn't sure if we needed it as the
justification provided in the gyp files for v8 is  -
"# Some versions of GCC 4.5 seem to need -fno-strict-aliasing.". Also the linked
Issue dates back to 2010 (and mostly talks about chromium-code), so I wasn't
sure if this was still a thing. But by your comment, I am assuming it is still
relevant, so I am adding it back now. (Initially I was aiming for the smallest
subset of flags to get everything built properly on the mentioned platforms, if
that makes sense. And there doesn't seem to be any errors caused by the
exclusion of the flag, at least on the platforms I have been testing on.)

As for the "-fvisibility-inlines-hidden" flag, I can confirm that gcc on AIX
does not have support for the visibility attribute. It was a mistake from my
part to exclude that one from the p/Linux and z/Linux builds though. Thanks for
catching that. Fixed now.

+      cflags += [ "-fno-strict-aliasing" ]  # See http://crbug.com/32204
+      cflags_cc += [
+        # Not exporting C++ inline functions can generally be applied anywhere
+        # so we do so here. Normal function visibility is controlled by
+        # //build/config/gcc:symbol_visibility_hidden.
+        "-fvisibility-inlines-hidden",
+      ]
+    }
 
     # Stack protection.
     if (is_mac) {
@@ -203,14 +207,16 @@ config("compiler") {
       # The x86 toolchain currently has problems with stack-protector.
       if (is_android && current_cpu == "x86") {
         cflags += [ "-fno-stack-protector" ]
-      } else {
+      } else if (current_os != "aix") {
+        # Not available on aix.
         cflags += [ "-fstack-protector" ]
       }
     }
 
     # Linker warnings.
     if (fatal_linker_warnings && !(is_chromeos && current_cpu == "arm") &&
-        !(is_android && use_order_profiling) && !is_mac && !is_ios) {
+        !(is_android && use_order_profiling) && !is_mac && !is_ios &&
+        current_os != "aix") {
       # TODO(jochen): Enable this on chromeos on arm. http://crbug.com/356580
       # TODO(lizeb,pasko): Fix link errors when linking with order_profiling=1
       # crbug.com/485542
@@ -439,7 +445,7 @@ config("compiler") {
 
   # C++11 compiler flags setup.
   # ---------------------------
-  if (is_linux || is_android || (is_nacl && is_clang)) {
+  if (is_linux || is_android || (is_nacl && is_clang) || current_os == "aix") {
     # gnu++11 instead of c++11 is needed because some code uses typeof() (a
     # GNU extension).
     # TODO(thakis): Eventually switch this to c++11 instead,
@@ -1151,7 +1157,7 @@ config("chromium_code") {
     ]
 
     if (!is_debug && !using_sanitizer &&
-        (!is_linux || !is_clang || is_official_build)) {
+        (!is_linux || !is_clang || is_official_build) && !is_power_or_z) {
       # _FORTIFY_SOURCE isn't really supported by Clang now, see
       # http://llvm.org/bugs/show_bug.cgi?id=16821.
       # It seems to work fine with Ubuntu 12 headers though, so use it in
@@ -1371,8 +1377,9 @@ if (is_win) {
       # Mac dead code stripping requires symbols.
       common_optimize_on_ldflags += [ "-Wl,-dead_strip" ]
     }
-  } else {
+  } else if (current_os != "aix") {
     # Non-Mac Posix flags.
+    # Aix does not support these.
 
     common_optimize_on_cflags += [
       # Don't emit the GCC version ident directives, they just end up in the