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

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")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
@@ skipping 144 matching lines @@
   if (is_win) {
     configs += [ "//build/config/win:compiler" ]
   } else if (is_android) {
     configs += [ "//build/config/android:compiler" ]
   } else if (is_linux) {
     configs += [ "//build/config/linux:compiler" ]
   } else if (is_nacl) {
     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.
   configs += [
     ":compiler_cpu_abi",
     ":compiler_codegen",
   ]
 
   # In general, Windows is totally different, but all the other builds share
   # some common GCC configuration.
   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 (current_os != "aix" &&

[Michael Achenbach, 2017/04/25 14:08:30]

Just double-checking: You don't need the aix check anymore?

[rayb, 2017/04/25 17:28:48]

We only support AIX on ppc64 BE. So further checking current_os != aix, seemed
redundant. Also I don't know the behavior for AIX running on other platforms,
but I do know AIX on ppc64 does not have support for these flags. 

+        !(is_linux && (current_cpu == "s390x" || current_cpu == "s390" ||
+                       current_cpu == "ppc64" || current_cpu == "ppc"))) {
+      cflags_cc += [

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

This doesn't include -fno-strict-aliasing in cflags anymore. Also for the
non-aix/non-ppc/etc cases. If this is intended, I'd prefer to have it in a
separate CL and with separate description.

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

Acknowledged.

+        "fno-strict-aliasing",
+
+        # 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) {
       # The strong variant of the stack protector significantly increases
       # binary size, so only enable it in debug mode.
       if (is_debug) {
         cflags += [ "-fstack-protector-strong" ]
       } else {
         cflags += [ "-fstack-protector" ]
       }
     } else if (is_posix && !is_chromeos && !is_nacl) {
       # TODO(phajdan.jr): Use -fstack-protector-strong when our gcc supports it.
       # See also https://crbug.com/533294
       cflags += [ "--param=ssp-buffer-size=4" ]
 
       # 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
       ldflags += [ "-Wl,--fatal-warnings" ]
     }
   }
 
   # Eliminate build metadata (__DATE__, __TIME__ and __TIMESTAMP__) for
   # deterministic build.  See https://crbug.com/314403
   if (!is_official_build) {
@@ skipping 208 matching lines @@
   # clang-cl (used if is_win) doesn't expose this flag.
   # Currently disabled for nacl since its toolchain lacks this flag (too old).
   # TODO(zforman): Once nacl's toolchain is updated, remove check.
   if (is_clang && is_linux && strip_absolute_paths_from_debug_symbols) {
     absolute_path = rebase_path("//.")
     cflags += [ "-fdebug-prefix-map=$absolute_path=." ]
   }
 
   # 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,
     # http://crbug.com/427584
     cflags_cc += [ "-std=gnu++11" ]
   } else if (!is_win && !is_nacl) {
     # TODO(mcgrathr) - the NaCl GCC toolchain doesn't support either gnu++11
     # or c++11; we technically don't need this toolchain any more, but there
     # are still a few buildbots using it, so until those are turned off
     # we need the !is_nacl clause and the (is_nacl && is_clang) clause, above.
@@ skipping 680 matching lines @@
     }
 
     # In Chromium code, we define __STDC_foo_MACROS in order to get the
     # C99 macros on Mac and Linux.
     defines = [
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
     ]
 
     if (!is_debug && !using_sanitizer &&
-        (!is_linux || !is_clang || is_official_build)) {
+        (!is_linux || !is_clang || is_official_build) &&
+        (current_cpu != "s390x" && current_cpu != "s390" &&
+         current_cpu != "ppc64" && current_cpu != "ppc")) {

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

nit: For readability, maybe we could add a helper variable somewhere for:
current_cpu != "s390x" && current_cpu != "s390" && current_cpu != "ppc64" &&
current_cpu != "ppc"

Or rather the inverse case, used in line 181. This or the inverse case are used
many times in multiple files. The four parts of the clause are always going
together and are hard to read if nested within other clauses.

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

Done.

       # _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
       # official builds.
       #
       # Non-chromium code is not guaranteed to compile cleanly with
       # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
       # disabled, so only do that for Release build.
       defines += [ "_FORTIFY_SOURCE=2" ]
     }
@@ skipping 199 matching lines @@
         "-Wl,--warn-shared-textrel",
       ]
     }
   }
 
   if (is_mac || is_ios) {
     if (symbol_level == 2) {
       # Mac dead code stripping requires symbols.
       common_optimize_on_ldflags += [ "-Wl,-dead_strip" ]
     }
-  } else {
+  } else if (current_os != "aix") {
     # Non-Mac Posix flags.
 
     common_optimize_on_cflags += [
       # Don't emit the GCC version ident directives, they just end up in the
       # .comment section taking up binary size.
       "-fno-ident",
 
       # Put data and code in their own sections, so that unused symbols
       # can be removed at link time with --gc-sections.
       "-fdata-sections",
       "-ffunction-sections",
     ]
 
-    common_optimize_on_ldflags += [
-      # Specifically tell the linker to perform optimizations.
-      # See http://lwn.net/Articles/192624/ .
-      "-Wl,-O1",
-      "-Wl,--gc-sections",
-    ]
+    if (current_os != "aix") {

[Michael Achenbach, 2017/04/18 13:46:03]

This is already nested in a current_os != "aix" scope.

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

Done.

+      common_optimize_on_ldflags += [
+        # Specifically tell the linker to perform optimizations.
+        # See http://lwn.net/Articles/192624/ .
+        "-Wl,-O1",
+        "-Wl,--gc-sections",
+      ]
+    }
   }
 }
 
 config("default_stack_frames") {
   if (is_posix) {
     if (enabled_frame_pointers) {
       cflags = [ "-fno-omit-frame-pointer" ]
     } else {
       cflags = [ "-fomit-frame-pointer" ]
     }
@@ skipping 327 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }