[interpeter] Move to table based peephole optimizer.

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 614 matching lines @@
       rebase_path("$root_out_dir/snapshot_blob.bin", root_build_dir),
     ]
   }
 
   if (v8_embed_script != "") {
     sources += [ v8_embed_script ]
     args += [ rebase_path(v8_embed_script, root_build_dir) ]
   }
 }
 
+action("run_mkpeephole") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+
+  deps = [
+    ":mkpeephole($v8_snapshot_toolchain)",
+  ]
+
+  outputs = [
+    "$target_gen_dir/bytecode-peephole-table.h"
+  ]
+
+  sources = []
+
+  script = "tools/run.py"
+
+  args = [
+    "./" + rebase_path(get_label_info(":mkpeephole($v8_snapshot_toolchain)",
+                                      "root_out_dir") + "/mkpeephole",
+                                      root_build_dir),
+   rebase_path("$target_gen_dir/bytecode-peephole-table.h", root_build_dir),
+  ]
+}
+
 action("v8_dump_build_config") {
   script = "tools/testrunner/utils/dump_build_config.py"
   outputs = [
     "$root_out_dir/v8_build_config.json",
   ]
   args = [
     rebase_path("$root_out_dir/v8_build_config.json", root_build_dir),
     "dcheck_always_on=$dcheck_always_on",
     "is_asan=$is_asan",
     "is_cfi=$is_cfi",
@@ skipping 634 matching lines @@
     "src/interpreter/bytecode-array-iterator.h",
     "src/interpreter/bytecode-array-writer.cc",
     "src/interpreter/bytecode-array-writer.h",
     "src/interpreter/bytecode-dead-code-optimizer.cc",
     "src/interpreter/bytecode-dead-code-optimizer.h",
     "src/interpreter/bytecode-generator.cc",
     "src/interpreter/bytecode-generator.h",
     "src/interpreter/bytecode-label.h",
     "src/interpreter/bytecode-peephole-optimizer.cc",
     "src/interpreter/bytecode-peephole-optimizer.h",
+    "$target_gen_dir/bytecode-peephole-table.h",

[rmcilroy, 2016/07/08 13:18:25]

I think this should be a separate target which needs to be built before trying
to build the rest of v8_base (otherwise bytecode-peephole-optimizer.cc could be
built before you build or rebuild bytecode-peephole-table.h, thus meaning it
would be built with the wrong table (or the build would break due to a missing
header). 

Thinking about it, could you make this a cc file and just rely on linking to the
table with a known name? That would mean you could make only the v8_*_snapshot
targets depend on this new target (in the same way as they depend on js2c).

[oth, 2016/07/08 15:12:33]

I'm not a GN expert, but it definitely detects if there is not action that
outputs this header and refuses to build. It knows that is a dependency and
builds it. I believe it's down to the specific value of the prefix held in
$target_gen_dir.
What happens in this path is rather convoluted. Okay, let's try it.

     "src/interpreter/bytecode-pipeline.cc",
     "src/interpreter/bytecode-pipeline.h",
     "src/interpreter/bytecode-register-allocator.cc",
     "src/interpreter/bytecode-register-allocator.h",
     "src/interpreter/bytecode-register-optimizer.cc",
     "src/interpreter/bytecode-register-optimizer.h",
     "src/interpreter/bytecode-traits.h",
     "src/interpreter/bytecodes.cc",
     "src/interpreter/bytecodes.h",
     "src/interpreter/constant-array-builder.cc",
@@ skipping 565 matching lines @@
       "src/s390/simulator-s390.h",
     ]
   }
 
   configs = [ ":internal_config" ]
 
   defines = []
   deps = [
     ":v8_libbase",
     ":v8_libsampler",
+    "//:run_mkpeephole"
   ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]
   }
 
   if (v8_enable_i18n_support) {
     deps += [ "//third_party/icu" ]
     if (is_win) {
@@ skipping 203 matching lines @@
     configs = [ ":internal_config" ]
 
     deps = [
       ":v8_base",
       ":v8_libplatform",
       ":v8_nosnapshot",
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",
     ]
   }
+
+  v8_executable("mkpeephole") {
+    # mkpeephole needs to be built for the build host so the peephole lookup
+    # table can built during build. The table depends on the properties of
+    # bytecodes that are described in bytecodes.{cc,h}.
+    visibility = [ ":*" ]  # Only targets in this file can depend on this.
+
+    sources = [
+      "src/interpreter/bytecode-peephole-optimizer.h",
+      "src/interpreter/bytecodes.cc",
+      "src/interpreter/bytecodes.h",
+      "src/interpreter/mkpeephole.cc"
+    ]
+
+    configs = [ ":internal_config" ]
+
+    deps = [ ":v8_libbase" ]
+  }
 }
 
 ###############################################################################
 # Public targets
 #
 
 want_v8_shell =
     (current_toolchain == host_toolchain && v8_toolset_for_shell == "host") ||
     (current_toolchain == v8_snapshot_toolchain &&
      v8_toolset_for_shell == "host") ||
@@ skipping 288 matching lines @@
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }
 
 v8_fuzzer("wasm_asmjs_fuzzer") {
 }