Revert of [build] Use -O2 on linux by default

gypfiles/toolchain.gypi

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 1165 matching lines @@
         },
         'variables': {
           'v8_enable_slow_dchecks%': 0,
         },
         'conditions': [
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" or \
             OS=="qnx" or OS=="aix"', {
             'cflags!': [
               '-O0',
               '-O1',
-              '-O3',
               '-Os',
             ],
             'cflags': [
               '-fdata-sections',
               '-ffunction-sections',
-              '-O2',
+            ],
+            'conditions': [
+              # TODO(crbug.com/272548): Avoid -O3 in NaCl
+              # Don't use -O3 with sanitizers.
+              ['nacl_target_arch=="none" and asan==0 and msan==0 and lsan==0 \
+                and tsan==0 and ubsan==0 and ubsan_vptr==0', {
+                'cflags': ['-O3'],
+                'cflags!': ['-O2'],
+                }, {
+                'cflags': ['-O2'],
+                'cflags!': ['-O3'],
+              }],
             ],
           }],
           ['OS=="mac"', {
             'xcode_settings': {
               'GCC_OPTIMIZATION_LEVEL': '3',  # -O3
               'GCC_STRICT_ALIASING': 'YES',
             },
           }],
           ['v8_enable_slow_dchecks==1', {
             'defines': [
@@ skipping 81 matching lines @@
       },  # Debug
       'ReleaseBase': {
         'abstract': 1,
         'variables': {
           'v8_enable_slow_dchecks%': 0,
         },
         'conditions': [
           ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" \
             or OS=="aix"', {
             'cflags!': [
-              '-O3',
               '-Os',
             ],
             'cflags': [
               '-fdata-sections',
               '-ffunction-sections',
               '<(wno_array_bounds)',
-              '-O2',
+            ],
+            'conditions': [
+              # TODO(crbug.com/272548): Avoid -O3 in NaCl
+              # Don't use -O3 with sanitizers.
+              ['nacl_target_arch=="none" and asan==0 and msan==0 and lsan==0 \
+                and tsan==0 and ubsan==0 and ubsan_vptr==0', {
+                'cflags': ['-O3'],
+                'cflags!': ['-O2'],
+              }, {
+                'cflags': ['-O2'],
+                'cflags!': ['-O3'],
+              }],
             ],
           }],
           ['OS=="android"', {
             'cflags!': [
               '-O3',
               '-Os',
             ],
             'cflags': [
               '-fdata-sections',
               '-ffunction-sections',
@@ skipping 58 matching lines @@
             ],
           },
           'Release_x64': {
             'inherit_from': ['ReleaseBase'],
           },
         }],
       ],
     },  # configurations
   },  # target_defaults
 }