Add -optimize-for-size flag to optimize for memory size

src/flag-definitions.h

 // Copyright 2012 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 204 matching lines @@
 DEFINE_bool(pretenuring_call_new, false, "pretenure call new")
 DEFINE_bool(track_fields, true, "track fields with only smi values")
 DEFINE_bool(track_double_fields, true, "track fields with double values")
 DEFINE_bool(track_heap_object_fields, true, "track fields with heap values")
 DEFINE_bool(track_computed_fields, true, "track computed boilerplate fields")
 DEFINE_implication(track_double_fields, track_fields)
 DEFINE_implication(track_heap_object_fields, track_fields)
 DEFINE_implication(track_computed_fields, track_fields)
 DEFINE_bool(smi_binop, true, "support smi representation in binary operations")
 
+// Flags for optimization types.
+DEFINE_bool(Os, false, "Optimize for size. Enables optimizations which reduce "

[Hannes Payer (out of office), 2013/09/23 11:38:43]

I just talked to danno: --optimize-for-size is a better name, --Os is to
cryptic.
Moreover, can you make the description generic? This mode should in the future
turn on all kinds of size specific optimizations. And the description should say
that it favors memory size over execution speed.

[rmcilroy, 2013/09/23 12:40:15]

Done.

+            "generated code size.")
+
 // Flags for data representation optimizations
 DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(string_slices, true, "use string slices")
 
 // Flags for Crankshaft.
 DEFINE_bool(crankshaft, true, "use crankshaft")
 DEFINE_string(hydrogen_filter, "*", "optimization filter")
 DEFINE_bool(use_range, true, "use hydrogen range analysis")
 DEFINE_bool(use_gvn, true, "use hydrogen global value numbering")
 DEFINE_bool(use_canonicalizing, true, "use hydrogen instruction canonicalizing")
@@ skipping 352 matching lines @@
 DEFINE_bool(preallocate_message_memory, false,
             "preallocate some memory to build stack traces.")
 DEFINE_bool(randomize_hashes,
             true,
             "randomize hashes to avoid predictable hash collisions "
             "(with snapshots this option cannot override the baked-in seed)")
 DEFINE_int(hash_seed,
            0,
            "Fixed seed to use to hash property keys (0 means random)"
            "(with snapshots this option cannot override the baked-in seed)")
-DEFINE_maybe_bool(force_memory_constrained,
-           "force (if true) or prevent (if false) the runtime from treating "
-           "the device as being memory constrained.")
 
 // v8.cc
 DEFINE_bool(preemption, false,
             "activate a 100ms timer that switches between V8 threads")
 
 // Regexp
 DEFINE_bool(regexp_optimization, true, "generate optimized regexp code")
 
 // Testing flags test/cctest/test-{flags,api,serialization}.cc
 DEFINE_bool(testing_bool_flag, true, "testing_bool_flag")
@@ skipping 234 matching lines @@
 #undef DEFINE_ALIAS_float
 #undef DEFINE_ALIAS_args
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA