Add -optimize-for-size flag to optimize for memory size (will be used by...

Add -optimize-for-size flag to optimize for memory size (will be used by pre-aging CL), and remove the is_memory_constrained ResourceConstraint.

BUG=292928
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/24018009

Patch from Ross McIlroy <rmcilroy@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16960 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -3762,20 +3762,12 @@ class V8_EXPORT ResourceConstraints {
   uint32_t* stack_limit() const { return stack_limit_; }
   // Sets an address beyond which the VM's stack may not grow.
   void set_stack_limit(uint32_t* value) { stack_limit_ = value; }
-  Maybe<bool> is_memory_constrained() const { return is_memory_constrained_; }
-  // If set to true, V8 will limit it's memory usage, at the potential cost of
-  // lower performance.  Note, this option is a tentative addition to the API
-  // and may be removed or modified without warning.
-  void set_memory_constrained(bool value) {
-    is_memory_constrained_ = Maybe<bool>(value);
-  }
 
  private:
   int max_young_space_size_;
   int max_old_space_size_;
   int max_executable_size_;
   uint32_t* stack_limit_;
-  Maybe<bool> is_memory_constrained_;
 };
 
 

src/api.cc

@@ -563,8 +563,7 @@ ResourceConstraints::ResourceConstraints()
   : max_young_space_size_(0),
     max_old_space_size_(0),
     max_executable_size_(0),
-    stack_limit_(NULL),
-    is_memory_constrained_() { }
+    stack_limit_(NULL) { }
 
 
 bool SetResourceConstraints(ResourceConstraints* constraints) {
@@ -585,11 +584,6 @@ bool SetResourceConstraints(ResourceConstraints* constraints) {
     uintptr_t limit = reinterpret_cast<uintptr_t>(constraints->stack_limit());
     isolate->stack_guard()->SetStackLimit(limit);
   }
-  if (constraints->is_memory_constrained().has_value &&
-      !i::FLAG_force_memory_constrained.has_value) {
-    isolate->set_is_memory_constrained(
-        constraints->is_memory_constrained().value);
-  }
   return true;
 }
 

src/flag-definitions.h

@@ -216,6 +216,11 @@ 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(optimize_for_size, false,
+            "Enables optimizations which favor memory size over execution "
+            "speed.")
+
 // Flags for data representation optimizations
 DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(string_slices, true, "use string slices")
@@ -589,9 +594,6 @@ 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,

src/isolate.cc

@@ -1792,10 +1792,6 @@ Isolate::Isolate()
       // TODO(bmeurer) Initialized lazily because it depends on flags; can
       // be fixed once the default isolate cleanup is done.
       random_number_generator_(NULL),
-      // TODO(rmcilroy) Currently setting this based on
-      // FLAG_force_memory_constrained in Isolate::Init; move to here when
-      // isolate cleanup is done
-      is_memory_constrained_(false),
       has_fatal_error_(false),
       use_crankshaft_(true),
       initialized_from_snapshot_(false),
@@ -2157,8 +2153,6 @@ bool Isolate::Init(Deserializer* des) {
   TRACE_ISOLATE(init);
 
   stress_deopt_count_ = FLAG_deopt_every_n_times;
-  if (FLAG_force_memory_constrained.has_value)
-    is_memory_constrained_ = FLAG_force_memory_constrained.value;
 
   has_fatal_error_ = false;
 

src/isolate.h

@@ -1132,13 +1132,6 @@ class Isolate {
   // Given an address occupied by a live code object, return that object.
   Object* FindCodeObject(Address a);
 
-  bool is_memory_constrained() const {
-    return is_memory_constrained_;
-  }
-  void set_is_memory_constrained(bool value) {
-    is_memory_constrained_ = value;
-  }
-
  private:
   Isolate();
 
@@ -1311,7 +1304,6 @@ class Isolate {
   unibrow::Mapping<unibrow::Ecma262Canonicalize> interp_canonicalize_mapping_;
   CodeStubInterfaceDescriptor* code_stub_interface_descriptors_;
   RandomNumberGenerator* random_number_generator_;
-  bool is_memory_constrained_;
 
   // True if fatal error has been signaled for this isolate.
   bool has_fatal_error_;