Lower heap size limits on systems that are short of virtual memory.

src/heap.cc

 // Copyright 2011 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
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@@ skipping 134 matching lines @@
       last_idle_notification_gc_count_init_(false),
       configured_(false),
       is_safe_to_read_maps_(true) {
   // Allow build-time customization of the max semispace size. Building
   // V8 with snapshots and a non-default max semispace size is much
   // easier if you can define it as part of the build environment.
 #if defined(V8_MAX_SEMISPACE_SIZE)
   max_semispace_size_ = reserved_semispace_size_ = V8_MAX_SEMISPACE_SIZE;
 #endif
 
+  intptr_t max_virtual = OS::MaxVirtualMemory();
+
+  if (max_virtual > 0) {
+    if (code_range_size_ > 0) {

[Kasper Lund, 2011/06/01 08:23:49]

It would be nice with a comment here that explains how the max virtual memory is
carved up. It's not completely clear why you use 1/4 on code and 1/2 on old gen
(what do you use the last 1/4 on)? If code_range_size_ == 0 why don't you want
to use the same fraction of max_virtual?

+      code_range_size_ = Min(code_range_size_, max_virtual >> 2);
+    }
+    max_old_generation_size_ = Min(max_old_generation_size_, max_virtual >> 1);
+  }
+
   memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
   global_contexts_list_ = NULL;
   mark_compact_collector_.heap_ = this;
   external_string_table_.heap_ = this;
 }
 
 
 intptr_t Heap::Capacity() {
   if (!HasBeenSetup()) return 0;
 
@@ skipping 5758 matching lines @@
 }
 
 
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 } }  // namespace v8::internal