Assembler changes for enabling GrowHeap in Wasm

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 367 matching lines @@
   // The maximum pc delta that will use the short encoding.
   static const int kMaxSmallPCDelta;
 
   enum Mode {
     // Please note the order is important (see IsCodeTarget, IsGCRelocMode).
     CODE_TARGET,  // Code target which is not any of the above.
     CODE_TARGET_WITH_ID,
     DEBUGGER_STATEMENT,  // Code target for the debugger statement.
     EMBEDDED_OBJECT,
     CELL,
+    // Marker for relocation when the heap changes, used only on wasm code
+    // objects

[Yang, 2016/03/03 06:21:56]

Can you change the comment to say "To relocate pointers into the wasm heap,
embedded in wasm code"? All reloc info are markers of some sort, so that part is
redundant.

[gdeepti1, 2016/03/03 18:00:10]

Done.

+    WASM_HEAP_OBJECT,

[titzer, 2016/03/03 18:11:59]

Can we name this WASM_MEMORY_REFERENCE?

We've been trying to avoid using the term "heap" to refer to the wasm memory.

[gdeepti1, 2016/03/03 22:59:15]

Done.

 
     // Everything after runtime_entry (inclusive) is not GC'ed.
     RUNTIME_ENTRY,
     COMMENT,
     POSITION,            // See comment for kNoPosition above.
     STATEMENT_POSITION,  // See comment for kNoPosition above.
 
     // Additional code inserted for debug break slot.
     DEBUG_BREAK_SLOT_AT_POSITION,
     DEBUG_BREAK_SLOT_AT_RETURN,
@@ skipping 22 matching lines @@
     // Pseudo-types
     NUMBER_OF_MODES,
     NONE32,             // never recorded 32-bit value
     NONE64,             // never recorded 64-bit value
     CODE_AGE_SEQUENCE,  // Not stored in RelocInfo array, used explictly by
                         // code aging.
 
     FIRST_REAL_RELOC_MODE = CODE_TARGET,
     LAST_REAL_RELOC_MODE = VENEER_POOL,
     LAST_CODE_ENUM = DEBUGGER_STATEMENT,
-    LAST_GCED_ENUM = CELL,
+    LAST_GCED_ENUM = WASM_HEAP_OBJECT,
   };
 
   STATIC_ASSERT(NUMBER_OF_MODES <= kBitsPerInt);
 
   explicit RelocInfo(Isolate* isolate) : isolate_(isolate) {
     DCHECK_NOT_NULL(isolate);
   }
 
   RelocInfo(Isolate* isolate, byte* pc, Mode rmode, intptr_t data, Code* host)
       : isolate_(isolate), pc_(pc), rmode_(rmode), data_(data), host_(host) {
@@ skipping 63 matching lines @@
   }
   static inline bool IsNone(Mode mode) {
     return mode == NONE32 || mode == NONE64;
   }
   static inline bool IsCodeAgeSequence(Mode mode) {
     return mode == CODE_AGE_SEQUENCE;
   }
   static inline bool IsGeneratorContinuation(Mode mode) {
     return mode == GENERATOR_CONTINUATION;
   }
+  static inline bool IsWasmCodeEntry(Mode mode) {

[Yang, 2016/03/03 06:21:56]

This name is misleading. I would have thought that this would be a pointer to
the entry of a wasm code object, instead into the wasm heap. How about
"IsWasmHeapReference"?

[gdeepti1, 2016/03/03 18:00:10]

Name was left over from a previous RelocInfo mode I was using, fixed to be
IsWasmHeapReference.

[titzer, 2016/03/03 18:11:59]

As above, IsWasmMemoryReference, for consistency.

+    return mode == WASM_HEAP_OBJECT;
+  }
   static inline int ModeMask(Mode mode) { return 1 << mode; }
 
   // Accessors
   Isolate* isolate() const { return isolate_; }
   byte* pc() const { return pc_; }
   void set_pc(byte* pc) { pc_ = pc; }
   Mode rmode() const {  return rmode_; }
   intptr_t data() const { return data_; }
   Code* host() const { return host_; }
   void set_host(Code* host) { host_ = host; }
@@ skipping 757 matching lines @@
     std::vector<ConstantPoolEntry> shared_entries;
   };
 
   Label emitted_label_;  // Records pc_offset of emitted pool
   PerTypeEntryInfo info_[ConstantPoolEntry::NUMBER_OF_TYPES];
 };
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_ASSEMBLER_H_