Assembler changes for enabling GrowHeap in Wasm

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index 45f50b9ea28e269a89c0a41bb4be0a5bd87ab70b..b0199abecf7b2e93204e42f4b293a58489302984 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -385,6 +385,8 @@ class RelocInfo {
     DEBUGGER_STATEMENT,  // Code target for the debugger statement.
     EMBEDDED_OBJECT,
     CELL,
+    // To relocate pointers into the wasm heap embedded in wasm code

[titzer, 2016/03/07 19:39:23]

s/wasm heap/wasm memory/

[gdeepti1, 2016/03/08 03:38:50]

Done.

+    WASM_MEMORY_REFERENCE,
 
     // Everything after runtime_entry (inclusive) is not GC'ed.
     RUNTIME_ENTRY,
@@ -427,7 +429,7 @@ class RelocInfo {
     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_MEMORY_REFERENCE,
   };
 
   STATIC_ASSERT(NUMBER_OF_MODES <= kBitsPerInt);
@@ -511,6 +513,9 @@ class RelocInfo {
   static inline bool IsGeneratorContinuation(Mode mode) {
     return mode == GENERATOR_CONTINUATION;
   }
+  static inline bool IsWasmMemoryReference(Mode mode) {
+    return mode == WASM_MEMORY_REFERENCE;
+  }
   static inline int ModeMask(Mode mode) { return 1 << mode; }
 
   // Accessors
@@ -571,6 +576,10 @@ class RelocInfo {
                                 ICacheFlushMode icache_flush_mode =
                                     FLUSH_ICACHE_IF_NEEDED));
 
+  INLINE(Address wasm_memory_reference());
+  INLINE(void update_wasm_memory_reference(

[titzer, 2016/03/07 19:39:23]

As per previous comments, let's do an update interface like:

void update_wasm_memory_reference(
  Address old_base,
  Address new_base,
  size_t old_size,
  size_t new_size,
  ICacheFlushMode mode)

Then we can keep the relative calculation hidden inside and even assert that the
old_base was within the old bounds.

[gdeepti1, 2016/03/08 03:38:50]

Misunderstood previous review comment, updated the interface now as above with
additional checks.

+      Address reference,
+      ICacheFlushMode icache_flush_mode = SKIP_ICACHE_FLUSH));
   // Returns the address of the constant pool entry where the target address
   // is held.  This should only be called if IsInConstantPool returns true.
   INLINE(Address constant_pool_entry_address());