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,
+    // 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,
     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_MEMORY_REFERENCE,
   };
 
   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 IsWasmMemoryReference(Mode mode) {
+    return mode == WASM_MEMORY_REFERENCE;
+  }
   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 40 matching lines @@
                               WriteBarrierMode write_barrier_mode =
                                   UPDATE_WRITE_BARRIER,
                               ICacheFlushMode icache_flush_mode =
                                   FLUSH_ICACHE_IF_NEEDED));
   INLINE(Handle<Object> code_age_stub_handle(Assembler* origin));
   INLINE(Code* code_age_stub());
   INLINE(void set_code_age_stub(Code* stub,
                                 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());
 
   // Read the address of the word containing the target_address in an
   // instruction stream.  What this means exactly is architecture-independent.
   // The only architecture-independent user of this function is the serializer.
   // The serializer uses it to find out how many raw bytes of instruction to
   // output before the next target.  Architecture-independent code shouldn't
   // dereference the pointer it gets back from this.
@@ skipping 713 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_