[compiler] Add relocatable pointer constants for wasm memory references.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index c11882405a25dd93bfcf9fcf0677c4e3bba00b99..10c0b58ed8336109b0463b0f6dd34abcf3bb66b2 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -838,6 +838,8 @@ const char* RelocInfo::RelocModeName(RelocInfo::Mode rmode) {
       return "code age sequence";
     case GENERATOR_CONTINUATION:
       return "generator continuation";
+    case WASM_MEMORY_REFERENCE:

[bradnelson, 2016/03/06 21:53:14]

Have you thought about what you'll want to call the heap size? WASM_MEMORY_SIZE?
I figure you'll be back through some of these for this purpose, so it might be
worth thinking about.

Actually, given that will touch many of the same spots, did you want to consider
adding the heap size in the same change?

[gdeepti1, 2016/03/08 04:22:51]

I was thinking about calling it WASM_MEMORY_SIZE. I want to keep it separate
from this change mostly because I'm a little fuzzy on exactly what is needed for
memory size. Specifically about what needs to be done for wasm if the
update_wasm_memory_reference takes care of bounds check and if anything needs to
be added for the asm.js CheckedLoad/Store semantics. 

+      return "wasm memory reference";
     case NUMBER_OF_MODES:
     case PC_JUMP:
       UNREACHABLE();
@@ -931,6 +933,7 @@ void RelocInfo::Verify(Isolate* isolate) {
     case DEBUG_BREAK_SLOT_AT_RETURN:
     case DEBUG_BREAK_SLOT_AT_CALL:
     case GENERATOR_CONTINUATION:
+    case WASM_MEMORY_REFERENCE:
     case NONE32:
     case NONE64:
       break;