Populate relocation information correctly for RelocatableInt32Constants.

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index e6429d98c931a8474f5927f177b21ba2d56a7fb6..9777c799a5dd13bf5a68ee1b1901cdba80976ef6 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -2458,7 +2458,11 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
             if (value == 0) {
               __ xorl(dst, dst);
             } else {
-              __ movl(dst, Immediate(value));
+              if (src.rmode() == RelocInfo::WASM_MEMORY_SIZE_REFERENCE) {

[titzer, 2016/08/26 08:21:10]

Why not if src.rmode() != RelocInfo::kNone?

[gdeepti, 2016/08/30 08:53:05]

My rationale for this is that it should be a deliberate choice between movl and
movq based on rmode. In this case a movl should suffice because memory size will
not exceed 32 bits, but for regular memory references there should be no such
restriction on x64 and should fall into the if statement above because after
patching the memory reference can exceed the space movl allocates. I've found
that missing RelocInfo is easier to debug than bugs in generated code because
enough space hasn't been allocated. 

The other option is to have the default be a movq with non zero rmode instead of
movl that swallows the rmode - I can change it to that if that is better.      

+                __ movl(dst, Immediate(value, src.rmode()));
+              } else {
+                __ movl(dst, Immediate(value));
+              }
             }
           }
           break;