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

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 0ce714db0915fa077e943853ede217ce6c69babc..f5f858e9e26e9501b8fb05f77d11d8f525f5e6e9 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -334,13 +334,20 @@ enum RoundingMode {
 class Immediate BASE_EMBEDDED {
  public:
   explicit Immediate(int32_t value) : value_(value) {}
+  explicit Immediate(Address value, RelocInfo::Mode rmode) {
+    value_ = static_cast<int32_t>(reinterpret_cast<intptr_t>(value));

[Yang, 2016/03/07 06:21:22]

Is this useful at all? Any address that you pass in here will be truncated to
32-bit. This would only make sense for x32, and I'm not sure x32 even works at
this point.

[titzer, 2016/03/07 19:34:09]

Yeah, I don't think we can allow addresses as immediates here.

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

Fixed to not use Address -
https://codereview.chromium.org/1759873002/diff/180001/src/x64/assembler-x64.h
It works on ia32 and x64 because for both the Immediate class is only used for
32-bit values, movq on x64 with the 64-bit case is handled separately. 

+    rmode_ = rmode;
+  }
   explicit Immediate(Smi* value) {
     DCHECK(SmiValuesAre31Bits());  // Only available for 31-bit SMI.
     value_ = static_cast<int32_t>(reinterpret_cast<intptr_t>(value));
   }
 
+  RelocInfo::Mode rmode() { return rmode_; }
+
  private:
   int32_t value_;
+  RelocInfo::Mode rmode_ = RelocInfo::NONE32;
 
   friend class Assembler;
 };
@@ -699,8 +706,10 @@ class Assembler : public AssemblerBase {
   void movp(Register dst, void* ptr, RelocInfo::Mode rmode);
 
   // Loads a 64-bit immediate into a register.
-  void movq(Register dst, int64_t value);
-  void movq(Register dst, uint64_t value);
+  void movq(Register dst, int64_t value,
+            RelocInfo::Mode rmode = RelocInfo::NONE64);
+  void movq(Register dst, uint64_t value,
+            RelocInfo::Mode rmode = RelocInfo::NONE64);
 
   void movsxbl(Register dst, Register src);
   void movsxbl(Register dst, const Operand& src);
@@ -1744,7 +1753,12 @@ class Assembler : public AssemblerBase {
                                RelocInfo::Mode rmode,
                                TypeFeedbackId ast_id = TypeFeedbackId::None());
   inline void emit_runtime_entry(Address entry, RelocInfo::Mode rmode);
-  void emit(Immediate x) { emitl(x.value_); }
+  void emit(Immediate x) {
+    if (!RelocInfo::IsNone(x.rmode_)) {
+      RecordRelocInfo(x.rmode_);
+    }
+    emitl(x.value_);
+  }
 
   // Emits a REX prefix that encodes a 64-bit operand size and
   // the top bit of both register codes.