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

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 7f64dce978bd6bc9c2f6631c7f569ab37db7fe96..bc6a241419103273b96c5ed8b3b9145fddb62af5 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -947,9 +947,12 @@ class Constant final {
   explicit Constant(Handle<HeapObject> obj)
       : type_(kHeapObject), value_(bit_cast<intptr_t>(obj)) {}
   explicit Constant(RpoNumber rpo) : type_(kRpoNumber), value_(rpo.ToInt()) {}
+  explicit Constant(RelocatablePtrConstantInfo info);
 
   Type type() const { return type_; }
 
+  RelocInfo::Mode rmode() const { return rmode_; }
+
   int32_t ToInt32() const {
     DCHECK(type() == kInt32 || type() == kInt64);
     const int32_t value = static_cast<int32_t>(value_);
@@ -992,6 +995,11 @@ class Constant final {
  private:
   Type type_;
   int64_t value_;
+#if V8_TARGET_ARCH_32_BIT
+  RelocInfo::Mode rmode_ = RelocInfo::NONE32;
+#else
+  RelocInfo::Mode rmode_ = RelocInfo::NONE64;
+#endif
 };