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

src/compiler/instruction.cc

Index: src/compiler/instruction.cc
diff --git a/src/compiler/instruction.cc b/src/compiler/instruction.cc
index c757557a0d750e97fa3ef9439679e09d280e1766..d43d669007263c7a2e5d3f43ce9e77d7b97e205c 100644
--- a/src/compiler/instruction.cc
+++ b/src/compiler/instruction.cc
@@ -504,6 +504,14 @@ std::ostream& operator<<(std::ostream& os,
 
 Constant::Constant(int32_t v) : type_(kInt32), value_(v) {}
 
+Constant::Constant(RelocatablePtrConstantInfo info)
+#ifdef V8_HOST_ARCH_32_BIT
+    : type_(kInt32), value_(info.value()), rmode_(info.rmode()) {
+}
+#else
+    : type_(kInt64), value_(info.value()), rmode_(info.rmode()) {
+}
+#endif
 
 std::ostream& operator<<(std::ostream& os, const Constant& constant) {
   switch (constant.type()) {