Support IAT_PVALUE string literals in the interpreter (#119011)

* Support IAT_PVALUE string literals in the interpreter
* Remove LDIND_O

Author: kg

src/coreclr/interpreter/compiler.cpp

@@ -3898,13 +3898,32 @@ void InterpCompiler::GenerateCode(CORINFO_METHOD_INFO* methodInfo)
                 int32_t token = getI4LittleEndian(m_ip + 1);
                 void *str;
                 InfoAccessType accessType = m_compHnd->constructStringLiteral(m_compScopeHnd, token, &str);
-                DeclarePointerIsString(str);
-                assert(accessType == IAT_VALUE);
                 // str should be forever pinned, so we can include its ref inside interpreter code
                 AddIns(INTOP_LDPTR);
+                m_pLastNewIns->data[0] = GetDataItemIndex(str);
+
+                if (accessType == IAT_PVALUE)
+                {
+                    // IAT_PVALUE means str is a `ref string` not a `String` so the LDPTR produced an I
+                    PushInterpType(InterpTypeI, nullptr);
+                    int tempVar = m_pStackPointer[-1].var;
+                    m_pLastNewIns->SetDVar(tempVar);
+
+                    // Now we generate an LDIND_I to get the actual string out of the ref
+                    AddIns(INTOP_LDIND_I);
+                    // LDIND offset
+                    m_pLastNewIns->data[0] = 0;
+                    m_pLastNewIns->SetSVar(tempVar);
+                    m_pStackPointer--;
+                }
+                else
+                {
+                    assert(accessType == IAT_VALUE);
+                    DeclarePointerIsString(str);
+                }
+
                 PushInterpType(InterpTypeO, m_compHnd->getBuiltinClass(CLASSID_STRING));
                 m_pLastNewIns->SetDVar(m_pStackPointer[-1].var);
-                m_pLastNewIns->data[0] = GetDataItemIndex(str);
                 m_ip += 5;
                 break;
             }

src/coreclr/interpreter/intops.def

@@ -338,7 +338,7 @@ OPDEF(INTOP_LDIND_I4, "ldind.i4", 4, 1, 1, InterpOpInt)
 OPDEF(INTOP_LDIND_I8, "ldind.i8", 4, 1, 1, InterpOpInt)
 OPDEF(INTOP_LDIND_R4, "ldind.r4", 4, 1, 1, InterpOpInt)
 OPDEF(INTOP_LDIND_R8, "ldind.r8", 4, 1, 1, InterpOpInt)
-OPDEF(INTOP_LDIND_O, "ldind.o", 4, 1, 1, InterpOpInt)
+// No LDIND_O, use LDIND_I
 OPDEF(INTOP_LDIND_VT, "ldind.vt", 5, 1, 1, InterpOpTwoInts)
 
 OPDEF(INTOP_STIND_I1, "stind.i1", 4, 0, 2, InterpOpInt)