Add dedicated interpreter opcodes for tailcalls and generate them

Author: kg

src/coreclr/interpreter/compiler.cpp

@@ -3074,7 +3074,7 @@ void InterpCompiler::EmitCall(CORINFO_RESOLVED_TOKEN* pConstrainedToken, bool re
             }
             else if (isCalli)
             {
-                AddIns(INTOP_CALLI);
+                AddIns(tailcall ? INTOP_CALLI_TAIL : INTOP_CALLI);
                 m_pLastNewIns->data[0] = GetDataItemIndex(calliCookie);
                 m_pLastNewIns->SetSVars2(CALL_ARGS_SVAR, callIFunctionPointerVar);
             }
@@ -3092,6 +3092,11 @@ void InterpCompiler::EmitCall(CORINFO_RESOLVED_TOKEN* pConstrainedToken, bool re
                     assert(!isPInvoke && !isMarshaledPInvoke);
                     AddIns(INTOP_CALLDELEGATE);
                 }
+                else if (tailcall)
+                {
+                    assert(!isPInvoke && !isMarshaledPInvoke);
+                    AddIns(INTOP_CALL_TAIL);
+                }
                 else
                 {
                     AddIns((isPInvoke && !isMarshaledPInvoke) ? INTOP_CALL_PINVOKE : INTOP_CALL);
@@ -3128,14 +3133,14 @@ void InterpCompiler::EmitCall(CORINFO_RESOLVED_TOKEN* pConstrainedToken, bool re
 
             calliCookie = m_compHnd->GetCookieForInterpreterCalliSig(&callInfo.sig);
 
-            AddIns(INTOP_CALLI);
+            AddIns(tailcall ? INTOP_CALLI_TAIL : INTOP_CALLI);
             m_pLastNewIns->data[0] = GetDataItemIndex(calliCookie);
             m_pLastNewIns->SetSVars2(CALL_ARGS_SVAR, codePointerLookupResult);
             break;
         }
         case CORINFO_VIRTUALCALL_VTABLE:
             // Traditional virtual call. In theory we could optimize this to using the vtable
-            AddIns(INTOP_CALLVIRT);
+            AddIns(tailcall ? INTOP_CALLVIRT_TAIL : INTOP_CALLVIRT);
             m_pLastNewIns->data[0] = GetDataItemIndex(callInfo.hMethod);
             break;
 
@@ -3163,13 +3168,13 @@ void InterpCompiler::EmitCall(CORINFO_RESOLVED_TOKEN* pConstrainedToken, bool re
 
                 calliCookie = m_compHnd->GetCookieForInterpreterCalliSig(&callInfo.sig);
 
-                AddIns(INTOP_CALLI);
+                AddIns(tailcall ? INTOP_CALLI_TAIL : INTOP_CALLI);
                 m_pLastNewIns->data[0] = GetDataItemIndex(calliCookie);
                 m_pLastNewIns->SetSVars2(CALL_ARGS_SVAR, synthesizedLdvirtftnPtrVar);
             }
             else
             {
-                AddIns(INTOP_CALLVIRT);
+                AddIns(tailcall ? INTOP_CALLVIRT_TAIL : INTOP_CALLVIRT);
                 m_pLastNewIns->data[0] = GetDataItemIndex(callInfo.hMethod);
             }
             break;

src/coreclr/interpreter/intops.def

@@ -365,6 +365,11 @@ OPDEF(INTOP_NEWOBJ, "newobj", 5, 1, 1, InterpOpMethodHandle)
 OPDEF(INTOP_NEWOBJ_GENERIC, "newobj.generic", 6, 1, 2, InterpOpMethodHandle)
 OPDEF(INTOP_NEWOBJ_VT, "newobj.vt", 5, 1, 1, InterpOpMethodHandle)
 
+// Tail calls
+OPDEF(INTOP_CALL_TAIL, "call.tail", 4, 1, 1, InterpOpMethodHandle)
+OPDEF(INTOP_CALLI_TAIL, "calli", 5, 1, 2, InterpOpLdPtr)
+OPDEF(INTOP_CALLVIRT_TAIL, "callvirt.tail", 4, 1, 1, InterpOpMethodHandle)
+
 // The following helper call instructions exist in 2 variants, one for normal methods, and one for cases where a shared generic lookup is needed.
 // In the case where a shared generic lookup is needed an extra argument is passed as an svar, which is a pointer to the generic context.
 // If there is a generic context argument it is always the first SVar to the instruction.