[jit] Add a intrinsic for ThrowForUnsupportedVectorBaseType<T>. (dotn…

…et#39965)

Part of dotnet#38718.

src/mono/mono/mini/intrinsics.c

@@ -1948,6 +1948,34 @@ mini_emit_inst_for_method (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 		}
 	}
 
+	if (in_corlib &&
+		!strcmp ("System", cmethod_klass_name_space) &&
+		!strcmp ("ThrowHelper", cmethod_klass_name) &&
+		!strcmp ("ThrowForUnsupportedVectorBaseType", cmethod->name)) {
+		/* The mono JIT can't optimize the body of this method away */
+		MonoGenericContext *ctx = mono_method_get_context (cmethod);
+		g_assert (ctx);
+		g_assert (ctx->method_inst);
+
+		MonoType *t = ctx->method_inst->type_argv [0];
+		switch (t->type) {
+		case MONO_TYPE_I1:
+		case MONO_TYPE_U1:
+		case MONO_TYPE_I2:
+		case MONO_TYPE_U2:
+		case MONO_TYPE_I4:
+		case MONO_TYPE_U4:
+		case MONO_TYPE_I8:
+		case MONO_TYPE_U8:
+		case MONO_TYPE_R4:
+		case MONO_TYPE_R8:
+			MONO_INST_NEW (cfg, ins, OP_NOP);
+			MONO_ADD_INS (cfg->cbb, ins);
+			return ins;
+		default:
+			break;
+		}
+	}
 #endif
 
 	ins = mono_emit_native_types_intrinsics (cfg, cmethod, fsig, args);