[mono] Fix Vector<T>.IsSupported intrinsic (#90023)

Fixes #88983
---------

Co-authored-by: Larry Ewing <lewing@microsoft.com>

src/mono/mono/mini/intrinsics.c

@@ -2141,58 +2141,20 @@ mini_emit_inst_for_method (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 		!strcmp ("System", cmethod_klass_name_space) &&
 		!strcmp ("ThrowHelper", cmethod_klass_name)) {
 
-		if (!strcmp ("ThrowForUnsupportedNumericsVectorBaseType", cmethod->name)) {
+		if (!strcmp ("ThrowForUnsupportedNumericsVectorBaseType", cmethod->name) ||
+			!strcmp ("ThrowForUnsupportedIntrinsicsVector64BaseType", cmethod->name) ||
+			!strcmp ("ThrowForUnsupportedIntrinsicsVector128BaseType", cmethod->name) ||
+			!strcmp ("ThrowForUnsupportedIntrinsicsVector256BaseType", 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:
-			case MONO_TYPE_I:
-			case MONO_TYPE_U:
-				MONO_INST_NEW (cfg, ins, OP_NOP);
-				MONO_ADD_INS (cfg->cbb, ins);
-				return ins;
-			default:
-				break;
-			}
-		}
-		else if (!strcmp ("ThrowForUnsupportedIntrinsicsVector64BaseType", cmethod->name) ||
-			 !strcmp ("ThrowForUnsupportedIntrinsicsVector128BaseType", cmethod->name) ||
-			 !strcmp ("ThrowForUnsupportedIntrinsicsVector256BaseType", 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:
+			if (MONO_TYPE_IS_VECTOR_PRIMITIVE (t)) {
 				MONO_INST_NEW (cfg, ins, OP_NOP);
 				MONO_ADD_INS (cfg->cbb, ins);
 				return ins;
-			default:
-				break;
 			}
 		}
 	}

src/mono/mono/mini/simd-intrinsics.c

@@ -2410,8 +2410,8 @@ emit_vector64_vector128_t (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 
 	MonoClass *klass = cmethod->klass;
 	MonoType *etype = mono_class_get_context (klass)->class_inst->type_argv [0];
-	gboolean supported = TRUE;
 
+	// Apart from filtering out non-primitive types this also filters out shared generic instance types like: T_BYTE which cannot be intrinsified
 	if (!MONO_TYPE_IS_VECTOR_PRIMITIVE (etype))
 		return NULL;
 
@@ -2428,9 +2428,17 @@ emit_vector64_vector128_t (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 		g_free (name);
 	}
 
+	// Special case SN_get_IsSupported intrinsic handling in this function which verifies whether a type parameter T is supported for a generic vector.
+	// As we got passed the MONO_TYPE_IS_VECTOR_PRIMITIVE check above, this should always return true for primitive types.
+	if (id == SN_get_IsSupported) {
+		MonoInst *ins = NULL;
+		EMIT_NEW_ICONST (cfg, ins, 1);
+		return ins;
+	}
+
 #if defined(TARGET_WASM)
 	if (!COMPILE_LLVM (cfg))
-		supported = FALSE;
+		return NULL;
 #endif
 
 // FIXME: Support Vector64 for mini JIT on arm64
@@ -2441,25 +2449,12 @@ emit_vector64_vector128_t (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
 
 #ifdef TARGET_AMD64
 	if (!COMPILE_LLVM (cfg) && (size != 16))
-		supported = FALSE;
+		return NULL;
 #ifdef TARGET_WIN32
-		supported = FALSE;
+		return NULL;
 #endif
 #endif
 
-	switch (id) {
-	case SN_get_IsSupported: {
-		MonoInst *ins = NULL;
-		EMIT_NEW_ICONST (cfg, ins, supported ? 1 : 0);
-		return ins;
-	}
-	default:
-		break;
-	}
-
-	if (!supported)
-		return NULL;
-
 	switch (id) {
 	case SN_get_Count: {
 		MonoInst *ins = NULL;