aarch64: Prevent use of SIMD fcvtz[su] instruction variant with "nosimd"

Currently, SF->SI and DF->DI conversions on Aarch64 with the "nosimd"
flag provided sometimes cause the emitting of a vector variant of the
fcvtz[su] instruction (e.g. fcvtzu s0, s0).

This modifies the corresponding pattern to only select the vector
variant of the instruction when generating code with SIMD enabled.

gcc/ChangeLog:

	* config/aarch64/aarch64.md
	(<optab>_trunc<fcvt_target><GPI:mode>2): Set the "arch"
	attribute to disambiguate between SIMD and FP variants of the
	instruction.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/fcvt_nosimd.c: New test.

gcc/config/aarch64/aarch64.md

@@ -5989,7 +5989,8 @@
   "@
    fcvtz<su>\t%<s>0, %<s>1
    fcvtz<su>\t%<w>0, %<s>1"
-  [(set_attr "type" "neon_fp_to_int_s,f_cvtf2i")]
+  [(set_attr "type" "neon_fp_to_int_s,f_cvtf2i")
+   (set_attr "arch" "simd,fp")]
 )
 
 ;; Convert HF -> SI or DI

gcc/testsuite/gcc.target/aarch64/fcvt_nosimd.c

@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-march=armv8-a+nosimd" } */
+
+#include <stdint.h>
+
+uint64_t test_double_to_uint64(double x) {
+  return (uint64_t)x;
+}
+
+int64_t test_double_to_int64(double x) {
+  return (int64_t)x;
+}
+
+uint32_t test_float_to_uint32(float x) {
+  return (uint32_t)x;
+}
+
+int32_t test_float_to_int32(float x) {
+  return (int32_t)x;
+}
+
+/* { dg-final { scan-assembler-not {\tfcvtz[su]\td[0-9]*, d[0-9]*} } } */
+/* { dg-final { scan-assembler-not {\tfcvtz[su]\ts[0-9]*, s[0-9]*} } } */