AArch64: Have -mcpu=native and -march=native enable extensions when CPU is unknown

Currently when using -mcpu=native or -march=native on a CPU that is unknown to
the compiler the compiler currently just used -march=armv8-a and enables none
of the extensions.

To make this a bit more useful this patch changes it to still use -march=armv8.a
but to enable the extensions.  We still cannot do tuning but at least if using
this on a future SVE core the compiler will at the very least enable SVE etc.

gcc/ChangeLog:

	* config/aarch64/driver-aarch64.c (DEFAULT_ARCH): New.
	(host_detect_local_cpu): Use it.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/cpunative/info_16: New test.
	* gcc.target/aarch64/cpunative/info_17: New test.
	* gcc.target/aarch64/cpunative/native_cpu_16.c: New test.
	* gcc.target/aarch64/cpunative/native_cpu_17.c: New test.

5 files changed, 52 insertions, 2 deletions

diff --git a/gcc/config/aarch64/driver-aarch64.c b/gcc/config/aarch64/driver-aarch64.c
index e2935a1..b58591d 100644
--- a/gcc/config/aarch64/driver-aarch64.c
+++ b/gcc/config/aarch64/driver-aarch64.c
@@ -58,6 +58,8 @@ struct aarch64_core_data
 #define INVALID_IMP ((unsigned char) -1)
 #define INVALID_CORE ((unsigned)-1)
 #define ALL_VARIANTS ((unsigned)-1)
+/* Default architecture to use if -mcpu=native did not detect a known CPU.  */
+#define DEFAULT_ARCH "8A"
 
 #define AARCH64_CORE(CORE_NAME, CORE_IDENT, SCHED, ARCH, FLAGS, COSTS, IMP, PART, VARIANT) \
   { CORE_NAME, #ARCH, IMP, PART, VARIANT, FLAGS },
@@ -390,10 +392,18 @@ host_detect_local_cpu (int argc, const char **argv)
             && (aarch64_cpu_data[i].variant == ALL_VARIANTS
                 || variants[0] == aarch64_cpu_data[i].variant))
 	  break;
+
       if (aarch64_cpu_data[i].name == NULL)
-        goto not_found;
+	{
+	  aarch64_arch_driver_info* arch_info
+	    = get_arch_from_id (DEFAULT_ARCH);
+
+	  gcc_assert (arch_info);
 
-      if (arch)
+	  res = concat ("-march=", arch_info->name, NULL);
+	  default_flags = arch_info->flags;
+	}
+      else if (arch)
 	{
 	  const char *arch_id = aarch64_cpu_data[i].arch;
 	  aarch64_arch_driver_info* arch_info = get_arch_from_id (arch_id);
diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/info_16 b/gcc/testsuite/gcc.target/aarch64/cpunative/info_16
new file mode 100644
index 0000000..b067957
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/cpunative/info_16
@@ -0,0 +1,8 @@
+processor	: 0
+BogoMIPS	: 100.00
+Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 asimddp sve sve2
+CPU implementer	: 0xff
+CPU architecture: 8
+CPU variant	: 0x0
+CPU part	: 0xd08
+CPU revision	: 2
diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/info_17 b/gcc/testsuite/gcc.target/aarch64/cpunative/info_17
new file mode 100644
index 0000000..b067957
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/cpunative/info_17
@@ -0,0 +1,8 @@
+processor	: 0
+BogoMIPS	: 100.00
+Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 asimddp sve sve2
+CPU implementer	: 0xff
+CPU architecture: 8
+CPU variant	: 0x0
+CPU part	: 0xd08
+CPU revision	: 2
diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_16.c b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_16.c
new file mode 100644
index 0000000..a424e7c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_16.c
@@ -0,0 +1,12 @@
+/* { dg-do compile { target { { aarch64*-*-linux*} && native } } } */
+/* { dg-set-compiler-env-var GCC_CPUINFO "$srcdir/gcc.target/aarch64/cpunative/info_16" } */
+/* { dg-additional-options "-mcpu=native" } */
+
+int main()
+{
+  return 0;
+}
+
+/* { dg-final { scan-assembler {\.arch armv8-a\+crypto\+crc\+dotprod\+sve2} } } */
+
+/* Test a normal looking procinfo.  */
diff --git a/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_17.c b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_17.c
new file mode 100644
index 0000000..c269c5f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/cpunative/native_cpu_17.c
@@ -0,0 +1,12 @@
+/* { dg-do compile { target { { aarch64*-*-linux*} && native } } } */
+/* { dg-set-compiler-env-var GCC_CPUINFO "$srcdir/gcc.target/aarch64/cpunative/info_17" } */
+/* { dg-additional-options "-march=native" } */
+
+int main()
+{
+  return 0;
+}
+
+/* { dg-final { scan-assembler {\.arch armv8-a\+crypto\+crc\+dotprod\+sve2} } } */
+
+/* Test a normal looking procinfo.  */