Enable SVE for GDB

Enable SVE support for GDB by reading the VQ when creating a
target description.

Also ensurse that SVE is taken into account when creating
the tdep structure, and store the current VQ value directly in tdep.

gdb/
	* aarch64-linux-nat.c (aarch64_linux_read_description): Support SVE.
	* aarch64-tdep.c (aarch64_get_tdesc_vq): New function.
	(aarch64_gdbarch_init): Check for SVE.
	* aarch64-tdep.h (gdbarch_tdep::has_sve): New function.

1 files changed, 9 insertions, 0 deletions

diff --git a/gdb/aarch64-tdep.h b/gdb/aarch64-tdep.h
index e41a5972d2e..b6b9b30e715 100644
--- a/gdb/aarch64-tdep.h
+++ b/gdb/aarch64-tdep.h
@@ -73,6 +73,15 @@ struct gdbarch_tdep
 
   /* syscall record.  */
   int (*aarch64_syscall_record) (struct regcache *regcache, unsigned long svc_number);
+
+  /* The VQ value for SVE targets, or zero if SVE is not supported.  */
+  long vq;
+
+  /* Returns true if the target supports SVE.  */
+  bool has_sve () const
+  {
+    return vq != 0;
+  }
 };
 
 const target_desc *aarch64_read_description (uint64_t vq);