[AArch64] Handle W registers as pseudo-registers instead of aliases of X registers

The aarch64 port handles W registers as aliases of X registers. This is
incorrect because X registers are 64-bit and W registers are 32-bit.

This patch teaches GDB how to handle W registers as pseudo-registers of
32-bit, the bottom half of the X registers.

Testcase included.

1 files changed, 4 insertions, 0 deletions

diff --git a/gdb/aarch64-tdep.h b/gdb/aarch64-tdep.h
index d8513023c37..55ccf2e777d 100644
--- a/gdb/aarch64-tdep.h
+++ b/gdb/aarch64-tdep.h
@@ -118,6 +118,10 @@ struct aarch64_gdbarch_tdep : gdbarch_tdep_base
   {
     return tls_regnum != -1;
   }
+
+  /* The W pseudo-registers.  */
+  int w_pseudo_base = 0;
+  int w_pseudo_count = 0;
 };
 
 const target_desc *aarch64_read_description (const aarch64_features &features);