[PATCH 01/31] gdbserver: make linux target op 'cannot_store_register' a predicate function

[Tankut Baris Aktemur <tankut dot baris dot aktemur at intel dot com>]

The comment for the linux target op 'cannot_store_register' states the
following:

  /* Returns 0 if we can store the register, 1 if we can not
     store the register, and 2 if failure to store the register
     is acceptable.  */

There is only one low target, linux-ppc-low, that potentially returns
2.  There are two places that call the 'cannot_store_register' target
op in linux-low.cc.  None of these locations distinguish a '2' from a
'1'.  Hence, to simplify the definition, make the function a predicate
that returns either 0 or 1.  This is also consistent with the
companion function, 'cannot_fetch_register'.

gdbserver/ChangeLog:
2020-03-06  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* linux-low.h (struct linux_target_ops): Update the comment for
	'cannot_store_register' to return 0 or 1.
	* linux-ppc-low.cc (ppc_cannot_store_register): Return 1 instead
	of 2.
---
 gdbserver/linux-low.h      | 7 +++----
 gdbserver/linux-ppc-low.cc | 4 ++--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index b69ade98e41..aaf882b8c5b 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -135,11 +135,10 @@ struct linux_target_ops
   void (*arch_setup) (void);
 
   const struct regs_info *(*regs_info) (void);
-  int (*cannot_fetch_register) (int);
 
-  /* Returns 0 if we can store the register, 1 if we can not
-     store the register, and 2 if failure to store the register
-     is acceptable.  */
+  /* Return 0 if we can fetch/store the register, 1 if we cannot
+     fetch/store the register.  */
+  int (*cannot_fetch_register) (int);
   int (*cannot_store_register) (int);
 
   /* Hook to fetch a register in some non-standard way.  Used for
diff --git a/gdbserver/linux-ppc-low.cc b/gdbserver/linux-ppc-low.cc
index fd6d0369c48..f3837e47960 100644
--- a/gdbserver/linux-ppc-low.cc
+++ b/gdbserver/linux-ppc-low.cc
@@ -152,13 +152,13 @@ ppc_cannot_store_register (int regno)
   /* Some kernels do not allow us to store fpscr.  */
   if (!(ppc_hwcap & PPC_FEATURE_HAS_SPE)
       && regno == find_regno (tdesc, "fpscr"))
-    return 2;
+    return 1;
 #endif
 
   /* Some kernels do not allow us to store orig_r3 or trap.  */
   if (regno == find_regno (tdesc, "orig_r3")
       || regno == find_regno (tdesc, "trap"))
-    return 2;
+    return 1;
 
   return 0;
 }
-- 
2.17.1