[PATCH v2 08/11] gdbserver: use REG_UNKNOWN for a regcache's register statuses

[Tankut Baris Aktemur]

When a regcache is initialized, the values of registers are not
fetched yet.  Thus, initialize the register statuses to REG_UNKNOWN
instead of REG_UNAVAILABLE, because the latter rather means "we
attempted to fetch but could not obtain the value".

The definitions of the reg status enums (from
gdbsupport/common-regcache.h) as a reminder:

    /* The register value is not in the cache, and we don't know yet
       whether it's available in the target (or traceframe).  */
    REG_UNKNOWN = 0,

    /* The register value is valid and cached.  */
    REG_VALID = 1,

    /* The register value is unavailable.  E.g., we're inspecting a
       traceframe, and this register wasn't collected.  Note that this
       "unavailable" is different from saying the register does not
       exist in the target's architecture --- in that case, the target
       should have given us a target description that does not include
       the register in the first place.  */
    REG_UNAVAILABLE = -1

Similarly, when the regcache is invalidated, change all the statuses
back to REG_UNKNOWN.
---
 gdbserver/regcache.cc | 4 ++--
 gdbserver/regcache.h  | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc
index eab6bdcfc86124c25013c565c5432c98dfc27500..03e975dc00154d01798765273534ca9cdcdc7eb7 100644
--- a/gdbserver/regcache.cc
+++ b/gdbserver/regcache.cc
@@ -52,7 +52,7 @@ get_thread_regcache (thread_info *thread, bool fetch)
 
       switch_to_thread (thread);
       /* Invalidate all registers, to prevent stale left-overs.  */
-      memset (regcache->register_status, REG_UNAVAILABLE,
+      memset (regcache->register_status, REG_UNKNOWN,
 	      regcache->tdesc->reg_defs.size ());
       fetch_inferior_registers (regcache, -1);
       regcache->registers_fetched = true;
@@ -142,7 +142,7 @@ regcache::regcache (const target_desc *tdesc)
   this->registers_owned = true;
   this->register_status
     = (unsigned char *) xmalloc (tdesc->reg_defs.size ());
-  memset ((void *) this->register_status, REG_UNAVAILABLE,
+  memset ((void *) this->register_status, REG_UNKNOWN,
 	  tdesc->reg_defs.size ());
 }
 
diff --git a/gdbserver/regcache.h b/gdbserver/regcache.h
index 08c2ddd04e1307e0493b45a944bd30b762b0663b..f3e99de443b884e13b02c8d858ea9e6ee668700f 100644
--- a/gdbserver/regcache.h
+++ b/gdbserver/regcache.h
@@ -43,7 +43,7 @@ struct regcache : public reg_buffer_common
   bool registers_owned = false;
   unsigned char *registers = nullptr;
 #ifndef IN_PROCESS_AGENT
-  /* One of REG_UNAVAILABLE or REG_VALID.  */
+  /* See gdbsupport/common-regcache.h.  */
   unsigned char *register_status = nullptr;
 
   /* Constructors.  */

-- 
2.34.1

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