gdbserver: by-pass regcache to access tdesc only

The `get_thread_regcache` function has a `fetch` option to skip
fetching the registers from the target.  It seems this option is set
to false only at uses where we just need to access the tdesc through
the regcache of the current thread, as in

  struct regcache *regcache = get_thread_regcache (current_thread, 0);
  ... regcache->tdesc ...

Since the tdesc of a regcache is set from the process of the thread
that owns the regcache, we can simplify the code to access the tdesc
via the process, as in

  ... current_process ()->tdesc ...

This is intended to be a refactoring with no behavioral change.

Tested only for the linux-x86-low target.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

3 files changed, 9 insertions, 22 deletions

diff --git a/gdbserver/linux-ppc-low.cc b/gdbserver/linux-ppc-low.cc
index b9d00b1..d3c8667 100644
--- a/gdbserver/linux-ppc-low.cc
+++ b/gdbserver/linux-ppc-low.cc
@@ -1607,8 +1607,7 @@ ppc_target::install_fast_tracepoint_jump_pad (CORE_ADDR tpoint,
   const CORE_ADDR entryaddr = *jump_entry;
   int rsz, min_frame, frame_size, tp_reg;
 #ifdef __powerpc64__
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-  int is_64 = register_size (regcache->tdesc, 0) == 8;
+  int is_64 = register_size (current_process ()->tdesc, 0) == 8;
   int is_opd = is_64 && !is_elfv2_inferior ();
 #else
   int is_64 = 0, is_opd = 0;
@@ -3379,9 +3378,7 @@ emit_ops *
 ppc_target::emit_ops ()
 {
 #ifdef __powerpc64__
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-
-  if (register_size (regcache->tdesc, 0) == 8)
+  if (register_size (current_process ()->tdesc, 0) == 8)
     {
       if (is_elfv2_inferior ())
 	return &ppc64v2_emit_ops_impl;
@@ -3397,8 +3394,7 @@ ppc_target::emit_ops ()
 int
 ppc_target::get_ipa_tdesc_idx ()
 {
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-  const struct target_desc *tdesc = regcache->tdesc;
+  const target_desc *tdesc = current_process ()->tdesc;
 
 #ifdef __powerpc64__
   if (tdesc == tdesc_powerpc_64l)
diff --git a/gdbserver/linux-s390-low.cc b/gdbserver/linux-s390-low.cc
index a91c77f..cd874f6 100644
--- a/gdbserver/linux-s390-low.cc
+++ b/gdbserver/linux-s390-low.cc
@@ -796,9 +796,7 @@ s390_target::low_get_thread_area (int lwpid, CORE_ADDR *addrp)
 {
   CORE_ADDR res = ptrace (PTRACE_PEEKUSER, lwpid, (long) PT_ACR0, (long) 0);
 #ifdef __s390x__
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-
-  if (register_size (regcache->tdesc, 0) == 4)
+  if (register_size (current_process ()->tdesc, 0) == 4)
     res &= 0xffffffffull;
 #endif
   *addrp = res;
@@ -1286,8 +1284,7 @@ s390_target::install_fast_tracepoint_jump_pad
   unsigned char jbuf[6] = { 0xc0, 0xf4, 0, 0, 0, 0 };	/* jg ... */
   CORE_ADDR buildaddr = *jump_entry;
 #ifdef __s390x__
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-  int is_64 = register_size (regcache->tdesc, 0) == 8;
+  int is_64 = register_size (current_process ()->tdesc, 0) == 8;
   int is_zarch = is_64 || have_hwcap_s390_high_gprs;
   int has_vx = have_hwcap_s390_vx;
 #else
@@ -1451,8 +1448,7 @@ s390_target::get_min_fast_tracepoint_insn_len ()
 int
 s390_target::get_ipa_tdesc_idx ()
 {
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-  const struct target_desc *tdesc = regcache->tdesc;
+  const target_desc *tdesc = current_process ()->tdesc;
 
 #ifdef __s390x__
   if (tdesc == tdesc_s390x_linux64)
@@ -2839,9 +2835,7 @@ emit_ops *
 s390_target::emit_ops ()
 {
 #ifdef __s390x__
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-
-  if (register_size (regcache->tdesc, 0) == 8)
+  if (register_size (current_process ()->tdesc, 0) == 8)
     return &s390x_emit_ops;
   else
 #endif
diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
index d955a71..ad7ed1c 100644
--- a/gdbserver/linux-x86-low.cc
+++ b/gdbserver/linux-x86-low.cc
@@ -284,9 +284,7 @@ static /*const*/ int i386_regmap[] =
 static int
 is_64bit_tdesc (thread_info *thread)
 {
-  struct regcache *regcache = get_thread_regcache (thread, 0);
-
-  return register_size (regcache->tdesc, 0) == 8;
+  return register_size (thread->process ()->tdesc, 0) == 8;
 }
 
 #endif
@@ -2876,8 +2874,7 @@ x86_target::low_supports_range_stepping ()
 int
 x86_target::get_ipa_tdesc_idx ()
 {
-  struct regcache *regcache = get_thread_regcache (current_thread, 0);
-  const struct target_desc *tdesc = regcache->tdesc;
+  const target_desc *tdesc = current_process ()->tdesc;
 
   if (!use_xml)
     {