[03/26] gdbserver: by-pass regcache to access tdesc only

Message ID cf41fe276e2db4e7301d9a400978d65db06a1c33.1677582744.git.tankut.baris.aktemur@intel.com
State New
Headers
Series gdbserver: refactor regcache and allow gradually populating |

Commit Message

Tankut Baris Aktemur Feb. 28, 2023, 11:28 a.m. UTC
  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.
---
 gdbserver/linux-ppc-low.cc  | 10 +++-------
 gdbserver/linux-s390-low.cc | 14 ++++----------
 gdbserver/linux-x86-low.cc  |  7 ++-----
 3 files changed, 9 insertions(+), 22 deletions(-)
  

Comments

Simon Marchi Dec. 21, 2023, 8:22 p.m. UTC | #1
On 2/28/23 06:28, Tankut Baris Aktemur via Gdb-patches wrote:
> 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.

Thanks, that LGTM.  You can apply it immediately, I think, it's good on
its own.

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

Simon
  

Patch

diff --git a/gdbserver/linux-ppc-low.cc b/gdbserver/linux-ppc-low.cc
index f8dd770b8eb..96c1da4d905 100644
--- a/gdbserver/linux-ppc-low.cc
+++ b/gdbserver/linux-ppc-low.cc
@@ -1609,8 +1609,7 @@  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;
@@ -3381,9 +3380,7 @@  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;
@@ -3399,8 +3396,7 @@  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 struct 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 48f64ef7bb3..11f207ea2f1 100644
--- a/gdbserver/linux-s390-low.cc
+++ b/gdbserver/linux-s390-low.cc
@@ -797,9 +797,7 @@  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;
@@ -1287,8 +1285,7 @@  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
@@ -1452,8 +1449,7 @@  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 struct target_desc *tdesc = current_process ()->tdesc;
 
 #ifdef __s390x__
   if (tdesc == tdesc_s390x_linux64)
@@ -2840,9 +2836,7 @@  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 4a538b107be..e08ebacee05 100644
--- a/gdbserver/linux-x86-low.cc
+++ b/gdbserver/linux-x86-low.cc
@@ -276,9 +276,7 @@  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 (get_thread_process (thread)->tdesc, 0) == 8;
 }
 
 #endif
@@ -2958,8 +2956,7 @@  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 struct target_desc *tdesc = current_process ()->tdesc;
 
 #ifdef __x86_64__
   return amd64_get_ipa_tdesc_idx (tdesc);