diff mbox

Remove some unnecessary inferior_ptid setting/restoring when fetching/storing registers

Message ID 20170322172919.26538-1-simon.marchi@ericsson.com
State New, archived
Headers

Commit Message

Simon Marchi March 22, 2017, 5:29 p.m. UTC 
  Now that the to_fetch_registers, to_store_registers and
to_prepare_to_store target methods don't rely on the value of
inferior_ptid anymore, we can remove a bunch of now unnecessary setting
and restoring of inferior_ptid.

The asserts added recently in target_fetch_registers and
target_store_registers, which validate that inferior_ptid matches the
regcache's ptid, must go away.  It's the whole point of this effort, to
not require inferior_ptid to have a particular value when calling these
functions.

One thing that I noticed is how sol-thread.c's ps_lgetregs and friends
use the current value of inferior_ptid instead of what's passed as
argument (ph->ptid), unlike proc-service.c's versions of the same
functions.  Is it expected?  I left it like this in the current patch,
but unless there's a good reason for it to be that way, I guess we
should make it use the parameter.

gdb/ChangeLog:

	* fbsd-tdep.c (fbsd_corefile_thread): Don't set/restore
	inferior_ptid.
	* proc-service.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
	ps_lsetfpregs): Likewise.
	* regcache.c (regcache_raw_update, regcache_raw_write): Likewise.
	* sol-thread.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
	ps_lsetfpregs): Likewise.
	* target.c (target_fetch_registers, target_store_registers):
	Remove asserts.
---
 gdb/fbsd-tdep.c    |  4 ----
 gdb/proc-service.c | 36 ++++++++++++------------------------
 gdb/regcache.c     | 17 +++--------------
 gdb/sol-thread.c   | 46 ++++++++++++----------------------------------
 gdb/target.c       |  4 ----
 5 files changed, 27 insertions(+), 80 deletions(-)

Comments

Simon Marchi March 22, 2017, 5:51 p.m. UTC | #1 
On 2017-03-22 13:29, Simon Marchi wrote:
> diff --git a/gdb/sol-thread.c b/gdb/sol-thread.c
> index efb3bd0b21..ae9b1411cf 100644
> --- a/gdb/sol-thread.c
> +++ b/gdb/sol-thread.c
> @@ -903,13 +897,9 @@ ps_err_e
>  ps_lsetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
>  	     const prgregset_t gregset)
>  {
> -  struct cleanup *old_chain;
> -  struct regcache *regcache;
> -
> -  old_chain = save_inferior_ptid ();
> -
> -  inferior_ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
> -  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch 
> ());
> +  ptid_t ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
> +  struct regcache *regcache
> +    = get_thread_arch_regcache (ptid, target_gdbarch ());
> 
>    supply_gregset (regcache, (const gdb_gregset_t *) gregset);
>    target_store_registers (regcache, -1);

I actually tried to build sol-thread.o on Solaris and noticed I forgot 
to remove a "do_cleanups (old_chain);" just below here.  I fixed it 
locally.

I couldn't get the whole of GDB to build however:

g++ -std=gnu++11 -g3 -O0   -I. -I. -I./common -I./config 
-DLOCALEDIR="\"/usr/local/share/locale\"" -DHAVE_CONFIG_H 
-I./../include/opcode -I./../opcodes/.. -I./../readline/.. -I./../zlib 
-I../bfd -I./../bfd -I./../include -I../libdecnumber -I./../libdecnumber 
  -I./gnulib/import -Ibuild-gnulib/import   -DTUI=1  
-I/usr/include/python2.7 -I/usr/include/python2.7 -Wall -Wpointer-arith 
-Wno-unused -Wunused-value -Wunused-function -Wno-switch 
-Wno-char-subscripts -Wempty-body -Wunused-but-set-parameter 
-Wunused-but-set-variable -Wno-sign-compare -Wno-write-strings 
-Wno-narrowing -Wformat-nonliteral -Wno-deprecated-declarations -Werror 
-c -o i386-sol2-nat.o -MT i386-sol2-nat.o -MMD -MP -MF 
.deps/i386-sol2-nat.Tpo i386-sol2-nat.c
In file included from /usr/include/sys/procfs.h:26:0,
                  from i386-sol2-nat.c:23:
/usr/include/sys/old_procfs.h:31:2: error: #error "Cannot use procfs in 
the large file compilation environment"
  #error "Cannot use procfs in the large file compilation environment"
   ^
gmake: *** [i386-sol2-nat.o] Error 1
Pedro Alves March 23, 2017, 4:19 p.m. UTC | #2 
On 03/22/2017 05:29 PM, Simon Marchi wrote:
> Now that the to_fetch_registers, to_store_registers and
> to_prepare_to_store target methods don't rely on the value of
> inferior_ptid anymore, we can remove a bunch of now unnecessary setting
> and restoring of inferior_ptid.
> 
> The asserts added recently in target_fetch_registers and
> target_store_registers, which validate that inferior_ptid matches the
> regcache's ptid, must go away.  It's the whole point of this effort, to
> not require inferior_ptid to have a particular value when calling these
> functions.
> 
> One thing that I noticed is how sol-thread.c's ps_lgetregs and friends
> use the current value of inferior_ptid instead of what's passed as
> argument (ph->ptid), unlike proc-service.c's versions of the same
> functions.  Is it expected?  I left it like this in the current patch,
> but unless there's a good reason for it to be that way, I guess we
> should make it use the parameter.

Probably no good reason.


> 
> gdb/ChangeLog:
> 
> 	* fbsd-tdep.c (fbsd_corefile_thread): Don't set/restore
> 	inferior_ptid.
> 	* proc-service.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
> 	ps_lsetfpregs): Likewise.
> 	* regcache.c (regcache_raw_update, regcache_raw_write): Likewise.
> 	* sol-thread.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
> 	ps_lsetfpregs): Likewise.
> 	* target.c (target_fetch_registers, target_store_registers):
> 	Remove asserts.

LGTM.

Thanks,
Pedro Alves
Pedro Alves March 23, 2017, 5 p.m. UTC | #3 
On 03/22/2017 05:51 PM, Simon Marchi wrote:

> I couldn't get the whole of GDB to build however:
> 
> g++ -std=gnu++11 -g3 -O0   -I. -I. -I./common -I./config
> -DLOCALEDIR="\"/usr/local/share/locale\"" -DHAVE_CONFIG_H
> -I./../include/opcode -I./../opcodes/.. -I./../readline/.. -I./../zlib
> -I../bfd -I./../bfd -I./../include -I../libdecnumber -I./../libdecnumber
>  -I./gnulib/import -Ibuild-gnulib/import   -DTUI=1 
> -I/usr/include/python2.7 -I/usr/include/python2.7 -Wall -Wpointer-arith
> -Wno-unused -Wunused-value -Wunused-function -Wno-switch
> -Wno-char-subscripts -Wempty-body -Wunused-but-set-parameter
> -Wunused-but-set-variable -Wno-sign-compare -Wno-write-strings
> -Wno-narrowing -Wformat-nonliteral -Wno-deprecated-declarations -Werror
> -c -o i386-sol2-nat.o -MT i386-sol2-nat.o -MMD -MP -MF
> .deps/i386-sol2-nat.Tpo i386-sol2-nat.c
> In file included from /usr/include/sys/procfs.h:26:0,
>                  from i386-sol2-nat.c:23:
> /usr/include/sys/old_procfs.h:31:2: error: #error "Cannot use procfs in
> the large file compilation environment"
>  #error "Cannot use procfs in the large file compilation environment"
>   ^
> gmake: *** [i386-sol2-nat.o] Error 1
> 

Yeah, the 32-bit build runs into that, unless you configure with
--disable-largefile.  See:

  https://sourceware.org/ml/gdb-patches/2016-10/msg00510.html

If you target 64-bit mode (may need CC="gcc -m64" CXX="g++ -m64",
and/or explicit --host, I don't recall exactly), then it should 
build OOTB.


Thanks,
Pedro Alves
Simon Marchi March 23, 2017, 5:39 p.m. UTC | #4 
On 2017-03-23 12:19, Pedro Alves wrote:
> On 03/22/2017 05:29 PM, Simon Marchi wrote:
>> Now that the to_fetch_registers, to_store_registers and
>> to_prepare_to_store target methods don't rely on the value of
>> inferior_ptid anymore, we can remove a bunch of now unnecessary 
>> setting
>> and restoring of inferior_ptid.
>> 
>> The asserts added recently in target_fetch_registers and
>> target_store_registers, which validate that inferior_ptid matches the
>> regcache's ptid, must go away.  It's the whole point of this effort, 
>> to
>> not require inferior_ptid to have a particular value when calling 
>> these
>> functions.
>> 
>> One thing that I noticed is how sol-thread.c's ps_lgetregs and friends
>> use the current value of inferior_ptid instead of what's passed as
>> argument (ph->ptid), unlike proc-service.c's versions of the same
>> functions.  Is it expected?  I left it like this in the current patch,
>> but unless there's a good reason for it to be that way, I guess we
>> should make it use the parameter.
> 
> Probably no good reason.
> 
> 
>> 
>> gdb/ChangeLog:
>> 
>> 	* fbsd-tdep.c (fbsd_corefile_thread): Don't set/restore
>> 	inferior_ptid.
>> 	* proc-service.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
>> 	ps_lsetfpregs): Likewise.
>> 	* regcache.c (regcache_raw_update, regcache_raw_write): Likewise.
>> 	* sol-thread.c (ps_lgetregs, ps_lsetregs, ps_lgetfpregs,
>> 	ps_lsetfpregs): Likewise.
>> 	* target.c (target_fetch_registers, target_store_registers):
>> 	Remove asserts.
> 
> LGTM.

Thanks, pushed.
diff mbox

Patch

diff --git a/gdb/fbsd-tdep.c b/gdb/fbsd-tdep.c
index e757910023..46875d8efd 100644
--- a/gdb/fbsd-tdep.c
+++ b/gdb/fbsd-tdep.c
@@ -193,15 +193,11 @@  static void
 fbsd_corefile_thread (struct thread_info *info,
 		      struct fbsd_corefile_thread_data *args)
 {
-  struct cleanup *old_chain;
   struct regcache *regcache;
 
   regcache = get_thread_arch_regcache (info->ptid, args->gdbarch);
 
-  old_chain = save_inferior_ptid ();
-  inferior_ptid = info->ptid;
   target_fetch_registers (regcache, -1);
-  do_cleanups (old_chain);
 
   args->note_data = fbsd_collect_thread_registers
     (regcache, info->ptid, args->obfd, args->note_data,
diff --git a/gdb/proc-service.c b/gdb/proc-service.c
index d39830cb69..415ba0a7f3 100644
--- a/gdb/proc-service.c
+++ b/gdb/proc-service.c
@@ -158,16 +158,13 @@  ps_pdwrite (gdb_ps_prochandle_t ph, psaddr_t addr,
 ps_err_e
 ps_lgetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, prgregset_t gregset)
 {
-  struct cleanup *old_chain = save_inferior_ptid ();
-  struct regcache *regcache;
-
-  inferior_ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   target_fetch_registers (regcache, -1);
   fill_gregset (regcache, (gdb_gregset_t *) gregset, -1);
 
-  do_cleanups (old_chain);
   return PS_OK;
 }
 
@@ -177,16 +174,13 @@  ps_lgetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, prgregset_t gregset)
 ps_err_e
 ps_lsetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, const prgregset_t gregset)
 {
-  struct cleanup *old_chain = save_inferior_ptid ();
-  struct regcache *regcache;
-
-  inferior_ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   supply_gregset (regcache, (const gdb_gregset_t *) gregset);
   target_store_registers (regcache, -1);
 
-  do_cleanups (old_chain);
   return PS_OK;
 }
 
@@ -197,16 +191,13 @@  ps_err_e
 ps_lgetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
 	       gdb_prfpregset_t *fpregset)
 {
-  struct cleanup *old_chain = save_inferior_ptid ();
-  struct regcache *regcache;
-
-  inferior_ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   target_fetch_registers (regcache, -1);
   fill_fpregset (regcache, (gdb_fpregset_t *) fpregset, -1);
 
-  do_cleanups (old_chain);
   return PS_OK;
 }
 
@@ -217,16 +208,13 @@  ps_err_e
 ps_lsetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
 	       const gdb_prfpregset_t *fpregset)
 {
-  struct cleanup *old_chain = save_inferior_ptid ();
-  struct regcache *regcache;
-
-  inferior_ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (ph->ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   supply_fpregset (regcache, (const gdb_fpregset_t *) fpregset);
   target_store_registers (regcache, -1);
 
-  do_cleanups (old_chain);
   return PS_OK;
 }
 
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 58d4f56292..71223a1dc4 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -666,11 +666,7 @@  regcache_raw_update (struct regcache *regcache, int regnum)
   if (!regcache->readonly_p
       && regcache_register_status (regcache, regnum) == REG_UNKNOWN)
     {
-      struct cleanup *old_chain = save_inferior_ptid ();
-
-      inferior_ptid = regcache->ptid;
       target_fetch_registers (regcache, regnum);
-      do_cleanups (old_chain);
 
       /* A number of targets can't access the whole set of raw
 	 registers (because the debug API provides no means to get at
@@ -937,8 +933,7 @@  void
 regcache_raw_write (struct regcache *regcache, int regnum,
 		    const gdb_byte *buf)
 {
-  struct cleanup *chain_before_save_inferior;
-  struct cleanup *chain_before_invalidate_register;
+  struct cleanup *old_chain;
 
   gdb_assert (regcache != NULL && buf != NULL);
   gdb_assert (regnum >= 0 && regnum < regcache->descr->nr_raw_registers);
@@ -956,24 +951,18 @@  regcache_raw_write (struct regcache *regcache, int regnum,
 		  regcache->descr->sizeof_register[regnum]) == 0))
     return;
 
-  chain_before_save_inferior = save_inferior_ptid ();
-  inferior_ptid = regcache->ptid;
-
   target_prepare_to_store (regcache);
   regcache_raw_set_cached_value (regcache, regnum, buf);
 
   /* Register a cleanup function for invalidating the register after it is
      written, in case of a failure.  */
-  chain_before_invalidate_register
-    = make_cleanup_regcache_invalidate (regcache, regnum);
+  old_chain = make_cleanup_regcache_invalidate (regcache, regnum);
 
   target_store_registers (regcache, regnum);
 
   /* The target did not throw an error so we can discard invalidating the
      register and restore the cleanup chain to what it was.  */
-  discard_cleanups (chain_before_invalidate_register);
-
-  do_cleanups (chain_before_save_inferior);
+  discard_cleanups (old_chain);
 }
 
 void
diff --git a/gdb/sol-thread.c b/gdb/sol-thread.c
index efb3bd0b21..ae9b1411cf 100644
--- a/gdb/sol-thread.c
+++ b/gdb/sol-thread.c
@@ -881,19 +881,13 @@  ps_ptwrite (gdb_ps_prochandle_t ph, gdb_ps_addr_t addr,
 ps_err_e
 ps_lgetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, prgregset_t gregset)
 {
-  struct cleanup *old_chain;
-  struct regcache *regcache;
-
-  old_chain = save_inferior_ptid ();
-
-  inferior_ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   target_fetch_registers (regcache, -1);
   fill_gregset (regcache, (gdb_gregset_t *) gregset, -1);
 
-  do_cleanups (old_chain);
-
   return PS_OK;
 }
 
@@ -903,13 +897,9 @@  ps_err_e
 ps_lsetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
 	     const prgregset_t gregset)
 {
-  struct cleanup *old_chain;
-  struct regcache *regcache;
-
-  old_chain = save_inferior_ptid ();
-
-  inferior_ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   supply_gregset (regcache, (const gdb_gregset_t *) gregset);
   target_store_registers (regcache, -1);
@@ -961,19 +951,13 @@  ps_err_e
 ps_lgetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
 	       prfpregset_t *fpregset)
 {
-  struct cleanup *old_chain;
-  struct regcache *regcache;
-
-  old_chain = save_inferior_ptid ();
-
-  inferior_ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   target_fetch_registers (regcache, -1);
   fill_fpregset (regcache, (gdb_fpregset_t *) fpregset, -1);
 
-  do_cleanups (old_chain);
-
   return PS_OK;
 }
 
@@ -983,19 +967,13 @@  ps_err_e
 ps_lsetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
 	       const prfpregset_t * fpregset)
 {
-  struct cleanup *old_chain;
-  struct regcache *regcache;
-
-  old_chain = save_inferior_ptid ();
-
-  inferior_ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
-  regcache = get_thread_arch_regcache (inferior_ptid, target_gdbarch ());
+  ptid_t ptid = ptid_build (ptid_get_pid (inferior_ptid), lwpid, 0);
+  struct regcache *regcache
+    = get_thread_arch_regcache (ptid, target_gdbarch ());
 
   supply_fpregset (regcache, (const gdb_fpregset_t *) fpregset);
   target_store_registers (regcache, -1);
 
-  do_cleanups (old_chain);
-
   return PS_OK;
 }
 
diff --git a/gdb/target.c b/gdb/target.c
index 359bf0dec9..0ff8515d3b 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -3587,8 +3587,6 @@  debug_print_register (const char * func,
 void
 target_fetch_registers (struct regcache *regcache, int regno)
 {
-  gdb_assert (ptid_equal (regcache_get_ptid (regcache), inferior_ptid));
-
   current_target.to_fetch_registers (&current_target, regcache, regno);
   if (targetdebug)
     debug_print_register ("target_fetch_registers", regcache, regno);
@@ -3600,8 +3598,6 @@  target_store_registers (struct regcache *regcache, int regno)
   if (!may_write_registers)
     error (_("Writing to registers is not allowed (regno %d)"), regno);
 
-  gdb_assert (ptid_equal (regcache_get_ptid (regcache), inferior_ptid));
-
   current_target.to_store_registers (&current_target, regcache, regno);
   if (targetdebug)
     {