Re: [PATCH v3 1/7] gdb/record: Refactor record history

[Guinevere Larsen <guinevere@redhat.com>]

On 5/26/26 5:33 AM, Schimpe, Christina wrote:
> Hi Guinevere,
>
> Please find some further comments below.
>
>> -----Original Message-----
>> From: Guinevere Larsen <guinevere@redhat.com>
>> Sent: Freitag, 15. Mai 2026 18:37
>> To: gdb-patches@sourceware.org
>> Cc: Guinevere Larsen <guinevere@redhat.com>; Thiago Jung Bauermann
>> <thiago.bauermann@linaro.org>
>> Subject: [PATCH v3 1/7] gdb/record: Refactor record history
>>
>> This is the first step in a large refactor in how GDB keeps execution
>> history.  Rather than using a linked list where multiple entries can
>> describe a single instruction, the history will now be stored in an
>> std::deque, each instruction being one entry in the deque.
>>
>> The choice was initially to use an std::vector, but it would become
>> unwieldy because it needs all the memory to be consecutive, which is
>> hard for 200 thousand entries. Deque was picked because it was a nice
>> midpoint between vector (maximum cache cohesion) and linked list
>> (maximum ease of finding space to store more).
>>
>> Each instruction in memory will be now one record_full_instruction
>> entry, which for this commit just contains a vector of
>> record_full_entry for the effects of the instruction, and the data that
>> was stored in the record_full_end entry (that is, the instruction number
>> and the signal, if any).
>>
>> This change introduced a minimal performance improvement (what's
>> important is that it isn't a degradation) and a  reduction in the total
>> memory footprint of roughly 20% if the entire history is used.
>>
>> Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
>> ---
>>   gdb/aarch64-tdep.c     |    2 -
>>   gdb/amd64-linux-tdep.c |    3 -
>>   gdb/arm-tdep.c         |    2 -
>>   gdb/i386-linux-tdep.c  |    3 -
>>   gdb/i386-tdep.c        |    4 -
>>   gdb/loongarch-tdep.c   |    2 -
>>   gdb/moxie-tdep.c       |    2 -
>>   gdb/ppc-linux-tdep.c   |    3 -
>>   gdb/record-full.c      | 1186 ++++++++++++++++------------------------
>>   gdb/record-full.h      |    1 -
>>   gdb/riscv-tdep.c       |    3 -
>>   gdb/rs6000-tdep.c      |    4 -
>>   gdb/s390-linux-tdep.c  |    3 -
>>   gdb/s390-tdep.c        |    2 -
>>   14 files changed, 484 insertions(+), 736 deletions(-)
>>
>> diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
>> index 4befaa2720d..a532992b1d8 100644
>> --- a/gdb/aarch64-tdep.c
>> +++ b/gdb/aarch64-tdep.c
>> @@ -6210,8 +6210,6 @@ aarch64_process_record (struct gdbarch
>> *gdbarch, struct regcache *regcache,
>>   	       aarch64_record.aarch64_mems[rec_no].len))
>>   	    ret = -1;
>>
>> -      if (record_full_arch_list_add_end ())
>> -	ret = -1;
>>       }
>>
>>     deallocate_reg_mem (&aarch64_record);
>> diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
>> index a5ac26654cf..9b23db72bbe 100644
>> --- a/gdb/amd64-linux-tdep.c
>> +++ b/gdb/amd64-linux-tdep.c
>> @@ -1591,9 +1591,6 @@ amd64_linux_record_signal (struct gdbarch
>> *gdbarch,
>>   				     + AMD64_LINUX_frame_size))
>>       return -1;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>> -
>>     return 0;
>>   }
>>
>> diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
>> index 08cce9dbad8..1ce0927f26b 100644
>> --- a/gdb/arm-tdep.c
>> +++ b/gdb/arm-tdep.c
>> @@ -14911,8 +14911,6 @@ arm_process_record (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>   	    }
>>   	}
>>
>> -      if (record_full_arch_list_add_end ())
>> -	ret = -1;
>>       }
>>
>>
>> diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c
>> index 23aeccac9fc..4f33766fcdd 100644
>> --- a/gdb/i386-linux-tdep.c
>> +++ b/gdb/i386-linux-tdep.c
>> @@ -949,9 +949,6 @@ i386_linux_record_signal (struct gdbarch *gdbarch,
>>   				     I386_LINUX_xstate +
>> I386_LINUX_frame_size))
>>       return -1;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>> -
>>     return 0;
>>   }
>>   
>> diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
>> index fa935b5fcdb..fee36b46a73 100644
>> --- a/gdb/i386-tdep.c
>> +++ b/gdb/i386-tdep.c
>> @@ -5201,8 +5201,6 @@ i386_record_vex (struct i386_record_s *ir, uint8_t
>> vex_w, uint8_t vex_r,
>>       }
>>
>>     record_full_arch_list_add_reg (ir->regcache, ir-
>>> regmap[X86_RECORD_REIP_REGNUM]);
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>
>>     return 0;
>>   }
>> @@ -8359,8 +8357,6 @@ Do you want to stop the program?"),
>>
>>     /* In the future, maybe still need to deal with need_dasm.  */
>>     I386_RECORD_FULL_ARCH_LIST_ADD_REG (X86_RECORD_REIP_REGNUM);
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>
>>     return 0;
>>
>> diff --git a/gdb/loongarch-tdep.c b/gdb/loongarch-tdep.c
>> index 225b1abb703..5ec6b2a48d0 100644
>> --- a/gdb/loongarch-tdep.c
>> +++ b/gdb/loongarch-tdep.c
>> @@ -2789,8 +2789,6 @@ loongarch_process_record (struct gdbarch
>> *gdbarch, struct regcache *regcache,
>>   					 LOONGARCH_PC_REGNUM))
>>   	return -1;
>>
>> -      if (record_full_arch_list_add_end ())
>> -	return -1;
>>       }
>>
>>     return ret;
>> diff --git a/gdb/moxie-tdep.c b/gdb/moxie-tdep.c
>> index c8a04d21f59..2f8f0186488 100644
>> --- a/gdb/moxie-tdep.c
>> +++ b/gdb/moxie-tdep.c
>> @@ -1040,8 +1040,6 @@ moxie_process_record (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>
>>     if (record_full_arch_list_add_reg (regcache, MOXIE_PC_REGNUM))
>>       return -1;
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>     return 0;
>>   }
>>
>> diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
>> index 19698eaacbe..e2f53551709 100644
>> --- a/gdb/ppc-linux-tdep.c
>> +++ b/gdb/ppc-linux-tdep.c
>> @@ -1565,9 +1565,6 @@ ppc_linux_record_signal (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>     if (record_full_arch_list_add_mem (sp, SIGNAL_FRAMESIZE +
>> sizeof_rt_sigframe))
>>       return -1;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>> -
>>     return 0;
>>   }
>>
>> diff --git a/gdb/record-full.c b/gdb/record-full.c
>> index 69d2c100e57..02a57726a95 100644
>> --- a/gdb/record-full.c
>> +++ b/gdb/record-full.c
>> @@ -47,6 +47,9 @@
>>   #include "interps.h"
>>   #include "cli/cli-style.h"
>>
>> +#include <vector>
>> +#include <optional>
>> +#include <deque>
>>   #include <signal.h>
>>
>>   /* This module implements "target record-full", also known as "process
>> @@ -72,20 +75,17 @@
>>   #define DEFAULT_RECORD_FULL_INSN_MAX_NUM	200000
>>
>>   #define RECORD_FULL_IS_REPLAY \
>> -  (record_full_list->next || ::execution_direction == EXEC_REVERSE)
>> +  ((record_full_next_insn != record_full_list.size ()) \
>> +    || ::execution_direction == EXEC_REVERSE)
>>
>>   #define RECORD_FULL_FILE_MAGIC	netorder32(0x20091016)
>>
>>   /* These are the core structs of the process record functionality.
>>
>>      A record_full_entry is a record of the value change of a register
>> -   ("record_full_reg") or a part of memory ("record_full_mem").  And each
>> -   instruction must have a struct record_full_entry ("record_full_end")
>> -   that indicates that this is the last struct record_full_entry of this
>> -   instruction.
>> -
>> -   Each struct record_full_entry is linked to "record_full_list" by "prev"
>> -   and "next" pointers.  */
>> +   ("record_full_reg") or a part of memory ("record_full_mem").
>> +   These are saved on the record_full_instruction struct, which also
>> +   contains some extra information, such as delivered signals.  */
> Optional suggestion (since it has been like this before already):
>
> The description for record_full_entry is not above the actual struct and the
> further structs miss a comment. In the description above the enum values
> are described '("record_full_reg") or a part of memory ("record_full_mem")',
> but not the actual structs.  I think it would be helpful to write this out a bit more,
> add comments to each struct and move the one for record_full_entry
> above its actual struct.
> Given that this commit is already big enough, a separate commit might be better.
Yeah, these can probably be better documented. I'll try to think of 
something and either add a commit at the end of this series, or send a 
follow up patch later (depends on how hard it is for me to think of 
something :) )
>
>>   struct record_full_mem_entry
>>   {
>> @@ -112,47 +112,14 @@ struct record_full_reg_entry
>>     } u;
>>   };
>>
>> -struct record_full_end_entry
>> -{
>> -  enum gdb_signal sigval;
>> -  ULONGEST insn_num;
>> -};
>> -
>>   enum record_full_type
>>   {
>> -  record_full_end = 0,
>>     record_full_reg,
>>     record_full_mem
>>   };
>>
>> -/* This is the data structure that makes up the execution log.
>> -
>> -   The execution log consists of a single linked list of entries
>> -   of type "struct record_full_entry".  It is doubly linked so that it
>> -   can be traversed in either direction.
>> -
>> -   The start of the list is anchored by a struct called
>> -   "record_full_first".  The pointer "record_full_list" either points
>> -   to the last entry that was added to the list (in record mode), or to
>> -   the next entry in the list that will be executed (in replay mode).
>> -
>> -   Each list element (struct record_full_entry), in addition to next
>> -   and prev pointers, consists of a union of three entry types: mem,
>> -   reg, and end.  A field called "type" determines which entry type is
>> -   represented by a given list element.
>> -
>> -   Each instruction that is added to the execution log is represented
>> -   by a variable number of list elements ('entries').  The instruction
>> -   will have one "reg" entry for each register that is changed by
>> -   executing the instruction (including the PC in every case).  It
>> -   will also have one "mem" entry for each memory change.  Finally,
>> -   each instruction will have an "end" entry that separates it from
>> -   the changes associated with the next instruction.  */
>> -
>>   struct record_full_entry
>>   {
>> -  struct record_full_entry *prev;
>> -  struct record_full_entry *next;
>>     enum record_full_type type;
>>     union
>>     {
>> @@ -160,11 +127,31 @@ struct record_full_entry
>>       struct record_full_reg_entry reg;
>>       /* mem */
>>       struct record_full_mem_entry mem;
>> -    /* end */
>> -    struct record_full_end_entry end;
>>     } u;
>>   };
>>
>> +/* This is the main structure that comprises the execution log.
>> +   Each instruction is comprised of:
>> +   * The instruction number: How many instructions were recorded before
>> +     this one;
>> +   * sigval: Whether the inferior received a signal while the following
>> +     instruction was being recorded;
>> +   * effects: A list of record_full_entry structures, each of which
>> +     describing one effect that the instruction has on the inferior.
>> +
>> +   Note, the signal is stored in the previous instruction for historical
>> +   reasons.  This is how it was first implemented, and no one has gotten
>> +   around to changing it yet.  */
>> +
>> +struct record_full_instruction
>> +{
>> +  /* This might be different from the index if
>> +     we had to remove the first few instructions.  */
>> +  uint32_t insn_num;
>> +  std::optional<gdb_signal> sigval;
>> +  std::vector<record_full_entry> effects;
>> +};
>> +
>>   /* If true, query if PREC cannot record memory
>>      change of next instruction.  */
>>   bool record_full_memory_query = false;
>> @@ -181,27 +168,25 @@ static detached_regcache
>> *record_full_core_regbuf = NULL;
>>   static std::vector<target_section> record_full_core_sections;
>>   static struct record_full_core_buf_entry *record_full_core_buf_list = NULL;
>>
>> -/* The following variables are used for managing the linked list that
>> -   represents the execution log.
>> +/* The following variables are used for managing the history of executed
>> +   instructions from the inferior.
>>
>> -   record_full_first is the anchor that holds down the beginning of
>> -   the list.
>> +   record_full_list contains all instructions that were fully executed and
>> +   saved to the log, so that we can replay the execution.
>>
>> -   record_full_list serves two functions:
>> -     1) In record mode, it anchors the end of the list.
>> -     2) In replay mode, it traverses the list and points to
>> -	the next instruction that must be emulated.
>> +   record_full_next_insn always points to the next instruction that would
>> +   be executed if the inferior executes forward.  In the special case when
>> +   the inferior is not replaying, record_full_next_insn points past the
>> +   end of the history.
>>
>> -   record_full_arch_list_head and record_full_arch_list_tail are used
>> -   to manage a separate list, which is used to build up the change
>> -   elements of the currently executing instruction during record mode.
>> -   When this instruction has been completely annotated in the "arch
>> -   list", it will be appended to the main execution log.  */
>> +   record_full_incomplete_instruction holds a partial instruction, while
>> +   the lower target is disassembling the instruction, or as partial xfers are
>> +   happening.  It is manipulated by the "arch list" functions for historical
>> +   reasons.  */
>>
>> -static struct record_full_entry record_full_first;
>> -static struct record_full_entry *record_full_list = &record_full_first;
>> -static struct record_full_entry *record_full_arch_list_head = NULL;
>> -static struct record_full_entry *record_full_arch_list_tail = NULL;
>> +static std::deque<record_full_instruction> record_full_list;
>> +static record_full_instruction record_full_incomplete_instruction;
>> +static int record_full_next_insn;
>>
>>   /* true ask user. false auto delete the last struct record_full_entry.  */
>>   static bool record_full_stop_at_limit = true;
>> @@ -361,6 +346,14 @@ record_full_target::kill ()
>>     record_kill (this);
>>   }
> This  function is still missing a comment.
oops, fixed.
>> +static void
>> +record_full_reset_incomplete ()
>> +{
>> +  record_full_incomplete_instruction.effects.clear ();
>> +  record_full_incomplete_instruction.sigval.reset ();
>> +  record_full_incomplete_instruction.insn_num = 0;
>> +}
>> +
>>   /* See record-full.h.  */
>>
>>   int
>> @@ -390,156 +383,124 @@ static struct cmd_list_element
>> *show_record_full_cmdlist;
>>   /* Command list for "record full".  */
>>   static struct cmd_list_element *record_full_cmdlist;
>>
>> -static void record_full_goto_insn (struct record_full_entry *entry,
>> +static void record_full_goto_insn (size_t target_insn,
>>   				   enum exec_direction_kind dir);
> Is this some general guideline to call this cleanup/init instead of release/alloc ?
> Since this patch is already so big, I just wonder why you changed it. 😊

There isn't any guideline, I just figured that alloc/release was no 
longer correct, since we were no longer allocating or releasing dynamic 
memory... This was before I realized how far I could take the 
C++ification and make them into proper constructors.

I can undo the change if you'd like, but since they are going to become 
the constructor I feel like it is not really necessary either way...

>> -/* Alloc and free functions for record_full_reg, record_full_mem, and
>> -   record_full_end entries.  */
>> +/* Initialization and cleanup functions for record_full_reg and
>> +   record_full_mem entries.  */
>>
>> -/* Alloc a record_full_reg record entry.  */
>> +/* Init a record_full_reg record entry.  */
>>
>> -static inline struct record_full_entry *
>> -record_full_reg_alloc (struct regcache *regcache, int regnum)
>> +static inline record_full_entry
>> +record_full_reg_init (struct regcache *regcache, int regnum)
>>   {
>> -  struct record_full_entry *rec;
>> +  record_full_entry rec;
>>     struct gdbarch *gdbarch = regcache->arch ();
>>
>> -  rec = XCNEW (struct record_full_entry);
>> -  rec->type = record_full_reg;
>> -  rec->u.reg.num = regnum;
>> -  rec->u.reg.len = register_size (gdbarch, regnum);
>> -  if (rec->u.reg.len > sizeof (rec->u.reg.u.buf))
>> -    rec->u.reg.u.ptr = (gdb_byte *) xmalloc (rec->u.reg.len);
>> +  rec.type = record_full_reg;
>> +  rec.u.reg.num = regnum;
>> +  rec.u.reg.len = register_size (gdbarch, regnum);
>> +  if (rec.u.reg.len > sizeof (rec.u.reg.u.buf))
>> +    rec.u.reg.u.ptr = (gdb_byte *) xmalloc (rec.u.reg.len);
>>
>>     return rec;
>>   }
>>
>> -/* Free a record_full_reg record entry.  */
>> +/* Cleanup a record_full_reg record entry.  */
>>
>>   static inline void
>> -record_full_reg_release (struct record_full_entry *rec)
>> +record_full_reg_cleanup (record_full_entry rec)
>>   {
>> -  gdb_assert (rec->type == record_full_reg);
>> -  if (rec->u.reg.len > sizeof (rec->u.reg.u.buf))
>> -    xfree (rec->u.reg.u.ptr);
>> -  xfree (rec);
>> +  gdb_assert (rec.type == record_full_reg);
>> +  if (rec.u.reg.len > sizeof (rec.u.reg.u.buf))
>> +    xfree (rec.u.reg.u.ptr);
>>   }
>>
>> -/* Alloc a record_full_mem record entry.  */
>> +/* Init a record_full_mem record entry.  */
>>
>> -static inline struct record_full_entry *
>> -record_full_mem_alloc (CORE_ADDR addr, int len)
>> +static inline record_full_entry
>> +record_full_mem_init (CORE_ADDR addr, int len)
>>   {
>> -  struct record_full_entry *rec;
>> +  record_full_entry rec;
>>
>> -  rec = XCNEW (struct record_full_entry);
>> -  rec->type = record_full_mem;
>> -  rec->u.mem.addr = addr;
>> -  rec->u.mem.len = len;
>> -  if (rec->u.mem.len > sizeof (rec->u.mem.u.buf))
>> -    rec->u.mem.u.ptr = (gdb_byte *) xmalloc (len);
>> +  rec.type = record_full_mem;
>> +  rec.u.mem.addr = addr;
>> +  rec.u.mem.len = len;
>> +  if (rec.u.mem.len > sizeof (rec.u.mem.u.buf))
>> +    rec.u.mem.u.ptr = (gdb_byte *) xmalloc (len);
>> +  rec.u.mem.mem_entry_not_accessible = 0;
>>
>>     return rec;
>>   }
>>
>> -/* Free a record_full_mem record entry.  */
>> +/* Cleanup a record_full_mem record entry.  */
>>
>>   static inline void
>> -record_full_mem_release (struct record_full_entry *rec)
>> +record_full_mem_cleanup (record_full_entry rec)
>>   {
>> -  gdb_assert (rec->type == record_full_mem);
>> -  if (rec->u.mem.len > sizeof (rec->u.mem.u.buf))
>> -    xfree (rec->u.mem.u.ptr);
>> -  xfree (rec);
>> +  gdb_assert (rec.type == record_full_mem);
>> +  if (rec.u.mem.len > sizeof (rec.u.mem.u.buf))
>> +    xfree (rec.u.mem.u.ptr);
>>   }
>>
>> -/* Alloc a record_full_end record entry.  */
>> -
>> -static inline struct record_full_entry *
>> -record_full_end_alloc (void)
>> -{
>> -  struct record_full_entry *rec;
>> -
>> -  rec = XCNEW (struct record_full_entry);
>> -  rec->type = record_full_end;
>> -
>> -  return rec;
>> -}
>> -
>> -/* Free a record_full_end record entry.  */
>> +/* Free one record entry, any type.  */
>>
>>   static inline void
>> -record_full_end_release (struct record_full_entry *rec)
>> +record_full_entry_cleanup (record_full_entry rec)
>>   {
>> -  xfree (rec);
>> -}
>> -
>> -/* Free one record entry, any type.
>> -   Return entry->type, in case caller wants to know.  */
>>
>> -static inline enum record_full_type
>> -record_full_entry_release (struct record_full_entry *rec)
>> -{
>> -  enum record_full_type type = rec->type;
>> -
>> -  switch (type) {
>> +  switch (rec.type) {
>>     case record_full_reg:
>> -    record_full_reg_release (rec);
>> +    record_full_reg_cleanup (rec);
>>       break;
>>     case record_full_mem:
>> -    record_full_mem_release (rec);
>> -    break;
>> -  case record_full_end:
>> -    record_full_end_release (rec);
>> +    record_full_mem_cleanup (rec);
>>       break;
>>     }
>> -  return type;
>>   }
>>
>> -/* Free all record entries in list pointed to by REC.  */
>> -
>>   static void
>> -record_full_list_release (struct record_full_entry *rec)
>> +record_full_reset_history ()
>>   {
>> -  if (!rec)
>> -    return;
>> -
>> -  while (rec->next)
>> -    rec = rec->next;
>> +  record_full_insn_num = 0;
>> +  record_full_insn_count = 0;
>> +  record_full_next_insn = 0;
>>
>> -  while (rec->prev)
>> +  for (auto &insn : record_full_list)
>>       {
>> -      rec = rec->prev;
>> -      record_full_entry_release (rec->next);
>> +      for (auto &entry : insn.effects)
>> +	record_full_entry_cleanup (entry);
>>       }
>>
>> -  if (rec == &record_full_first)
>> +  record_full_list.clear ();
>> +}
> This function is missing a comment.
oops, fixed
>
>> +static void
>> +record_full_list_release_following (int index)
>> +{
>> +  for (int i = record_full_list.size () - 1; i > index; i--)
>>       {
>> -      record_full_insn_num = 0;
>> -      record_full_first.next = NULL;
>> +      for (auto &entry : record_full_list[i].effects)
>> +	record_full_entry_cleanup (entry);
>> +      record_full_list.pop_back ();
>>       }
>> -  else
>> -    record_full_entry_release (rec);
>> +  /* Set the next instruction to be past the end of the log so we
>> +     start recording if the user moves forward again.  */
>> +  record_full_next_insn = index;
>>   }
>>
>> -/* Free all record entries forward of the given list position.  */
>> +/* Save the incomplete instruction in the log.  */
>>
>>   static void
>> -record_full_list_release_following (struct record_full_entry *rec)
>> +record_full_save_instruction ()
>>   {
>> -  struct record_full_entry *tmp = rec->next;
>> +  ++record_full_insn_count;
>> +  record_full_incomplete_instruction.insn_num = record_full_insn_count;
>> +  record_full_incomplete_instruction.effects.shrink_to_fit ();
>> +  record_full_list.push_back (std::move
>> (record_full_incomplete_instruction));
>> +  record_full_next_insn++;
>>
>> -  rec->next = NULL;
>> -  while (tmp)
>> -    {
>> -      rec = tmp->next;
>> -      if (record_full_entry_release (tmp) == record_full_end)
>> -	{
>> -	  record_full_insn_num--;
>> -	  record_full_insn_count--;
>> -	}
>> -      tmp = rec;
>> -    }
>> +  record_full_reset_incomplete ();
>>   }
>>
>>   /* Delete the first instruction from the beginning of the log, to make
>> @@ -550,52 +511,22 @@ record_full_list_release_following (struct
>> record_full_entry *rec)
>>   static void
>>   record_full_list_release_first (void)
>>   {
>> -  struct record_full_entry *tmp;
>> -
>> -  if (!record_full_first.next)
>> +  if (record_full_list.empty ())
>>       return;
>>
>> -  /* Loop until a record_full_end.  */
>> -  while (1)
>> -    {
>> -      /* Cut record_full_first.next out of the linked list.  */
>> -      tmp = record_full_first.next;
>> -      record_full_first.next = tmp->next;
>> -      tmp->next->prev = &record_full_first;
>> -
>> -      /* tmp is now isolated, and can be deleted.  */
>> -      if (record_full_entry_release (tmp) == record_full_end)
>> -	break;	/* End loop at first record_full_end.  */
>> +  for (auto &entry : record_full_list[0].effects)
>> +    record_full_entry_cleanup (entry);
>>
>> -      if (!record_full_first.next)
>> -	{
>> -	  gdb_assert (record_full_insn_num == 1);
>> -	  break;	/* End loop when list is empty.  */
>> -	}
>> -    }
>> +  record_full_list.pop_front ();
>> +  --record_full_next_insn;
>>   }
>>
>>   /* Add a struct record_full_entry to record_full_arch_list.  */
>>
>>   static void
>> -record_full_arch_list_add (struct record_full_entry *rec)
>> +record_full_arch_list_add (record_full_entry &rec)
>>   {
>> -  if (record_debug > 1)
>> -    gdb_printf (gdb_stdlog,
>> -		"Process record: record_full_arch_list_add %s.\n",
>> -		host_address_to_string (rec));
>> -
>> -  if (record_full_arch_list_tail)
>> -    {
>> -      record_full_arch_list_tail->next = rec;
>> -      rec->prev = record_full_arch_list_tail;
>> -      record_full_arch_list_tail = rec;
>> -    }
>> -  else
>> -    {
>> -      record_full_arch_list_head = rec;
>> -      record_full_arch_list_tail = rec;
>> -    }
>> +  record_full_incomplete_instruction.effects.push_back (rec);
> Now since this is one line only, do we really need a separate function for this?
I guess not, but I think at the same time it would make the patch that 
much harder to review because the fact that this being how you add to 
the incomplete list is not obvious...
>
>>   }
>>
>>   /* Return the value storage location of a record entry.  */
>> @@ -613,7 +544,6 @@ record_full_get_loc (struct record_full_entry *rec)
>>         return rec->u.reg.u.ptr;
>>       else
>>         return rec->u.reg.u.buf;
>> -  case record_full_end:
>>     default:
>>       gdb_assert_not_reached ("unexpected record_full_entry type");
>>       return NULL;
>> @@ -625,7 +555,7 @@ record_full_get_loc (struct record_full_entry *rec)
>>   int
>>   record_full_arch_list_add_reg (struct regcache *regcache, int regnum)
>>   {
>> -  struct record_full_entry *rec;
>> +  record_full_entry rec;
>>
>>     if (record_debug > 1)
>>       gdb_printf (gdb_stdlog,
>> @@ -633,9 +563,9 @@ record_full_arch_list_add_reg (struct regcache
>> *regcache, int regnum)
>>   		"record list.\n",
>>   		regnum);
>>
>> -  rec = record_full_reg_alloc (regcache, regnum);
>> +  rec = record_full_reg_init (regcache, regnum);
>>
>> -  regcache->cooked_read (regnum, record_full_get_loc (rec));
>> +  regcache->cooked_read (regnum, record_full_get_loc (&rec));
>>
>>     record_full_arch_list_add (rec);
>>
>> @@ -648,7 +578,7 @@ record_full_arch_list_add_reg (struct regcache
>> *regcache, int regnum)
>>   int
>>   record_full_arch_list_add_mem (CORE_ADDR addr, int len)
>>   {
>> -  struct record_full_entry *rec;
>> +  record_full_entry rec;
>>
>>     if (record_debug > 1)
>>       gdb_printf (gdb_stdlog,
>> @@ -659,12 +589,12 @@ record_full_arch_list_add_mem (CORE_ADDR
>> addr, int len)
>>     if (!addr)	/* FIXME: Why?  Some arch must permit it...  */
>>       return 0;
>>
>> -  rec = record_full_mem_alloc (addr, len);
>> +  rec = record_full_mem_init (addr, len);
>>
>>     if (record_read_memory (current_inferior ()->arch (), addr,
>> -			  record_full_get_loc (rec), len))
>> +			  record_full_get_loc (&rec), len))
>>       {
>> -      record_full_mem_release (rec);
>> +      record_full_mem_cleanup (rec);
>>         return -1;
>>       }
>>
>> @@ -673,27 +603,6 @@ record_full_arch_list_add_mem (CORE_ADDR addr,
>> int len)
>>     return 0;
>>   }
>>
>> -/* Add a record_full_end type struct record_full_entry to
>> -   record_full_arch_list.  */
>> -
>> -int
>> -record_full_arch_list_add_end (void)
>> -{
>> -  struct record_full_entry *rec;
>> -
>> -  if (record_debug > 1)
>> -    gdb_printf (gdb_stdlog,
>> -		"Process record: add end to arch list.\n");
>> -
>> -  rec = record_full_end_alloc ();
>> -  rec->u.end.sigval = GDB_SIGNAL_0;
>> -  rec->u.end.insn_num = ++record_full_insn_count;
>> -
>> -  record_full_arch_list_add (rec);
>> -
>> -  return 0;
>> -}
>> -
>>   static void
>>   record_full_check_insn_num (void)
>>   {
>> @@ -725,8 +634,7 @@ record_full_message (struct regcache *regcache,
>> enum gdb_signal signal)
>>
>>     try
>>       {
>> -      record_full_arch_list_head = NULL;
>> -      record_full_arch_list_tail = NULL;
>> +      record_full_reset_incomplete ();
>>
>>         /* Check record_full_insn_num.  */
>>         record_full_check_insn_num ();
>> @@ -746,20 +654,16 @@ record_full_message (struct regcache *regcache,
>> enum gdb_signal signal)
>>   	 the user says something different, like "deliver this signal"
>>   	 during the replay mode).
>>
>> -	 User should understand that nothing he does during the replay
>> -	 mode will change the behavior of the child.  If he tries,
>> +	 User should understand that nothing they do during the replay
>> +	 mode will change the behavior of the child.  If they try,
>>   	 then that is a user error.
>>
>>   	 But we should still deliver the signal to gdb during the replay,
>>   	 if we delivered it during the recording.  Therefore we should
>>   	 record the signal during record_full_wait, not
>>   	 record_full_resume.  */
>> -      if (record_full_list != &record_full_first)  /* FIXME better way
>> -						      to check */
>> -	{
>> -	  gdb_assert (record_full_list->type == record_full_end);
>> -	  record_full_list->u.end.sigval = signal;
>> -	}
>> +      if (signal != GDB_SIGNAL_0 && !record_full_list.empty ())
>> +	record_full_list[record_full_next_insn - 1].sigval = signal;
>>
>>         if (signal == GDB_SIGNAL_0
>>   	  || !gdbarch_process_record_signal_p (gdbarch))
>> @@ -778,13 +682,11 @@ record_full_message (struct regcache *regcache,
>> enum gdb_signal signal)
>>       }
>>     catch (const gdb_exception &ex)
>>       {
>> -      record_full_list_release (record_full_arch_list_tail);
>> +      record_full_reset_incomplete ();
>>         throw;
>>       }
>>
>> -  record_full_list->next = record_full_arch_list_head;
>> -  record_full_arch_list_head->prev = record_full_list;
>> -  record_full_list = record_full_arch_list_tail;
>> +  record_full_save_instruction ();
>>
>>     if (record_full_insn_num == record_full_insn_max_num)
>>       record_full_list_release_first ();
>> @@ -829,9 +731,9 @@ static enum target_stop_reason
>> record_full_stop_reason
>>      entries and memory entries, followed by an 'end' entry.  */
>>
>>   static inline void
>> -record_full_exec_insn (struct regcache *regcache,
>> -		       struct gdbarch *gdbarch,
>> -		       struct record_full_entry *entry)
>> +record_full_exec_entry (regcache *regcache,
>> +			gdbarch *gdbarch,
>> +			record_full_entry *entry)
>>   {
>>     switch (entry->type)
>>       {
>> @@ -909,6 +811,15 @@ record_full_exec_insn (struct regcache *regcache,
>>       }
>>   }
> Again function comment.. 😉

Darn I'm really bad at these lol

Fixed :)

>
>> +static inline void
>> +record_full_exec_insn (regcache *regcache,
>> +		       gdbarch *gdbarch,
>> +		       record_full_instruction &insn)
>> +{
>> +  for (auto &entry : insn.effects)
>> +    record_full_exec_entry (regcache, gdbarch, &entry);
>> +}
>> +
>>   static void record_full_restore (struct bfd &cbfd);
>>
>>   /* Asynchronous signal handle registered as event loop source for when
>> @@ -983,10 +894,7 @@ record_full_open (const char *args, int from_tty)
>>     record_preopen ();
>>
>>     /* Reset */
>> -  record_full_insn_num = 0;
>> -  record_full_insn_count = 0;
>> -  record_full_list = &record_full_first;
>> -  record_full_list->next = NULL;
>> +  record_full_reset_history ();
>>
>>     bfd *cbfd = get_inferior_core_bfd (current_inferior ());
>>     if (cbfd != nullptr)
>> @@ -1014,7 +922,7 @@ record_full_base_target::close ()
>>     if (record_debug)
>>       gdb_printf (gdb_stdlog, "Process record: record_full_close\n");
>>
>> -  record_full_list_release (record_full_list);
>> +  record_full_reset_history ();
>>
>>     /* Release record_full_core_regbuf.  */
>>     if (record_full_core_regbuf)
>> @@ -1313,7 +1221,6 @@ record_full_wait_1 (struct target_ops *ops,
>>         struct gdbarch *gdbarch = regcache->arch ();
>>         const address_space *aspace = current_inferior ()->aspace.get ();
>>         int continue_flag = 1;
>> -      int first_record_full_end = 1;
>>
>>         try
>>   	{
>> @@ -1322,7 +1229,6 @@ record_full_wait_1 (struct target_ops *ops,
>>   	  record_full_stop_reason = TARGET_STOPPED_BY_NO_REASON;
>>   	  status->set_stopped (GDB_SIGNAL_0);
>>
>> -	  /* Check breakpoint when forward execute.  */
>>   	  if (execution_direction == EXEC_FORWARD)
>>   	    {
>>   	      tmp_pc = regcache_read_pc (regcache);
>> @@ -1330,8 +1236,7 @@ record_full_wait_1 (struct target_ops *ops,
>>
>> &record_full_stop_reason))
>>   		{
>>   		  if (record_debug)
>> -		    gdb_printf (gdb_stdlog,
>> -				"Process record: break at %s.\n",
>> +		    gdb_printf (gdb_stdlog, "Process record: break at %s.\n",
>>   				paddress (gdbarch, tmp_pc));
>>   		  goto replay_out;
>>   		}
>> @@ -1344,10 +1249,10 @@ record_full_wait_1 (struct target_ops *ops,
>>   	     the signal.  */
>>   	  target_terminal::ours ();
>>
>> -	  /* In EXEC_FORWARD mode, record_full_list points to the tail of
>> prev
>> -	     instruction.  */
>> -	  if (execution_direction == EXEC_FORWARD && record_full_list-
>>> next)
>> -	    record_full_list = record_full_list->next;
>> +	  /* In EXEC_FORWARD mode, record_full_next_insn is the next
>> +	     instruction to be executed.  */
>> +	  if (execution_direction == EXEC_REVERSE)
>> +	    record_full_next_insn--;
>>
>>   	  /* Loop over the record_full_list, looking for the next place to
>>   	     stop.  */
>> @@ -1355,108 +1260,92 @@ record_full_wait_1 (struct target_ops *ops,
>>   	    {
>>   	      /* Check for beginning and end of log.  */
>>   	      if (execution_direction == EXEC_REVERSE
>> -		  && record_full_list == &record_full_first)
>> +		  && record_full_next_insn < 0)
>>   		{
>>   		  /* Hit beginning of record log in reverse.  */
>>   		  status->set_no_history ();
>> +		  record_full_next_insn = 0;
>>   		  break;
>>   		}
>>   	      if (execution_direction != EXEC_REVERSE
>> -		  && !record_full_list->next)
>> +		  && record_full_next_insn == record_full_list.size ())
>>   		{
>>   		  /* Hit end of record log going forward.  */
>>   		  status->set_no_history ();
>>   		  break;
>>   		}
>>
>> -	      record_full_exec_insn (regcache, gdbarch, record_full_list);
>> +	      record_full_exec_insn
>> +		(regcache, gdbarch,
>> +		 record_full_list[record_full_next_insn]);
>>
>> -	      if (record_full_list->type == record_full_end)
>> +	      /* step */
>> +	      if (record_full_resume_step)
>>   		{
>>   		  if (record_debug > 1)
>> -		    gdb_printf
>> -		      (gdb_stdlog,
>> -		       "Process record: record_full_end %s to "
>> -		       "inferior.\n",
>> -		       host_address_to_string (record_full_list));
>> -
>> -		  if (first_record_full_end
>> -		      && execution_direction == EXEC_REVERSE)
>> -		    {
>> -		      /* When reverse execute, the first
>> -			 record_full_end is the part of current
>> -			 instruction.  */
>> -		      first_record_full_end = 0;
>> -		    }
>> -		  else
>> -		    {
>> -		      /* In EXEC_REVERSE mode, this is the
>> -			 record_full_end of prev instruction.  In
>> -			 EXEC_FORWARD mode, this is the
>> -			 record_full_end of current instruction.  */
>> -		      /* step */
>> -		      if (record_full_resume_step)
>> -			{
>> -			  if (record_debug > 1)
>> -			    gdb_printf (gdb_stdlog,
>> -					"Process record: step.\n");
>> -			  continue_flag = 0;
>> -			}
>> -
>> -		      /* check breakpoint */
>> -		      tmp_pc = regcache_read_pc (regcache);
>> -		      if (record_check_stopped_by_breakpoint
>> -			  (aspace, tmp_pc, &record_full_stop_reason))
>> -			{
>> -			  if (record_debug)
>> -			    gdb_printf (gdb_stdlog,
>> -					"Process record: break "
>> -					"at %s.\n",
>> -					paddress (gdbarch, tmp_pc));
>> +		    gdb_printf (gdb_stdlog,
>> +				"Process record: step.\n");
>> +		  continue_flag = 0;
>> +		}
>>
>> -			  continue_flag = 0;
>> -			}
>> +	      /* check breakpoint */
>> +	      tmp_pc = regcache_read_pc (regcache);
>> +	      if (record_check_stopped_by_breakpoint
>> +		  (aspace, tmp_pc, &record_full_stop_reason))
>> +		{
>> +		  if (record_debug)
>> +		    gdb_printf (gdb_stdlog,
>> +				"Process record: break "
>> +				"at %s.\n",
>> +				paddress (gdbarch, tmp_pc));
>>
>> -		      if (record_full_stop_reason
>> -			  == TARGET_STOPPED_BY_WATCHPOINT)
>> -			{
>> -			  if (record_debug)
>> -			    gdb_printf (gdb_stdlog,
>> -					"Process record: hit hw "
>> -					"watchpoint.\n");
>> -			  continue_flag = 0;
>> -			}
>> -		      /* Check target signal */
>> -		      if (record_full_list->u.end.sigval != GDB_SIGNAL_0)
>> -			/* FIXME: better way to check */
>> -			continue_flag = 0;
>> -		    }
>> +		  continue_flag = 0;
>>   		}
>>
>> -	      if (continue_flag)
>> +	      if (record_full_stop_reason
>> +		  == TARGET_STOPPED_BY_WATCHPOINT)
>>   		{
>> -		  if (execution_direction == EXEC_REVERSE)
>> -		    {
>> -		      if (record_full_list->prev)
>> -			record_full_list = record_full_list->prev;
>> -		    }
>> -		  else
>> -		    {
>> -		      if (record_full_list->next)
>> -			record_full_list = record_full_list->next;
>> -		    }
>> +		  if (record_debug)
>> +		    gdb_printf (gdb_stdlog,
>> +				"Process record: hit hw "
>> +				"watchpoint.\n");
>> +		  continue_flag = 0;
>>   		}
>> +	      if (record_full_list[record_full_next_insn].sigval.has_value ())
>> +		continue_flag = 0;
>> +
>> +	      if (execution_direction == EXEC_REVERSE)
>> +		record_full_next_insn--;
>> +	      else
>> +		record_full_next_insn++;
>>   	    }
>>   	  while (continue_flag);
>>
>> +	  if (record_full_next_insn < 0)
>> +	    {
>> +	      gdb_assert (execution_direction == EXEC_REVERSE);
>> +	      record_full_next_insn = 0;
>> +	    }
>> +	  else if (record_full_next_insn > record_full_list.size ())
>> +	    {
>> +	      gdb_assert (execution_direction == EXEC_FORWARD);
>> +	      record_full_next_insn = record_full_list.size ();
>> +	    }
>> +	  /* Reset the current instruction to point to the one to be replayed
>> +	     moving forward.  */
>> +	  else if (execution_direction == EXEC_REVERSE)
>> +	    record_full_next_insn++;
>> +
>>   	replay_out:
>>   	  if (status->kind () == TARGET_WAITKIND_STOPPED)
>>   	    {
>> +	      int insn = (execution_direction == EXEC_FORWARD)
>> +			 ? record_full_next_insn - 1 : record_full_next_insn;
>>   	      if (record_full_get_sig)
>>   		status->set_stopped (GDB_SIGNAL_INT);
>> -	      else if (record_full_list->u.end.sigval != GDB_SIGNAL_0)
>> -		/* FIXME: better way to check */
>> -		status->set_stopped (record_full_list->u.end.sigval);
>> +	      else if (record_full_list[insn].sigval.has_value ())
>> +		status->set_stopped
>> +		  (record_full_list[insn].sigval.value ());
>>   	      else
>>   		status->set_stopped (GDB_SIGNAL_TRAP);
>>   	    }
>> @@ -1464,12 +1353,9 @@ record_full_wait_1 (struct target_ops *ops,
>>         catch (const gdb_exception &ex)
>>   	{
>>   	  if (execution_direction == EXEC_REVERSE)
>> -	    {
>> -	      if (record_full_list->next)
>> -		record_full_list = record_full_list->next;
>> -	    }
>> +	    record_full_next_insn++;
>>   	  else
>> -	    record_full_list = record_full_list->prev;
>> +	    record_full_next_insn--;
>>
>>   	  throw;
>>   	}
>> @@ -1557,8 +1443,7 @@ record_full_registers_change (struct regcache
>> *regcache, int regnum)
>>     /* Check record_full_insn_num.  */
>>     record_full_check_insn_num ();
>>
>> -  record_full_arch_list_head = NULL;
>> -  record_full_arch_list_tail = NULL;
>> +  record_full_reset_incomplete ();
>>
>>     if (regnum < 0)
>>       {
>> @@ -1568,7 +1453,7 @@ record_full_registers_change (struct regcache
>> *regcache, int regnum)
>>   	{
>>   	  if (record_full_arch_list_add_reg (regcache, i))
>>   	    {
>> -	      record_full_list_release (record_full_arch_list_tail);
>> +	      record_full_reset_incomplete ();
>>   	      error (_("Process record: failed to record execution log."));
>>   	    }
>>   	}
>> @@ -1577,18 +1462,11 @@ record_full_registers_change (struct regcache
>> *regcache, int regnum)
>>       {
>>         if (record_full_arch_list_add_reg (regcache, regnum))
>>   	{
>> -	  record_full_list_release (record_full_arch_list_tail);
>> +	  record_full_reset_incomplete ();
>>   	  error (_("Process record: failed to record execution log."));
>>   	}
>>       }
>> -  if (record_full_arch_list_add_end ())
>> -    {
>> -      record_full_list_release (record_full_arch_list_tail);
>> -      error (_("Process record: failed to record execution log."));
>> -    }
>> -  record_full_list->next = record_full_arch_list_head;
>> -  record_full_arch_list_head->prev = record_full_list;
>> -  record_full_list = record_full_arch_list_tail;
>> +  record_full_save_instruction ();
>>
>>     if (record_full_insn_num == record_full_insn_max_num)
>>       record_full_list_release_first ();
>> @@ -1607,7 +1485,7 @@ record_full_target::store_registers (struct
>> regcache *regcache, int regno)
>>   	{
>>   	  int n;
>>
>> -	  /* Let user choose if he wants to write register or not.  */
>> +	  /* Let user choose if they want to write register or not.  */
> It might be cleaner to move such changes in a separate commit,
> since they just make this big patch even bigger.
Considering it is just a tiny change to a comment, I don't  think it 
makes that much of a difference, really.
>
>>   	  if (regno < 0)
>>   	    n =
>>   	      query (_("Because GDB is in replay mode, changing the "
>> @@ -1642,7 +1520,7 @@ record_full_target::store_registers (struct
>> regcache *regcache, int regno)
>>   	    }
>>
>>   	  /* Destroy the record from here forward.  */
>> -	  record_full_list_release_following (record_full_list);
>> +	  record_full_list_release_following (record_full_next_insn);
>>   	}
>>
>>         record_full_registers_change (regcache, regno);
>> @@ -1675,36 +1553,24 @@ record_full_target::xfer_partial (enum
>> target_object object,
>>   	    error (_("Process record canceled the operation."));
>>
>>   	  /* Destroy the record from here forward.  */
>> -	  record_full_list_release_following (record_full_list);
>> +	  record_full_list_release_following (record_full_next_insn);
>>   	}
>>
>>         /* Check record_full_insn_num */
>>         record_full_check_insn_num ();
>>
>>         /* Record registers change to list as an instruction.  */
>> -      record_full_arch_list_head = NULL;
>> -      record_full_arch_list_tail = NULL;
>> +      record_full_reset_incomplete ();
>>         if (record_full_arch_list_add_mem (offset, len))
>>   	{
>> -	  record_full_list_release (record_full_arch_list_tail);
>> -	  if (record_debug)
>> -	    gdb_printf (gdb_stdlog,
>> -			"Process record: failed to record "
>> -			"execution log.");
>> -	  return TARGET_XFER_E_IO;
>> -	}
>> -      if (record_full_arch_list_add_end ())
>> -	{
>> -	  record_full_list_release (record_full_arch_list_tail);
>> +	  record_full_reset_incomplete ();
>>   	  if (record_debug)
>>   	    gdb_printf (gdb_stdlog,
>>   			"Process record: failed to record "
>>   			"execution log.");
>>   	  return TARGET_XFER_E_IO;
>>   	}
>> -      record_full_list->next = record_full_arch_list_head;
>> -      record_full_arch_list_head->prev = record_full_list;
>> -      record_full_list = record_full_arch_list_tail;
>> +      record_full_save_instruction ();
>>
>>         if (record_full_insn_num == record_full_insn_max_num)
>>   	record_full_list_release_first ();
>> @@ -1865,9 +1731,11 @@ record_full_base_target::get_bookmark (const
>> char *args, int from_tty)
>>   {
>>     char *ret = NULL;
>>
>> +  if (record_full_list.empty ())
>> +    return (gdb_byte *) ret;
>> +
>>     /* Return stringified form of instruction count.  */
>> -  if (record_full_list && record_full_list->type == record_full_end)
>> -    ret = xstrdup (pulongest (record_full_list->u.end.insn_num));
>> +  ret = xstrdup (pulongest
>> (record_full_list[record_full_next_insn].insn_num));
>>
>>     if (record_debug)
>>       {
>> @@ -1923,30 +1791,22 @@ record_full_base_target::record_method
>> (ptid_t ptid)
>>   void
>>   record_full_base_target::info_record ()
>>   {
>> -  struct record_full_entry *p;
>> -
>>     if (RECORD_FULL_IS_REPLAY)
>>       gdb_printf (_("Replay mode:\n"));
>>     else
>>       gdb_printf (_("Record mode:\n"));
>>
>> -  /* Find entry for first actual instruction in the log.  */
>> -  for (p = record_full_first.next;
>> -       p != NULL && p->type != record_full_end;
>> -       p = p->next)
>> -    ;
>> -
>>     /* Do we have a log at all?  */
>> -  if (p != NULL && p->type == record_full_end)
>> +  if (!record_full_list.empty ())
>>       {
>>         /* Display instruction number for first instruction in the log.  */
>> -      gdb_printf (_("Lowest recorded instruction number is %s.\n"),
>> -		  pulongest (p->u.end.insn_num));
>> +      gdb_printf (_("Lowest recorded instruction number is %u.\n"),
>> +		  record_full_list[0].insn_num);
>>
>>         /* If in replay mode, display where we are in the log.  */
>>         if (RECORD_FULL_IS_REPLAY)
>> -	gdb_printf (_("Current instruction number is %s.\n"),
>> -		    pulongest (record_full_list->u.end.insn_num));
>> +	gdb_printf (_("Current instruction number is %u.\n"),
>> +		    record_full_list[record_full_next_insn].insn_num);
>>
>>         /* Display instruction number for last instruction in the log.  */
>>         gdb_printf (_("Highest recorded instruction number is %s.\n"),
>> @@ -1975,7 +1835,7 @@ record_full_base_target::supports_delete_record
>> ()
>>   void
>>   record_full_base_target::delete_record ()
>>   {
>> -  record_full_list_release_following (record_full_list);
>> +  record_full_reset_history ();
>>   }
>>
>>   /* The "record_is_replaying" target method.  */
>> @@ -2001,23 +1861,23 @@ record_full_base_target::record_will_replay
>> (ptid_t ptid, int dir)
>>   /* Go to a specific entry.  */
>>
>>   static void
>> -record_full_goto_entry (struct record_full_entry *p)
>> +record_full_goto_entry (size_t target_insn)
>>   {
>> -  if (p == NULL)
>> +  if (target_insn >= record_full_list.size ())
>>       error (_("Target insn not found."));
>> -  else if (p == record_full_list)
>> +  else if (target_insn == record_full_next_insn)
>>       error (_("Already at target insn."));
>> -  else if (p->u.end.insn_num > record_full_list->u.end.insn_num)
>> +  else if (target_insn > record_full_next_insn)
>>       {
>>         gdb_printf (_("Go forward to insn number %s\n"),
>> -		  pulongest (p->u.end.insn_num));
>> -      record_full_goto_insn (p, EXEC_FORWARD);
>> +		  pulongest (record_full_list[target_insn].insn_num));
>> +      record_full_goto_insn (target_insn, EXEC_FORWARD);
>>       }
>>     else
>>       {
>>         gdb_printf (_("Go backward to insn number %s\n"),
>> -		  pulongest (p->u.end.insn_num));
>> -      record_full_goto_insn (p, EXEC_REVERSE);
>> +		  pulongest (target_insn));
>> +      record_full_goto_insn (target_insn, EXEC_REVERSE);
>>       }
>>
>>     registers_changed ();
>> @@ -2033,13 +1893,7 @@ record_full_goto_entry (struct record_full_entry
>> *p)
>>   void
>>   record_full_base_target::goto_record_begin ()
>>   {
>> -  struct record_full_entry *p = NULL;
>> -
>> -  for (p = &record_full_first; p != NULL; p = p->next)
>> -    if (p->type == record_full_end)
>> -      break;
>> -
>> -  record_full_goto_entry (p);
>> +  record_full_goto_entry (0);
>>   }
>>
>>   /* The "goto_record_end" target method.  */
>> @@ -2047,15 +1901,7 @@ record_full_base_target::goto_record_begin ()
>>   void
>>   record_full_base_target::goto_record_end ()
>>   {
>> -  struct record_full_entry *p = NULL;
>> -
>> -  for (p = record_full_list; p->next != NULL; p = p->next)
>> -    ;
>> -  for (; p!= NULL; p = p->prev)
>> -    if (p->type == record_full_end)
>> -      break;
>> -
>> -  record_full_goto_entry (p);
>> +  record_full_goto_entry (record_full_list.size () - 1);
>>   }
>>
>>   /* The "goto_record" target method.  */
>> @@ -2063,13 +1909,7 @@ record_full_base_target::goto_record_end ()
>>   void
>>   record_full_base_target::goto_record (ULONGEST target_insn)
>>   {
>> -  struct record_full_entry *p = NULL;
>> -
>> -  for (p = &record_full_first; p != NULL; p = p->next)
>> -    if (p->type == record_full_end && p->u.end.insn_num == target_insn)
>> -      break;
>> -
>> -  record_full_goto_entry (p);
>> +  record_full_goto_entry (target_insn);
>>   }
>>
>>   /* The "record_stop_replaying" target method.  */
>> @@ -2339,19 +2179,96 @@ netorder32 (uint32_t input)
>>     return ret;
>>   }
> Function comment. And I think it would be cleaner to move this refactoring in
> a separate patch, too. Or is this separate function only possible due to the change
> from using a list to std::deque?
This function could be in a patch of its own, yeah. Will do that for v4
>
>> +static void
>> +record_full_read_entry_from_bfd (bfd *cbfd, asection *osec, int *bfd_offset)
>> +{
>> +  uint8_t rectype;
>> +  uint32_t regnum, len;
>> +  uint64_t addr;
>> +  regcache *cache = get_thread_regcache (inferior_thread ());
>> +
>> +  bfdcore_read (cbfd, osec, &rectype, sizeof (rectype), bfd_offset);
>> +  switch (rectype)
>> +    {
>> +    case record_full_reg: /* reg */
>> +      {
>> +	/* Get register number to regnum.  */
>> +	bfdcore_read (cbfd, osec, &regnum, sizeof (regnum), bfd_offset);
>> +	regnum = netorder32 (regnum);
>> +
>> +	record_full_entry rec;
>> +
>> +	rec = record_full_reg_init (cache, regnum);
>> +
>> +	/* Get val.  */
>> +	bfdcore_read (cbfd, osec, record_full_get_loc (&rec),
>> +		      rec.u.reg.len, bfd_offset);
>> +
>> +	if (record_debug)
>> +	  gdb_printf (gdb_stdlog,
>> +		      "  Reading register %d (1 "
>> +		      "plus %lu plus %d bytes)\n",
>> +		      rec.u.reg.num,
>> +		      (unsigned long) sizeof (regnum),
>> +		      rec.u.reg.len);
>> +
>> +	record_full_arch_list_add (rec);
>> +	break;
>> +      }
>> +
>> +    case record_full_mem: /* mem */
>> +      {
>> +	/* Get len.  */
>> +	bfdcore_read (cbfd, osec, &len, sizeof (len), bfd_offset);
>> +	len = netorder32 (len);
>> +
>> +	/* Get addr.  */
>> +	bfdcore_read (cbfd, osec, &addr, sizeof (addr),
>> +		      bfd_offset);
>> +	addr = netorder64 (addr);
>> +
>> +	record_full_entry rec;
>> +	rec = record_full_mem_init (addr, len);
>> +
>> +	/* Get val.  */
>> +	bfdcore_read (cbfd, osec, record_full_get_loc (&rec), len,
>> +		      bfd_offset);
>> +
>> +	if (record_debug)
>> +	  gdb_printf (gdb_stdlog,
>> +		      "  Reading memory %s (1 plus "
>> +		      "%lu plus %lu plus %d bytes)\n",
>> +		      paddress (get_current_arch (),
>> +				rec.u.mem.addr),
>> +		      (unsigned long) sizeof (addr),
>> +		      (unsigned long) sizeof (len),
>> +		      len);
>> +
>> +	record_full_arch_list_add (rec);
>> +	break;
>> +      }
>> +
>> +    default:
>> +      error (_("Bad entry type %d, offset %d of %lu in core file %ps."),
>> +	     rectype, *bfd_offset, bfd_section_size (osec),
>> +	     styled_string (file_name_style.style (),
>> +			    bfd_get_filename (cbfd)));
>> +      break;
>> +    }
>> +}
>> +
>>   /* Restore the execution log from core file CBFD.  */
>>
>>   static void
>>   record_full_restore (struct bfd &cbfd)
>>   {
>>     uint32_t magic;
>> -  struct record_full_entry *rec;
>>     asection *osec;
>>     uint32_t osec_size;
>>     int bfd_offset = 0;
>>
>>     /* "record_full_restore" can only be called when record list is empty.  */
>> -  gdb_assert (record_full_first.next == NULL);
>> +  gdb_assert (record_full_list.empty ());
>>
>>     if (record_debug)
>>       gdb_printf (gdb_stdlog, "Restoring recording from core file.\n");
>> @@ -2379,124 +2296,47 @@ record_full_restore (struct bfd &cbfd)
>>   		"RECORD_FULL_FILE_MAGIC (0x%s)\n",
>>   		phex_nz (netorder32 (magic), 4));
>>
>> -  /* Restore the entries in recfd into record_full_arch_list_head and
>> -     record_full_arch_list_tail.  */
>> -  record_full_arch_list_head = NULL;
>> -  record_full_arch_list_tail = NULL;
>>     record_full_insn_num = 0;
>>
>>     try
>>       {
>> -      regcache *regcache = get_thread_regcache (inferior_thread ());
>> -
>> -      while (1)
>> +      while (bfd_offset < osec_size)
>>   	{
>> -	  uint8_t rectype;
>> -	  uint32_t regnum, len, signal, count;
>> -	  uint64_t addr;
>> +	  record_full_reset_incomplete ();
>> +	  uint32_t eff_count = 0;
>> +	  uint8_t sigval;
>> +	  uint32_t insn_num;
>>
>> -	  /* We are finished when offset reaches osec_size.  */
>> -	  if (bfd_offset >= osec_size)
>> -	    break;
>> -	  bfdcore_read (&cbfd, osec, &rectype, sizeof (rectype), &bfd_offset);
>> +	  /* First read the generic information for an instruction.  */
>> +	  bfdcore_read (&cbfd, osec, &sigval, sizeof (uint8_t), &bfd_offset);
>> +	  bfdcore_read (&cbfd, osec, &eff_count, sizeof (uint32_t),
>> +			&bfd_offset);
>> +	  bfdcore_read (&cbfd, osec, &insn_num, sizeof (uint32_t),
>> +			&bfd_offset);
>>
>> -	  switch (rectype)
>> -	    {
>> -	    case record_full_reg: /* reg */
>> -	      /* Get register number to regnum.  */
>> -	      bfdcore_read (&cbfd, osec, &regnum, sizeof (regnum),
>> -			    &bfd_offset);
>> -	      regnum = netorder32 (regnum);
>> -
>> -	      rec = record_full_reg_alloc (regcache, regnum);
>> -
>> -	      /* Get val.  */
>> -	      bfdcore_read (&cbfd, osec, record_full_get_loc (rec),
>> -			    rec->u.reg.len, &bfd_offset);
>> -
>> -	      if (record_debug)
>> -		gdb_printf (gdb_stdlog,
>> -			    "  Reading register %d (1 "
>> -			    "plus %lu plus %d bytes)\n",
>> -			    rec->u.reg.num,
>> -			    (unsigned long) sizeof (regnum),
>> -			    rec->u.reg.len);
>> -	      break;
>> +	  record_full_incomplete_instruction.insn_num = netorder32
>> (insn_num);
>> +	  if (sigval != GDB_SIGNAL_0)
>> +	    record_full_incomplete_instruction.sigval = (gdb_signal) sigval;
>>
>> -	    case record_full_mem: /* mem */
>> -	      /* Get len.  */
>> -	      bfdcore_read (&cbfd, osec, &len, sizeof (len), &bfd_offset);
>> -	      len = netorder32 (len);
>> -
>> -	      /* Get addr.  */
>> -	      bfdcore_read (&cbfd, osec, &addr, sizeof (addr), &bfd_offset);
>> -	      addr = netorder64 (addr);
>> -
>> -	      rec = record_full_mem_alloc (addr, len);
>> -
>> -	      /* Get val.  */
>> -	      bfdcore_read (&cbfd, osec, record_full_get_loc (rec),
>> -			    rec->u.mem.len, &bfd_offset);
>> -
>> -	      if (record_debug)
>> -		gdb_printf (gdb_stdlog,
>> -			    "  Reading memory %s (1 plus "
>> -			    "%lu plus %lu plus %d bytes)\n",
>> -			    paddress (get_current_arch (),
>> -				      rec->u.mem.addr),
>> -			    (unsigned long) sizeof (addr),
>> -			    (unsigned long) sizeof (len),
>> -			    rec->u.mem.len);
>> -	      break;
>> +	  eff_count = netorder32 (eff_count);
>>
>> -	    case record_full_end: /* end */
>> -	      rec = record_full_end_alloc ();
>> -	      record_full_insn_num ++;
>> -
>> -	      /* Get signal value.  */
>> -	      bfdcore_read (&cbfd, osec, &signal, sizeof (signal),
>> -			    &bfd_offset);
>> -	      signal = netorder32 (signal);
>> -	      rec->u.end.sigval = (enum gdb_signal) signal;
>> -
>> -	      /* Get insn count.  */
>> -	      bfdcore_read (&cbfd, osec, &count, sizeof (count), &bfd_offset);
>> -	      count = netorder32 (count);
>> -	      rec->u.end.insn_num = count;
>> -	      record_full_insn_count = count + 1;
>> -	      if (record_debug)
>> -		gdb_printf (gdb_stdlog,
>> -			    "  Reading record_full_end (1 + "
>> -			    "%lu + %lu bytes), offset == %s\n",
>> -			    (unsigned long) sizeof (signal),
>> -			    (unsigned long) sizeof (count),
>> -			    paddress (get_current_arch (),
>> -				      bfd_offset));
>> -	      break;
>> +	  /* This deals with all the side effects.  */
>> +	 while (eff_count > 0)
>> +	   {
>> +	     eff_count--;
>>
>> -	    default:
>> -	      error (_("Bad entry type in core file %ps."),
>> -		     styled_string (file_name_style.style (),
>> -				    bfd_get_filename (&cbfd)));
>> -	      break;
>> -	    }
>> +	     record_full_read_entry_from_bfd (&cbfd, osec, &bfd_offset);
>> +	   }
>>
>> -	  /* Add rec to record arch list.  */
>> -	  record_full_arch_list_add (rec);
>> +	  record_full_save_instruction ();
>>   	}
>>       }
>>     catch (const gdb_exception &ex)
>>       {
>> -      record_full_list_release (record_full_arch_list_tail);
>> +      record_full_reset_incomplete ();
>>         throw;
>>       }
>>
>> -  /* Add record_full_arch_list_head to the end of record list.  */
>> -  record_full_first.next = record_full_arch_list_head;
>> -  record_full_arch_list_head->prev = &record_full_first;
>> -  record_full_arch_list_tail->next = NULL;
>> -  record_full_list = &record_full_first;
>> -
>>     /* Update record_full_insn_max_num.  */
>>     if (record_full_insn_num > record_full_insn_max_num)
>>       {
>> @@ -2505,6 +2345,10 @@ record_full_restore (struct bfd &cbfd)
>>   	       record_full_insn_max_num);
>>       }
>>
>> +  /* When loading a recording, we'll always start at the oldest possible
>> +     instruction, no matter where the original recording was stopped.  */
>> +  record_full_next_insn = 0;
>> +
>>     /* Succeeded.  */
>>     gdb_printf (_("Restored records from core file %s.\n"),
>>   	      bfd_get_filename (&cbfd));
>> @@ -2538,13 +2382,73 @@ cmd_record_full_restore (const char *args, int
>> from_tty)
>>     record_full_open (nullptr, from_tty);
>>   }
> Function comment. And similar comment for separate patch.
>
> I believe sth. like a follow-up commit that introduces the functions
> record_full_read_entry_from_bfd and record_full_write_entry_to_bfd
> would make this much easier to review.
yeah same as above, will make this patch 2 of the series.
>
>> +static void
>> +record_full_write_entry_to_bfd (record_full_entry &entry,
>> +				gdb_bfd_ref_ptr obfd,
>> +				asection *osec, int *bfd_offset,
>> +				gdbarch *gdbarch)
>> +{
>> +  /* Save entry.  */
>> +  uint8_t type;
>> +  uint32_t regnum, len;
>> +  uint64_t addr;
>> +
>> +  type = entry.type;
>> +  bfdcore_write (obfd.get (), osec, &type, sizeof (type), bfd_offset);
>> +
>> +  switch (entry.type)
>> +    {
>> +    case record_full_reg: /* reg */
>> +      if (record_debug)
>> +	gdb_printf (gdb_stdlog,
>> +		    "  Writing register %d (1 "
>> +		    "plus %lu plus %d bytes)\n",
>> +		    entry.u.reg.num,
>> +		    (unsigned long) sizeof (regnum),
>> +		    entry.u.reg.len);
>> +
>> +      /* Write regnum.  */
>> +      regnum = netorder32 (entry.u.reg.num);
>> +      bfdcore_write (obfd.get (), osec, &regnum, sizeof (regnum), bfd_offset);
>> +
>> +      /* Write regval.  */
>> +      bfdcore_write (obfd.get (), osec, record_full_get_loc (&entry),
>> +		     entry.u.reg.len, bfd_offset);
>> +      break;
>> +
>> +    case record_full_mem: /* mem */
>> +      if (record_debug)
>> +	gdb_printf (gdb_stdlog,
>> +		    "  Writing memory %s (1 plus "
>> +		    "%lu plus %lu plus %d bytes)\n",
>> +		    paddress (gdbarch,
>> +			      entry.u.mem.addr),
>> +		    (unsigned long) sizeof (addr),
>> +		    (unsigned long) sizeof (len),
>> +		    entry.u.mem.len);
>> +
>> +      /* Write memlen.  */
>> +      len = netorder32 (entry.u.mem.len);
>> +      bfdcore_write (obfd.get (), osec, &len, sizeof (len), bfd_offset);
>> +
>> +      /* Write memaddr.  */
>> +      addr = netorder64 (entry.u.mem.addr);
>> +      bfdcore_write (obfd.get (), osec, &addr, sizeof (addr), bfd_offset);
>> +
>> +      /* Write memval.  */
>> +      bfdcore_write (obfd.get (), osec, record_full_get_loc (&entry),
>> +		     entry.u.mem.len, bfd_offset);
>> +      break;
>> +    }
>> +
>> +}
>> +
>>   /* Save the execution log to a file.  We use a modified elf corefile
>>      format, with an extra section for our data.  */
>>
>>   void
>>   record_full_base_target::save_record (const char *recfilename)
>>   {
>> -  struct record_full_entry *cur_record_full_list;
>>     uint32_t magic;
>>     struct gdbarch *gdbarch;
>>     int save_size = 0;
>> @@ -2562,9 +2466,6 @@ record_full_base_target::save_record (const char
>> *recfilename)
>>     /* Arrange to remove the output file on failure.  */
>>     gdb::unlinker unlink_file (recfilename);
>>
>> -  /* Save the current record entry to "cur_record_full_list".  */
>> -  cur_record_full_list = record_full_list;
>> -
>>     /* Get the values of regcache and gdbarch.  */
>>     regcache *regcache = get_thread_regcache (inferior_thread ());
>>     gdbarch = regcache->arch ();
>> @@ -2574,34 +2475,27 @@ record_full_base_target::save_record (const
>> char *recfilename)
>>       = record_full_gdb_operation_disable_set ();
>>
>>     /* Reverse execute to the begin of record list.  */
>> -  while (1)
>> -    {
>> -      /* Check for beginning and end of log.  */
>> -      if (record_full_list == &record_full_first)
>> -	break;
>> -
>> -      record_full_exec_insn (regcache, gdbarch, record_full_list);
>> -
>> -      if (record_full_list->prev)
>> -	record_full_list = record_full_list->prev;
>> -    }
>> +  for (int i = record_full_next_insn - 1; i >= 0; i--)
>> +    record_full_exec_insn (regcache, gdbarch,
>> +			   record_full_list[i]);
>>
>>     /* Compute the size needed for the extra bfd section.  */
>>     save_size = 4;	/* magic cookie */
>> -  for (record_full_list = record_full_first.next; record_full_list;
>> -       record_full_list = record_full_list->next)
>> -    switch (record_full_list->type)
>> -      {
>> -      case record_full_end:
>> -	save_size += 1 + 4 + 4;
>> -	break;
>> -      case record_full_reg:
>> -	save_size += 1 + 4 + record_full_list->u.reg.len;
>> -	break;
>> -      case record_full_mem:
>> -	save_size += 1 + 4 + 8 + record_full_list->u.mem.len;
>> -	break;
>> -      }
>> +  for (int i = record_full_list.size () - 1; i >= 0; i--)
>> +    {
>> +      /* Number of effects of an instruction.  */
>> +      save_size += sizeof (uint32_t) + sizeof (uint8_t) + sizeof (uint32_t);
>> +      for (auto &entry : record_full_list[i].effects)
>> +	switch (entry.type)
>> +	  {
>> +	  case record_full_reg:
>> +	    save_size += 1 + 4 + entry.u.reg.len;
>> +	    break;
>> +	  case record_full_mem:
>> +	    save_size += 1 + 4 + 8 + entry.u.mem.len;
>> +	    break;
>> +	  }
>> +    }
>>
>>     /* Make the new bfd section.  */
>>     osec = bfd_make_section_anyway_with_flags (obfd.get (), "precord",
>> @@ -2630,108 +2524,32 @@ record_full_base_target::save_record (const
>> char *recfilename)
>>
>>     /* Save the entries to recfd and forward execute to the end of
>>        record list.  */
>> -  record_full_list = &record_full_first;
>> -  while (1)
>> +  for (int i = 0; i < record_full_list.size (); i++)
>>       {
>> -      /* Save entry.  */
>> -      if (record_full_list != &record_full_first)
>> +      uint32_t eff_count = (uint32_t) record_full_list[i].effects.size ();
>> +      uint32_t insn_num = record_full_list[i].insn_num;
>> +      uint8_t sigval = (record_full_list[i].sigval.has_value ())
>> +			 ? record_full_list[i].sigval.value ()
>> +			 : GDB_SIGNAL_0;
>> +
>> +      /* Signal.  */
>> +      bfdcore_write (obfd.get (), osec, &sigval, sizeof (sigval), &bfd_offset);
>> +      eff_count = netorder32 (eff_count);
>> +      /* Number of effects.  */
>> +      bfdcore_write (obfd.get (), osec, &eff_count, sizeof (eff_count),
>> +		     &bfd_offset);
>> +      /* Instruction number.  */
>> +      bfdcore_write (obfd.get (), osec, &insn_num, sizeof (uint32_t),
>> +		     &bfd_offset);
>> +
>> +      for (auto &entry : record_full_list[i].effects)
>>   	{
>> -	  uint8_t type;
>> -	  uint32_t regnum, len, signal, count;
>> -	  uint64_t addr;
>> -
>> -	  type = record_full_list->type;
>> -	  bfdcore_write (obfd.get (), osec, &type, sizeof (type), &bfd_offset);
>> -
>> -	  switch (record_full_list->type)
>> -	    {
>> -	    case record_full_reg: /* reg */
>> -	      if (record_debug)
>> -		gdb_printf (gdb_stdlog,
>> -			    "  Writing register %d (1 "
>> -			    "plus %lu plus %d bytes)\n",
>> -			    record_full_list->u.reg.num,
>> -			    (unsigned long) sizeof (regnum),
>> -			    record_full_list->u.reg.len);
>> -
>> -	      /* Write regnum.  */
>> -	      regnum = netorder32 (record_full_list->u.reg.num);
>> -	      bfdcore_write (obfd.get (), osec, &regnum,
>> -			     sizeof (regnum), &bfd_offset);
>> -
>> -	      /* Write regval.  */
>> -	      bfdcore_write (obfd.get (), osec,
>> -			     record_full_get_loc (record_full_list),
>> -			     record_full_list->u.reg.len, &bfd_offset);
>> -	      break;
>> -
>> -	    case record_full_mem: /* mem */
>> -	      if (record_debug)
>> -		gdb_printf (gdb_stdlog,
>> -			    "  Writing memory %s (1 plus "
>> -			    "%lu plus %lu plus %d bytes)\n",
>> -			    paddress (gdbarch,
>> -				      record_full_list->u.mem.addr),
>> -			    (unsigned long) sizeof (addr),
>> -			    (unsigned long) sizeof (len),
>> -			    record_full_list->u.mem.len);
>> -
>> -	      /* Write memlen.  */
>> -	      len = netorder32 (record_full_list->u.mem.len);
>> -	      bfdcore_write (obfd.get (), osec, &len, sizeof (len),
>> -			     &bfd_offset);
>> -
>> -	      /* Write memaddr.  */
>> -	      addr = netorder64 (record_full_list->u.mem.addr);
>> -	      bfdcore_write (obfd.get (), osec, &addr,
>> -			     sizeof (addr), &bfd_offset);
>> -
>> -	      /* Write memval.  */
>> -	      bfdcore_write (obfd.get (), osec,
>> -			     record_full_get_loc (record_full_list),
>> -			     record_full_list->u.mem.len, &bfd_offset);
>> -	      break;
>> -
>> -	      case record_full_end:
>> -		if (record_debug)
>> -		  gdb_printf (gdb_stdlog,
>> -			      "  Writing record_full_end (1 + "
>> -			      "%lu + %lu bytes)\n",
>> -			      (unsigned long) sizeof (signal),
>> -			      (unsigned long) sizeof (count));
>> -		/* Write signal value.  */
>> -		signal = netorder32 (record_full_list->u.end.sigval);
>> -		bfdcore_write (obfd.get (), osec, &signal,
>> -			       sizeof (signal), &bfd_offset);
>> -
>> -		/* Write insn count.  */
>> -		count = netorder32 (record_full_list->u.end.insn_num);
>> -		bfdcore_write (obfd.get (), osec, &count,
>> -			       sizeof (count), &bfd_offset);
>> -		break;
>> -	    }
>> +	  record_full_write_entry_to_bfd (entry, obfd, osec, &bfd_offset,
>> +					  gdbarch);
>>   	}
>> -
>>         /* Execute entry.  */
>> -      record_full_exec_insn (regcache, gdbarch, record_full_list);
>> -
>> -      if (record_full_list->next)
>> -	record_full_list = record_full_list->next;
>> -      else
>> -	break;
>> -    }
>> -
>> -  /* Reverse execute to cur_record_full_list.  */
>> -  while (1)
>> -    {
>> -      /* Check for beginning and end of log.  */
>> -      if (record_full_list == cur_record_full_list)
>> -	break;
>> -
>> -      record_full_exec_insn (regcache, gdbarch, record_full_list);
>> -
>> -      if (record_full_list->prev)
>> -	record_full_list = record_full_list->prev;
>> +      if (i < record_full_next_insn)
>> +	record_full_exec_insn (regcache, gdbarch, record_full_list[i]);
>>       }
>>
>>     unlink_file.keep ();
>> @@ -2742,11 +2560,11 @@ record_full_base_target::save_record (const
>> char *recfilename)
>>   }
>>
>>   /* record_full_goto_insn -- rewind the record log (forward or backward,
>> -   depending on DIR) to the given entry, changing the program state
>> -   correspondingly.  */
>> +   depending on DIR) to the entry in position TARGET_INSN in the history,
>> +   changing the program state correspondingly.  */
>>
>>   static void
>> -record_full_goto_insn (struct record_full_entry *entry,
>> +record_full_goto_insn (size_t target_insn,
>>   		       enum exec_direction_kind dir)
>>   {
>>     scoped_restore restore_operation_disable
>> @@ -2757,17 +2575,12 @@ record_full_goto_insn (struct record_full_entry
>> *entry,
>>     /* Assume everything is valid: we will hit the entry,
>>        and we will not hit the end of the recording.  */
>>
>> -  if (dir == EXEC_FORWARD)
>> -    record_full_list = record_full_list->next;
>> -
>> -  do
>> -    {
>> -      record_full_exec_insn (regcache, gdbarch, record_full_list);
>> -      if (dir == EXEC_REVERSE)
>> -	record_full_list = record_full_list->prev;
>> -      else
>> -	record_full_list = record_full_list->next;
>> -    } while (record_full_list != entry);
>> +  if (dir == EXEC_REVERSE)
>> +    for (int i = record_full_next_insn; i > target_insn; i--)
>> +      record_full_exec_insn (regcache, gdbarch, record_full_list[i - 1]);
>> +  else
>> +    for (int i = record_full_next_insn; i < target_insn; i++)
>> +      record_full_exec_insn (regcache, gdbarch, record_full_list[i]);
>>   }
>>
>>   /* Alias for "target record-full".  */
>> @@ -2798,61 +2611,36 @@ set_record_full_insn_max_num (const char
>> *args, int from_tty,
>>   static void
>>   maintenance_print_record_instruction (const char *args, int from_tty)
>>   {
>> -  struct record_full_entry *to_print = record_full_list;
>> +  if (record_full_list.empty ())
>> +    error (_("Not enough recorded history"));
>>
>> +  int offset = record_full_next_insn - 1;
>> +  /* Reduce the offset by 1 if the record_full_next_insn is after the end
>> +     so that we show the last recorded instruction instead of crashing.  */
>> +  if (offset == record_full_list.size ())
>> +    offset--;
>>     if (args != nullptr)
>>       {
>> -      int offset = value_as_long (parse_and_eval (args));
>> -      if (offset > 0)
>> -	{
>> -	  /* Move forward OFFSET instructions.  We know we found the
>> -	     end of an instruction when to_print->type is record_full_end.  */
>> -	  while (to_print->next != nullptr && offset > 0)
>> -	    {
>> -	      to_print = to_print->next;
>> -	      if (to_print->type == record_full_end)
>> -		offset--;
>> -	    }
>> -	  if (offset != 0)
>> -	    error (_("Not enough recorded history"));
>> -	}
>> -      else
>> -	{
>> -	  while (to_print->prev != nullptr && offset < 0)
>> -	    {
>> -	      to_print = to_print->prev;
>> -	      if (to_print->type == record_full_end)
>> -		offset++;
>> -	    }
>> -	  if (offset != 0)
>> -	    error (_("Not enough recorded history"));
>> -	}
>> +      offset += value_as_long (parse_and_eval (args));
>> +      if (offset >= record_full_list.size () || offset < 0)
>> +	error (_("Not enough recorded history"));
>>       }
>> -  gdb_assert (to_print != nullptr);
>> +  auto to_print = record_full_list.begin () + offset;
>>
>>     gdbarch *arch = current_inferior ()->arch ();
>>
>> -  /* Go back to the start of the instruction.  */
>> -  while (to_print->prev != nullptr && to_print->prev->type != record_full_end)
>> -    to_print = to_print->prev;
>> -
>> -  /* if we're in the first record, there are no actual instructions
>> -     recorded.  Warn the user and leave.  */
>> -  if (to_print == &record_full_first)
>> -    error (_("Not enough recorded history"));
>> -
>> -  while (to_print->type != record_full_end)
>> +  for (auto entry : to_print->effects)
>>       {
>> -      switch (to_print->type)
>> +      switch (entry.type)
>>   	{
>>   	  case record_full_reg:
>>   	    {
>> -	      type *regtype = gdbarch_register_type (arch, to_print-
>>> u.reg.num);
>> +	      type *regtype = gdbarch_register_type (arch, entry.u.reg.num);
>>   	      value *val
>>   		  = value_from_contents (regtype,
>> -					 record_full_get_loc (to_print));
>> +					 record_full_get_loc (&entry));
>>   	      gdb_printf ("Register %s changed: ",
>> -			  gdbarch_register_name (arch, to_print-
>>> u.reg.num));
>> +			  gdbarch_register_name (arch, entry.u.reg.num));
>>   	      struct value_print_options opts;
>>   	      get_user_print_options (&opts);
>>   	      opts.raw = true;
>> @@ -2862,17 +2650,16 @@ maintenance_print_record_instruction (const
>> char *args, int from_tty)
>>   	    }
>>   	  case record_full_mem:
>>   	    {
>> -	      gdb_byte *b = record_full_get_loc (to_print);
>> +	      gdb_byte *b = record_full_get_loc (&entry);
>>   	      gdb_printf ("%d bytes of memory at address %s changed from:",
>> -			  to_print->u.mem.len,
>> -			  print_core_address (arch, to_print->u.mem.addr));
>> -	      for (int i = 0; i < to_print->u.mem.len; i++)
>> +			  entry.u.mem.len,
>> +			  print_core_address (arch, entry.u.mem.addr));
>> +	      for (int i = 0; i < entry.u.mem.len; i++)
>>   		gdb_printf (" %02x", b[i]);
>>   	      gdb_printf ("\n");
>>   	      break;
>>   	    }
>>   	}
>> -      to_print = to_print->next;
>>       }
>>   }
>>
>> @@ -2880,11 +2667,6 @@ INIT_GDB_FILE (record_full)
>>   {
>>     struct cmd_list_element *c;
>>
>> -  /* Init record_full_first.  */
>> -  record_full_first.prev = NULL;
>> -  record_full_first.next = NULL;
>> -  record_full_first.type = record_full_end;
>> -
>>     add_target (record_full_target_info, record_full_open);
>>     add_deprecated_target_alias (record_full_target_info, "record");
>>     add_target (record_full_core_target_info, record_full_open);
>> diff --git a/gdb/record-full.h b/gdb/record-full.h
>> index 51effe74560..c327d879a8a 100644
>> --- a/gdb/record-full.h
>> +++ b/gdb/record-full.h
>> @@ -41,7 +41,6 @@ enum record_result
>>
>>   extern int record_full_arch_list_add_reg (struct regcache *regcache, int
>> num);
>>   extern int record_full_arch_list_add_mem (CORE_ADDR addr, int len);
>> -extern int record_full_arch_list_add_end (void);
>>
>>   /* Returns true if the process record target is open.  */
>>   extern int record_full_is_used (void);
>> diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
>> index 6b5c9c02d46..f5b1f66844c 100644
>> --- a/gdb/riscv-tdep.c
>> +++ b/gdb/riscv-tdep.c
>> @@ -5466,8 +5466,5 @@ riscv_process_record (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>     if (res != RECORD_SUCCESS)
>>       return res;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>> -
>>     return 0;
>>   }
>> diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
>> index e135df94a40..f964889a49f 100644
>> --- a/gdb/rs6000-tdep.c
>> +++ b/gdb/rs6000-tdep.c
>> @@ -7138,8 +7138,6 @@ ppc_process_prefix_instruction (int insn_prefix,
>> int insn_suffix,
>>     if (record_full_arch_list_add_reg (regcache, PPC_PC_REGNUM))
>>       return -1;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>     return 0;
>>   }
>>
>> @@ -7447,8 +7445,6 @@ ppc_process_record (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>
>>     if (record_full_arch_list_add_reg (regcache, PPC_PC_REGNUM))
>>       return -1;
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>     return 0;
>>   }
>>
>> diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
>> index 3cd6b359d13..6bea30f08dc 100644
>> --- a/gdb/s390-linux-tdep.c
>> +++ b/gdb/s390-linux-tdep.c
>> @@ -910,9 +910,6 @@ s390_linux_record_signal (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>     if (record_full_arch_list_add_mem (sp, sizeof_rt_sigframe))
>>       return -1;
>>
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>> -
>>     return 0;
>>   }
>>
>> diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c
>> index f9d7bdd04e4..36ce659ea15 100644
>> --- a/gdb/s390-tdep.c
>> +++ b/gdb/s390-tdep.c
>> @@ -7019,8 +7019,6 @@ s390_process_record (struct gdbarch *gdbarch,
>> struct regcache *regcache,
>>
>>     if (record_full_arch_list_add_reg (regcache, S390_PSWA_REGNUM))
>>       return -1;
>> -  if (record_full_arch_list_add_end ())
>> -    return -1;
>>     return 0;
>>   }
>>
>> --
>> 2.54.0
>>
> Christina
>
> Intel Deutschland GmbH
> Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
> Tel: +49 89 991 430, www.intel.de
> Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
> Chairperson of the Supervisory Board: Nicole Lau
> Registered Seat: Munich
> Commercial Register: Amtsgericht Muenchen HRB 186928
>

-- 
Cheers,
Guinevere Larsen
It/she