This patch refactors the ppc64 function call and return value handling code
in ppc-sysv-tdep.c. The main problem to be addressed by this refactoring
is the code duplication caused by certain aggregate types:
According to the ABI, some types are to be decomposed into component types
for parameter and return value handling. For example, complex types are
to be passed as if the real and imaginary component were separate arguments.
Similarly, certain OpenCL vector types are passed as if they were multiple
separate arguments of the vector element type. With the new ELFv2 ABI,
there is another case: "homogeneous aggregates" (e.g. a struct containing
4 floats) are passed in multiple floating point registers as well.
Unfortunately, the current code is not structured to easily model these
ABI properties. For example, code to pass complex values re-implements
code to pass the underlying (floating-point) type. This has already
led to some unfortunate code duplication, and with the addition of
ELFv2 ABI support, I would have had to add yet more such duplication.
To avoid that, I've decided to refactor the code in order to re-use
subroutines that handle the "base" types when handling those aggregate
types. This was not intended to cause any difference on current
(ELFv1) ABI code, but in fact it fixes a bug:
FAIL: gdb.base/varargs.exp: print find_max_float_real(4, fc1, fc2, fc3, fc4)
This was caused by the old code in ppc64_sysv_abi_push_float incorrectly
handling floating-point arguments to vararg routines, which just happens
to work out correctly automatically in the refactored code ...
gdb/ChangeLog:
* ppc-sysv-tdep.c (get_decimal_float_return_value): Update comment.
(struct ppc64_sysv_argpos): New data structure.
(ppc64_sysv_abi_push_float): Remove.
(ppc64_sysv_abi_push_val): New function.
(ppc64_sysv_abi_push_integer): Likewise.
(ppc64_sysv_abi_push_freg): Likewise.
(ppc64_sysv_abi_push_vreg): Likewise.
(ppc64_sysv_abi_push_param): Likewise.
(ppc64_sysv_abi_push_dummy_call): Refactor to use those new routines.
(ppc64_sysv_abi_return_value_base): New function.
(ppc64_sysv_abi_return_value): Refactor to use it.
gdb/ChangeLog:
* sparc64obsd-tdep.c (sparc64obsd_gregset): New variable.
(sparc64obsd_supply_gregset): Handle registers sets used in ELF
core dumps.
(sparc64obsd_init_abi): Adjust minimum size of the general purpose
register set used in ELF core dumps. Add floating-point register set.
This change updates the mn10300 dwarf register map. It reduces the
failure count when doing simulator testing against the default
multilib from 788 to 99.
gdb/ChangeLog:
* mn10300-tdep.c (mn10300_dwarf2_reg_to_regnum): Rewrite
dwarf2_to_gdb[] table using symbolic constants. Adjust
penultimate entry from number representing the PC register
to symbolic constant representing the MDR register. Add
constant for the PC register to the end of the table.
I happen to notice this extern function declaration in ada-lang.h
which does not actually exist...
gdb/ChangeLog:
* ada-lang.h (clear_ada_sym_cache): Delete.
Recent ppc64 Linux kernels provide a new auxv entry AT_HWCAP2,
which is currently not recognized by GDB, causing every use of
"info auxv" to show an error.
This commit adds the AT_HWCAP2 define to include/elf/common.h
and handles it in GDB.
include/elf/ChangeLog:
* common.h (AT_HWCAP2): Define.
gdb/ChangeLog:
* auxv.c (fprint_target_auxv): Handle AT_HWCAP2.
breakpoint is set in a `ta 0x6d´ which is not a sigreturn syscall. In
these cases no rt_frame exists in the stack and thus the read PC is
wrong.
ChangeLog
2014-01-29 Jose E. Marchesi <jose.marchesi@oracle.com>
* sparc64-linux-tdep.c (sparc64_linux_step_trap): Get PC from
the sigreturn register save area only if the syscall is
sigreturn.
testsuite/ChangeLog
2014-01-29 Jose E. Marchesi <jose.marchesi@oracle.com>
* gdb.arch/sparc-sysstep.exp: New file.
* gdb.arch/sparc-sysstep.c: Likewise.
* gdb.arch/Makefile.in (EXECUTABLES): Add sparc-sysstep.
I noticed that a small lexical block was over indented by 2 characters.
So this patch starts by reducing the indentation.
While looking at this area of the code, I also noticed a couple of lines
that had trailing spaces, so this patch also removes them.
And finally, it fixes one tiny to put the assignment operator at
the start of the next line, rather than at the end of the first line.
gdb/ChangeLog:
* valops.c (value_slice): Minor reformatting.
The ppc64_standard_linkage7 pattern added by Alan's recent patch:
https://sourceware.org/ml/gdb-patches/2013-11/msg00274.html
contains a typo: the ELFv2 TOC slot offset is 24, not 40.
This was correct in the comment, but not the actual code.
ChangeLog:
* ppc64-tdep.c (ppc64_standard_linkage7): Fix typo.
Currently, Ada debugging requires the use of certain GNAT-specific
encodings, which are generated by the compiler. These encodings
were created a long time ago to work around the fairly limited
capabilities of the stabs debugging format. With DWARF, the vast
majority of the encodings could be abandoned in favor of a pure
DWARF approach.
In order to make it easier to evaluate the quality of the DWARF
debugging information generated by the compiler, and how the debugger
handles it, we are introducing a small Ada-specific maintenance
setting which changes the debugger's behavior to ignore descriptive
types. Descriptive types are artificial types generated by the
compiler purely to give the debugger hints as to how to properly
decode certain properties of a type. For instance, for array
types, it generates a parallel type whose name is the name of
the array suffixed with ___XA, whose contents tells us what
the array's index type is, and possibly its bounds. See GCC's
gcc/ada/exp_dbug.ads for the full description of all encodings.
This is only a first step, as this setting does not deactivate
all encodings; More settings dedicated to each type of encoding
will likely be implemented in the future, as we make progress.
gdb/ChangeLog:
* ada-lang.c (maint_set_ada_cmdlist, maint_show_ada_cmdlist):
New static globals.
(maint_set_ada_cmd, maint_show_ada_cmd): New functions.
(ada_ignore_descriptive_types_p): New static global.
(find_parallel_type_by_descriptive_type): Return immediately
if ada_ignore_descriptive_types_p is set.
(_initialize_ada_language): Register new commands "maintenance
set ada", "maintenance show ada", "maintenance set ada
ignore-descriptive-types" and "maintenance show ada
ignore-descriptive-types".
* NEWS: Add entry for new "maint ada set/show
ignore-descriptive-types" commands.
gdb/doc/ChangeLog:
* gdb.texinfo (Ada Glitches): Document the new "maint ada set/show
ignore-descriptive-types". commands.
The to_teardown_btrace target method is used to free btrace resources
during shutdown when target record has already been unpushed and we
can't reliably talk to a remote target to disable branch tracing.
Tracing resources are freed for each thread when the thread is removed;
both on the GDB side and on the gdbserver side.
In the remote case, the remote target that provides to_teardown_btrace
to free the GDB side resources has already been unpushed when threads
are destroyed. This results in a complaint "You can't do this ..." and
in a few bytes of memory leaked for each thread.
Initiate btrace teardown in record_btrace_close, so the remote target is
still in place.
2014-01-27 Markus Metzger <markus.t.metzger@intel.com>
* record-btrace.c (record_btrace_close): Call btrace_teardown
for all threads.
Currently, ada-lang.c pretends to include "ui-out.h" as follow:
#ifdef UI_OUT
#include "ui-out.h"
#endif
However, UI_OUT is never defined as far as I can tell. This is confirmed
by rebuilding with a #error pragma inside the #ifdef UI_OUT block,
which never triggers.
Since this unit makes references to declarations from ui-out.h,
this patch simply removes the #ifdef/#endif condition. This has not
been an error so far because "ui-out.h" indirectly gets included,
via one of the other .h files being included.
gdb/ChangeLog:
* ada-lang.c: Remove "#ifdef UI_OUT" condition for including
"ui-out.h".
type Char_Table is array (Character range Character'First .. Character'Last)
of Natural;
Trying to print the type description of this type currently yields:
(gdb) ptype char_table
type = array ('["00"]' .. '["ff"]') of natural
Although technically correct, it seemed more useful to print the array
range as:
(gdb) ptype char_table
type = array (character) of natural
This patch implements this suggestion.
gdb/ChangeLog:
* ada-typeprint (type_is_full_subrange_of_target_type):
New function.
(print_range): Add parameter bounds_prefered_p. If not set,
try printing range types using the name of their base type.
(print_range_type): Add parameter bounds_prefered_p.
Use it in call to print_range.
(print_array_type, ada_print_type): Update calls to print_range
and print_range_type.
gdb/testsuite/ChangeLog:
* gdb.ada/array_char_idx: New testcase.
These declarations are unncessary, and make it extra work when trying
to change the profile of one of these functions. This patch just
removes them.
Note that one of them (print_dynamic_range_bound), was improperly
indented.
gdb/ChangeLog:
* ada-typeprint.c (print_array_type, print_choices, print_range)
(print_range_bound, print_dynamic_range_bound, print_range_type):
Remove declaration.
Consider the following declarations:
type Range_Type is (One, Two, Three);
type Array_Type is array (Range_Type range One .. Two) of Integer;
A : Array_Type := (1, 2);
Trying to print A can yield:
(gdb) print a
$1 = (one => 1, 2)
The bound of the first element should not have been printed, since
"one" is the first enumerate of type Range_Type. Similarly, with
the following declarations:
type Array2_Type is array (Range_Type range Two .. Three) of Integer;
A2 : Array2_Type := (2, 3);
GDB is failing to print the bound of the first element of "A2":
(gdb) print a2
$2 = (2, 3)
This is because the index type for both types Array_Type and Array2_Type
are subranges (by DWARF definition for arrays), of an anonymous subrange
type. When deciding whether to print the bound of the first element,
we handle subranges, but only up to one level. This patch enhanced
the code to handle any number of subrange levels.
gdb/ChangeLog:
* ada-valprint.c (print_optional_low_bound): Get index_type's
target type for as long as it is a TYPE_CODE_RANGE.
No testcase with this patch, but this will be tested via the testcase
of another patch, which uses the DWARF assembler to generate debugging
info for an array indexed by an enum.
On x86-solaris, the gcore command sometimes triggers the following
internal error:
(gdb) gcore
/[...]/procfs.c:5523: internal-error: procfs_make_note_section: Assertion `thread_args.note_data != note_data' failed.
The problem is extremely elusive, for reasons that will become clearer
as I explain what is going on.
The program used to produce this issue was really simple:
| void break_me (void) { }
|
| int
| main (void)
| {
| break_me ();
| return 0;
| }
The procfs_make_note_section builds a buffer incrementally with
the contents of the core's notes section. The interesting bits are:
char *note_data = NULL;
[...]
note_data = (char *) elfcore_write_prpsinfo (obfd,
note_data,
note_size,
fname,
psargs);
This is the first call to bfd's elfcore which initializes note_data.
After that, we have a few more calls, which keep updating notes_data
and note_size, but our interest lies in the following part of
the function:
thread_args.note_data = note_data;
[...]
proc_iterate_over_threads (pi, procfs_corefile_thread_callback,
&thread_args);
/* There should be always at least one thread. */
gdb_assert (thread_args.note_data != note_data);
The comment implies that the assert is to verify that our loop
iterated over at least one thread. The check is relying on the
fact that the notes_data returned by the elfcore module changes
at each iteration, via (in procfs_corefile_thread_callback):
args->note_data = procfs_do_thread_registers (args->obfd, ptid,
args->note_data,
args->note_size,
args->stop_signal);
(which calls elfcore_write_lwpstatus).
But, while it happens most of the time, thanks to a call to realloc
in elfcore_write_note (the function that actually appends the data
at the end of the notes buffer),...
buf = (char *) realloc (buf, *bufsiz + newspace);
... this is by no means guarantied. In fact, under the right
circumstances, the buffer was grown twice without changing
addresses. Unfortunately, the circumstances are very sensitive,
thus making this bug very elusive.
This patch fixes the problem by simply removing the assert.
This means we're losing the assertion that there is at least one
thread, but I think that's OK. If we still want to keep the
assertion, we have the option of either checking the buffer
size, or else adding a boolean flag in the context structure
that we'd set to true as soon as we have a thread.
gdb/ChangeLog:
* procfs.c (procfs_make_note_section): Remove assertion and
associated comment.
Functions remote_read_bytes and get_core_siginfo are the callees of
target to_xfer_partial interface, so argument 'len' should be changed
to type ULONGEST.
gdb:
2014-01-24 Yao Qi <yao@codesourcery.com>
* remote.c (remote_read_bytes): Change type of len to ULONGEST.
* corelow.c (get_core_siginfo): Likewise.
Hi,
This patch changes the type of 'len' from ssize_t to ULONGEST.
At the beginning Siddhesh Poyarekar proposed this patch
[PATCH] Memory reads and writes should have size_t length
https://sourceware.org/ml/gdb-patches/2012-05/msg01073.html
to change type of 'len' to size_t. However, after Jan's review, we
decide to change it to ssize_t, because callers of these functions
may pass signed type to them.
AFAICS, the target layer is a boundary. In one side, we pass size_t
or ssize_t to target related APIs, and in the other side, the
implementation side, we used LONGEST (ULONGEST in latest code) because
of to_xfer_partial.
Since remote_write_bytes_aux and remote_write_bytes belong to the
implementation of remote target, we should use ULONGEST for len, IMO.
Regression tested on x86_64-linux. Is it OK?
gdb:
2014-01-24 Yao Qi <yao@codesourcery.com>
* remote.c (remote_write_bytes_aux): Change type of 'len' to
ULONGEST. Don't check 'len' is negative.
(remote_write_bytes): Change type of 'len' to ULONGEST.
This fixes a bug in FrameDecorator.py.
FrameVars seems to assume that Frame.block can return None if there is
no block. However, it actually throws an exception.
I saw this bug while developing a frame filter, but unfortunately I
don't know how to reproduce it. It seems to me that the SAL tests in
_is_limited_frame should exclude the bad cases; and in my attempts to
write a test they do.
Nevertheless I think the fix is reasonably obvious and ought to go in.
2014-01-23 Tom Tromey <tromey@redhat.com>
PR python/16485:
* python/lib/gdb/FrameDecorator.py: (FrameVars.fetch_frame_args):
Handle exception from frame.block.
(FrameVars.fetch_frame_locals): Likewise.
This fixes PR python/16487.
The bug here is that the function-name-handling code in py_print_frame
had a small logic error (really a misplaced closing brace). This
error could lead to a Py_DECREF(NULL), which crashes.
This patch fixes the bug in the obvious way.
Built and regtested on x86-64 Fedora 18. New test case included.
2014-01-23 Tom Tromey <tromey@redhat.com>
PR python/16487:
* python/py-framefilter.c (py_print_frame): Don't call Py_DECREF
on a NULL pointer. Move "goto error" to correct place.
2014-01-23 Tom Tromey <tromey@redhat.com>
PR python/16487:
* gdb.python/py-framefilter.exp: Add test using "Error" filter.
* gdb.python/py-framefilter.py (ErrorInName, ErrorFilter): New
classes.
apply_frame_filter calls ensure_python_env before computing the
gdbarch to use. This means that python_gdbarch can be NULL while in
Python code, and if a frame filter depends on this somehow (easy to
do), gdb will crash.
The fix is to compute the gdbarch first.
Built and regtested on x86-64 Fedora 18.
New test case included.
2014-01-23 Tom Tromey <tromey@redhat.com>
PR python/16491:
* python/py-framefilter.c (apply_frame_filter): Call
ensure_python_env after computing gdbarch.
2014-01-23 Tom Tromey <tromey@redhat.com>
PR python/16491:
* gdb.python/py-framefilter.py (Reverse_Function.function): Read a
string from an inferior frame.
* gdb.python/py-framefilter-mi.exp: Update.
This patch changes the argument type to gdb_byte * in order to align
with the to_xfer_partial interface.
gdb:
2014-01-23 Yao Qi <yao@codesourcery.com>
* target.c (raw_memory_xfer_partial): Change argument type
from void * to gdb_byte *.
(memory_xfer_partial_1, memory_xfer_partial): Likewise.
* syscalls/s390x-linux.xml: New file.
* syscalls/s390-linux.xml: New file.
* s390-linux-tdep.c (XML_SYSCALL_FILENAME_S390): New macro.
(XML_SYSCALL_FILENAME_S390X): Likewise.
(op_svc): New enum value for SVC opcode.
(s390_sigtramp_frame_sniffer): Replace literal by 'op_svc'.
(s390_linux_get_syscall_number): New function.
(s390_gdbarch_init): Register '*get_syscall_number' and the
syscall xml file name.
* data-directory/Makefile.in (SYSCALLS_FILES): Add
"s390-linux.xml" and "s390x-linux.xml".
* NEWS: Announce new feature.
gdb/testsuite/ChangeLog:
* gdb.base/catch-syscall.exp: Activate test on s390*-linux.
On 64-bit hosts unsigned long is 64 bit. Use uint32_t instead.
gdb/
2014-01-22 Baruch Siach <baruch@tkos.co.il>
* xtensa-tdep.h (xtensa_elf_greg_t): Change type to uint32_t.
The ARI script flagged the use of the __func__ variable, which
is normally not allowed (not defined in C90). However, this particular
use is OK, as the reference is only made when __STDC_VERSION__ >=
199901L. So, add an "ARI:" comment to explicitly OK this use.
gdb/ChangeLog:
* common/common-utils.h: Add "ARI:" comment beside __func__
reference.
While looking at this macro, I noticed that it wasn't always necessarily
defined. That prompted me to search the current sources to make sure
that all uses were adequately protected, which they were. But to help
prevent future uses to be made unprotected, this patch expands the
current macro documentation a bit.
gdb/ChangeLog:
* common/common-utils.h (FUNCTION_NAME): Expand the macro's
documentation a bit.
gdb/
* configure.ac: Call AM_PROG_INSTALL_STRIP.
* configure: Regenerate.
* aclocal.m4: Regenerate.
* Makefile.in (install_sh, INSTALL_STRIP_PROGRAM, STRIP):
New substituted variables.
(install-strip): New target.
(INSTALL_SCRIPT): New substituted variable.
(FLAGS_TO_PASS): Add it.
(install-only): Use $(INSTALL_SCRIPT) rather than
$(INSTALL_PROGRAM) for gcore.
This moves all the bitfields in struct cmd_list_element to be closer
together. This packs the structure somewhat better. On a 64 bit
machine, this simple rearrangement saves around 50k at startup.
2014-01-20 Tom Tromey <tromey@redhat.com>
* cli/cli-decode.h (struct cmd_list_element): Move all bitfields
together.
This changes various flags struct cmd_list_element into bitfields. In
general I think bitfields are cleaner than flag words, at least in a
case like this where there is no need to pass the flags around
independently of the enclosing struct.
2014-01-20 Tom Tromey <tromey@redhat.com>
* cli/cli-decode.c (add_cmd, deprecate_cmd, add_alias_cmd)
(add_setshow_cmd_full, delete_cmd, lookup_cmd_1)
(deprecated_cmd_warning, complete_on_cmdlist): Update.
* cli/cli-decode.h (CMD_DEPRECATED, DEPRECATED_WARN_USER)
(MALLOCED_REPLACEMENT, DOC_ALLOCATED): Remove.
(struct cmd_list_element) <flags>: Remove.
<cmd_deprecated, deprecated_warn_user, malloced_replacement,
doc_allocated>: New fields.
<hook_in, allow_unknown, abbrev_flag, type, var_type>: Now
bitfields.
* maint.c (maintenance_do_deprecate): Update.
* top.c (execute_command): Update.
Currently, xtensa code using the Linux ptrace interface only include
sys/ptrace.h. This file comes from the C library (glibc and uClibc,
at least), and includes a declaration of the ptrace() functions, along
with some cross architecture constants that are mostly copied from the
file located at include/uapi/linux/ptrace.h in recent Linux kernels.
For xtensa specific constants like PTRACE_GETXTREGS and
PTRACE_SETXTREGS the asm/ptrace.h include from the Linux kernel UAPI
is needed. The code in gdbserver xtensa specific part doesn't call
ptrace() directly, so we can remove the unneeded sys/ptrace.h include.
The gdb xtensa specific code needs both headers, since it calls
ptrace().
gdb/
* xtensa-linux-nat.c: Include asm/ptrace.h.
gdb/gdbserver/
* linux-xtensa-low.c: Include asm/ptrace.h instead of
sys/ptrace.h.
is intended to house other D language support functions.
gdb/ChangeLog:
2014-01-17 Iain Buclaw <ibuclaw@gdcproject.org>
* Makefile.in (SFILES): Add d-support.c.
(COMMON_OBS): Add d-support.o.
* d-lang.h (d_parse_symbol): Add comment, now defined in
d-support.c.
* d-lang.c (parse_call_convention)
(parse_attributes, parse_function_types)
(parse_function_args, parse_type, parse_identifier)
(call_convention_p, d_parse_symbol): Move functions to ...
* d-support.c: ... New file.
While doing something else, I found that those 2 places were incorrectly
declaring a "struct gdb_exception" without using the "volatile" keyword.
This commit fixes that.
2014-01-17 Sergio Durigan Junior <sergiodj@redhat.com>
* breakpoint.c (insert_bp_location): Add "volatile" keyword to "struct
gdb_exception" declaration.
* remote.c (getpkt_or_notif_sane): Likewise.
* common/gdb_vecs.c (delim_string_to_char_ptr_vec_append): New
function, contents of dirnames_to_char_ptr_vec_append moved here.
(delim_string_to_char_ptr_vec): New function.
(dirnames_to_char_ptr_vec_append): Rewrite.
* common/gdb_vecs.h (delim_string_to_char_ptr_vec): Declare.
This patch rearranges struct value a tiny bit, moving the "regnum"
field into a hole. This saves 8 bytes per value on a 64-bit machine,
and 4 bytes per value on a 32 bit machine. I think it does not
negatively affect readability or performance.
Built and regtested on x86-64 Fedora 18.
2014-01-16 Tom Tromey <tromey@redhat.com>
* value.c (struct value) <regnum>: Move earlier.
I noticed that extended_remote_create_inferior_1 is called from a
single spot. This patch unifies the callee and caller. It's just a
simple cleanup that made the coming refactoring simpler.
2014-01-16 Tom Tromey <tromey@redhat.com>
* remote.c (extended_remote_create_inferior): Rename from
extended_remote_create_inferior_1. Add "ops" argument. Remove
old implementation.
The test fails on s390 with:
-trace-find frame-number 0^M
&"PC not available\n"^M
^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="<unavailable>",func="??",args=[]}^M
(gdb) ^M
FAIL: gdb.trace/mi-traceframe-changed.exp: tfile: -trace-find frame-number 0
tfile knows to infer the PC from the tracepoint's address if the PC
wasn't collected (tfile_fetch_registers) but, that only works on
targets whose PC register is a raw register, and on s390, the PC
register is a pseudo register.
But even if GDB doesn't know how to infer the value of PC, saying the
current frame is level -1 is a bug:
^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="<unavailable>",func="??",args=[]}^M
^^^^^^^^^
'-1' is the level of the sentinel frame, which should never be visible.
This is caused by the s390's heuristic unwinder accepting the frame
(the fallback heuristic unwinders _always_ accept the frame), but then
the unwind->this_id method throws that "PC not available\n" error.
IOW, the s390's heuristic unwinder was never adjusted to handle
unavailable register values gracefully, which can happen with e.g., a
trimmed core file too.
This is just the minimal necessary for
<unavailable> frames, which at least gets us:
(gdb) tfind
Found trace frame 0, tracepoint 1
#0 <unavailable> in ?? ()
That is, frame #0 instead of -1.
We could get better info out of "info frame" (this patch makes us show
"outermost"), but this change would still be necessary.
gdb/
2014-01-16 Pedro Alves <palves@redhat.com>
* s390-linux-tdep.c (s390_frame_unwind_cache): Swallow
NOT_AVAILABLE_ERROR errors while parsing the prologue or reading
the backchain.
Provide to_resume and to_wait target methods for the btrace record target
to allow reverse stepping and replay support.
Replay is limited in the sense that only stepping and source correlation
are supported. We do not record data and thus can not show variables.
Non-stop mode is not working. Do not allow record-btrace in non-stop mode.
2014-01-16 Markus Metzger <markus.t.metzger@intel.com>
* btrace.h (btrace_thread_flag): New.
(struct btrace_thread_info) <flags>: New.
* record-btrace.c (record_btrace_resume_thread)
(record_btrace_find_thread_to_move, btrace_step_no_history)
(btrace_step_stopped, record_btrace_start_replaying)
(record_btrace_step_thread, record_btrace_decr_pc_after_break)
(record_btrace_find_resume_thread): New.
(record_btrace_resume, record_btrace_wait): Extend.
(record_btrace_can_execute_reverse): New.
(record_btrace_open): Fail in non-stop mode.
(record_btrace_set_replay): Split into this, ...
(record_btrace_stop_replaying): ... this, ...
(record_btrace_clear_histories): ... and this.
(init_record_btrace_ops): Init to_can_execute_reverse.
* NEWS: Announce it.
testsuite/
* gdb.btrace/delta.exp: Check reverse stepi.
* gdb.btrace/tailcall.exp: Update. Add stepping tests.
* gdb.btrace/finish.exp: New.
* gdb.btrace/next.exp: New.
* gdb.btrace/nexti.exp: New.
* gdb.btrace/record_goto.c: Add comments.
* gdb.btrace/step.exp: New.
* gdb.btrace/stepi.exp: New.
* gdb.btrace/multi-thread-step.c: New.
* gdb.btrace/multi-thread-step.exp: New.
* gdb.btrace/rn-dl-bind.c: New.
* gdb.btrace/rn-dl-bind.exp: New.
* gdb.btrace/data.c: New.
* gdb.btrace/data.exp: New.
* gdb.btrace/Makefile.in (EXECUTABLES): Add new.
doc/
* gdb.texinfo: Document limited reverse/replay support
for target record-btrace.
