Re: [PATCH 2/2] Make collect_probes return an std::vector

[Sergio Durigan Junior <sergiodj at redhat dot com>]

On Sunday, September 10 2017, Simon Marchi wrote:

> Change collect_probes so it returns an std::vector<bound_probe> instead
> of a VEC(bound_probe_s).  This allows removing some cleanups.  It also
> seems like enable_probes_command and disable_probes_command were not
> freeing that vector.
>
> The comparison function compare_probes needs to be updated to return a
> bool indicating whether the first parameter is "less than" the second
> parameter.
>
> I defined two constructors to bound_probe.  The default constructor is
> needed, for example, so the instance in struct bp_location can be
> constructed without parameters.  The constructor with parameters is
> useful so we can use emplace_back and pass the values directly.
>
> The s390 builder on the buildbot shows a weird failure that I can't
> explain:
>
> ../../binutils-gdb/gdb/elfread.c: In function void probe_key_free(bfd*, void*):
> ../../binutils-gdb/gdb/elfread.c:1346:8: error: types may not be defined in a for-range-declaration [-Werror]
>    for (struct probe *probe : *probes)
>         ^~~~~~

As I've told you on IRC, I've also stumbled upon this problem.  The
"solution" is to use the typedef instead of the full name of the type:

  for (probe *probe : *probes)

> I guess it's a bug with that specific version< of the compiler, since no
> other gcc gives me that error.  It is using:
>
>   g++ (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1)
>
> Any idea about this problem?

It seems to me this is indeed a compiler problem.  I've found at least
one report on GCC's bugzilla about a related issue.

Mark, you're the responsible for this specific slave
(marist-fedora-s390x); can you check if it's possible to update the GCC
there, please?

> gdb/ChangeLog:
>
> 	* probe.h (struct bound_probe): Define constructors.
> 	* probe.c (bound_probe_s): Remove typedef.
> 	(DEF_VEC_O (bound_probe_s)): Remove VEC.
> 	(collect_probes): Change return type to std::vector, remove
> 	cleanup.
> 	(compare_probes): Return bool, change parameter type.  Change
> 	semantic to "less than".
> 	(gen_ui_out_table_header_info): Change parameter to std::vector
> 	and update.
> 	(exists_probe_with_pops): Likewise.
> 	(info_probes_for_ops): Update to std::vector change.
> 	(enable_probes_command): Likewise.
> 	(disable_probes_command): Likewise.
> ---
>  gdb/probe.c | 147 ++++++++++++++++++++++++------------------------------------
>  gdb/probe.h |  19 +++++---
>  2 files changed, 72 insertions(+), 94 deletions(-)
>
> diff --git a/gdb/probe.c b/gdb/probe.c
> index 2d68437..384ea9d 100644
> --- a/gdb/probe.c
> +++ b/gdb/probe.c
> @@ -38,11 +38,6 @@
>  #include <algorithm>
>  #include "common/gdb_optional.h"
>  
> -typedef struct bound_probe bound_probe_s;
> -DEF_VEC_O (bound_probe_s);
> -
> -
> -
>  /* A helper for parse_probes that decodes a probe specification in
>     SEARCH_PSPACE.  It appends matching SALs to RESULT.  */
>  
> @@ -267,17 +262,14 @@ find_probe_by_pc (CORE_ADDR pc)
>     If POPS is not NULL, only probes of this certain probe_ops will match.
>     Each argument is a regexp, or NULL, which matches anything.  */
>  
> -static VEC (bound_probe_s) *
> +static std::vector<bound_probe>
>  collect_probes (char *objname, char *provider, char *probe_name,
>  		const struct probe_ops *pops)
>  {
>    struct objfile *objfile;
> -  VEC (bound_probe_s) *result = NULL;
> -  struct cleanup *cleanup;
> +  std::vector<bound_probe> result;
>    gdb::optional<compiled_regex> obj_pat, prov_pat, probe_pat;
>  
> -  cleanup = make_cleanup (VEC_cleanup (bound_probe_s), &result);
> -
>    if (provider != NULL)
>      prov_pat.emplace (provider, REG_NOSUB, _("Invalid provider regexp"));
>    if (probe_name != NULL)
> @@ -301,8 +293,6 @@ collect_probes (char *objname, char *provider, char *probe_name,
>  
>        for (struct probe *probe : probes)
>  	{
> -	  struct bound_probe bound;
> -
>  	  if (pops != NULL && probe->pops != pops)
>  	    continue;
>  
> @@ -314,46 +304,39 @@ collect_probes (char *objname, char *provider, char *probe_name,
>  	      && probe_pat->exec (probe->name, 0, NULL, 0) != 0)
>  	    continue;
>  
> -	  bound.objfile = objfile;
> -	  bound.probe = probe;
> -	  VEC_safe_push (bound_probe_s, result, &bound);
> +	  result.emplace_back (probe, objfile);
>  	}
>      }
>  
> -  discard_cleanups (cleanup);
>    return result;
>  }
>  
>  /* A qsort comparison function for bound_probe_s objects.  */
>  
> -static int
> -compare_probes (const void *a, const void *b)
> +static bool
> +compare_probes (const bound_probe &a, const bound_probe &b)
>  {
> -  const struct bound_probe *pa = (const struct bound_probe *) a;
> -  const struct bound_probe *pb = (const struct bound_probe *) b;
>    int v;
>  
> -  v = strcmp (pa->probe->provider, pb->probe->provider);
> -  if (v)
> -    return v;
> +  v = strcmp (a.probe->provider, b.probe->provider);
> +  if (v != 0)
> +    return v < 0;
>  
> -  v = strcmp (pa->probe->name, pb->probe->name);
> -  if (v)
> -    return v;
> +  v = strcmp (a.probe->name, b.probe->name);
> +  if (v != 0)
> +    return v < 0;
>  
> -  if (pa->probe->address < pb->probe->address)
> -    return -1;
> -  if (pa->probe->address > pb->probe->address)
> -    return 1;
> +  if (a.probe->address != b.probe->address)
> +    return a.probe->address < b.probe->address;
>  
> -  return strcmp (objfile_name (pa->objfile), objfile_name (pb->objfile));
> +  return strcmp (objfile_name (a.objfile), objfile_name (b.objfile)) < 0;
>  }
>  
>  /* Helper function that generate entries in the ui_out table being
>     crafted by `info_probes_for_ops'.  */
>  
>  static void
> -gen_ui_out_table_header_info (VEC (bound_probe_s) *probes,
> +gen_ui_out_table_header_info (const std::vector<bound_probe> &probes,
>  			      const struct probe_ops *p)
>  {
>    /* `headings' refers to the names of the columns when printing `info
> @@ -382,11 +365,9 @@ gen_ui_out_table_header_info (VEC (bound_probe_s) *probes,
>         VEC_iterate (info_probe_column_s, headings, ix, column);
>         ++ix)
>      {
> -      struct bound_probe *probe;
> -      int jx;
>        size_t size_max = strlen (column->print_name);
>  
> -      for (jx = 0; VEC_iterate (bound_probe_s, probes, jx, probe); ++jx)
> +      for (const bound_probe &probe : probes)
>  	{
>  	  /* `probe_fields' refers to the values of each new field that this
>  	     probe will display.  */
> @@ -395,11 +376,11 @@ gen_ui_out_table_header_info (VEC (bound_probe_s) *probes,
>  	  const char *val;
>  	  int kx;
>  
> -	  if (probe->probe->pops != p)
> +	  if (probe.probe->pops != p)
>  	    continue;
>  
>  	  c2 = make_cleanup (VEC_cleanup (const_char_ptr), &probe_fields);
> -	  p->gen_info_probes_table_values (probe->probe, &probe_fields);
> +	  p->gen_info_probes_table_values (probe.probe, &probe_fields);
>  
>  	  gdb_assert (VEC_length (const_char_ptr, probe_fields)
>  		      == headings_size);
> @@ -526,14 +507,14 @@ get_number_extra_fields (const struct probe_ops *pops)
>     featuring the given POPS.  It returns 0 otherwise.  */
>  
>  static int
> -exists_probe_with_pops (VEC (bound_probe_s) *probes,
> +exists_probe_with_pops (const std::vector<bound_probe> &probes,
>  			const struct probe_ops *pops)
>  {
>    struct bound_probe *probe;
>    int ix;
>  
> -  for (ix = 0; VEC_iterate (bound_probe_s, probes, ix, probe); ++ix)
> -    if (probe->probe->pops == pops)
> +  for (const bound_probe &probe : probes)
> +    if (probe.probe->pops == pops)
>        return 1;
>  
>    return 0;
> @@ -565,15 +546,13 @@ info_probes_for_ops (const char *arg, int from_tty,
>  {
>    char *provider, *probe_name = NULL, *objname = NULL;
>    struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
> -  VEC (bound_probe_s) *probes;
> -  int i, any_found;
> +  int any_found;
>    int ui_out_extra_fields = 0;
>    size_t size_addr;
>    size_t size_name = strlen ("Name");
>    size_t size_objname = strlen ("Object");
>    size_t size_provider = strlen ("Provider");
>    size_t size_type = strlen ("Type");
> -  struct bound_probe *probe;
>    struct gdbarch *gdbarch = get_current_arch ();
>  
>    parse_probe_linespec (arg, &provider, &probe_name, &objname);
> @@ -581,8 +560,8 @@ info_probes_for_ops (const char *arg, int from_tty,
>    make_cleanup (xfree, probe_name);
>    make_cleanup (xfree, objname);
>  
> -  probes = collect_probes (objname, provider, probe_name, pops);
> -  make_cleanup (VEC_cleanup (probe_p), &probes);
> +  std::vector<bound_probe> probes
> +    = collect_probes (objname, provider, probe_name, pops);
>  
>    if (pops == NULL)
>      {
> @@ -609,27 +588,23 @@ info_probes_for_ops (const char *arg, int from_tty,
>    {
>      ui_out_emit_table table_emitter (current_uiout,
>  				     5 + ui_out_extra_fields,
> -				     VEC_length (bound_probe_s, probes),
> -				     "StaticProbes");
> +				     probes.size (), "StaticProbes");
>  
> -    if (!VEC_empty (bound_probe_s, probes))
> -      qsort (VEC_address (bound_probe_s, probes),
> -	     VEC_length (bound_probe_s, probes),
> -	     sizeof (bound_probe_s), compare_probes);
> +    std::sort (probes.begin (), probes.end (), compare_probes);
>  
>      /* What's the size of an address in our architecture?  */
>      size_addr = gdbarch_addr_bit (gdbarch) == 64 ? 18 : 10;
>  
>      /* Determining the maximum size of each field (`type', `provider',
>         `name' and `objname').  */
> -    for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +    for (const bound_probe &probe : probes)
>        {
> -	const char *probe_type = probe->probe->pops->type_name (probe->probe);
> +	const char *probe_type = probe.probe->pops->type_name (probe.probe);
>  
>  	size_type = std::max (strlen (probe_type), size_type);
> -	size_name = std::max (strlen (probe->probe->name), size_name);
> -	size_provider = std::max (strlen (probe->probe->provider), size_provider);
> -	size_objname = std::max (strlen (objfile_name (probe->objfile)),
> +	size_name = std::max (strlen (probe.probe->name), size_name);
> +	size_provider = std::max (strlen (probe.probe->provider), size_provider);
> +	size_objname = std::max (strlen (objfile_name (probe.objfile)),
>  				 size_objname);
>        }
>  
> @@ -657,18 +632,18 @@ info_probes_for_ops (const char *arg, int from_tty,
>      current_uiout->table_header (size_objname, ui_left, "object", _("Object"));
>      current_uiout->table_body ();
>  
> -    for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +    for (const bound_probe &probe : probes)
>        {
> -	const char *probe_type = probe->probe->pops->type_name (probe->probe);
> +	const char *probe_type = probe.probe->pops->type_name (probe.probe);
>  
>  	ui_out_emit_tuple tuple_emitter (current_uiout, "probe");
>  
>  	current_uiout->field_string ("type",probe_type);
> -	current_uiout->field_string ("provider", probe->probe->provider);
> -	current_uiout->field_string ("name", probe->probe->name);
> -	current_uiout->field_core_addr (
> -					"addr", probe->probe->arch,
> -					get_probe_address (probe->probe, probe->objfile));
> +	current_uiout->field_string ("provider", probe.probe->provider);
> +	current_uiout->field_string ("name", probe.probe->name);
> +	current_uiout->field_core_addr ("addr", probe.probe->arch,
> +					get_probe_address (probe.probe,
> +							   probe.objfile));
>  
>  	if (pops == NULL)
>  	  {
> @@ -677,20 +652,20 @@ info_probes_for_ops (const char *arg, int from_tty,
>  
>  	    for (ix = 0; VEC_iterate (probe_ops_cp, all_probe_ops, ix, po);
>  		 ++ix)
> -	      if (probe->probe->pops == po)
> -		print_ui_out_info (probe->probe);
> +	      if (probe.probe->pops == po)
> +		print_ui_out_info (probe.probe);
>  	      else if (exists_probe_with_pops (probes, po))
>  		print_ui_out_not_applicables (po);
>  	  }
>  	else
> -	  print_ui_out_info (probe->probe);
> +	  print_ui_out_info (probe.probe);
>  
>  	current_uiout->field_string ("object",
> -				     objfile_name (probe->objfile));
> +				     objfile_name (probe.objfile));
>  	current_uiout->text ("\n");
>        }
>  
> -    any_found = !VEC_empty (bound_probe_s, probes);
> +    any_found = !probes.empty ();
>    }
>    do_cleanups (cleanup);
>  
> @@ -713,17 +688,15 @@ enable_probes_command (char *arg, int from_tty)
>  {
>    char *provider, *probe_name = NULL, *objname = NULL;
>    struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
> -  VEC (bound_probe_s) *probes;
> -  struct bound_probe *probe;
> -  int i;
>  
>    parse_probe_linespec ((const char *) arg, &provider, &probe_name, &objname);
>    make_cleanup (xfree, provider);
>    make_cleanup (xfree, probe_name);
>    make_cleanup (xfree, objname);
>  
> -  probes = collect_probes (objname, provider, probe_name, NULL);
> -  if (VEC_empty (bound_probe_s, probes))
> +  std::vector<bound_probe> probes
> +    = collect_probes (objname, provider, probe_name, NULL);
> +  if (probes.empty ())
>      {
>        current_uiout->message (_("No probes matched.\n"));
>        do_cleanups (cleanup);
> @@ -732,19 +705,19 @@ enable_probes_command (char *arg, int from_tty)
>  
>    /* Enable the selected probes, provided their backends support the
>       notion of enabling a probe.  */
> -  for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +  for (const bound_probe &probe: probes)
>      {
> -      const struct probe_ops *pops = probe->probe->pops;
> +      const struct probe_ops *pops = probe.probe->pops;
>  
>        if (pops->enable_probe != NULL)
>  	{
> -	  pops->enable_probe (probe->probe);
> +	  pops->enable_probe (probe.probe);
>  	  current_uiout->message (_("Probe %s:%s enabled.\n"),
> -				  probe->probe->provider, probe->probe->name);
> +				  probe.probe->provider, probe.probe->name);
>  	}
>        else
>  	current_uiout->message (_("Probe %s:%s cannot be enabled.\n"),
> -				probe->probe->provider, probe->probe->name);
> +				probe.probe->provider, probe.probe->name);
>      }
>  
>    do_cleanups (cleanup);
> @@ -757,17 +730,15 @@ disable_probes_command (char *arg, int from_tty)
>  {
>    char *provider, *probe_name = NULL, *objname = NULL;
>    struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
> -  VEC (bound_probe_s) *probes;
> -  struct bound_probe *probe;
> -  int i;
>  
>    parse_probe_linespec ((const char *) arg, &provider, &probe_name, &objname);
>    make_cleanup (xfree, provider);
>    make_cleanup (xfree, probe_name);
>    make_cleanup (xfree, objname);
>  
> -  probes = collect_probes (objname, provider, probe_name, NULL /* pops */);
> -  if (VEC_empty (bound_probe_s, probes))
> +  std::vector<bound_probe> probes
> +    = collect_probes (objname, provider, probe_name, NULL /* pops */);
> +  if (probes.empty ())
>      {
>        current_uiout->message (_("No probes matched.\n"));
>        do_cleanups (cleanup);
> @@ -776,19 +747,19 @@ disable_probes_command (char *arg, int from_tty)
>  
>    /* Disable the selected probes, provided their backends support the
>       notion of enabling a probe.  */
> -  for (i = 0; VEC_iterate (bound_probe_s, probes, i, probe); ++i)
> +  for (const bound_probe &probe : probes)
>      {
> -      const struct probe_ops *pops = probe->probe->pops;
> +      const struct probe_ops *pops = probe.probe->pops;
>  
>        if (pops->disable_probe != NULL)
>  	{
> -	  pops->disable_probe (probe->probe);
> +	  pops->disable_probe (probe.probe);
>  	  current_uiout->message (_("Probe %s:%s disabled.\n"),
> -				  probe->probe->provider, probe->probe->name);
> +				  probe.probe->provider, probe.probe->name);
>  	}
>        else
>  	current_uiout->message (_("Probe %s:%s cannot be disabled.\n"),
> -				probe->probe->provider, probe->probe->name);
> +				probe.probe->provider, probe.probe->name);
>      }
>  
>    do_cleanups (cleanup);
> diff --git a/gdb/probe.h b/gdb/probe.h
> index 61e3031..75e9a5c 100644
> --- a/gdb/probe.h
> +++ b/gdb/probe.h
> @@ -214,15 +214,22 @@ struct probe
>     their point of use.  */
>  
>  struct bound_probe
> -  {
> -    /* The probe.  */
> +{
> +  bound_probe ()
> +  {}
>  
> -    struct probe *probe;
> +  bound_probe (struct probe *probe_, struct objfile *objfile_)
> +  : probe (probe_), objfile (objfile_)
> +  {}

What do you think about putting simple comments on these constructors
summarizing what you explained in the commit message?

>  
> -    /* The objfile in which the probe originated.  */
> +  /* The probe.  */
>  
> -    struct objfile *objfile;
> -  };
> +  struct probe *probe = NULL;
> +
> +  /* The objfile in which the probe originated.  */
> +
> +  struct objfile *objfile = NULL;
> +};
>  
>  /* A helper for linespec that decodes a probe specification.  It
>     returns a std::vector<symtab_and_line> object and updates LOC or
> -- 
> 2.7.4

Otherwise, LGTM.

Thanks,

-- 
Sergio
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