Re: [PATCH v2] gdb/dwarf: dump cooked index contents in cooked_index_functions::dump

[Andrew Burgess <aburgess@redhat.com>]

Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

> From: Simon Marchi <simon.marchi@polymtl.ca>
>
> New in v2:
>
>  - move the implementation to the cooked_index_vector class
>  - use the gdbarch from the objfile
>  - add some QUIT macro calls
>  - add call to wait, to ensure the index is finished
>
> As I am investigating a crash I see with the cooked index, I thought it
> would be useful to have a way to dump the index contents.  For those not
> too familiar with it (that includes me), it can help get a feel of what
> it contains and how it is structured.
>
> The cooked_index_functions::dump function is called as part of the
> "maintenance print objfiles" command.  I tried to make the output
> well structured and indented to help readability, as this prints a lot
> of text.
>
> The dump function first dumps all cooked index entries, like this:
>
>     [25] ((cooked_index_entry *) 0x621000121220)
>     name:       __ioinit
>     canonical:  __ioinit
>     DWARF tag:  DW_TAG_variable
>     flags:      0x2 [IS_STATIC]
>     DIE offset: 0x21a4
>     parent:     ((cooked_index_entry *) 0x6210000f9610) [std]
>
> Then the information about the main symbol:
>
>     main: ((cooked_index_entry *) 0x621000123b40) [main]
>
> And finally the address map contents:
>
>     [1] ((addrmap *) 0x6210000f7910)
>
>       [0x0] ((dwarf2_per_cu_data *) 0)
>       [0x118a] ((dwarf2_per_cu_data *) 0x60c000007f00)
>       [0x1cc7] ((dwarf2_per_cu_data *) 0)
>       [0x1cc8] ((dwarf2_per_cu_data *) 0x60c000007f00)
>       [0x1cdf] ((dwarf2_per_cu_data *) 0)
>       [0x1ce0] ((dwarf2_per_cu_data *) 0x60c000007f00)
>
> The display of address maps above could probably be improved, to show it
> more as ranges, but I think this is a reasonable start.
>
> Note that this patch depends on Pedro Alves' patch "enum_flags
> to_string" [1].  If my patch is to be merged before Pedro's series, I
> will cherry-pick this patch from his series and merge it before mine.
>
> [1] https://inbox.sourceware.org/gdb-patches/20221212203101.1034916-8-pedro@palves.net/
>
> Change-Id: Ida13e479fd4c8d21102ddd732241778bc3b6904a
> ---
>  gdb/dwarf2/cooked-index.c | 93 +++++++++++++++++++++++++++++++++++++++
>  gdb/dwarf2/cooked-index.h |  7 +++
>  gdb/dwarf2/read.c         | 10 ++++-
>  3 files changed, 109 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c
> index 646bc76575cd..0ee7afb7b978 100644
> --- a/gdb/dwarf2/cooked-index.c
> +++ b/gdb/dwarf2/cooked-index.c
> @@ -20,6 +20,7 @@
>  #include "defs.h"
>  #include "dwarf2/cooked-index.h"
>  #include "dwarf2/read.h"
> +#include "dwarf2/stringify.h"
>  #include "cp-support.h"
>  #include "c-lang.h"
>  #include "ada-lang.h"
> @@ -30,6 +31,22 @@
>  
>  /* See cooked-index.h.  */
>  
> +std::string
> +to_string (cooked_index_flag flags)
> +{
> +  static constexpr cooked_index_flag::string_mapping mapping[] = {
> +    MAP_ENUM_FLAG (IS_MAIN),
> +    MAP_ENUM_FLAG (IS_STATIC),
> +    MAP_ENUM_FLAG (IS_ENUM_CLASS),
> +    MAP_ENUM_FLAG (IS_LINKAGE),
> +    MAP_ENUM_FLAG (IS_TYPE_DECLARATION),
> +  };
> +
> +  return flags.to_string (mapping);
> +}
> +
> +/* See cooked-index.h.  */
> +
>  bool
>  cooked_index_entry::compare (const char *stra, const char *strb,
>  			     bool completing)
> @@ -442,6 +459,82 @@ cooked_index_vector::get_main () const
>    return result;
>  }
>  
> +/* See cooked-index.h.  */
> +
> +void
> +cooked_index_vector::dump (gdbarch *arch) const
> +{
> +  /* Ensure the index is done building.  */
> +  this->wait ();
> +
> +  gdb_printf ("  entries:\n");
> +  gdb_printf ("\n");
> +
> +  size_t i = 0;
> +  for (const cooked_index_entry *entry : this->all_entries ())
> +    {
> +      QUIT;
> +
> +      gdb_printf ("    [%zu] ((cooked_index_entry *) %p)\n", i++, entry);
> +      gdb_printf ("    name:       %s\n", entry->name);
> +      gdb_printf ("    canonical:  %s\n", entry->canonical);
> +      gdb_printf ("    DWARF tag:  %s\n", dwarf_tag_name (entry->tag));
> +      gdb_printf ("    flags:      %s\n", to_string (entry->flags).c_str ());
> +      gdb_printf ("    DIE offset: 0x%lx\n",
> +		  to_underlying (entry->die_offset));
> +
> +      if (entry->parent_entry != nullptr)
> +	gdb_printf ("    parent:     ((cooked_index_entry *) %p) [%s]\n",
> +		    entry->parent_entry, entry->parent_entry->name);
> +      else
> +	gdb_printf ("    parent:     ((cooked_index_entry *) 0)\n");
> +
> +      gdb_printf ("\n");
> +    }
> +
> +  const cooked_index_entry *main_entry = this->get_main ();
> +  if (main_entry != nullptr)
> +    gdb_printf ("  main: ((cooked_index_entry *) %p) [%s]\n", main_entry,
> +		  main_entry->name);
> +  else
> +    gdb_printf ("  main: ((cooked_index_entry *) 0)\n");
> +
> +  gdb_printf ("\n");
> +  gdb_printf ("  address maps:\n");
> +  gdb_printf ("\n");
> +
> +  std::vector<const addrmap *> addrmaps = this->get_addrmaps ();
> +  for (i = 0; i < addrmaps.size (); ++i)
> +    {
> +      const addrmap &addrmap = *addrmaps[i];
> +
> +      gdb_printf ("    [%zu] ((addrmap *) %p)\n", i, &addrmap);
> +      gdb_printf ("\n");
> +
> +      addrmap.foreach ([arch] (CORE_ADDR start_addr, const void *obj)
> +	{
> +	  QUIT;
> +
> +	  const char *start_addr_str = paddress (arch, start_addr);
> +
> +	  if (obj != nullptr)
> +	    {
> +	      const dwarf2_per_cu_data *per_cu
> +		= static_cast<const dwarf2_per_cu_data *> (obj);
> +	      gdb_printf ("      [%s] ((dwarf2_per_cu_data *) %p)\n",
> +			  start_addr_str, per_cu);
> +	    }
> +	  else
> +	    gdb_printf ("      [%s] ((dwarf2_per_cu_data *) 0)\n",
> +			start_addr_str);
> +
> +	  return 0;
> +	});
> +
> +      gdb_printf ("\n");
> +    }
> +}
> +
>  void _initialize_cooked_index ();
>  void
>  _initialize_cooked_index ()
> diff --git a/gdb/dwarf2/cooked-index.h b/gdb/dwarf2/cooked-index.h
> index 7299a4f77b44..9d9be517c3a9 100644
> --- a/gdb/dwarf2/cooked-index.h
> +++ b/gdb/dwarf2/cooked-index.h
> @@ -54,6 +54,10 @@ enum cooked_index_flag_enum : unsigned char
>  };
>  DEF_ENUM_FLAGS_TYPE (enum cooked_index_flag_enum, cooked_index_flag);
>  
> +/* Return a string representation of FLAGS.  */
> +
> +std::string to_string (cooked_index_flag flags);
> +
>  /* A cooked_index_entry represents a single item in the index.  Note
>     that two entries can be created for the same DIE -- one using the
>     name, and another one using the linkage name, if any.
> @@ -373,6 +377,9 @@ class cooked_index_vector : public dwarf_scanner_base
>  
>    quick_symbol_functions_up make_quick_functions () const override;
>  
> +  /* Dump a human-readable form of the contents of the index.  */
> +  void dump (gdbarch *arch) const;
> +
>  private:
>  
>    /* The vector of cooked_index objects.  This is stored because the
> diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
> index 9d8952a4eb8d..16559133a3d0 100644
> --- a/gdb/dwarf2/read.c
> +++ b/gdb/dwarf2/read.c
> @@ -18589,7 +18589,15 @@ struct cooked_index_functions : public dwarf2_base_index_functions
>  
>    void dump (struct objfile *objfile) override
>    {
> -    gdb_printf ("Cooked index in use\n");
> +    gdb_printf ("Cooked index in use:\n");
> +    gdb_printf ("\n");
> +
> +    dwarf2_per_objfile *per_objfile = get_dwarf2_per_objfile (objfile);
> +    cooked_index_vector *index
> +      = (gdb::checked_static_cast<cooked_index_vector *>
> +         (per_objfile->per_bfd->index_table.get ()));
> +

With this patch I'm seeing this failure:


(gdb) PASS: gdb.dwarf2/dw2-error.exp: file dw2-error
maint print objfiles /tmp/build/gdb/testsuite/outputs/gdb.dwarf2/dw2-error/dw2-error

Object file /tmp/build/gdb/testsuite/outputs/gdb.dwarf2/dw2-error/dw2-error:  Objfile at 0x40dada0, bfd at 0x426bf70, 50 minsyms

Cooked index in use:

../../src/gdb/../gdbsupport/gdb-checked-static-cast.h:58: internal-error: checked_static_cast: Assertion `result != nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
----- Backtrace -----
FAIL: gdb.dwarf2/dw2-error.exp: maint print objfiles /tmp/build/gdb/testsuite/outputs/gdb.dwarf2/dw2-error/dw2-error (GDB internal error)
PATH: gdb.dwarf2/dw2-error.exp: maint print objfiles /tmp/build/gdb/testsuite/outputs/gdb.dwarf2/dw2-error/dw2-error (GDB internal error)
Resyncing due to internal error.
0x5ff81a gdb_internal_backtrace_1
        ../../src/gdb/bt-utils.c:122
0x5ff8bd _Z22gdb_internal_backtracev
        ../../src/gdb/bt-utils.c:168
0xf4f770 internal_vproblem
        ../../src/gdb/utils.c:401
0xf4fb3f _Z15internal_verrorPKciS0_P13__va_list_tag
        ../../src/gdb/utils.c:481
0x1701002 _Z18internal_error_locPKciS0_z
        ../../src/gdbsupport/errors.cc:58
0x835778 ???
0x82a86d ???
0xdc63a9 _ZN7objfile4dumpEv
        ../../src/gdb/symfile-debug.c:317
0xdea35f dump_objfile
        ../../src/gdb/symmisc.c:122
0xdec5e9 maintenance_print_objfiles
        ../../src/gdb/symmisc.c:728
0x67c1fc do_simple_func
        ../../src/gdb/cli/cli-decode.c:95
0x681318 _Z8cmd_funcP16cmd_list_elementPKci
        ../../src/gdb/cli/cli-decode.c:2737
0xe72b87 _Z15execute_commandPKci
        ../../src/gdb/top.c:688
0x897cb5 _Z15command_handlerPKc
        ../../src/gdb/event-top.c:620
0x8981bb _Z20command_line_handlerOSt10unique_ptrIcN3gdb13xfree_deleterIcEEE
        ../../src/gdb/event-top.c:856
...etc...


Thanks,
Andrew