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

Andrew Burgess via Gdb-patches
2023-01-30T21:36:10Z

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