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This commit changes how GDB processes command arguments for the
following commands:
compile file
maint print c-tdesc
save gdb-index
After this commit these commands will now expect their single filename
argument to be (optionally) quoted if it contains any special
characters (e.g. whit space or quotes).
If the filename does not contain any special characters then nothing
changes. As an example:
(gdb) save gdb-index /path/to/some/directory/
will work before and after this patch. However, if the directory
name contains a white space then before this patch a user would write:
(gdb) save gdb-index /path/to some/directory/
But this will now fail as GDB will consider this as two arguments,
'/path/to' and 'some/directory/'. To pass this single directory name
a user must now do one of these:
(gdb) save gdb-index "/path/to some/directory/"
(gdb) save gdb-index '/path/to some/directory/'
(gdb) save gdb-index /path/to\ some/directory/
This brings these commands into line with commands like 'file' and
'symbol-file', which have supported quoted filenames for a while.
The motivation for this change is to make handling of filename
arguments consistent throughout GDB. We can't move to all commands
taking non-quoted filenames as the non-quoted style only allows for a
single argument. Additionally, the non-quoted style doesn't allow for
filenames that end in white space (though this is probably pretty
rare). So, if we want to have consistency the only choice is to move
towards supporting quote filenames.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
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Following on from the previous commit, this commit marks the old
unquoted filename completion related functions as deprecated.
The aim of doing this is to make it more obvious to someone adding a
new command that they should not be using the older unquoted style
filename argument handling.
I split this change from the previous to make for an easier review.
This commit touches more files, but is _just_ function renaming.
Check out gdb/completer.{c,h} for what has been renamed. All the
other files have just been updated to use the new names.
There should be no user visible changes after this commit.
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Cleanup includes in dwarf2/*.
1. Add the necessary includes so that clangd reports no errors when
opening header files. This ensures that header files include what
they use.
2. Remove all includes reported as unused by clangd (except
gdb-safe-ctype.h, which I think does some magic that affects what
follows).
Built-tested --enable-threading at "yes" and "no", since there are some
portions of code gated by `#ifdef CXX_STD_THREAD`.
Change-Id: I21debffcd7c2caf90f08e1e0fbba3ce30422d042
Approved-By: Tom Tromey <tom@tromey.com>
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Remove some includes reported as unused by clangd. Add some includes in
other files that were previously relying on the transitive include.
Change-Id: Ibdd0a998b04d21362a20d0ca8e5267e21e2e133e
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Most files including gdbcmd.h currently rely on it to access things
actually declared in cli/cli-cmds.h (setlist, showlist, etc). To make
things easy, replace all includes of gdbcmd.h with includes of
cli/cli-cmds.h. This might lead to some unused includes of
cli/cli-cmds.h, but it's harmless, and much faster than going through
the 170 or so files by hand.
Change-Id: I11f884d4d616c12c05f395c98bbc2892950fb00f
Approved-By: Tom Tromey <tom@tromey.com>
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Now that defs.h, server.h and common-defs.h are included via the
`-include` option, it is no longer necessary for source files to include
them. Remove all the inclusions of these files I could find. Update
the generation scripts where relevant.
Change-Id: Ia026cff269c1b7ae7386dd3619bc9bb6a5332837
Approved-By: Pedro Alves <pedro@palves.net>
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Today I realized that while the .debug_names writer uses DW_FORM_udata
for the DIE offset, DW_FORM_ref_addr would be more appropriate here.
This patch makes this change.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31361
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This patch changes the DWARF reader to use the new symbol domains. It
also adjusts many bits of associated code to adapt to this change.
The non-DWARF readers are updated on a best-effort basis. This is
somewhat simpler since most of them only support C and C++. I have no
way to test a few of these.
I went back and forth a few times on how to handle the "tag"
situation. The basic problem is that C has a special namespace for
tags, which is separate from the type namespace. Other languages
don't do this. So, the question is, should a DW_TAG_structure_type
end up in the tag domain, or the type domain, or should it be
language-dependent?
I settled on making it language-dependent using a thought experiment.
Suppose there was a Rust compiler that only emitted nameless
DW_TAG_structure_type objects, and specified all structure type names
using DW_TAG_typedef. This DWARF would be correct, in that it
faithfully represents the source language -- but would not work with a
purely struct-domain implementation in gdb. Therefore gdb would be
wrong.
Now, this approach is a little tricky for C++, which uses tags but
also enters a typedef for them. I notice that some other readers --
like stabsread -- actually emit a typedef symbol as well. And, I
think this is a reasonable approach. It uses more memory, but it
makes the internals simpler. However, DWARF never did this for
whatever reason, and so in the interest of keeping the series slightly
shorter, I've left some C++-specific hacks in place here.
Note that this patch includes language_minimal as a language that uses
tags. I did this to avoid regressing gdb.dwarf2/debug-names-tu.exp,
which doesn't specify the language for a type unit. Arguably this
test case is wrong.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30164
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This rewrites GDB's .debug_names writer. It is now closer to the form
imagined in the DWARF spec. In particular, names are emitted exactly
as they appear in the original DWARF.
In order to make the reader work nicely, some extensions were needed.
These were all documented in an earlier patch. Note that in
particular this writer solves the "main name" problem by putting a
flag into the table.
GDB does not use the .debug_names hash table, so it also does not
write one. I consider this hash table to be essentially useless in
general, due to the name canonicalization problem -- while DWARF says
that writers should use the system demangling style, (1) this style
varies across systems, so it can't truly be relied on; and (2) at
least GCC and one other compiler don't actually follow this part of
the spec anyway.
It's important to note, though, that even if the hash was somehow
useful, GDB probably still would not use it -- a sorted list of names
is needed for completion and performs reasonably well for other
lookups, so a hash table is just overhead, IMO.
String emission is also simplified. There's no need in this writer to
ingest the contents of .debug_str.
A couple of tests are updated to reflect the fact that they now "fail"
because the tests don't include .debug_aranges in the .S file.
Arguably the .debug_names writer should also create this section; but
I did not implement that in this series, and there is a separate bug
about it.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24820
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24549
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The new .debug_names reader will work by creating a cooked index from
.debug_names. This patch updates cooked_index::maybe_write_index to
avoid writing the index in this case.
However, in order to do this in a clean way, the readers are changed
so that a nullptr result from index_for_writing means "cannot be
done", and then the error message is moved into write_dwarf_index
(where it historically lived).
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This adds a new 'lang' member to cooked_index_entry. This holds the
language of the symbol. This is primarily useful for the new
.debug_names reader, which will not scan the CUs for languages up
front.
This also changes cooked_index_shard::add to return a non-const
pointer. This doesn't impact the current code, but is needed for the
new reader.
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This commit is the result of the following actions:
- Running gdb/copyright.py to update all of the copyright headers to
include 2024,
- Manually updating a few files the copyright.py script told me to
update, these files had copyright headers embedded within the
file,
- Regenerating gdbsupport/Makefile.in to refresh it's copyright
date,
- Using grep to find other files that still mentioned 2023. If
these files were updated last year from 2022 to 2023 then I've
updated them this year to 2024.
I'm sure I've probably missed some dates. Feel free to fix them up as
you spot them.
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Fortran provides additional entry points for subroutines and functions.
These entry points may use only a subset (or a different set) of the
parameters of the original subroutine. The entry points may be described
via the DWARF tag DW_TAG_entry_point.
This commit adds support for parsing the DW_TAG_entry_point DWARF tag.
Currently, between ifx/ifort/gfortran, only ifort is actually emitting
this tag. Both, ifx and gfortran use the DW_TAG_subprogram tag as
workaround/alternative. Thus, this patch really only adds more ifort
support. Even so, some of the attached tests still fail for ifort, due
to some wrong line info generated for the entry points in ifort.
After this patch it is possible to set a breakpoint in gdb with the
ifort compiled example at the entry points 'foo' and 'foobar', which was not
possible before.
As gcc and ifx do not emit the tag I also added a test to gdb.dwarf2
which uses some underlying c compiled code and adds some Fortran style DWARF
to it emitting the DW_TAG_entry_point. Before this patch it was not
possible to actually define breakpoint at the entry point tags.
For gfortran there actually exists a bug on bugzilla, asking for the use
of DW_TAG_entry_point over DW_TAG_subprogram:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37134
This patch was originally posted here
https://sourceware.org/legacy-ml/gdb-patches/2017-07/msg00317.html
but its review/pinging got lost after a while. I reworked it to fit the
current GDB.
Co-authored-by: Bernhard Heckel <bernhard.heckel@intel.com>
Co-authored-by: Tim Wiederhake <tim.wiederhake@intel.com>
Approved-by: Tom Tromey <tom@tromey.com>
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While making recent changes to 'save gdb-index' command I triggered
some errors -- of the kind a user might be expected to trigger if they
do something wrong -- and I didn't find GDB's output as helpful as it
might be.
For example:
$ gdb -q /tmp/hello.x
...
(gdb) save gdb-index /non_existing_dir
Error while writing index for `/tmp/hello': mkstemp: No such file or directory.
That the error message mentions '/tmp/hello', which does exist, but
doesn't mention '/non_existing_dir', which doesn't is, I think,
confusing.
Also, I find the 'mkstemp' in the error message confusing for a user
facing error. A user might not know what mkstemp means, and even if
they do, that it appears in the error message is an internal GDB
detail. The user doesn't care what function failed, but wants to know
what was wrong with their input, and what they should do to fix
things.
Similarly, for a directory that does exist, but can't be written to:
(gdb) save gdb-index /no_access_dir
Error while writing index for `/tmp/hello': mkstemp: Permission denied.
In this case, the 'Permission denied' might make the user thing there
is a permissions issue with '/tmp/hello', which is not the case.
After this patch, the new errors are:
(gdb) save gdb-index /non_existing_dir
Error while writing index for `/tmp/hello': `/non_existing_dir': No such file or directory.
and:
(gdb) save gdb-index /no_access_dir
Error while writing index for `/tmp/hello': `/no_access_dir': Permission denied.
we also have:
(gdb) save gdb-index /tmp/not_a_directory
Error while writing index for `/tmp/hello': `/tmp/not_a_directory': Is not a directory.
I think these do a better job of guiding the user towards fixing the
problem.
I've added a new test that exercises all of these cases, and also
checks the case where a user tries to use an executable that already
contains an index in order to generate an index. As part of the new
test I've factored out some code from ensure_gdb_index (lib/gdb.exp)
into a new proc (get_index_type), which I've then used in the new
test. I've confirmed that all the tests that use ensure_gdb_index
still pass.
During review it was pointed out that the testsuite proc
have_index (lib/gdb.exp) is similar to the new get_index_type proc, so
I've rewritten have_index to also use get_index_type, I've confirmed
that all the tests that use have_index still pass.
Nothing that worked correctly before this patch should give an error
after this patch; I've only changed the output when the user was going
to get an error anyway.
Reviewed-By: Tom de Vries <tdevries@suse.de>
Reviewed-By: Tom Tromey <tom@tromey.com>
Approved-By: Tom Tromey <tom@tromey.com>
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index-write.c has a comment indicating that C++17's try_emplace could
be used. This patch makes the change.
Approved-By: Pedro Alves <pedro@palves.net>
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Similar to the previous commit, this commit ensures that the dwarf-5
index files are generated identically as the number of worker-threads
changes.
Building the dwarf-5 index makes use of a closed hash table, the
bucket_hash local within debug_names::build(). Entries are added to
bucket_hash from m_name_to_value_set, which, in turn, is populated
by calls to debug_names::insert() in write_debug_names. The insert
calls are ordered based on the entries within the cooked_index, and
the ordering within cooked_index depends on the number of worker
threads that GDB is using.
My proposal is to sort each chain within the bucket_hash closed hash
table prior to using this to build the dwarf-5 index.
The buckets within bucket_hash will always have the same ordering (for
a given GDB build with a given executable), and by sorting the chains
within each bucket, we can be sure that GDB will see each entry in a
deterministic order.
I've extended the index creation test to cover this case.
Approved-By: Tom Tromey <tom@tromey.com>
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It was observed that changing the number of worker threads that GDB
uses (maintenance set worker-threads NUM) would have an impact on the
layout of the generated gdb-index.
The cause seems to be how the CU are distributed between threads, and
then symbols that appear in multiple CU can be encountered earlier or
later depending on whether a particular CU moves between threads.
I certainly found this behaviour was reproducible when generating an
index for GDB itself, like:
gdb -q -nx -nh -batch \
-eiex 'maint set worker-threads NUM' \
-ex 'save gdb-index /tmp/'
And then setting different values for NUM will change the generated
index.
Now, the question is: does this matter?
I would like to suggest that yes, this does matter. At Red Hat we
generate a gdb-index as part of the build process, and we would
ideally like to have reproducible builds: for the same source,
compiled with the same tool-chain, we should get the exact same output
binary. And we do .... except for the index.
Now we could simply force GDB to only use a single worker thread when
we build the index, but, I don't think the idea of reproducible builds
is that strange, so I think we should ensure that our generated
indexes are always reproducible.
To achieve this, I propose that we add an extra step when building the
gdb-index file. After constructing the initial symbol hash table
contents, we will pull all the symbols out of the hash, sort them,
then re-insert them in sorted order. This will ensure that the
structure of the generated hash will remain consistent (given the same
set of symbols).
I've extended the existing index-file test to check that the generated
index doesn't change if we adjust the number of worker threads used.
Given that this test is already rather slow, I've only made one change
to the worker-thread count. Maybe this test should be changed to use
a smaller binary, which is quicker to load, and for which we could
then try many different worker thread counts.
Approved-By: Tom Tromey <tom@tromey.com>
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Make static the functions add_index_entry, find_slot, and hash_expand,
member functions of the mapped_symtab class.
Fold an additional snippet of code from write_gdbindex into
mapped_symtab::minimize, this code relates to minimisation, so this
seems like a good home for it.
Make the n_elements, data, and m_string_obstack member variables of
mapped_symtab private. Provide a new obstack() member function to
provide access to the obstack when needed, and also add member
functions begin(), end(), cbegin(), and cend() so that the
mapped_symtab class can be treated like a contained and iterated
over.
I've also taken this opportunity to split out the logic for whether
the hash table (m_data) needs expanding, this is the new function
hash_needs_expanding. This will be useful in a later commit.
There should be no user visible changes after this commit.
Approved-By: Tom Tromey <tom@tromey.com>
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I noticed in passing that out algorithm for generating the gdb-index
file is incorrect. When building the hash table in add_index_entry we
count every incoming entry rehash when the number of entries gets too
large. However, some of the incoming entries will be duplicates,
which don't actually result in new items being added to the hash
table.
As a result, we grow the gdb-index hash table far too often.
With an unmodified GDB, generating a gdb-index for GDB, I see a file
size of 90M, with a hash usage (in the generated index file) of just
2.6%.
With a patched GDB, generating a gdb-index for the _same_ GDB binary,
I now see a gdb-index file size of 30M, with a hash usage of 41.9%.
This is a 67% reduction in gdb-index file size.
Obviously, not every gdb-index file is going to see such big savings,
however, the larger a program, and the more symbols that are
duplicated between compilation units, the more GDB would over count,
and so, over-grow the index.
The gdb-index hash table we create has a minimum size of 1024, and
then we grow the hash when it is 75% full, doubling the hash table at
that time. Given this, then we expect that either:
a. The hash table is size 1024, and less than 75% full, or
b. The hash table is between 37.5% and 75% full.
I've include a test that checks some of these constraints -- I've not
bothered to check the upper limit, and over full hash table isn't
really a problem here, but if the fill percentage is less than 37.5%
then this indicates that we've done something wrong (obviously, I also
check for the 1024 minimum size).
Approved-By: Tom Tromey <tom@tromey.com>
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Add proper support for option completion to the 'save gdb-index'
command. Update save_gdb_index_command function to make use of the
new option_def data structures for parsing the '-dwarf-5' option.
Approved-By: Tom Tromey <tom@tromey.com>
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Add a call to gdb_tilde_expand in the save_gdb_index_command function,
this means that we can now do:
(gdb) save gdb-index ~/blah/
Previous this wouldn't work.
Approved-By: Tom Tromey <tom@tromey.com>
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Since GDB now requires C++17, we don't need the internally maintained
gdb::optional implementation. This patch does the following replacing:
- gdb::optional -> std::optional
- gdb::in_place -> std::in_place
- #include "gdbsupport/gdb_optional.h" -> #include <optional>
This change has mostly been done automatically. One exception is
gdbsupport/thread-pool.* which did not use the gdb:: prefix as it
already lives in the gdb namespace.
Change-Id: I19a92fa03e89637bab136c72e34fd351524f65e9
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>
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dwarf2/read.h includes cooked-index.h, but it doesn't need to. This
patch removes the inclusion from this header, and adds one to
index-write.c to make up for the absence.
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I noticed a few more style issues in commit 8b9c08eddac ("[gdb/symtab] Add
name_of_main and language_of_main to the DWARF index"), after checking it
with gcc's check_GNU_style.{sh,py}.
Fix these.
Build on x86_64-linux.
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The recent change to record the DWARF language in the per-CU data
yielded a race warning in my testing:
ThreadSanitizer: data race ../../binutils-gdb/gdb/dwarf2/read.c:21779 in prepare_one_comp_unit
This patch fixes the bug by applying the same style of fix that was
done for the ordinary (gdb) language.
I wonder if this code could be improved. Requiring an atomic for the
language in particular seems unfortunate, as it is often consulted
during index finalization. However, I haven't investigated this.
Regression tested on x86-64 Fedora 38.
Reviewed-by: Tom de Vries <tdevries@suse.de>
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While reviewing gdb/dwarf2/index-write.c I noticed two style issues.
Fix these.
Tested on x86_64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
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Post-commit review pointed out a few style issues in commit 8b9c08eddac
("[gdb/symtab] Add name_of_main and language_of_main to the DWARF index").
Fix these.
Tested on x86_64-linux.
Reported-By: Tom Tromey <tom@tromey.com>
Approved-By: Tom Tromey <tom@tromey.com>
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This patch adds a new section to the DWARF index containing the name
and the language of the main function symbol, gathered from
`cooked_index::get_main`, if available. Currently, for lack of a better name,
this section is called the "shortcut table". The way this name is both saved and
applied upon an index being loaded in mirrors how it is done in
`cooked_index_functions`, more specifically, the full name of the main function
symbol is saved and `set_objfile_main_name` is used to apply it after it is
loaded.
The main use case for this patch is in improving startup times when dealing with
large binaries. Currently, when an index is used, GDB has to expand symtabs
until it finds out what the language of the main function symbol is. For some
large executables, this may take a considerable amount of time to complete,
slowing down startup. This patch bypasses that operation by having both the name
and language of the main function symbol be provided ahead of time by the index.
In my testing (a binary with about 1.8GB worth of DWARF data) this change brings
startup time down from about 34 seconds to about 1.5 seconds.
When testing the patch with target board cc-with-gdb-index, test-case
gdb.fortran/nested-funcs-2.exp starts failing, but this is due to a
pre-existing issue, filed as PR symtab/30946.
Tested on x86_64-linux, with target board unix and cc-with-gdb-index.
PR symtab/24549
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24549
Approved-By: Tom de Vries <tdevries@suse.de>
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There are two methods to factor out type information in a dwarf4 executable:
- use -fdebug-info-types to generate type units in a .debug_types section, and
- use dwz to create partial units.
The dwz method has an extra benefit: it also allows to factor out information
between executables into a newly created .dwz file, pointed to by a
.gnu_debugaltlink section.
There is nothing prohibiting a .gnu_debugaltlink file to contain a
.debug_types section.
It's just not generated by dwz or any other tool atm, and consequently gdb has
no support for it. Enhancement PR symtab/30838 is open about the lack of
support.
Make the current situation explicit by emitting a dwarf error:
...
(gdb) file struct-with-sig-2^M
Reading symbols from struct-with-sig-2...^M
Dwarf Error: .debug_types section not supported in dwz file^M
...
and add an assert in write_gdbindex:
...
+ /* See enhancement PR symtab/30838. */
+ gdb_assert (!(per_cu->is_dwz && per_cu->is_debug_types));
...
to clarify why we can use:
...
data_buf &cu_list = (per_cu->is_debug_types
? types_cu_list
: per_cu->is_dwz ? dwz_cu_list : objfile_cu_list);
...
The test-case is a modified copy from gdb.dwarf2/struct-with-sig.exp, so it
keeps the copyright years range.
Tested on x86_64-linux.
Tested-By: Guinevere Larsen <blarsen@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30838
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Add a unit test which checks that write_gdb_index_1 will throw
an error when the size of the file would exceed the maximum value
capable of being represented by 'offset_type'.
The unit test fails on 32-bit systems due to wrapping overflow. Fix this by
changing the type of total_len in write_gdbindex_1 from size_t to uint64_t.
Tested on x86_64-linux.
Co-Authored-By: Kevin Buettner <kevinb@redhat.com>
Approved-by: Kevin Buettner <kevinb@redhat.com>
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The header in a .gdb_index section uses 32-bit unsigned offsets to
refer to other areas of the section. Thus, there is a size limit of
2^32-1 which is currently unaccounted for by GDB's code for outputting
these sections.
At the moment, when GDB creates an overly large section, it will exit
abnormally due to an internal error, which is caused by a failed
assert in assert_file_size, which in turn is called from
write_gdbindex_1, both of which are in gdb/dwarf2/index-write.c.
This is what happens when that assert fails:
$ gdb -q -nx -iex 'set auto-load no' -iex 'set debuginfod enabled off' -ex file ./libgraph_tool_inference.so -ex "save gdb-index `pwd`/"
Reading symbols from ./libgraph_tool_inference.so...
No executable file now.
Discard symbol table from `libgraph_tool_inference.so'? (y or n) n
Not confirmed.
../../gdb/dwarf2/index-write.c:1069: internal-error: assert_file_size: Assertion `file_size == expected_size' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
----- Backtrace -----
0x55fddb4d78b0 gdb_internal_backtrace_1
../../gdb/bt-utils.c:122
0x55fddb4d78b0 _Z22gdb_internal_backtracev
../../gdb/bt-utils.c:168
0x55fddb98b5d4 internal_vproblem
../../gdb/utils.c:396
0x55fddb98b8de _Z15internal_verrorPKciS0_P13__va_list_tag
../../gdb/utils.c:476
0x55fddbb71654 _Z18internal_error_locPKciS0_z
../../gdbsupport/errors.cc:58
0x55fddb5a0f23 assert_file_size
../../gdb/dwarf2/index-write.c:1069
0x55fddb5a1ee0 assert_file_size
/usr/include/c++/13/bits/stl_iterator.h:1158
0x55fddb5a1ee0 write_gdbindex_1
../../gdb/dwarf2/index-write.c:1119
0x55fddb5a51be write_gdbindex
../../gdb/dwarf2/index-write.c:1273
[...]
---------------------
../../gdb/dwarf2/index-write.c:1069: internal-error: assert_file_size: Assertion `file_size == expected_size' failed.
This problem was encountered while building the python-graph-tool
package on Fedora. The Fedora bugzilla bug can be found here:
https://bugzilla.redhat.com/show_bug.cgi?id=1773651
This commit prevents the internal error from occurring by calling error()
when the file size exceeds 2^32-1.
Using a gdb built with this commit, I now see this behavior instead:
$ gdb -q -nx -iex 'set auto-load no' -iex 'set debuginfod enabled off' -ex file ./libgraph_tool_inference.so -ex "save gdb-index `pwd`/"
Reading symbols from ./libgraph_tool_inference.so...
No executable file now.
Discard symbol table from `/mesquite2/fedora-bugs/1773651/libgraph_tool_inference.so'? (y or n) n
Not confirmed.
Error while writing index for `/mesquite2/fedora-bugs/1773651/libgraph_tool_inference.so': gdb-index maximum file size of 4294967295 exceeded
(gdb)
I wish I could provide a test case, but due to the sizes of both the
input and output files, I think that testing resources would be
strained or exceeded in many environments.
My testing on Fedora 38 shows no regressions.
Approved-by: Tom Tromey <tom@tromey.com>
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With test-case gdb.ada/same_enum.exp and target board dwarf4-gdb-index we run
into:
...
(gdb) print red^M
No definition of "red" in current context.^M
(gdb) FAIL: gdb.ada/same_enum.exp: print red
...
[ This is a regression since commit 844a72efbce ("Simplify gdb_index writing"),
so this is broken in gdb 12 and 13. ]
The easiest way to see what's going wrong is with readelf. We have in section
.gdb_index:
...
[7194] pck__red:
2 [static, variable]
3 [static, variable]
...
which points to the CUs 2 and 3 in the CU list (shown using "2" and "3"), but
should be pointing to the TUs 2 and 3 in the TU list (shown using "T2" and
"T3").
Fix this by removing the counter / types_counter distinction in
write_gdbindex, such that we get the expected:
...
[7194] pck__red:
T2 [static, variable]
T3 [static, variable]
...
[ While reading write_gdbindex I noticed a few oddities related to dwz
handling, I've filed PR30829 about this. ]
Tested on x86_64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR symtab/30827
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30827
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When running test-case gdb.python/py-symbol.exp with target board
cc-with-gdb-index, we run into:
...
(gdb) python print (len (gdb.lookup_static_symbols ('rr')))^M
1^M
(gdb) FAIL: gdb.python/py-symbol.exp: print (len (gdb.lookup_static_symbols ('rr')))
...
[ Note that the test-case contains rr in both py-symtab.c:
...
static int __attribute__ ((used)) rr = 42; /* line of rr */
...
and py-symtab-2.c:
...
static int __attribute__ ((used)) rr = 99; /* line of other rr */
... ]
This passes with gdb-12-branch, and fails with gdb-13-branch.
AFAIU the current code in symtab_index_entry::minimize makes the assumption
that it's fine to store only one copy of rr in the gdb-index, because
"print rr" will only ever print one, and always the same.
But that fails to recognize that gdb supports gdb.lookup_static_symbols, which
returns a list of variables rather than the first one.
In other words, the current approach breaks feature parity between cooked
index and gdb-index.
Note btw that also debug-names has both instances:
...
[ 5] #00597969 rr:
<4> DW_TAG_variable DW_IDX_compile_unit=3 DW_IDX_GNU_internal=1
<4> DW_TAG_variable DW_IDX_compile_unit=4 DW_IDX_GNU_internal=1
...
Fix this in symtab_index_entry::minimize, by not deduplicating variables.
Tested on x86_64-linux, with target boards unix and cc-with-gdb-index.
Reviewed-by: Kevin Buettner <kevinb@redhat.com>
PR symtab/30720
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30720
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When running test-case gdb.dwarf2/pr13961.exp with target-board
cc-with-debug-names, I run into:
...
Running gdb.dwarf2/pr13961.exp ...
gdb compile failed, gdb/dwarf2/index-write.c:1305: internal-error: \
write_debug_names: Assertion `counter == per_bfd->all_units.size ()' failed.
...
This is a regression since commit 542a33e348a ("Only use the per-BFD object to
write a DWARF index"), which did:
...
- gdb_assert (counter == per_objfile->per_bfd->all_comp_units.size ());
+ gdb_assert (counter == per_bfd->all_units.size ());
...
Fix this by reverting to using all_comp_units:
...
gdb_assert (counter == per_bfd->all_comp_units.size ());
...
Tested on x86_64-linux, using target boards unix and cc-with-debug-names.
PR symtab/30741
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30741
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I filed PR29179 about the following FAIL in test-case
gdb.ada/O2_float_param.exp with target board cc-with-gdb-index:
...
(gdb) break increment^M
Function "increment" not defined.^M
Make breakpoint pending on future shared library load? (y or [n]) n^M
(gdb) FAIL: gdb.ada/O2_float_param.exp: scenario=all: gdb_breakpoint: \
set breakpoint at increment
...
The FAIL was a regression since commit 2cf349be0e3 ("Do not put linkage names
into .gdb_index").
Before that commit we had:
...
$ readelf -w foo > READELF
$ grep callee.*increment READELF
[1568] callee__increment: 5 [global, function]
[3115] callee.increment: 5 [global, function]
...
but after only:
...
$ grep callee.*increment READELF
[3115] callee.increment: 5 [global, function]
...
The regression was fixed by commit 67e83a0deef ("Fix regression in
c-linkage-name.exp with gdb index"), which got us again:
...
$ grep callee.*increment READELF
[1568] callee__increment: 5 [global, function]
[3115] callee.increment: 5 [global, function]
...
The commit however did not claim that particular PR. A subsequent commit,
commit 5fea9794325 ("Improve Ada support in .gdb_index") did claim to fix it,
together with commit dd05fc7071a ("Change .gdb_index de-duplication
implementation").
The commit 5fea9794325 contained the following addition in write_cooked_index:
...
+ if (entry->per_cu->lang () == language_ada)
+ {
+ /* We want to ensure that the Ada main function's name
+ appears verbatim in the index. However, this name will
+ be of the form "_ada_mumble", and will be rewritten by
+ ada_decode. So, recognize it specially here and add it
+ to the index by hand. */
+ if (entry->tag == DW_TAG_subprogram
+ && strcmp (main_for_ada, name) == 0)
+ {
+ /* Leave it alone. */
+ }
+ else
+ {
+ /* In order for the index to work when read back into
+ gdb, it has to use the encoded name, with any
+ suffixes stripped. */
+ std::string encoded = ada_encode (name, false);
+ name = obstack_strdup (&symtab->m_string_obstack,
+ encoded.c_str ());
+ }
+ }
...
The code contains some special handling related to the Ada main function, so
let's look at that one: foo. Before commit 67e83a0deef we have:
...
$ grep foo.*function READELF
[3733] foo: 7 [global, function]
...
and after:
...
$ grep foo.*function READELF
[2738] _ada_foo: 7 [global, function]
[3733] foo: 7 [global, function]
...
so that looks identical to the callee.increment case.
At commit 5fea9794325, we have slightly different index numbers:
...
$ grep foo.*function READELF
[1658] foo: 7 [global, function]
[2738] _ada_foo: 7 [global, function]
...
but otherwise the same result.
If we disable the special handling of the Ada main function like so:
...
- if (entry->tag == DW_TAG_subprogram
+ if (false && entry->tag == DW_TAG_subprogram
...
we still have the exact same result because:
...
(gdb) p main_for_ada
$1 = 0x352e6a0 "_ada_foo"
...
and ada_encode ("_ada_foo", false) == "_ada_foo".
The comment seems to be copied from debug_names::insert, which does indeed use
ada_decode, while the code in write_cooked_index uses ada_encode instead.
Remove the superfluous special handling of Ada main in write_cooked_index.
Tested on x86_64-linux, with target boards unix and cc-with-gdb-index.
Approved-By: Tom Tromey <tom@tromey.com>
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The DWARF index does not need access to the objfile or per-objfile
objects when writing -- it's entirely based on the objfile-independent
per-BFD data.
This patch implements this idea by changing the entire API to only be
passed the per-BFD object. This simplifies some lifetime reasoning
for the next patch.
This patch removes some code that ensures that the BFD came from a
file. It seems to me that checking for the existence of a build-id is
good enough for the index cache.
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See previous patch's commit message for rationale.
Change-Id: I6b8cdc045dffccc1c01ed690ff258af09f6ff076
Approved-By: Tom Tromey <tom@tromey.com>
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After the cooked index is created, the addrmaps should be const.
Change-Id: I8234520ab346ced40a8dd6e478ba21fc438c2ba2
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Users of addrmap::find and addrmap::foreach that have a const addrmap
should ideally receive const pointers to objects, to indicate they
should not be modified. However, users that have a non-const addrmap
should still receive a non-const pointer.
To achieve this, without adding more virtual methods, make the existing
find and foreach virtual methods private and prefix them with "do_".
Add small non-const and const wrappers for find and foreach.
Obviously, the const can be cast away, but if using static_cast
instead of C-style casts, then the compiler won't let you cast
the const away. I changed all the callers of addrmap::find and
addrmap::foreach I could find to make them use static_cast.
Change-Id: Ia8e69d022564f80d961413658fe6068edc71a094
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This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
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PR symtab/29694 points out a regression caused by the new DWARF
scanner when the cc-with-gdb-index target board is used.
What happens here is that an older version of gdb will make an index
describing the "A" type as:
[737] A: 1 [global, type]
whereas the new gdb says:
[1008] A: 0 [global, type]
Here the old one is correct because the A in CU 0 is just a
declaration without a size:
<1><45>: Abbrev Number: 10 (DW_TAG_structure_type)
<46> DW_AT_name : A
<48> DW_AT_declaration : 1
<48> DW_AT_sibling : <0x6d>
This patch fixes the problem by introducing the idea of a "type
declaration". I think gdb still needs to recurse into these types,
searching for methods, but by marking the type itself as a
declaration, gdb can skip this type during lookups and when writing
the index.
Regression tested on x86-64 using the cc-with-gdb-index board.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29694
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While investigating PR symtab/29179, I found that one Ada test failed
because, although a certain symbol was present in the index, with the
new DWARF reader it pointed to a different CU than was chosen by
earlier versions of gdb.
This patch changes how symbol de-duplication is done, deferring the
process until the entire symbol table has been constructed. This way,
it's possible to always choose the lower-numbered CU among duplicates,
which is how gdb (implicitly) previously worked.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29179
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The cooked index work changed how .gdb_index is constructed, and in
the process broke .gdb_index support. This is PR symtab/29179.
This patch partially fixes the problem. It arranges for Ada names to
be encoded in the form expected by the index code. In particular,
linkage names for Ada are emitted, including the "main" name; names
are Ada-encoded; and names are no longer case-folded, something that
prevented operator names from round-tripping correctly.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29179
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c-linkage-name.exp started failing with the gdb-index target board due
to an earlier patch. The problem here is that some linkage names must
be in the index -- but, based on inspection, not C++ linkage names.
This patch updates the code to exclude only these.
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The class debug_names has two 'insert' overloads, but only one of them
is ever called externally, and it simply forwards to the other
implementation. It seems cleaner to me to have a single method, so
this patch merges the two.
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Add all_comp_units/all_type_units views on all_units.
Having the views allows us to:
- easily get the number of CUs or TUs in all_units, and
- easily access the nth CU or TU.
This minimizes the use of tu_stats.nr_tus.
Tested on x86_64-linux.
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Mechanically rename all_comp_units to all_units:
...
$ sed -i 's/all_comp_units/all_units/' gdb/dwarf2/*
...
Tested on x86_64-linux.
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This changes struct objfile to use a gdb_bfd_ref_ptr. In addition to
removing some manual memory management, this fixes a use-after-free
that was introduced by the registry rewrite series. The issue there
was that, in some cases, registry shutdown could refer to memory that
had already been freed. This help fix the bug by delaying the
destruction of the BFD reference (and thus the per-bfd object) until
after the registry has been shut down.
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With gdb build with -fsanitize=thread and test-case
gdb.dwarf2/dw4-sig-types.exp and target board cc-with-dwz-m we run into a data
race between:
...
Write of size 4 at 0x7b2800002268 by thread T4:^M
#0 cutu_reader::cutu_reader(dwarf2_per_cu_data*, dwarf2_per_objfile*, \
abbrev_table*, dwarf2_cu*, bool, abbrev_cache*) gdb/dwarf2/read.c:6236 \
(gdb+0x82f525)^M
...
and this read:
...
Previous read of size 4 at 0x7b2800002268 by thread T1:^M
#0 dwarf2_find_containing_comp_unit gdb/dwarf2/read.c:23444 \
(gdb+0x86e22e)^M
...
In other words, between this write:
...
this_cu->length = cu->header.get_length ();
...
and this read:
...
&& mid_cu->sect_off + mid_cu->length > sect_off))
...
of per_cu->length.
Fix this similar to the per_cu->dwarf_version case, by only setting it if
needed, and otherwise verifying that the same value is used. [ Note that the
same code is already present in the other cutu_reader constructor. ]
Move this logic into into a member function set_length to make sure it's used
consistenly, and make the field private in order to enforce access through the
member functions, and rename it to m_length.
This exposes (running test-case gdb.dwarf2/fission-reread.exp) that in
fill_in_sig_entry_from_dwo_entry, the m_length field is overwritten.
For now, allow for that exception.
While we're at it, make sure that the length is set before read.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29344
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The dwarf2_per_cu_data fields lang and unit_type both have a dont-know
initial value (respectively language_unknown and (dwarf_unit_type)0), which
allows us to add certain checks, f.i. checking that that a field is not read
before written.
Add get/set member functions for the two fields as a convenient location to
add such checks, make the fields private to enforce using the member
functions, and add the m_ prefix.
Tested on x86_64-linux.
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