DWARF v5 introduces DW_AT_call_all_calls, a subprogram attribute which
indicates that all calls (both regular and tail) within the subprogram
have call site entries. The information within these call site entries
can be used by a debugger to populate backtraces with synthetic tail
call frames.
Tail calling frames go missing in backtraces because the frame of the
caller is reused by the callee. Call site entries allow a debugger to
reconstruct a sequence of (tail) calls which led from one function to
another. This improves backtrace quality. There are limitations: tail
recursion isn't handled, variables within synthetic frames may not
survive to be inspected, etc. This approach is not novel, see:
https://gcc.gnu.org/wiki/summit2010?action=AttachFile&do=get&target=jelinek.pdf
This patch adds an IR-level flag (DIFlagAllCallsDescribed) which lowers
to DW_AT_call_all_calls. It adds the minimal amount of DWARF generation
support needed to emit standards-compliant call site entries. For easier
deployment, when the debugger tuning is LLDB, the DWARF requirement is
adjusted to v4.
Testing: Apart from check-{llvm, clang}, I built a stage2 RelWithDebInfo
clang binary. Its dSYM passed verification and grew by 1.4% compared to
the baseline. 151,879 call site entries were added.
rdar://42001377
Differential Revision: https://reviews.llvm.org/D49887
llvm-svn: 343883
- Add fix so that all code paths that create DWARFContext
with an ObjectFile initialise the target architecture in the context
- Add an assert that the Arch is known in the Dwarf CallFrameString method
llvm-svn: 343317
This caused the DebugInfo/Sparc/gnu-window-save.ll test to fail.
> Functions that have signed return addresses need additional dwarf support:
> - After signing the LR, and before authenticating it, the LR register is in a
> state the is unusable by a debugger or unwinder
> - To account for this a new directive, .cfi_negate_ra_state, is added
> - This directive says the signed state of the LR register has now changed,
> i.e. unsigned -> signed or signed -> unsigned
> - This directive has the same CFA code as the SPARC directive GNU_window_save
> (0x2d), adding a macro to account for multiply defined codes
> - This patch matches the gcc implementation of this support:
> https://patchwork.ozlabs.org/patch/800271/
>
> Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343103
Functions that have signed return addresses need additional dwarf support:
- After signing the LR, and before authenticating it, the LR register is in a
state the is unusable by a debugger or unwinder
- To account for this a new directive, .cfi_negate_ra_state, is added
- This directive says the signed state of the LR register has now changed,
i.e. unsigned -> signed or signed -> unsigned
- This directive has the same CFA code as the SPARC directive GNU_window_save
(0x2d), adding a macro to account for multiply defined codes
- This patch matches the gcc implementation of this support:
https://patchwork.ozlabs.org/patch/800271/
Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343089
Instead of indexing local variables by DIE offset, use the variable
name + the path through the lexical block tree. This makes the lookup
key consistent across duplicate abstract origins in different CUs.
llvm-svn: 342776
Errors found processing the DW_AT_ranges attribute are propagated by lower level
routines and reported by their callers.
Reviewer: JDevlieghere
Differential Revision: https://reviews.llvm.org/D48344
llvm-svn: 335188
Summary:
This method was not correct for entries in DWO files as it assumed it
could just add up the CU and DIE offsets to get the absolute DIE offset.
This is not correct for the DWO files, as here the CU offset will
reference the skeleton unit, whereas the DIE offset will be the offset
in the full unit in the DWO file.
Unfortunately, this means that we are not able to determine the absolute
DIE offset using the information in the .debug_names section alone,
which means we have to offload some of this work to the users of this
class.
To demonstrate how this can be done, I've added/fixed the ability to
lookup entries using accelerator tables in DWO files in llvm-dwarfdump.
To make this happen, I've needed to make two extra changes in other
classes:
- made the DWARFContext method to lookup a CU based on the section
offset public. I've needed this functionality to lookup a CU, and this
seems like a useful thing in general.
- made DWARFUnit::getDWOId call extractDIEsIfNeeded. Before this, the
DWOId was filled in only if the root DIE happened to be parsed
before we called the accessor. Since the lazy parsing is supposed to
happen under the hood, calling extractDIEsIfNeeded seems appropriate.
Reviewers: JDevlieghere, aprantl, dblaikie
Subscribers: mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D48009
llvm-svn: 334578
Summary:
Both (Apple and DWARF5) implementations of the iterators had bugs which
resulted in crashes if one attempted to iterate through the accelerator
tables all the way.
For the Apple tables, the issue was that we did not clear the DataOffset
field when we reached the end, which made our iterator compare unequal
to the "end" iterator. For the Dwarf5 tables, the problem was that we
incremented the CurrentIndex pointer and then used the incremented
(possibly invalid) pointer to check whether we have reached the end of
the index list.
The reason these bugs went undetected is because their only user
(dwarfdump) only ever searched for the first match. Besides allowing us
to test this fix, changing llvm-dwarfdump --find to display all matches
seems like a good improvement (it makes the behavior consistent with the
--name option), so I change llvm-dwarfdump to do that.
The existing tests would be sufficient to test this fix with the new
llvm-dwarfdump behavior, but I add a special test that demonstrates that
the tool indeed displays multiple results. The find.test test needed to
be tweaked a bit as the tool now does not print the ".debug_info
contents" header (also consistent with how --name works).
Reviewers: JDevlieghere, aprantl, dblaikie
Subscribers: mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D47543
llvm-svn: 333635
This commit adds a color category so tools can document this option and
enables it for dwarfdump and dsymuttil.
rdar://problem/40498996
llvm-svn: 333176
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.
In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.
Differential Revision: https://reviews.llvm.org/D43624
llvm-svn: 332240
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
llvm-svn: 331272
We have a few functions that virtually all command wants to run on
process startup/shutdown. This patch adds InitLLVM class to do that
all at once, so that we don't need to copy-n-paste boilerplate code
to each llvm command's main() function.
Differential Revision: https://reviews.llvm.org/D45602
llvm-svn: 330046
Summary:
Even though the getDIEOffset offset function was common for the two
accelerator table implementations, it was doing two different things:
for the Apple tables, it was returning the die offset relative to the
start of the section, whereas for DWARF v5 tables, it was relative to
the start of the CU.
I resolve this by renaming the function to getDIESectionOffset to make
it obvious what the function returns, and change the DWARF
implementation to return the section offset. I also keep the CU-relative
accessor, but only in the DWARF implementation (there is no way to get
this information for the Apple tables). This was not caught by existing
tests because the hand-written inputs also erroneously used section
offsets instead of CU-relative ones.
While looking at this, I noticed that the Apple implementation was not
fully correct either -- the header contains a DIEOffsetBase field, which
should be added to offsets encoded with the DW_FORM_ref*** family, but
this was not being used. This went unnoticed because all current writers
set this field to zero anyway. I fix this as well and add a hand-written
test which demonstrates the issue.
Reviewers: JDevlieghere, dblaikie
Subscribers: aprantl, llvm-commits
Differential Revision: https://reviews.llvm.org/D44202
llvm-svn: 327116
- an ambiguous reference to Optional<T> in llvm-dwarfdump.cpp (fixed
with an explicit prefix).
- a missing base class initialization in Entry copy constructor (fixed
by using the implicitly default constructor, which is possible after
some changes which were done during review).
llvm-svn: 326006
Summary:
This patch implements the name lookup functionality of the .debug_names
accelerator table and hooks it up to "llvm-dwarfdump -find". To make the
interface of the two kinds of accelerator tables more consistent, I've
created an abstract "DWARFAcceleratorTable::Entry" class, which provides
a consistent interface to access the common functionality of the table
entries (such as getting the die offset, die tag, etc.). I've also
modified the apple table to vend entries conforming to this interface.
Reviewers: JDevlieghere, aprantl, probinson, dblaikie
Subscribers: vleschuk, clayborg, echristo, llvm-commits
Differential Revision: https://reviews.llvm.org/D43067
llvm-svn: 326003
Before this patch, llvm-dwarfdump would reject `bundel.dSYM/` as input,
while `bundel.dSYM` was accepted. The reason is that `path::extension()`
returns an empty string for the former, leading to the argument not
being recognized as a dSYM bundle.
llvm-svn: 324621
Summary:
This commit renames DWARFAcceleratorTable to AppleAcceleratorTable to free up
the first name as an interface for the different accelerator tables.
Then I add a DWARFDebugNames class for the dwarf5 table.
Presently, the only common functionality of the two classes is the dump()
method, because this is the only method that was necessary to implement
dwarfdump -debug-names; and because the rest of the
AppleAcceleratorTable interface does not directly transfer to the dwarf5
tables (the main reason for that is that the present interface assumes
the tables are homogeneous, but the dwarf5 tables can have different
keys associated with each entry).
I expect to make the common interface richer as I add more functionality
to the new class (and invent a way to represent it in generic way).
In terms of sharing the implementation, I found the format of the two
tables sufficiently different to frustrate any attempts to have common
parsing or dumping code, so presently the implementations share just low
level code for formatting dwarf constants.
Reviewers: vleschuk, JDevlieghere, clayborg, aprantl, probinson, echristo, dblaikie
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42297
llvm-svn: 323638
This frees up the first name to be used as an base class for the
apple table and the dwarf5 .debug_names accel table. The rename was
split off from D42297 (adding of debug_names support), which is still
under review.
llvm-svn: 323113
Before this patch, dwarfdump's lookup parameter only accepts unsigned.
Given that for many current platforms the load address already exceeds
unsigned (e.g. arm64 w/ 0x100000000), dwarfdump needs an unsigned long
long parameter.
Patch by: Dr. Michael 'Mickey' Lauer <mickey@vanille-media.de>
llvm-svn: 321064
Add the option to lookup an address in the debug information and print
out the file, function, block and line table details.
Differential revision: https://reviews.llvm.org/D38409
llvm-svn: 316619
At the last LLVM dev meeting we had a debug info for optimized code
BoF session. In that session I presented some graphs that showed how
the quality of the debug info produced by LLVM changed over the last
couple of years. This is a cleaned up version of the patch I used to
collect the this data. It is implemented as an extension of
llvm-dwarfdump, adding a new --statistics option. The intended
use-case is to automatically run this on the debug info produced by,
e.g., our bots, to identify eyebrow-raising changes or regressions
introduced by new transformations that we could act on.
In the current form, two kinds of data are being collected:
- The number of variables that have a debug location versus the number
of variables in total (this takes into account inlined instances of
the same function, so if a variable is completely missing form only
one instance it will be found).
- The PC range covered by variable location descriptions versus the PC
range of all variables' containing lexical scopes.
The output format is versioned and extensible, so I'm looking forward
to both bug fixes and ideas for other data that would be interesting
to track.
Differential Revision: https://reviews.llvm.org/D36627
llvm-svn: 315101
The test fails on Linux; see follow-up email on the llvm-commits list.
> Add the option to lookup an address in the debug information and print
> out the file, function, block and line table details.
>
> Differential revision: https://reviews.llvm.org/D38409
This also reverts the follow-up r314818:
> [test] Fix llvm-dwarfdump/cmdline.test
>
> Fixes test/tools/llvm-dwarfdump/cmdline.test
llvm-svn: 314825
Add the option to lookup an address in the debug information and print
out the file, function, block and line table details.
Differential revision: https://reviews.llvm.org/D38409
llvm-svn: 314817
This patch implements the dwarfdump option --find=<name>. This option
looks for a DIE in the accelerator tables and dumps it if found. This
initial patch only adds support for .apple_names to keep the review
small, adding the other sections and pubnames support should be
trivial though.
Differential Revision: https://reviews.llvm.org/D38282
llvm-svn: 314439
