Commit Graph

685 Commits

Author SHA1 Message Date
Greg Clayton 08748d15b8 Fix a check that was attempting to see if an object file was in memory.
Checking if an object file is in memory should use the ObjectFile::IsInMemory(), not test ObjectFile::BaseAddress(). ObjectFile::BaseAddress() is designed to be overridden by all classes and is for mach-o, ELF and COFF plug-ins. They find the header base adddress and return that as a section offset address. The default implementation of ObjectFile::BaseAddress() does try and make an Address() from the ObjectFile::m_memory_addr, but I switched it to a correct function call.

Differential Revision: https://reviews.llvm.org/D86122
2020-08-18 13:24:22 -07:00
Jonas Devlieghere 75966ee241 [lldb] Get rid of helper CMake variables for Python
This patch is a big sed to rename the following variables:

  s/PYTHON_LIBRARIES/Python3_LIBRARIES/g
  s/PYTHON_INCLUDE_DIRS/Python3_INCLUDE_DIRS/g
  s/PYTHON_EXECUTABLE/Python3_EXECUTABLE/g
  s/PYTHON_RPATH/Python3_RPATH/g

I've also renamed the CMake module to better express its purpose and for
consistency with FindLuaAndSwig.

Differential revision: https://reviews.llvm.org/D85976
2020-08-17 08:47:52 -07:00
Adrian Prantl 05df9cc703 Correctly detect legacy iOS simulator Mach-O objectfiles
The code in ObjectFileMachO didn't disambiguate between ios and
ios-simulator object files for Mach-O objects using the legacy
ambiguous LC_VERSION_MIN load commands. This used to not matter before
taught ArchSpec that ios and ios-simulator are no longer compatible.

rdar://problem/66545307

Differential Revision: https://reviews.llvm.org/D85358
2020-08-06 12:40:45 -07:00
Jim Ingham 1c1ffa6a30 GetPath() returns a std::string temporary. You can't reference just the c_str.
Found by the static analyzer.
2020-08-05 19:12:15 -07:00
Fred Riss 22c16360dd [lldb/ObjectFileMachO] Correctly account for resolver symbols
Summary:
The resolver addresses stored in the dyld trie are relative to the base
of the __TEXT segment. This is usually 0 in a dylib, so this was never
noticed, but it is not 0 for most dylibs integrated in the shared cache.
As we started using the shared cache images recently as symbol source,
this causes LLDB to fail to resolve symbols which go through a runtime
resolver.

Reviewers: jasonmolenda, jingham

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D84083
2020-07-24 09:19:17 -07:00
Martin Storsjö f07ddbc9c4 [LLDB] [COFF] Fix handling of symbols with more than one aux symbol
Differential Revision: https://reviews.llvm.org/D84070
2020-07-20 22:42:28 +03:00
Pavel Labath ede7c02b38 [lldb/COFF] Remove strtab zeroing hack
Summary:
This code (recently responsible for a unaligned access sanitizer
failure) claims that the string table offset zero should result in an
empty string.

I cannot find any mention of this detail in the Microsoft COFF
documentation, and the llvm COFF parser also does not handle offset zero
specially. This code was introduced in 0076e7159, which also does not go
into specifics, citing "various bugfixes".

Given that this is obviously a hack, and does not cause tests to fail, I
think we should just delete it.

Reviewers: amccarth, markmentovai

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D83881
2020-07-17 13:24:59 +02:00
Fred Riss 8113a8bb79 [lldb/ObjectFileMachO] Fetch shared cache images from our own shared cache
Summary:
On macOS 11, the libraries that have been integrated in the system
shared cache are not present on the filesystem anymore. LLDB was
using those files to get access to the symbols of those libraries.
LLDB can get the images from the target process memory though.

This has 2 consequences:
 - LLDB cannot load the images before the process starts, reporting
   an error if someone tries to break on a system symbol.
 - Loading the symbols by downloading the data from the inferior
   is super slow. It takes tens of seconds at the start of the
   debug session to populate the Module list.

To fix this, we can use the library images LLDB has in its own
mapping of the shared cache. Shared cache images are somewhat
special as their LINKEDIT segment is moved to the end of the cache
and thus the images are not contiguous in memory. All of this can
hidden in ObjectFileMachO.

This patch fixes a number of test failures on macOS 11 due to the
first problem described above and adds some specific unittesting
for the new SharedCache Host utilities.

Reviewers: jasonmolenda, labath

Subscribers: llvm-commits, lldb-commits

Tags: #lldb, #llvm

Differential Revision: https://reviews.llvm.org/D83023
2020-07-16 10:37:37 -07:00
Davide Italiano 61cf9f4e72 [ObjectFilePECOFF] Try to avoid unaligned access.
Fixes an UBSAN error.
2020-07-14 18:53:23 -07:00
Fred Riss a4a00ced0c [lldb/Module] Allow for the creation of memory-only modules
Summary:
This patch extends the ModuleSpec class to include a
DataBufferSP which contains the module data. If this
data is provided, LLDB won't try to hit the filesystem
to create the Module, but use only the data stored in
the ModuleSpec.

Reviewers: labath, espindola

Subscribers: emaste, MaskRay, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D83512
2020-07-14 08:45:44 -07:00
Pavel Labath d372a8e8bc [lldb/pecoff] Use a different llvm createBinary overload for parsing
Change the code the use the version which accepts a memory buffer,
instead of the one taking a file name.

This ensures we are not loading the file into memory twice
(ObjectFilePECOFF also loads a copy), reducing our memory footprint, as
well as enabling additional goodies in the future, like being able to
open files which don't exist on disk (D83512).
2020-07-10 11:57:11 +02:00
Fred Riss e529d774c4 [lldb] Use enum constant instead of raw value 2020-07-09 09:43:50 -07:00
Jonas Devlieghere 06412dae82 [lldb] Use std::make_unique<> (NFC)
Update the rest of lldb to use std::make_unique<>. I used clang-tidy to
automate this, which probably missed cases that are wrapped in ifdefs.
2020-06-24 17:48:40 -07:00
Davide Italiano 63d597093c [ObjectFileMachO] Check for TARGET_EMBEDDED instead of listing architectures.
Now that Apple Silicon is a thing, we need to generalize the check.
2020-06-23 12:37:45 -07:00
Jonas Devlieghere 388afd8406 [lldb] Remove redundant access specifiers (NFC) 2020-06-15 21:34:13 -07:00
Reid Kleckner 1c03389c29 Re-land "Migrate the rest of COFFObjectFile to Error"
This reverts commit 101fbc0138.

Remove leftover debugging attribute.

Update LLDB as well, which was missed before.
2020-06-11 14:46:16 -07:00
Jaroslav Sevcik 1beffc1888 Support build-ids of other sizes than 16 in UUID::SetFromStringRef
SBTarget::AddModule currently handles the UUID parameter in a very
weird way: UUIDs with more than 16 bytes are trimmed to 16 bytes. On
the other hand, shorter-than-16-bytes UUIDs are completely ignored. In
this patch, we change the parsing code to handle UUIDs of arbitrary
size.

To support arbitrary size UUIDs in SBTarget::AddModule, this patch
changes UUID::SetFromStringRef to parse UUIDs of arbitrary length. We
subtly change the semantics of SetFromStringRef - SetFromStringRef now
only succeeds if the entire input is consumed to prevent some
prefix-parsing confusion. This is up for discussion, but I believe
this is more consistent - we always return false for invalid UUIDs
rather than sometimes truncating to a valid prefix. Also, all the
call-sites except the API and interpreter seem to expect to consume
the entire input.

This also adds tests for adding existing modules 4-, 16-, and 20-byte
build-ids. Finally, we took the liberty of testing the minidump
scenario we care about - removing placeholder module from minidump and
replacing it with the real module.

Reviewed By: labath, friss

Differential Revision: https://reviews.llvm.org/D80755
2020-06-07 10:03:41 +00:00
Pavel Labath 3a16829748 [lldb] Switch Section-dumping code to raw_ostream
Also, add a basic test for dumping sections.
2020-05-14 11:59:18 +02:00
Jason Molenda 836534f997 Add more detailed symbol type categorization, based on a swift patch by
Greg Clayton a few years ago.

My patch to augment the symbol table in Mach-O files with the
dyld trie exports data structure only categorized symbols as code
or data, but Greg Clayton had a patch to do something similar to
swift a few years ago that had a more extensive categorization of
symbols, as well as extracting some objc class/ivar names from the
entries. This patch is basically just Greg's, updated a bit and
with a test case added to it.

<rdar://problem/50791451>

Differential Revision: https://reviews.llvm.org/D77369
2020-04-06 14:05:33 -07:00
Kazuaki Ishizaki e9264b746b [lldb] NFC: Fix trivial typo in comments, documents, and messages
Differential Revision: https://reviews.llvm.org/D77460
2020-04-07 01:06:16 +09:00
Martin Storsjö aa786b881f [lldb] [PECOFF] Only use PECallFrameInfo on the one supported architecture
The RuntimeFunction struct, which PECallFrameInfo interprets, has a
different layout and differnet semantics on all architectures.

Differential Revision: https://reviews.llvm.org/D77000
2020-04-01 12:39:21 +03:00
Benjamin Kramer e8f13f4f62 Replace std::string::find == 0 with StringRef::startswith
This is both more readable and faster. Found by clang-tidy's
abseil-string-find-startswith.
2020-03-31 21:01:09 +02:00
Kai Wang 581ba35291 [RISCV] ELF attribute section for RISC-V.
Leverage ARM ELF build attribute section to create ELF attribute section
for RISC-V. Extract the common part of parsing logic for this section
into ELFAttributeParser.[cpp|h] and ELFAttributes.[cpp|h].

Differential Revision: https://reviews.llvm.org/D74023
2020-03-31 16:16:19 +08:00
Jason Molenda f0a5af906b Merge in symbols from Mach-O dyld trie to the symbol table
In ObjectFileMachO we construct the symbol table from multiple
sources -- primarily the binary's nlist records, but when the nlist
symbols have been stripped, we would augment those with function
start address from the LC_FUNCTION_STARTS or eh_frame.  This patch
adds another source of symbols - the exported symbols that the
dynamic linker, dyld, uses at runtime from its trie structure.  This
provides us names and addresses for these functions/data.

This patch removes the code from ParseSymtab that would reject an
empty symbol table / nlist source.  It adds a new symbols_added
set which tracks the address of every symbol we've added to the
symtab.  We add symbols in most-information-ful order, and before
adding a symbol from less-informational-ful source (e.g.
LC_FUNCTION_STARTS with no function name), we check if that symbol
has already been added.

On targets with thumb code generation, instead of using the 0th bit
in these addresses in FunctionStarts (or now the trie entries), we
use the data field of FunctionStarts (formerly used to track if the
func_start should be added) and a flag for the trie entries to
encode this, and only store the actual addresses in the symbols_seen
and these vectors.

<rdar://problem/50791451>

Differential revision: https://reviews.llvm.org/D76758
2020-03-27 22:53:15 -07:00
Davide Italiano 34ee941f6d [ObjectFileMachO] Fix a build error on embedded. 2020-02-26 14:31:48 -08:00
Pavel Labath 7b59ff2fa0 [lldb] Add boilerplate to recognize the .debug_tu_index section
It's just like debug_cu_index, only for type units.
2020-02-20 13:44:21 +01:00
Pavel Labath b807a28787 [lldb] Merge RangeArray and RangeVector
The two classes are equivalent, except:
- the former uses a llvm::SmallVector (with a configurable size), while
  the latter uses std::vector.
- the former has a typo in one of the functions name

This patch just leaves one class, using llvm::SmallVector, and defaults
the small size to zero. This is the same thing we did with the
RangeDataVector class in D56170.
2020-02-18 15:22:55 +01:00
Jonas Devlieghere cdc514e4c6 [lldb] Update header guards to be consistent and compliant with LLVM (NFC)
LLDB has a few different styles of header guards and they're not very
consistent because things get moved around or copy/pasted. This patch
unifies the header guards across LLDB and converts everything to match
LLVM's style.

Differential revision: https://reviews.llvm.org/D74743
2020-02-17 23:15:40 -08:00
Jonas Devlieghere aa2ae6af81 [lldb/Plugins] Add missing initialize/terminate calls
Add missing initialize and terminate calls for DynamicLoaderHexagonDYLD
and ObjectFileJIT.
2020-02-17 21:28:16 -08:00
Jonas Devlieghere 50c9cd9526 Revert "[lldb/CMake] Auto-generate the Initialize and Terminate calls for plugin"
This is still failing spectacularly on the Windows bot and I still have
no clue what's going on.
2020-02-17 19:04:50 -08:00
Jonas Devlieghere 9b12dc98fd Re-land "[lldb/CMake] Auto-generate the Initialize and Terminate calls for plugin"
This patch changes the way we initialize and terminate the plugins in
the system initializer. It uses an approach similar to LLVM's
TARGETS_TO_BUILD with a def file that enumerates the plugins.

The previously landed patch got reverted because it was lacking:

 (1) A plugin definition for the Objective-C language runtime,
 (2) The dependency between the Static and WASM dynamic loader,
 (3) Explicit initialization of ScriptInterpreterNone for lldb-test.

All issues have been addressed in this patch.

Differential revision: https://reviews.llvm.org/D73067
2020-02-17 14:43:05 -08:00
Jonas Devlieghere 058cb1b47f Revert "[lldb/CMake] Auto-generate the Initialize and Terminate calls for plugin"
This temporarily reverts commit 7d6da329de
because it's causing test failures on the bots.
2020-02-17 12:34:21 -08:00
Jonas Devlieghere 7d6da329de [lldb/CMake] Auto-generate the Initialize and Terminate calls for plugin
This patch changes the way we initialize and terminate the plugins in
the system initializer. It uses an approach similar to LLVM's
TARGETS_TO_BUILD with a def file that enumerates the plugins.

Differential revision: https://reviews.llvm.org/D73067
2020-02-17 09:07:00 -08:00
Paolo Severini c1121908aa [LLDB] Add DynamicLoaderWasmDYLD plugin for WebAssembly debugging
Add a dynamic loader plug-in class for WebAssembly modules.

Differential Revision: https://reviews.llvm.org/D72751
2020-02-17 12:42:23 +01:00
Jonas Devlieghere bba9ba8d95 [lldb/Plugin] s/LLDB_PLUGIN/LLDB_PLUGIN_DEFINE/ (NFC)
Rename LLDB_PLUGIN to LLDB_PLUGIN_DEFINE as Pavel suggested in D73067 to
avoid name conflict.
2020-02-14 09:58:24 -08:00
Jan Kratochvil 98c940bf51 [NFC] [lldb] Remove unused declaration
ObjectFileELF::GetSectionIndexByType declaration without definition was
added by commit 17220c1886.
2020-02-11 14:59:52 +01:00
Martin Storsjö 6115bd9ba2 [LLDB] Fix GCC warnings about extra semicolons. NFC. 2020-02-10 11:20:44 +02:00
Jonas Devlieghere fbb4d1e43d [lldb/Plugins] Use external functions to (de)initialize plugins
This is a step towards making the initialize and terminate calls be
generated by CMake, which in turn is towards making it possible to
disable plugins at configuration time.

Differential revision: https://reviews.llvm.org/D74245
2020-02-07 15:28:27 -08:00
Pavel Labath 40efa65de8 Revert "[LLDB] Add DynamicLoaderWasmDYLD plugin for WebAssembly debugging"
This patch has a couple of outstanding issues. The test is not python3
compatible, and it also seems to fail with python2 (at least under some
circumstances) due to an overambitious assertion.

This reverts the patch as well as subsequent fixup attempts:
014ea93376,
f5f70d1c8f.
4697e701b8.
5c15e8e682.
3ec28da6d6.
2020-02-05 16:22:19 -08:00
Paolo Severini 3ec28da6d6 [LLDB] Add DynamicLoaderWasmDYLD plugin for WebAssembly debugging
Add a dynamic loader plug-in class for WebAssembly modules.

Differential Revision: https://reviews.llvm.org/D72751
2020-02-05 14:49:36 -08:00
Michał Górny 98594a44aa [lldb] [ObjectFile/ELF] Fix negated seg ids on 32-bit arches
Scale segment identifier up to user_id_t before negating it.  This fixes
the identifers being wrongly e.g. 0x00000000fffffffe instead of
0xfffffffffffffffe.  Fix suggested by Pavel Labath.

This fixes 5 tests failing on i386 (PR #44748):

  lldb-shell :: ObjectFile/ELF/PT_LOAD-overlap-PT_INTERP.yaml
  lldb-shell :: ObjectFile/ELF/PT_LOAD-overlap-PT_TLS.yaml
  lldb-shell :: ObjectFile/ELF/PT_LOAD-overlap-section.yaml
  lldb-shell :: ObjectFile/ELF/PT_LOAD.yaml
  lldb-shell :: ObjectFile/ELF/PT_TLS-overlap-PT_LOAD.yaml

Differential Revision: https://reviews.llvm.org/D73914
2020-02-04 05:50:56 +01:00
Alex Langford 22b044877d [lldb][NFCI] Remove unused LanguageType parameters
These parameters are unused in these methods, and some of them only had a
LanguageType parameter to pipe to other methods that don't use it
either.
2020-01-30 21:57:23 -08:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Raphael Isemann 808142876c [lldb][NFC] Fix all formatting errors in .cpp file headers
Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).

This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).

Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73258
2020-01-24 08:52:55 +01:00
Derek Schuff d34e4152e3 [LLDB] Convert Plugins/ObjectFile/wasm/ObjectFileWasm.h to unix line endings 2020-01-16 09:38:37 -08:00
Paolo Severini 9b3254dbf9 [LLDB] Add SymbolVendorWasm plugin for WebAssembly debugging
Add plugin class SymbolVendorWasm, with the logic to manage debug symbols
for Wasm modules.

Reviewers: clayborg, labath, aprantl, sbc100, teemperor

Reviewed By: labath

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D72650
2020-01-16 09:36:17 -08:00
Jim Ingham cd9e5c3230 Fix the macos build after D71575.
size_t and uint64_t are spelled slightly differently on macOS, which was
causing the compiler to error out calling std::min - since the two types have
to be the same.

I fixed this by casting the uint64_t computation to a size_t.  That's probably
not the cleanest solution, but it gets us back to building.
2020-01-15 18:13:44 -08:00
Paolo Severini 4bafceced6 [LLDB] Add ObjectFileWasm plugin for WebAssembly debugging
Summary:
This is the first in a series of patches to enable LLDB debugging of
WebAssembly targets.

Current versions of Clang emit (partial) DWARF debug information in WebAssembly
modules and we can leverage this debug information to give LLDB the ability to
do source-level debugging of Wasm code that runs in a WebAssembly engine.

A way to do this could be to use the remote debugging functionalities provided
by LLDB via the GDB-remote protocol. Remote debugging can indeed be useful not
only to connect a debugger to a process running on a remote machine, but also to
connect the debugger to a managed VM or script engine that runs locally,
provided that the engine implements a GDB-remote stub that offers the ability to
access the engine runtime internal state.

To make this work, the GDB-remote protocol would need to be extended with a few
Wasm-specific custom query commands, used to access aspects of the Wasm engine
state (like the Wasm memory, Wasm local and global variables, and so on).
Furthermore, the DWARF format would need to be enriched with a few Wasm-specific
extensions, here detailed: https://yurydelendik.github.io/webassembly-dwarf.

This CL introduce classes **ObjectFileWasm**, a file plugin to represent a Wasm
module loaded in a debuggee process. It knows how to parse Wasm modules and
store the Code section and the DWARF-specific sections.

Reviewers: jasonmolenda, clayborg, labath

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D71575
2020-01-15 16:25:35 -08:00
Pavel Labath 4b5bc38802 [lldb/DWARF] Move location list sections into DWARFContext
These are the last sections not managed by the DWARFContext object. I
also introduce separate SectionType enums for dwo section variants, as
this is necessary for proper handling of single-file split dwarf.
2020-01-14 15:19:29 +01:00
Jan Kratochvil bf7225888a [lldb] Fix lookup of symbols with the same address range but different binding
This fixes a failing testcase on Fedora 30 x86_64 (regression Fedora 29->30):

PASS:
./bin/lldb ./lldb-test-build.noindex/functionalities/unwind/noreturn/TestNoreturnUnwind.test_dwarf/a.out -o 'settings set symbols.enable-external-lookup false' -o r -o bt -o quit
  * frame #0: 0x00007ffff7aa6e75 libc.so.6`__GI_raise + 325
    frame #1: 0x00007ffff7a91895 libc.so.6`__GI_abort + 295
    frame #2: 0x0000000000401140 a.out`func_c at main.c:12:2
    frame #3: 0x000000000040113a a.out`func_b at main.c:18:2
    frame #4: 0x0000000000401134 a.out`func_a at main.c:26:2
    frame #5: 0x000000000040112e a.out`main(argc=<unavailable>, argv=<unavailable>) at main.c:32:2
    frame #6: 0x00007ffff7a92f33 libc.so.6`__libc_start_main + 243
    frame #7: 0x000000000040106e a.out`_start + 46

vs.

FAIL - unrecognized abort() function:
./bin/lldb ./lldb-test-build.noindex/functionalities/unwind/noreturn/TestNoreturnUnwind.test_dwarf/a.out -o 'settings set symbols.enable-external-lookup false' -o r -o bt -o quit
  * frame #0: 0x00007ffff7aa6e75 libc.so.6`.annobin_raise.c + 325
    frame #1: 0x00007ffff7a91895 libc.so.6`.annobin_loadmsgcat.c_end.unlikely + 295
    frame #2: 0x0000000000401140 a.out`func_c at main.c:12:2
    frame #3: 0x000000000040113a a.out`func_b at main.c:18:2
    frame #4: 0x0000000000401134 a.out`func_a at main.c:26:2
    frame #5: 0x000000000040112e a.out`main(argc=<unavailable>, argv=<unavailable>) at main.c:32:2
    frame #6: 0x00007ffff7a92f33 libc.so.6`.annobin_libc_start.c + 243
    frame #7: 0x000000000040106e a.out`.annobin_init.c.hot + 46

The extra ELF symbols are there due to Annobin (I did not investigate why this
problem happened specifically since F-30 and not since F-28).

It is due to:

Symbol table '.dynsym' contains 2361 entries:
Valu e          Size Type   Bind   Vis     Name
0000000000022769   5 FUNC   LOCAL  DEFAULT _nl_load_domain.cold
000000000002276e   0 NOTYPE LOCAL  HIDDEN  .annobin_abort.c.unlikely
...
000000000002276e   0 NOTYPE LOCAL  HIDDEN  .annobin_loadmsgcat.c_end.unlikely
...
000000000002276e   0 NOTYPE LOCAL  HIDDEN  .annobin_textdomain.c_end.unlikely
000000000002276e 548 FUNC   GLOBAL DEFAULT abort
000000000002276e 548 FUNC   GLOBAL DEFAULT abort@@GLIBC_2.2.5
000000000002276e 548 FUNC   LOCAL  DEFAULT __GI_abort
0000000000022992   0 NOTYPE LOCAL  HIDDEN  .annobin_abort.c_end.unlikely

GDB has some more complicated preferences between overlapping and/or sharing
address symbols, I have made here so far the most simple fix for this case.

Differential revision: https://reviews.llvm.org/D63540
2020-01-13 12:05:26 +01:00