We recently saw an uptick in internal reports complaining that LLDB is
slow when sources on network file systems are inaccessible. I looked at
the SourceManger and its cache and I think there’s some room for
improvement in terms of reducing file system accesses:
1. We always resolve the path.
2. We always check the timestamp.
3. We always recheck the file system for negative cache hits.
D153726 fixes (1) but (2) and (3) are necessary because of the cache’s
current design. Source files are cached at the debugger level which
means that the source file cache can span multiple targets and
processes. It wouldn't be correct to not reload a modified or new file
from disk.
We can however significantly reduce the number of file system accesses
by using a two level cache design: one cache at the debugger level and
one at the process level:
- The cache at the debugger level works the way it does today. There is
no negative cache: if we can't find the file on disk, we'll try again
next time the cache is queried. If a cached file's timestamp changes
or if its path remapping changes, the cached file is evicted and we
reload it from disk.
- The cache at the process level is design to avoid accessing the file
system. It doesn't check the file's modification time. It caches
negative results, so if a file didn't exist, it doesn't try to reread
it from disk. Checking if the path remapping changed is cheap
(doesn't involve checking the file system) and is the only way for a
file to get evicted from the process cache.
The result of this patch is that LLDB will not show you new content if a
file is modified or created while a process is running. I would argue
that this is what most people would expect, but it is a change from how
LLDB behaves today.
For an average stop, we query the source cache 4 times. With the current
implementation, that's 4 stats to get the modification time, If the file
doesn't exist on disk, that's an additional 4 stats. Before D153726, if
the path starts with a ~ there are another additional 4 calls to
realpath. When debugging sources on a slow (network) file system, this
quickly adds up.
In addition to the two level caching, this patch also adds a source
logging channel and synchronization to the source file cache. The
logging was helpful during development and hopefully will help us triage
issues in the future. The synchronization isn't a new requirement: as
the cache is shared across targets, there is no guarantees that it can't
be accessed concurrently. The patch also fixes a bug where we would only
set the source remapping ID if the un-remapped file didn't exist, which
led to the file getting evicted from the cache on every access.
rdar://110787562
Differential revision: https://reviews.llvm.org/D153834
Currently, source files are cached by their resolved path. This means
that before we can query the cache, we potentially have to resolve the
path, which can be slow. This patch avoids the call to FileSystem::Resolve
by caching both the resolved and unresolved path. We now only resolve
the path once when we create and cache a new file.
rdar://110787562
Differential revision: https://reviews.llvm.org/D153726
Add two new source subcommands: source cache dump and source cache
clear. As the name implies the first one dumps the source cache while
the later clears the cache.
This patch was motivated by a handful of (internal) bug reports related
to sources not being available. Right now those issues can be hard to
diagnose. The new commands give users, as well as us as developers, more
insight into and control over the source cache.
Differential revision: https://reviews.llvm.org/D153685
Re-lands 04aa943be8ed5c03092e2a90112ac638360ec253 with modifications
to fix tests.
I originally reverted this because it caused a test to fail on Linux.
The problem was that I inverted a condition on accident.
There are many situations where we'll iterate over a SymbolContextList
with the pattern:
```
SymbolContextList sc_list;
// Fill in sc_list here
for (auto i = 0; i < sc_list.GetSize(); i++) {
SymbolContext sc;
sc_list.GetSymbolAtContext(i, sc);
// Do work with sc
}
```
Adding an iterator to iterate over the instances directly means we don't
have to do bounds checking or create a copy of every element of the
SymbolContextList.
Differential Revision: https://reviews.llvm.org/D149900
A follow on to my patch for https://reviews.llvm.org/D126435
hit by an x86_64 linux bot; I assumed that a FileSpec had a
directory component and checked if the first character was a
'~'. This was not a valid assumption.
When reading source path remappings out of a dSYM, lldb currently
does tilde expansion -- expanding the tilde-username and checking
that the destination pathname exists, for each dSYM with the path
remappings. This cost happens during lldb's initial process launch
/ load, an especially perf-sensitive time. Inside Apple, we have
dSYMs with source path remappings pointing to NFS directories where
these extra stats for every dSYM can be very expensive if the network
is slow.
This patch instead keeps the source path mapping in the original
tilde-username terms and does the tilde expansion when we need
to read a specific source file from one of the modules. We'll
be stat'ing all of those inodes to load the source file anyway,
so the fact that we do the tilde expansion on every source file
we load, it doesn't cost us significantly.
Differential Revision: https://reviews.llvm.org/D126435
rdar://77091379
(cherry picked from commit c274b6e5830ea88d3f55d6dc1d2b99e38cf6595e)
When reading source path remappings out of a dSYM, lldb currently
does tilde expansion -- expanding the tilde-username and checking
that the destination pathname exists, for each dSYM with the path
remappings. This cost happens during lldb's initial process launch
/ load, an especially perf-sensitive time. Inside Apple, we have
dSYMs with source path remappings pointing to NFS directories where
these extra stats for every dSYM can be very expensive if the network
is slow.
This patch instead keeps the source path mapping in the original
tilde-username terms and does the tilde expansion when we need
to read a specific source file from one of the modules. We'll
be stat'ing all of those inodes to load the source file anyway,
so the fact that we do the tilde expansion on every source file
we load, it doesn't cost us significantly.
Differential Revision: https://reviews.llvm.org/D126435
rdar://77091379
Currently, all data buffers are assumed to be writable. This is a
problem on macOS where it's not allowed to load unsigned binaries in
memory as writable. To be more precise, MAP_RESILIENT_CODESIGN and
MAP_RESILIENT_MEDIA need to be set for mapped (unsigned) binaries on our
platform.
Binaries are mapped through FileSystem::CreateDataBuffer which returns a
DataBufferLLVM. The latter is backed by a llvm::WritableMemoryBuffer
because every DataBuffer in LLDB is considered to be writable. In order
to use a read-only llvm::MemoryBuffer I had to split our abstraction
around it.
This patch distinguishes between a DataBuffer (read-only) and
WritableDataBuffer (read-write) and updates LLDB to use the appropriate
one.
rdar://74890607
Differential revision: https://reviews.llvm.org/D122856
Rather than passing two booleans around, which is especially error prone
with them being next to each other, use a struct with named fields
instead.
Differential revision: https://reviews.llvm.org/D107295
This is an NFC modernization refactoring that replaces the combination
of a bool return + reference argument, with an Optional return value.
Differential Revision: https://reviews.llvm.org/D104405
The C headers are deprecated so as requested in D102845, this is replacing them
all with their (not deprecated) C++ equivalent.
Reviewed By: shafik
Differential Revision: https://reviews.llvm.org/D103084
Summary:
...and replace it with m_last_file_spec instead.
When Source Cache is enabled, the value stored in m_last_file_sp is
already in the Source Cache, and caching it again in SourceManager
brings no extra benefit. All we need is to "remember" the last used
file, and FileSpec can serve the same purpose.
When Source Cache is disabled, the user explicitly requested no caching
of source files, and therefore, m_last_file_sp should NOT be used.
Bug: llvm.org/PR45310
Depends on D76805.
Reviewers: labath, jingham
Reviewed By: jingham
Subscribers: labath, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D76806
Summary:
Lookup and subsequent insert was done using uninitialized
FileSpec object, which caused the cache to be a no-op.
Bug: llvm.org/PR45310
Depends on D76804.
Reviewers: labath, JDevlieghere
Reviewed By: labath
Subscribers: mgorny, jingham, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D76805
Summary:
LLDB memory-maps large source files, and at the same time, caches
all source files in the Source Cache.
On Windows, memory-mapped source files are not writeable, causing
bad user experience in IDEs (such as errors when saving edited files).
IDEs should have the ability to disable the Source Cache at LLDB
startup, so that users can edit source files while debugging.
Bug: llvm.org/PR45310
Reviewers: labath, JDevlieghere, jingham
Reviewed By: labath
Subscribers: lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D76804
Highlight the color marker similar to what we do for the column marker.
The default color matches the color of the current PC marker (->) in the
default disassembly format.
Differential revision: https://reviews.llvm.org/D75070
Summary:
All of our lookup APIs either use `CompilerDeclContext &` or `CompilerDeclContext *` semi-randomly it seems.
This leads to us constantly converting between those two types (and doing nullptr checks when going from
pointer to reference). It also leads to the confusing situation where we have two possible ways to express
that we don't have a CompilerDeclContex: either a nullptr or an invalid CompilerDeclContext (aka a default
constructed CompilerDeclContext).
This moves all APIs to use references and gets rid of all the nullptr checks and conversions.
Reviewers: labath, mib, shafik
Reviewed By: labath, shafik
Subscribers: shafik, arphaman, abidh, JDevlieghere, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D74607
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
Summary:
The FileSpec class is often used as a sort of a pattern -- one specifies
a bare file name to search, and we check if in matches the full file
name of an existing module (for example).
These comparisons used FileSpec::Equal, which had some support for it
(via the full=false argument), but it was not a good fit for this job.
For one, it did a symmetric comparison, which makes sense for a function
called "equal", but not for typical searches (when searching for
"/foo/bar.so", we don't want to find a module whose name is just
"bar.so"). This resulted in patterns like:
if (FileSpec::Equal(pattern, file, pattern.GetDirectory()))
which would request a "full" match only if the pattern really contained
a directory. This worked, but the intended behavior was very unobvious.
On top of that, a lot of the code wanted to handle the case of an
"empty" pattern, and treat it as matching everything. This resulted in
conditions like:
if (pattern && !FileSpec::Equal(pattern, file, pattern.GetDirectory())
which are nearly impossible to decipher.
This patch introduces a FileSpec::Match function, which does exactly
what most of FileSpec::Equal callers want, an asymmetric match between a
"pattern" FileSpec and a an actual FileSpec. Empty paterns match
everything, filename-only patterns match only the filename component.
I've tried to update all callers of FileSpec::Equal to use a simpler
interface. Those that hardcoded full=true have been changed to use
operator==. Those passing full=pattern.GetDirectory() have been changed
to use FileSpec::Match.
There was also a handful of places which hardcoded full=false. I've
changed these to use FileSpec::Match too. This is a slight change in
semantics, but it does not look like that was ever intended, and it was
more likely a result of a misunderstanding of the "proper" way to use
FileSpec::Equal.
[In an ideal world a "FileSpec" and a "FileSpec pattern" would be two
different types, but given how widespread FileSpec is, it is unlikely
we'll get there in one go. This at least provides a good starting point
by centralizing all matching behavior.]
Reviewers: teemperor, JDevlieghere, jdoerfert
Subscribers: emaste, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D70851
Summary:
CompileUnit is a complicated class. Having it be implicitly convertible
to a FileSpec makes reasoning about it even harder.
This patch replaces the inheritance by a simple member and an accessor
function. This avoid the need for casting in places where one needed to
force a CompileUnit to be treated as a FileSpec, and does not add much
verbosity elsewhere.
It also fixes a bug where we were wrongly comparing CompileUnit& and a
CompileUnit*, which compiled due to a combination of this inheritance
and the FileSpec*->FileSpec implicit constructor.
Reviewers: teemperor, JDevlieghere, jdoerfert
Subscribers: lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D70827
This patch removes the size_t return value and the append parameter
from the remainder of the Find.* functions in LLDB's internal API. As
in the previous patches, this is motivated by the fact that these
parameters aren't really used, and in the case of the append parameter
were frequently implemented incorrectly.
Differential Revision: https://reviews.llvm.org/D69119
llvm-svn: 375160
Summary:
NFC = [[ https://llvm.org/docs/Lexicon.html#nfc | Non functional change ]]
This commit is the result of modernizing the LLDB codebase by using
`nullptr` instread of `0` or `NULL`. See
https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html
for more information.
This is the command I ran and I to fix and format the code base:
```
run-clang-tidy.py \
-header-filter='.*' \
-checks='-*,modernize-use-nullptr' \
-fix ~/dev/llvm-project/lldb/.* \
-format \
-style LLVM \
-p ~/llvm-builds/debug-ninja-gcc
```
NOTE: There were also changes to `llvm/utils/unittest` but I did not
include them because I felt that maybe this library shall be updated in
isolation somehow.
NOTE: I know this is a rather large commit but it is a nobrainer in most
parts.
Reviewers: martong, espindola, shafik, #lldb, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: arsenm, jvesely, nhaehnle, hiraditya, JDevlieghere, teemperor, rnkovacs, emaste, kubamracek, nemanjai, ki.stfu, javed.absar, arichardson, kbarton, jrtc27, MaskRay, atanasyan, dexonsmith, arphaman, jfb, jsji, jdoerfert, lldb-commits, llvm-commits
Tags: #lldb, #llvm
Differential Revision: https://reviews.llvm.org/D61847
llvm-svn: 361484
A lot of comments in LLDB are surrounded by an ASCII line to delimit the
begging and end of the comment.
Its use is not really consistent across the code base, sometimes the
lines are longer, sometimes they are shorter and sometimes they are
omitted. Furthermore, it looks kind of weird with the 80 column limit,
where the comment actually extends past the line, but not by much.
Furthermore, when /// is used for Doxygen comments, it looks
particularly odd. And when // is used, it incorrectly gives the
impression that it's actually a Doxygen comment.
I assume these lines were added to improve distinguishing between
comments and code. However, given that todays editors and IDEs do a
great job at highlighting comments, I think it's worth to drop this for
the sake of consistency. The alternative is fixing all the
inconsistencies, which would create a lot more churn.
Differential revision: https://reviews.llvm.org/D60508
llvm-svn: 358135
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
This patch simplifies boolean expressions acorss LLDB. It was generated
using clang-tidy with the following command:
run-clang-tidy.py -checks='-*,readability-simplify-boolean-expr' -format -fix $PWD
Differential revision: https://reviews.llvm.org/D55584
llvm-svn: 349215
This patch removes the comments following the header includes. They were
added after running IWYU over the LLDB codebase. However they add little
value, are often outdates and burdensome to maintain.
Differential revision: https://reviews.llvm.org/D54385
llvm-svn: 346625
This moves construction of data buffers into the FileSystem class. Like
some of the previous refactorings we don't translate the path yet
because the functionality hasn't been landed in LLVM yet.
Differential revision: https://reviews.llvm.org/D54272
llvm-svn: 346598
This patch removes the Exists method from FileSpec and updates its uses
with calls to the FileSystem.
Differential revision: https://reviews.llvm.org/D53845
llvm-svn: 345854
This patch extends the FileSystem class with a bunch of functions that
are currently implemented as methods of the FileSpec class. These
methods will be removed in future commits and replaced by calls to the
file system.
The new functions are operated in terms of the virtual file system which
was recently moved from clang into LLVM so it could be reused in lldb.
Because the VFS is stateful, we turned the FileSystem class into a
singleton.
Differential revision: https://reviews.llvm.org/D53532
llvm-svn: 345783
When we get the `resolve_scope` parameter from the SB API, it's a
`uint32_t`. We then pass it through all of LLDB this way, as a uint32.
This is unfortunate, because it means the user of an API never actually
knows what they're dealing with. We can call it something like
`resolve_scope` and have comments saying "this is a value from the
`SymbolContextItem` enumeration, but it makes more sense to just have it
actually *be* the correct type in the actual C++ type system to begin
with. This way the person reading the code just knows what it is.
The reason to use integers instead of enumerations for flags is because
when you do bitwise operations on enumerations they get promoted to
integers, so it makes it tedious to constantly be casting them back
to the enumeration types, so I've introduced a macro to make this
happen magically. By writing LLDB_MARK_AS_BITMASK_ENUM after defining
an enumeration, it will define overloaded operators so that the
returned type will be the original enum. This should address all
the mechanical issues surrounding using rich enum types directly.
This way, we get a better debugger experience, and new users to
the codebase can get more easily acquainted with the codebase because
their IDE features can help them understand what the types mean.
Differential Revision: https://reviews.llvm.org/D53597
llvm-svn: 345313
Summary:
Similar to what we did in D50681, we now stop manually byte counting here
in the SourceManager.
Reviewers: #lldb, JDevlieghere
Reviewed By: #lldb, JDevlieghere
Subscribers: JDevlieghere, abidh, lldb-commits
Differential Revision: https://reviews.llvm.org/D50809
llvm-svn: 342121
Summary:
The syntax highlighting feature so far is mutually exclusive with the lldb feature
that marks the current column in the line by underlining it via an ANSI color code.
Meaning that if you enable one, the other is automatically disabled by LLDB.
This was caused by the fact that both features inserted color codes into the the
source code and were likely to interfere with each other (which would result
in a broken source code printout to the user).
This patch moves the cursor code into the highlighting framework, which provides
the same feature to the user in normal non-C source code. For any source code
that is highlighted by Clang, we now also have cursor marking for the whole token
that is under the current source location. E.g., before we underlined only the '!' in the
expression '1 != 2', but now the whole token '!=' is underlined. The same for function
calls and so on. Below you can see two examples where we before only underlined
the first character of the token, but now underline the whole token.
{F7075400}
{F7075414}
It also simplifies the DisplaySourceLines method in the SourceManager as most of
the code in there was essentially just for getting this column marker to work as
a FormatEntity.
Reviewers: aprantl
Reviewed By: aprantl
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D51466
llvm-svn: 341003
Summary:
This removes the manual byte counting mechanism from the syntax highlighting
code. This is no longer necessary as the Stream class now has built-in support for
automatically counting the bytes that were written to it so far.
The advantage of automatic byte counting via Stream is that it is less error-prone
than the manual version and we need to write less boilerplate code.
Reviewers: labath
Reviewed By: labath
Subscribers: labath, lldb-commits
Differential Revision: https://reviews.llvm.org/D50676
llvm-svn: 339695
Summary:
This patch adds syntax highlighting support to LLDB. When enabled (and lldb is allowed
to use colors), printed source code is annotated with the ANSI color escape sequences.
So far we have only one highlighter which is based on Clang and is responsible for all
languages that are supported by Clang. It essentially just runs the raw lexer over the input
and then surrounds the specific tokens with the configured escape sequences.
Reviewers: zturner, davide
Reviewed By: davide
Subscribers: labath, teemperor, llvm-commits, mgorny, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D49334
llvm-svn: 338662
This is intended as a clean up after the big clang-format commit
(r280751), which unfortunately resulted in many of the comment
paragraphs in LLDB being very hard to read.
FYI, the script I used was:
import textwrap
import commands
import os
import sys
import re
tmp = "%s.tmp"%sys.argv[1]
out = open(tmp, "w+")
with open(sys.argv[1], "r") as f:
header = ""
text = ""
comment = re.compile(r'^( *//) ([^ ].*)$')
special = re.compile(r'^((([A-Z]+[: ])|([0-9]+ )).*)|(.*;)$')
for line in f:
match = comment.match(line)
if match and not special.match(match.group(2)):
# skip intentionally short comments.
if not text and len(match.group(2)) < 40:
out.write(line)
continue
if text:
text += " " + match.group(2)
else:
header = match.group(1)
text = match.group(2)
continue
if text:
filled = textwrap.wrap(text, width=(78-len(header)),
break_long_words=False)
for l in filled:
out.write(header+" "+l+'\n')
text = ""
out.write(line)
os.rename(tmp, sys.argv[1])
Differential Revision: https://reviews.llvm.org/D46144
llvm-svn: 331197
This adjusts header file includes for headers and source files
in Core. In doing so, one dependency cycle is eliminated
because all the includes from Core to that project were dead
includes anyway. In places where some files in other projects
were only compiling due to a transitive include from another
header, fixups have been made so that those files also include
the header they need. Tested on Windows and Linux, and plan
to address failures on OSX and FreeBSD after watching the
bots.
llvm-svn: 299714
This functionality is subsumed by DataBufferLLVM, which is
also more efficient since it will try to mmap. However, we
don't yet support mmaping writable private sections, and in
some cases we were using ReadFileContents and then modifying
the buffer. To address that I've added a flag to the
DataBufferLLVM methods that allow you to map privately, which
disables the mmaping path entirely. Eventually we should teach
DataBufferLLVM to use mmap with writable private, but that is
orthogonal to this effort.
Differential Revision: https://reviews.llvm.org/D30622
llvm-svn: 297095
This moves the following classes from Core -> Utility.
ConstString
Error
RegularExpression
Stream
StreamString
The goal here is to get lldbUtility into a state where it has
no dependendencies except on itself and LLVM, so it can be the
starting point at which to start untangling LLDB's dependencies.
These are all low level and very widely used classes, and
previously lldbUtility had dependencies up to lldbCore in order
to use these classes. So moving then down to lldbUtility makes
sense from both the short term and long term perspective in
solving this problem.
Differential Revision: https://reviews.llvm.org/D29427
llvm-svn: 293941
