2016-02-10 07:45:21 +08:00
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add_lldb_unittest(LLDBCoreTests
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Fix a race in Broadcaster/Listener interaction
Summary:
The following problem was occuring:
- broadcaster B had two listeners: L1 and L2 (thread T1)
- (T1) B has started to broadcast an event, it has locked a shared_ptr to L1 (in
ListenerIterator())
- on another thread T2 the penultimate reference to L1 was destroyed (the transient object in B is
now the last reference)
- (T2) the last reference to L2 was destroyed as well
- (T1) B has finished broadcasting the event to L1 and destroyed the last shared_ptr
- (T1) this triggered the destructor, which called into B->RemoveListener()
- (T1) all pointers in the m_listeners list were now stale, so RemoveListener emptied the list
- (T1) Eventually control returned to the ListenerIterator() for doing broadcasting, which was
still in the middle of iterating through the list
- (T1) Only now, it was holding onto a dangling iterator. BOOM.
I fix this issue by making sure nothing can interfere with the
iterate-and-remove-expired-pointers loop, by moving this logic into a single function, which
first locks (or clears) the whole list and then returns the list of valid and locked Listeners
for further processing. Instead of std::list I use an llvm::SmallVector which should hopefully
offset the fact that we create a copy of the list for the common case where we have only a few
listeners (no heap allocations).
A slight difference in behaviour is that now RemoveListener does not remove an element from the
list -- it only sets it's mask to 0, which means it will be removed during the next iteration of
GetListeners(). This is purely an implementation detail and it should not be externally
noticable.
I was not able to reproduce this bug reliably without inserting sleep statements into the code,
so I do not add a test for it. Instead, I add some unit tests for the functions that I do modify.
Reviewers: clayborg, jingham
Subscribers: tberghammer, lldb-commits
Differential Revision: https://reviews.llvm.org/D23406
llvm-svn: 278664
2016-08-15 17:53:08 +08:00
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BroadcasterTest.cpp
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Handle bit fields on big-endian systems correctly
Currently, the DataExtractor::GetMaxU64Bitfield and GetMaxS64Bitfield
routines assume the incoming "bitfield_bit_offset" parameter uses
little-endian bit numbering, i.e. a bitfield_bit_offset 0 refers to
a bitfield whose least-significant bit coincides with the least-
significant bit of the surrounding integer.
On many big-endian systems, however, the big-endian bit numbering
is used for bit fields. Here, a bitfield_bit_offset 0 refers to
a bitfield whose most-significant bit conincides with the most-
significant bit of the surrounding integer.
Now, in principle LLDB could arbitrarily choose which semantics of
bitfield_bit_offset to use. However, there are two problems with
the current approach:
- When parsing DWARF, LLDB decodes bit offsets in little-endian
bit numbering on LE systems, but in big-endian bit numbering
on BE systems. Passing those offsets later on into the
DataExtractor routines gives incorrect results on BE.
- In the interim, LLDB's type layer combines byte and bit offsets
into a single number. I.e. instead of recording bitfields by
specifying the byte offset and byte size of the surrounding
integer *plus* the bit offset of the bit field within that field,
it simply records a single bit offset number.
Now, note that converting from byte offset + bit offset to a
single offset value and back is well-defined if we either use
little-endian byte order *and* little-endian bit numbering,
or use big-endian byte order *and* big-endian bit numbering.
Any other combination will yield incorrect results.
Therefore, the simplest approach would seem to be to always use
the bit numbering that matches the system byte order. This makes
storing a single bit offset valid, and makes the existing DWARF
code correct. The only place to fix is to teach DataExtractor
to use big-endian bit numbering on big endian systems.
However, there is only additional caveat: we also get bit offsets
from LLDB synthetic bitfields. While the exact semantics of those
doesn't seem to be well-defined, from test cases it appears that
the intent was for the user-provided synthetic bitfield offset to
always use little-endian bit numbering. Therefore, on a big-endian
system we now have to convert those to big-endian bit numbering
to remain consistent.
Differential Revision: http://reviews.llvm.org/D18982
llvm-svn: 266312
2016-04-14 22:32:57 +08:00
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DataExtractorTest.cpp
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2018-07-24 18:49:14 +08:00
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EventTest.cpp
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2016-11-25 01:10:10 +08:00
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ListenerTest.cpp
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Use LLVM's new ItaniumPartialDemangler in LLDB
Summary:
Replace the existing combination of FastDemangle and the fallback to llvm::itaniumDemangle() with LLVM's new ItaniumPartialDemangler. It slightly reduces complexity and slightly improves performance, but doesn't introduce conceptual changes. This patch is preparing for more fundamental improvements on LLDB's demangling approach.
Reviewers: friss, jingham, erik.pilkington, labath, clayborg, mgorny, davide, JDevlieghere
Reviewed By: JDevlieghere
Subscribers: teemperor, JDevlieghere, labath, clayborg, davide, lldb-commits, mgorny, erik.pilkington
Differential Revision: https://reviews.llvm.org/D49612
llvm-svn: 337931
2018-07-25 23:19:04 +08:00
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MangledTest.cpp
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Use rich mangling information in Symtab::InitNameIndexes()
Summary:
I set up a new review, because not all the code I touched was marked as a change in old one anymore.
In preparation for this review, there were two earlier ones:
* https://reviews.llvm.org/D49612 introduced the ItaniumPartialDemangler to LLDB demangling without conceptual changes
* https://reviews.llvm.org/D49909 added a unit test that covers all relevant code paths in the InitNameIndexes() function
Primary goals for this patch are:
(1) Use ItaniumPartialDemangler's rich mangling info for building LLDB's name index.
(2) Provide a uniform interface.
(3) Improve indexing performance.
The central implementation in this patch is our new function for explicit demangling:
```
const RichManglingInfo *
Mangled::DemangleWithRichManglingInfo(RichManglingContext &, SkipMangledNameFn *)
```
It takes a context object and a filter function and provides read-only access to the rich mangling info on success, or otherwise returns null. The two new classes are:
* `RichManglingInfo` offers a uniform interface to query symbol properties like `getFunctionDeclContextName()` or `isCtorOrDtor()` that are forwarded to the respective provider internally (`llvm::ItaniumPartialDemangler` or `lldb_private::CPlusPlusLanguage::MethodName`).
* `RichManglingContext` works a bit like `LLVMContext`, it the actual `RichManglingInfo` returned from `DemangleWithRichManglingInfo()` and handles lifetime and configuration. It is likely stack-allocated and can be reused for multiple queries during batch processing.
The idea here is that `DemangleWithRichManglingInfo()` acts like a gate keeper. It only provides access to `RichManglingInfo` on success, which in turn avoids the need to handle a `NoInfo` state in every single one of its getters. Having it stored within the context, avoids extra heap allocations and aids (3). As instantiations of the IPD the are considered expensive, the context is the ideal place to store it too. An efficient filtering function `SkipMangledNameFn` is another piece in the performance puzzle and it helps to mimic the original behavior of `InitNameIndexes`.
Future potential:
* `DemangleWithRichManglingInfo()` is thread-safe, IFF using different contexts in different threads. This may be exploited in the future. (It's another thing that it has in common with `LLVMContext`.)
* The old implementation only parsed and indexed Itanium mangled names. The new `RichManglingInfo` can be extended for various mangling schemes and languages.
One problem with the implementation of RichManglingInfo is the inaccessibility of class `CPlusPlusLanguage::MethodName` (defined in source/Plugins/Language/..), from within any header in the Core components of LLDB. The rather hacky solution is to store a type erased reference and cast it to the correct type on access in the cpp - see `RichManglingInfo::get<ParserT>()`. At the moment there seems to be no better way to do it. IMHO `CPlusPlusLanguage::MethodName` should be a top-level class in order to enable forward delcarations (but that is a rather big change I guess).
First simple profiling shows a good speedup. `target create clang` now takes 0.64s on average. Before the change I observed runtimes between 0.76s an 1.01s. This is still no bulletproof data (I only ran it on one machine!), but it's a promising indicator I think.
Reviewers: labath, jingham, JDevlieghere, erik.pilkington
Subscribers: zturner, clayborg, mgorny, lldb-commits
Differential Revision: https://reviews.llvm.org/D50071
llvm-svn: 339291
2018-08-09 05:57:37 +08:00
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RichManglingContextTest.cpp
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2017-02-10 19:49:21 +08:00
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StreamCallbackTest.cpp
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2017-02-02 06:17:00 +08:00
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LINK_LIBS
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lldbCore
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lldbHost
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2018-08-02 18:13:18 +08:00
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lldbSymbol
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lldbPluginObjectFileELF
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lldbPluginSymbolVendorELF
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lldbUtilityHelpers
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2017-02-02 06:17:00 +08:00
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LINK_COMPONENTS
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Support
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2016-02-10 01:28:01 +08:00
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)
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2018-08-02 18:13:18 +08:00
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add_dependencies(LLDBCoreTests yaml2obj)
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add_definitions(-DYAML2OBJ="$<TARGET_FILE:yaml2obj>")
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set(test_inputs
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mangled-function-names.yaml
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)
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add_unittest_inputs(LLDBCoreTests "${test_inputs}")
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