Summary:
When we want to compare a ConstString against a string literal (or any other non-ConstString),
we currently have to explicitly turn the other string into a ConstString. This makes sense as
comparing ConstStrings against each other is only a fast pointer comparison.
However, currently we (rather incorrectly) use in several places in LLDB temporary ConstStrings when
we just want to compare a given ConstString against a hardcoded value, for example like this:
```
if (extension != ConstString(".oat") && extension != ConstString(".odex"))
```
Obviously this kind of defeats the point of ConstStrings. In the comparison above we would
construct two temporary ConstStrings every time we hit the given code. Constructing a
ConstString is relatively expensive: we need to go to the StringPool, take a read and possibly
an exclusive write-lock and then look up our temporary string in the string map of the pool.
So we do a lot of heavy work for essentially just comparing a <6 characters in two strings.
I initially wanted to just fix these issues by turning the temporary ConstString in static variables/
members, but that made the code much less readable. Instead I propose to add a new overload
for the ConstString comparison operator that takes a StringRef. This comparison operator directly
compares the ConstString content against the given StringRef without turning the StringRef into
a ConstString.
This means that the example above can look like this now:
```
if (extension != ".oat" && extension != ".odex")
```
It also no longer has to unlock/lock two locks and call multiple functions in other TUs for constructing
the temporary ConstString instances. Instead this should end up just being a direct string comparison
of the two given strings on most compilers.
This patch also directly updates all uses of temporary and short ConstStrings in LLDB to use this new
comparison operator. It also adds a some unit tests for the new and old comparison operator.
Reviewers: #lldb, JDevlieghere, espindola, amccarth
Reviewed By: JDevlieghere, amccarth
Subscribers: amccarth, clayborg, JDevlieghere, emaste, arichardson, MaskRay, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D60667
llvm-svn: 359281
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
Summary:
This issue came up because it caused problems in our unit tests. The StringPool did connect counterparts only once and silently ignored the values passed in subsequent calls.
The simplest solution for the unit tests would be silent overwrite. In practice, however, it seems useful to assert that we never overwrite a different mangled counterpart.
If we ever have mangled counterparts for other languages than C++, this makes it more likely to notice collisions.
I added an assertion that allows the following cases:
* inserting a new value
* overwriting the empty string
* overwriting with an identical value
I fixed the unit tests, which used "random" strings and thus produced collisions.
It would be even better if there was a way to reset or isolate the StringPool, but that's a different story.
Reviewers: jingham, friss, labath
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D50536
llvm-svn: 339669
Summary: It was not immediately clear to me whether or not non-null-terminated StringRef's are supported in ConstString and/or the counterpart mechanism. From this test it seems to be fine. Maybe useful to keep?
Reviewers: labath
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D50334
llvm-svn: 339292
Summary: `IsEmpty()` and `operator bool() == false` have equal semantics. Usage in Mangled::GetDemangledName() was incorrect. What it actually wants is a check for null-string. Split this off of D50071 and added a test to clarify usage.
Reviewers: labath, jingham
Subscribers: erik.pilkington, lldb-commits
Differential Revision: https://reviews.llvm.org/D50327
llvm-svn: 339014
Summary:
Per discussion in D28616, having two ways two request logging (log
enable lldb XXX verbose && log enable -v lldb XXX) is confusing. This
removes the first option and standardizes all code to use the second
one.
I've added a LLDB_LOGV macro as a shorthand for if(log &&
log->GetVerbose()) and switched most of the affected log statements to
use that (I've only left a couple of cases that were doing complex
computations in an if(log) block).
Reviewers: jingham, zturner
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D29510
llvm-svn: 294113
Raphael Isemann