7644d8ba4d
Fix handling concurrent watchpoint events so that they are reported
correctly in LLDB.
If multiple watchpoints are hit concurrently, the NetBSD kernel reports
them as series of SIGTRAPs with a thread specified, and the debugger
investigates DR6 in order to establish which watchpoint was hit. This
is normally fine.
However, LLDB disables and reenables the watchpoint on all threads after
each hit, which results in the hit status from DR6 being wiped.
As a result, it can't establish which watchpoint was hit in successive
SIGTRAP processing.
In order to workaround this problem, clear DR6 only if the breakpoint
is overwritten with a new one. More specifically, move cleaning DR6
from ClearHardwareWatchpoint() to SetHardwareWatchpointWithIndex(),
and do that only if the newly requested watchpoint is different
from the one being set previously. This ensures that the disable-enable
logic of LLDB does not clear watchpoint hit status for the remaining
threads.
This also involves refactoring of watchpoint logic. With the old logic,
clearing watchpoint involved wiping dr6 & dr7, and setting it setting
dr{0..3} & dr7. With the new logic, only enable bit is cleared
from dr7, and the remaining bits are cleared/overwritten while setting
new watchpoint.
Differential Revision: https://reviews.llvm.org/D70025
The LLVM Compiler Infrastructure
This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments.
Getting Started with the LLVM System
Taken from https://llvm.org/docs/GettingStarted.html.
Overview
Welcome to the LLVM project!
The LLVM project has multiple components. The core of the project is itself called "LLVM". This contains all of the tools, libraries, and header files needed to process intermediate representations and converts it into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer. It also contains basic regression tests.
C-like languages use the Clang front end. This component compiles C, C++, Objective C, and Objective C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
Getting the Source Code and Building LLVM
The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.
This is an example workflow and configuration to get and build the LLVM source:
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Checkout LLVM (including related subprojects like Clang):
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git clone https://github.com/llvm/llvm-project.git -
Or, on windows,
git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git
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Configure and build LLVM and Clang:
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cd llvm-project -
mkdir build -
cd build -
cmake -G <generator> [options] ../llvmSome common generators are:
Ninja--- for generating Ninja build files. Most llvm developers use Ninja.Unix Makefiles--- for generating make-compatible parallel makefiles.Visual Studio--- for generating Visual Studio projects and solutions.Xcode--- for generating Xcode projects.
Some Common options:
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-DLLVM_ENABLE_PROJECTS='...'--- semicolon-separated list of the LLVM subprojects you'd like to additionally build. Can include any of: clang, clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld, polly, or debuginfo-tests.For example, to build LLVM, Clang, libcxx, and libcxxabi, use
-DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi". -
-DCMAKE_INSTALL_PREFIX=directory--- Specify for directory the full pathname of where you want the LLVM tools and libraries to be installed (default/usr/local). -
-DCMAKE_BUILD_TYPE=type--- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug. -
-DLLVM_ENABLE_ASSERTIONS=On--- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).
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Run your build tool of choice!
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The default target (i.e.
ninjaormake) will build all of LLVM. -
The
check-alltarget (i.e.ninja check-all) will run the regression tests to ensure everything is in working order. -
CMake will generate build targets for each tool and library, and most LLVM sub-projects generate their own
check-<project>target. -
Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for
make, usemake -j NNN(NNN is the number of parallel jobs, use e.g. number of CPUs you have.)
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For more information see CMake
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Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.