47e7ecdd7d
Right now we have one large AST for all types in LLDB. All ODR violations in types we reconstruct are resolved by just letting the ASTImporter handle the conflicts (either by merging types or somehow trying to introduce a duplicated declaration in the AST). This works ok for the normal types we build from debug information as most of them are just simple CXXRecordDecls or empty template declarations. However, with a loaded `std` C++ module we have alternative versions of pretty much all declarations in the `std` namespace that are much more fleshed out than the debug information declarations. They have all the information that is lost when converting to DWARF, such as default arguments, template default arguments, the actual uninstantiated template declarations and so on. When we merge these C++ module types into the big scratch AST (that might already contain debug information types) we give the ASTImporter the tricky task of somehow creating a consistent AST out of all these declarations. Usually this ends in a messy AST that contains a mostly broken mix of both module and debug info declarations. The ASTImporter in LLDB is also importing types with the MinimalImport setting, which usually means the only information we have when merging two types is often just the name of the declaration and the information that it contains some child declarations. This makes it pretty much impossible to even implement a better merging logic (as the names of C++ module declarations and debug info declarations are identical). This patch works around this whole merging problem by separating C++ module types from debug information types. This is done by splitting up the single scratch AST into two: One default AST for debug information and a dedicated AST for C++ module types. The C++ module AST is implemented as a 'specialised AST' that lives within the default ScratchTypeSystemClang. When we select the scratch AST we can explicitly request that we want such a isolated sub-AST of the scratch AST. I kept the infrastructure more general as we probably can use the same mechanism for other features that introduce conflicting types (such as programs that are compiled with a custom -wchar-size= option). There are just two places where we explicitly have request the C++ module AST: When we export persistent declarations (`$mytype`) and when we create our persistent result variable (`$0`, `$1`, ...). There are a few formatters that were previously assuming that there is only one scratch AST which I cleaned up in a preparation revision here (D92757). Reviewed By: aprantl Differential Revision: https://reviews.llvm.org/D92759 |
||
|---|---|---|
| .github/workflows | ||
| clang | ||
| clang-tools-extra | ||
| compiler-rt | ||
| debuginfo-tests | ||
| flang | ||
| libc | ||
| libclc | ||
| libcxx | ||
| libcxxabi | ||
| libunwind | ||
| lld | ||
| lldb | ||
| llvm | ||
| mlir | ||
| openmp | ||
| parallel-libs | ||
| polly | ||
| pstl | ||
| utils/arcanist | ||
| .arcconfig | ||
| .arclint | ||
| .clang-format | ||
| .clang-tidy | ||
| .git-blame-ignore-revs | ||
| .gitignore | ||
| CONTRIBUTING.md | ||
| README.md | ||
README.md
The LLVM Compiler Infrastructure
This directory and its sub-directories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The README briefly describes how to get started with building LLVM. For more information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
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 work-flow and configuration to get and build the LLVM source:
-
Checkout LLVM (including related sub-projects like Clang):
-
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
-
-
Configure and build LLVM and Clang:
-
cd llvm-project -
mkdir build -
cd build -
cmake -G <generator> [options] ../llvmSome common build system 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:
-
-DLLVM_ENABLE_PROJECTS='...'--- semicolon-separated list of the LLVM sub-projects 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 path name 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).
-
cmake --build . [-- [options] <target>]or your build system specified above directly.-
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 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, use the option-j NNN, whereNNNis the number of parallel jobs, e.g. the number of CPUs you have.
-
-
For more information see CMake
-
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.