5ab9fa44cd
Summary: LLDB associates additional information with Types and Declarations which it calls ClangASTMetadata. ClangASTMetadata is stored by the ClangASTSourceCommon which is implemented by having a large map of `void *` keys to associated `ClangASTMetadata` values. To make this whole mechanism even unsafer we also decided to use `clang::Decl *` as one of pointers we throw in there (beside `clang::Type *`). The Decl class hierarchy uses multiple inheritance which means that not all pointers have the same address when they are implicitly converted to pointers of their parent classes. For example `clang::Decl *` and `clang::DeclContext *` won't end up being the same address when they are implicitly converted from one of the many Decl-subclasses that inherit from both. As we use the addresses as the keys in our Metadata map, this means that any implicit type conversions to parent classes (or anything else that changes the addresses) will break our metadata tracking in obscure ways. Just to illustrate how broken this whole mechanism currently is: ```lang=cpp // m_ast is our ClangASTContext. Let's double check that from GetTranslationUnitDecl // in ClangASTContext and ASTContext return the same thing (one method just calls the other). assert(m_ast->GetTranslationUnitDecl() == m_ast->getASTContext()->getTranslationUnitDecl()); // Ok, both methods have the same TU*. Let's store metadata with the result of one method call. m_ast->SetMetadataAsUserID(m_ast->GetTranslationUnitDecl(), 1234U); // Retrieve the same Metadata for the TU by using the TU* from the other method... which fails? EXPECT_EQ(m_ast->GetMetadata(m_ast->getASTContext()->getTranslationUnitDecl())->GetUserID(), 1234U); // Turns out that getTranslationUnitDecl one time returns a TranslationUnitDecl* but the other time // we return one of the parent classes of TranslationUnitDecl (DeclContext). ``` This patch splits up the `void *` API into two where one does the `clang::Type *` tracking and one the `clang::Decl *` mapping. Type and Decl are disjoint class hierarchies so there is no implicit conversion possible that could influence the address values. I had to change the storing of `clang::QualType` opaque pointers to their `clang::Type *` equivalents as opaque pointers are already `void *` pointers to begin with. We don't seem to ever set any qualifier in any of these QualTypes to this conversion should be NFC. Reviewers: labath, shafik, aprantl Reviewed By: labath Subscribers: JDevlieghere, lldb-commits Tags: #lldb Differential Revision: https://reviews.llvm.org/D71409
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.
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 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.