Contributing to LLVM

Map the phases of a traditional compiler (frontend, optimizer, backend) to the components of the LLVM ecosystem (e.g., Clang, opt, llc).

Explain the three-phase design of the LLVM compiler infrastructure and its benefits.

Identify the core libraries, subprojects (Clang, LLDB, MLIR), and tools within the LLVM project ecosystem.

Set up, build, and configure the LLVM monolith from source using CMake and Ninja.

Compile and run LLVM tools with AddressSanitizer (ASan) to diagnose memory bugs.

Explain the concept and benefits of Static Single Assignment (SSA) form.

Read and interpret basic LLVM IR syntax for functions, basic blocks, and instructions.

Identify the primitive and derived data types in LLVM IR.

Trace control flow in LLVM IR using branch and phi instructions.

Explain the role and syntax of metadata in LLVM IR, focusing on debug information.

Describe the purpose of intrinsic functions and identify common categories.

Search and filter the LLVM GitHub issues for subprojects like Clang, LLDB, and MLIR.

Navigate the LLVM source tree directory structure to locate core components (include, lib, tools, test).

Run the LLVM regression test suite using the llvm-lit testing tool.

Write a pattern-matching test case using the FileCheck utility.

Extract a minimal reproducible C++ or IR example from a complex bug report.

Use the llvm-reduce tool to automatically minimize an LLVM IR test case.

Use git bisect to identify the commit that introduced a regression.

Prepare and submit a pull request to the LLVM project following their GitHub code review workflow.

Identify the distinct roles of the Lexer, Preprocessor, Parser, and Sema in Clang.

Explain the logical structure and hierarchy of the Clang Abstract Syntax Tree (AST).

Use clang -Xclang -ast-dump to inspect the AST of a C/C++ program.

Describe the general flow of how Clang's Parser and Sema cooperate to build AST nodes.

Explain the role of Clang's DiagnosticsEngine in reporting compiler errors.

Set up a debug build of Clang and use a debugger (GDB/LLDB) to set a breakpoint in Clang's C++ parsing logic.

Step through the parsing of a simple expression in the debugger to observe the creation of the corresponding AST node.