Calling conventions for C++ compilers and OS

Course overview

This practical, example-driven overview explains how calling conventions and ABI (application binary interface) details determine the runtime behavior of C++ programs and libraries. It connects language-level features—overloading, templates, function pointers—with machine-level realities such as register allocation, stack layout, return-value conventions, and symbol decoration. Emphasis is placed on reproducible experiments and annotated assembly so you can verify behavior across compilers and operating systems.

What you will learn

This material focuses on actionable knowledge that makes low-level C++ interactions predictable and maintainable. Outcomes include:

• How compilers encode type and linkage information into decorated symbol names and techniques for reading and demangling those names.
• Precise parameter-passing rules: which arguments go in registers, which go on the stack, and how aggregates and return values are actually handled.
• Compatibility and portability issues that arise when mixing compilers, runtimes, or OS ABIs, and strategies to design stable binary interfaces.
• How templates, overload resolution, and function-pointer semantics interact with calling conventions and symbol layout in real builds.
• Debugging and performance techniques to locate convention-related faults and optimize call-heavy code paths.

How the material is presented

The guide pairs concise conceptual explanations with minimal, reproducible code examples, compiler and linker commands, and annotated disassembly. Each topic includes short experiments you can run on popular toolchains to observe calling sequences, register moves, and symbol names. The intent is to teach interpretation of tool output so you can make informed engineering choices rather than rely on guesswork.

Target audience and difficulty

Category: systems programming, interoperability, and performance engineering. Difficulty: intermediate to advanced. It assumes familiarity with C++ syntax and basic toolchain usage, and is aimed at developers who want a deeper operational model of how language constructs map to CPU and OS behavior.

Who benefits most

• Application developers: better understand why certain language choices affect binary size, linkage, or runtime costs.
• Library and framework authors: learn techniques to create robust, portable ABIs and avoid subtle cross-compiler link failures.
• Systems programmers and performance engineers: apply ABI knowledge to tune hot paths, design stable plugin interfaces, and debug low-level crashes.

Practical applications

Knowledge of calling conventions helps you stabilize plugin boundaries and foreign-function interfaces (for example, when using extern "C"), diagnose symbol mismatches, and choose argument-passing patterns that reduce overhead. The guide clarifies when by-value passing becomes costly and when compiler/ABI choices will measurably affect performance.

Hands-on exercises and project ideas

• Compare compiler outputs for identical functions compiled with different compilers and optimization levels to observe register allocation and stack-frame differences.
• Create stable wrappers using extern "C" and test cross-compiler linkage in small mixed-toolchain projects.
• Benchmark alternatives for passing large aggregates (by value, by const reference, by pointer) to quantify platform-specific trade-offs.

Common pitfalls and expert tips

Be vigilant for mismatches between caller and callee conventions and for subtle name-mangling differences when mixing toolchains. Practical tips: document any public ABI you expose, routinely inspect symbol tables and assembler when diagnosing linkage issues, and measure before applying calling-convention micro-optimizations.

Next steps

Use the guide as a laboratory: read concise theory, run the provided experiments, and adapt examples to your compilers and target platforms. That iterative workflow builds confidence diagnosing ABI issues and applying calling-convention insights to production code.

Why this is worth your time

Understanding the mapping from C++ constructs to machine-level calling behavior reduces surprises when linking binaries, improves interoperability across toolchains, and uncovers realistic opportunities for performance improvement. If your work touches cross-compiler linking, low-level debugging, or performance tuning, the focused, reproducible examples in this overview will accelerate your ability to troubleshoot and design stable interfaces.