Insights on GCC Optimizations based on Object Lifecycle

Insights on GCC Optimizations based on Object Lifecycle

[Ισίδωρος Τσαούσης]

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Dear GCC Developer Team,

I hope this message finds you well. I am preparing a talk on Lifetime
Management and I am reaching out to you as the foremost experts on the
subject. Specifically I would like to inquire about GCC's utilization of
the C++ object lifecycle in applying optimizations.

The goal of my talk is to emphasize that it's undefined behavior to cast
raw data to C++ objects and interact with them before their lifetimes have
begun. I intend to dispel the common misconception of C++ as merely
'higher-level assembly.' I want to demonstrate how the high-level object
model provides the compiler with the liberty to perform certain
optimizations and simplifications.

This becomes more important as compilers employ increasingly sophisticated
optimizations, and I would love to get the word out about them. Your
insights would undoubtedly add significant depth and precision to my
discussion. If you could spare some time, I would like to understand:

a. What are some notable optimizations that GCC can implement due to the
well-defined nature of the C++ object lifecycle?

b. Can you share specific instances where violation of object lifecycle
rules may lead to unexpected behavior or faulty program execution,
resulting from the assumptions made by the GCC compiler?

c. Can you share specific instances where violation of object lifecycle
rules may deprive GCC from performing optimizations?

Your insights on these matters will not only significantly enrich my
discussion, but also offer invaluable and otherwise unknown guidance to our
community of developers. Moreover, your team and contributions will be duly
acknowledged during the presentation.

I understand how busy you must be, and I genuinely appreciate any time and
consideration you can afford to this request.

Hoping to hear from you soon,

Isidoros Tsaousis-Seiras

Github: https://github.com/isidorostsa