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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114421] arm-none-eabi thumb -Os (and -O2) incorrectly
 optimizes out needed class member call
Date: Thu, 21 Mar 2024 21:46:56 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114421

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
https://en.cppreference.com/w/cpp/language/memory_model#Forward_progress is=
 a
decent reference when it comes to what it means by forward progress in C++.
Note C and C++ have slightly different requirements. And C++17 has different
from previous versions of C++ also.




(In reply to Xi Ruoyao from comment #3)
> In C++ there is no "the controlling expression is a constant expression"
> exempt, so even while (true); can be optimized out.  AFAIK GCC does not
> optimize away while (true); in C++, but Clang is actively doing this.  Th=
ere
> is a WG21 paper to add the constant expression exemption for C++ like C (I
> cannot remember its Nxxxx ID though).

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2809r0.html is the
paper about C++'s `while(true);`=