[Bug tree-optimization/66512] PRE fails to optimize calls to pure functions in C++, ok in C

[i at maskray dot me via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66512

Fangrui Song <i at maskray dot me> changed:

           What    |Removed                     |Added
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                 CC|                            |i at maskray dot me

--- Comment #4 from Fangrui Song <i at maskray dot me> ---
Should this be reopened?

https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html 'const' is
not clarified on its interaction with threads
(https://gcc.gnu.org/legacy-ml/gcc/2015-09/msg00365.html)

and 

void f()
{
  for (;;)
    g(p());
}

is still pessimized for C++ (I tend to agree that 'const' should imply
'nothrow'; even if no, the #c2 case should be resolved properly)