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Doc: Clean up New/Delete Builtins manual section

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I noticed that the "New/Delete Builtins" section failed to explicitly
name or describe the arguments of the builtin functions it purported
to document, outside of using them in an example.  I've fixed that
and cleaned up the whole section.

gcc/ChangeLog
	* doc/extend.texi (New/Delete Builtins): Cleanup up the text and
	explicitly list the builtins being documented.
This commit is contained in:
Sandra Loosemore 2025-03-26 18:25:51 +00:00
parent 7af7e80d85
commit 37f35ebc7c
1 changed files with 29 additions and 12 deletions
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gcc/doc/extend.texi
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@ -16985,18 +16985,20 @@ is called and the @var{flag} argument passed to it.
@node New/Delete Builtins
@section Built-in functions for C++ allocations and deallocations
@findex __builtin_operator_new
@findex __builtin_operator_delete
Calling these C++ built-in functions is similar to calling
@code{::operator new} or @code{::operator delete} with the same arguments,
except that it is an error if the selected @code{::operator new} or
@code{::operator delete} overload is not a replaceable global operator
and for optimization purposes calls to pairs of these functions can be
omitted if access to the allocation is optimized out, or could be replaced
with implementation provided buffer on the stack, or multiple allocation
calls can be merged into a single allocation. In C++ such optimizations
are normally allowed just for calls to such replaceable global operators
from @code{new} and @code{delete} expressions.
@cindex builtins for C++ @code{new} and @code{delete} operators
@cindex @code{new} and @code{delete} builtins
GNU C++ provides builtins that are equivalent to calling
@code{::operator new} or @code{::operator delete} with the same arguments.
It is an error if the selected @code{::operator new} or
@code{::operator delete} overload is not a replaceable global operator.
For optimization purposes, calls to pairs of these
builtins can be omitted if access to the allocation is optimized out,
or could be replaced with an implementation-provided buffer on the stack,
or multiple allocation calls can be merged into a single allocation.
In C++ such optimizations are normally allowed just for calls to such
replaceable global operators from @code{new} and @code{delete}
expressions.
@smallexample
void foo () @{
@ -17010,6 +17012,21 @@ void foo () @{
@}
@end smallexample
These built-ins are only available in C++.
@defbuiltin{{void *} __builtin_operator_new (std::size_t @var{size}, ...)}
This is the built-in form of @code{operator new}. It accepts the same
argument forms as a ``usual allocation function'', as described in the
C++ standard.
@enddefbuiltin
@defbuiltin{void __builtin_operator_delete (void * @var{ptr}, ...)}
This is the built-in form of @code{operator delete}. It accepts the same
argument forms as a ``usual deallocation function'', as described in the
C++ standard.
@enddefbuiltin
@node Other Builtins
@section Other Built-in Functions Provided by GCC