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Stack allocation

Class stack_allocator

A coroutine uses internally a context which manages a set of registers and a stack. The memory used by the stack is allocated/deallocated via a stack-allocator which is required to model a stack-allocator concept.

stack-allocator concept

A stack-allocator must satisfy the stack-allocator concept requirements shown in the following table, in which a is an object of a stack-allocator type, p is a void *, and s is a std::size_t:


return type


a.allocate( s)

void *

returns a pointer to s bytes allocated from the stack

a.deallocate( p, s)


deallocates s bytes of memory beginning at p, a pointer previously returned by a.allocate()

[Important] Important

The implementation of allocate() might include logic to protect against exceeding the context's available stack size rather than leaving it as undefined behaviour.

[Important] Important

Calling deallocate() with a pointer not returned by allocate() results in undefined behaviour.

[Note] Note

The stack is not required to be aligned; alignment takes place inside coroutine.

[Note] Note

Depending on the architecture allocate() returns an address from the top of the stack (growing downwards) or the bottom of the stack (growing upwards).