https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86488
Bug ID: 86488
Summary: malloc attribute when pointer is returned as part of a
struct
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gonzalobg88 at gmail dot com
Target Milestone: ---
I am trying to implementing P0901r0 [0] in jemalloc. The signature of the new
memory allocation function looks like this:
typedef struct {
void *ptr;
size_t usize;
} smallocx_return_t;
smallocx_return_t je_smallocx(size_t size, int flags);
I'd like to set the "malloc" [1] attribute for this function but AFAICT this is
not currently possible for this new function because the pointer
smallocx_return_t::ptr is part of a struct.
[0]: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0901r0.html
[1]: From https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
> malloc
> This tells the compiler that a function is malloc-like, i.e., that the
> pointer P
> returned by the function cannot alias any other pointer valid when the
> function
> returns, and moreover no pointers to valid objects occur in any storage
> addressed by P.
>
> Using this attribute can improve optimization. Functions like malloc and
> calloc
> have this property because they return a pointer to uninitialized or
> zeroed-out
> storage. However, functions like realloc do not have this property, as they
> can
> return a pointer to storage containing pointers.
