Re: HELP: Will the reordering happen? Re: [V3][PATCH 0/3] New attribute "counted_by" to annotate bounds for C99 FAM(PR108896)

[Siddhesh Poyarekar]

On 2023-10-24 16:30, Qing Zhao wrote:
Situation 2: With O0, the routine “get_size_from” was NOT inlined into “foo”, 
therefore, the call to __bdos is Not in the same routine as the instantiation 
of the object, As a result, the TYPE info and the attached counted_by info of 
the object can NOT be USED by the __bdos call.

But __bos/__bdos are barely useful without optimization; you need a 
minimum of -O1.  You're right that if the call is never inlined then we 
don't care because the __bdos call does not get expanded to obj->size.

However, the point of situation 2 is that the TYPE info cannot be used 
by the __bdos call *only for a while* (i.e. until the call gets inlined) 
and that window is an opportunity for the reordering/DSE to break things.

Thanks.
Sid