[LLVMdev] Status of YAML IO?
shankare at codeaurora.org
Wed Oct 31 19:46:44 PDT 2012
>> The range of flags would be integers ranging from LOW_PROC .. HIGH_PROC.
>> The Generic flags would be within the range less than LOW_PROC and greater HIGH_PROC. Any value within the range LOW_PROC .. HIGH_PROC is os/platform specific.
>> What I was thinking was there could be a uint32_t flags() in the definedAtom which returns the flags, and platforms can act accordingly on the meaning of the flags in their pieces of code.
>> What do you think ?
> You still have not given an example of what information is missing in the current Atom model that is driving the need for this.
> It sounds like your flags() returns a value - not a set of bits. Which means it can only be used for one thing. What if you need two or more kinds of information/attributes not in the Atom model? I don't see why LOW_PROC, HIGH_PROC is needed. If we decide there are new kinds of information/attributes that are general we would just define new methods on Atom, rather than define a value to be returned by flags().
There are two usecases that I can think of now :-
1) flags :- These are used to determine what the Atom contains in
addition to the content, could be that the Atom has
a) follow on reference
b) atom is part of a group, where other atoms are part of
The flags could be used to determine if there is a follow up atom or if
the atom is part of a group.
Both of them would be useful than iterating through the reference list
and iterating it and figuring out if there is a follow on reference /
atom being part of a group.
2) Atom specific content types
This is where the LOW_PROC, and HIGH_PROC comes in, there are content
types which are architecture specific.
Currently there are many types defined within contentType which are
operating system specific. As more environments start using lld, I feel
that many architectures would want to add.
Example for GNU support would include
c) gnu prelink library list
I believe both of them would be solvable, by using a 64bit unsigned
integer, where in the lower half is used by content type and the upper
is used by flags. I dont think we would need more than 32 flags anytime
soon. But atleast there is a possibility of adding more flags.
I think flags should be supported only by lld Core.
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