[llvm] r185484 - Debug Info: use module flag to set up Dwarf version.

[Eric Christopher]

On Mon, Jul 8, 2013 at 4:33 PM, Manman Ren <mren at apple.com> wrote:
>
> On Jul 8, 2013, at 4:14 PM, Eric Christopher wrote:
>
>> I'm not sure what you mean here?
>>
>> -eric
>>
>> On Mon, Jul 8, 2013 at 4:07 PM, Manman Ren <mren at apple.com> wrote:
>>>
>>>
>>> Adding a ModFlagBehavior Min or Max only makes sense for flag that is a ConstantInt.
>>> Is the behavior general enough?
>
> This is referring to the request of using Min or Max when merging two modules with different dwarf versions.
> Since the type of a module flag is "Value*" and "Min or Max" only makes sense when the Value is a ConstantInt,
> I was asking whether adding a behavior "Min or Max" is general enough.
>
> BTW, have we decided whether we should use Min or Max? It seems the discussion is still ongoing.
>

The discussion is going something like this:

a) Max: Probably makes the most users happiest when they've got some
weird library/target that specifies -gdwarf-2 (or something) on the
command line in a legacy mode.
b) Min: Handles the problem of "no, I really meant 2 for those
files/compile units/libraries" because there's some bug I can't work
around and now I have no recourse during LTO.
c) Compile unit: Solves the above problem with Min by making it per
CU, but now we've got different set of debug versions mixed into a
final compilation (involving a little more complexity during compile
time) when a single version works in the majority of cases and could
probably even be max.

Mostly involves how much annoyance we've got in all of these situations.

-eric

> Manman
>
>>>
>>> Manman
>