[PATCH]: Add a flag to the DWARF Compile Unit to indicate if it was compiled with ARC

[John McCall]

On May 13, 2013, at 1:44 PM, Eric Christopher <echristo at gmail.com> wrote:
> On Mon, May 13, 2013 at 1:25 PM, Adrian Prantl <aprantl at apple.com> wrote:
>> 
>> On May 13, 2013, at 11:57 AM, Eric Christopher <echristo at gmail.com> wrote:
>> 
>>> Eh? Curious what this will be used for?
>> This would be interesting mostly for the debugger but I guess tools like Instruments would also like to know.
> 
> In what way? I.e. why add it?

It's a language mode, Eric.  It's smaller in scope than C++ but on approximately the same scope as OpenCL.  Users have a reasonable expectation that source-aware tools like debuggers and profilers will know what language the source code is written in.

Off-hand, here are some ways that a tool might take advantage of knowing that it's analyzing an ARC program:
  - it could enable better support for printing weak variables
  - it could automatically use appropriate semantics for assigning into weak or strong variables with an expression
  - it could correctly handle ARC-specific language constructs in the expression evaluator
  - it could take it as a general license to intercept the ARC runtime calls
  - it could monitor retain/release events and advise the user when a retain cycle was formed or broken

John.