[PATCH] D11635: DebugInfo: Emit DW_AT_address_class for non-0 address space

[Matt Arsenault]

On 07/31/2015 06:46 AM, Robinson, Paul wrote:
>
> The debug info generally should be mapping the source to the code/data 
> as actually generated, even after optimizations shuffle things around. 
> If the original code thinks it's allocating something in AS 0 but 
> optimization puts it in AS 3, and the user asks the debugger to 
> display the value, how does the debugger know to look in AS 3?  Asking 
> the debugger to troll around looking for an instruction that it might 
> guess is loading/storing the value and assuming that address is the 
> actual location… seems like asking a bit much.
>
> --paulr
>
It seems like a single attribute for the debug address space isn't 
enough then to describe both. I'm fine with just keeping it as the 
constant source, and saying that this is one of those optimizations that 
destroys hope of sensible debugging. We also have some possible use 
cases for non-optimization purposes where an address space ID would be 
changed in the backend, but would be an alias for the original address 
space. The object isn't literally moved to a different address space, 
and is for the backend's benefit so ideally the user debugging would 
never be aware that this occurred.

-Matt
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