[llvm] r269969 - When looking for a spill slot in reg scavenger, find one that matches RC

[Quentin Colombet via llvm-commits]

> On May 20, 2016, at 9:11 AM, Krzysztof Parzyszek via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Getting to this particular place in register scavenger is an indication of a problem.  That should not happen under any conditions, so it qualifies for llvm_unreachable.  There is nothing that the user can do to remedy this situation once it happens.  That ties to your comment about when to use unreachable vs report_fatal_error.
> 
> I was under impression that llvm_unreachable expands to nothing in release mode---turns out it is not true.  I'd rather remove the report_fatal_error and keep the unreachable in this case.

My bad, llvm_unreachable does generate a call to abort. I could have swear I saw unreachable just being dropped.


> 
> -Krzysztof
> 
> 
> 
> On 5/20/2016 11:01 AM, Benjamin Kramer wrote:
>> report_fatal_error produces user-visible errors, I don't think
>> including stack traces there is in any way helpful and will only cause
>> confusion. If a compiler dev doesn't like using a debugger they can
>> still grep for the error message and quickly find where it's coming
>> from ...
>> 
>> On Fri, May 20, 2016 at 5:51 PM, Krzysztof Parzyszek
>> <kparzysz at codeaurora.org> wrote:
>>> On 5/20/2016 10:43 AM, Benjamin Kramer wrote:
>>>> 
>>>> You can
>>>> easily get a stack trace from a debugger, no need to use
>>>> llvm_unreachable for that.
>>> 
>>> 
>>> That forces people to use debuggers, which I really don't like.
>>> 
>>> Maybe printing the stack trace from report_fatal_error (when assertions are
>>> enabled) would be an option?
>>> 
>>> -Krzysztof
>>> 
>>> 
>>> 
>>> --
>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by
>>> The Linux Foundation
> 
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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