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Re: [PATCH] Update source location for PRE inserted stmt


On Wed, Oct 31, 2012 at 12:57 AM, Xinliang David Li <davidxl@google.com> wrote:
> It will make the location info for the newly synthesized stmt more
> deterministic, I think.

Maybe, but it will increase the jumpiness in the debugger without actually
being accurate, no?  For example if the partially redundant expression is

  i + j;

then when computed at the insertion point the values of i and j do not
necessarily reflect the computed value!  Instead we may compute the
result of i + j using completely different components / operation.

Thus I think inserted expressions should not have any debug information
at all because they do not correspond to a source line.

Richard.

> David
>
> On Tue, Oct 30, 2012 at 4:38 PM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
>> On Wed, Oct 31, 2012 at 12:00 AM, Dehao Chen wrote:
>>> This patch aims to improve debugging of optimized code. It ensures
>>> that PRE inserted statements have the same source location as the
>>> statement at the insertion point, instead of UNKNOWN_LOCATION.
>>
>> Wrong patch attached.
>>
>> However, is it really better to have the location of the insertion
>> point than to have UNKNOWN_LOCATION? It's not where the value is
>> computed in the source program...
>>
>> Ciao!
>> Steven


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