On Tue, Oct 30, 2012 at 3:49 PM, Michael Matz <m...@suse.de> wrote:
> Hi,
>
> On Tue, 30 Oct 2012, Richard Biener wrote:
>
>> On Tue, Oct 30, 2012 at 3:17 PM, Dehao Chen <de...@google.com> wrote:
>> >> And tree expressions don't have TREE_BLOCK before gimple-low either.
>> >> So IMNSHO it is gimple-low.c that should set TREE_BLOCK of all the gimple
>> >> stmts as well as all expression in the operands.
>
> That would be a step away from the ideal situation, so we rather should
> first analyze why the testcase fails with my patch. I expected some
> fallout and am actually surprised it's only one testcase :)
>
> What we should end up with in the ideal world is that we simply have no
> expressions in gimple (and hence no place to store any locations for
> them), except via gimple statements.
>
>> I question the need of BLOCK info on expression trees. If BLOCKs are
>> relevant then the tree ends up referencing a declaration with a BLOCK as
>> context, no? Thus, the case
>>
>> int tem, a;
>> {
>> int a;
>> ...
>> tem = a;
>> }
>> int b = tem + 5;
>>
>> where we may end up with gimple like
>>
>> b = a + 5;
>>
>> thus mixing two BLOCKs inside a stmt (and no expression trees to
>> attach different BLOCKs) is no different from the case where we end
>> up with expression trees.
>>
>> Thus my original question - why isn't a NULL BLOCK treated the same
>> as UNKNOWN_LOCATION?
>
> Since merging location and block a null BLOCK doesn't imply no location.
> It can very well have a location without a block. What we might want to
> imply is that a null BLOCK implies the BLOCK from the statement. But as
> you say, first we should find out why my patch breaks the one testcase.
Yes, I mean we happily leave the stmt line location the same if we have
a stmt with UNKNOWN_LOCATION (thus it inherits that of the previous stmt),
we should do the same with BLOCKs - if a stmt has a location with NULL
BLOCK then it should inherit the block info from the previous stmt.
Richard.
>> Or rather, _why_ does Michas patch not work? Did you analyze the guality
>> fails?
>
>
> Ciao,
> Michael.
