Re: Add a shared constant pool

[Mark Mitchell <mark at codesourcery dot com>]

Richard Sandiford wrote:

>> Walk me through the logic here a bit.  For example, on ARM, we use
>> per-function constant pools so that we can use PC-relative addressing to
>> find constants.  Now, I know that on ARM we don't currently have any of
>> the new object block hooks wired up, but, suppose we did.  Then, your
>> thinking is that we would define use_blocks_for_constant_p to always
>> return false on this target because we really want to put things in
>> per-function pools?
> 
> Right.

OK, got it.

>> What about things like:
>>
>>   static const int i = 3;
>>   static const int *ip = &i;
>>
>> Here, wouldn't we possibly want to put 3 (or, equivalently, "i") into a
>> block?  Or, does all this apply only to constants that are not variable
>> initializers?
> 
> The hook only applies to _rtx_ constant pools, i.e. those forced into
> memory by force_const_mem.  It doesn't have any say on what we do
> with VAR_DECLs or tree constants.

OK, I understand.  I always get confused by the fact that we have two
different ways of emitting constants.

The patch looks fine to me.  Please give others 24 hours to comment;
then commit, assuming no objections.

Thanks,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713