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Re: [ast-optimizer-branch] PATCH to simplify array base


>>>>> "Richard" == Richard Henderson <rth@redhat.com> writes:

> On Sat, Jun 08, 2002 at 07:04:04AM +0100, Jason Merrill wrote:
>> We haven't been simplifying array bases, but we should.  Given an
>> expression like k.d[2][3] where k.d is of type int[3][4], this will now
>> simplify to
>> 
>> int (*t1)[3][4];
>> int t2;
>> t1 = &k.d;
>> t2 = (*t1)[2][3];

> I think this is wrong.  The only reason not to decompose all array
> arithmetic to pointer arithmetic immediately is to make it easier
> for dependence analysis to do its job.  Given this is the case, your
> change hamstrings dependence analysis, requiring that it search
> backward for whatever t1 references.

...though we will eventually want dependence analysis to handle that sort
of thing anyway, as code like

type *p = array;
while (elt = *p++)
  ...;

is pretty common.

Jason


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