[patch, fortran] PR 40628, front-end optimization pass

[Toon Moene]

Daniel Kraft wrote:

> I just wonder if there is not yet any way to tell the middle-end that it 
> is allowed to optimize function calls away (like marking the functions 
> "pure" -- according to the c.l.f thread, this should be allowed for all 
> Fortran functions (if I understood it correctly)).

No, that's not sufficient, as I argued in my 2007 GCC Summit paper (see 
paragraph 6.3 - you also have to get rid of the temporaries that are 
allocated to hold the function results, which can be quite large (i.e., 
when eliding MATMUL calls).

It is hard to see how the middle end could do this.

-- 
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
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