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Re: Regimplification enhancements 1/3


On 06/16/2014 01:24 PM, Richard Biener wrote:
On Mon, Jun 16, 2014 at 12:56 PM, Bernd Schmidt <bernds@codesourcery.com> wrote:
For the ptx port, I've needed to write a new pass which ensures all objects
go into address spaces as required by the machine. This uses the
regimplification code in gimplify-me.c, and that requires some fixes and
upgrades.

Can you explain how and why you need re-gimplification here?  IMHO
you should apply the necessary steps yourself, not put in GENERIC
into GIMPLE and rely on the gimplifier.

That's not actually what's happening - the pass modifies the address spaces of all objects (local & global vars etc.) and I have one additional patch in gimplify.c that recognizes address space mismatches on an ADDR_EXPR (also testing a new TYPE_QUAL_AS_IMPLICIT bit to ensure it only triggers in situations it's intended to) and inserts the necessary ADDR_SPACE_CONVERT_EXPR. With that I can pass all statements through regimplification to get a consistent view of the world again.

You can't turn a x = &foo; into x = (convert)&foo; this way abusing
the re-gimplification routines.
The re-gimplification routines do _not_ accept random GENERIC
operands.  They were written to handle registers becoming non-registers
and nothing more.

It seems to work fine is all I can say. What it was written for and what it can be useful for are two different things.


Bernd


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