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Re: [PATCH] Fix tree parts of PR18041
- From: Michael Matz <matz at suse dot de>
- To: Richard Guenther <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 10 May 2011 14:26:40 +0200 (CEST)
- Subject: Re: [PATCH] Fix tree parts of PR18041
- References: <alpine.LNX.2.00.1105101321520.810@zhemvz.fhfr.qr>
Hi,
On Tue, 10 May 2011, Richard Guenther wrote:
> struct B {
> unsigned bit0 : 1;
> unsigned bit1 : 1;
> };
>
> void
> foo (struct B *b)
> {
> b->bit0 = b->bit0 | b->bit1;
> }
>
> we with this patch generate
>
> D.2686_2 = b_1(D)->bit0;
> D.2688_4 = b_1(D)->bit1;
> D.2693_10 = D.2688_4 ^ D.2686_2;
> b_1(D)->bit0 = D.2693_10;
I assume that this generates a XOR instead of an OR is a typo not a
feature of the patch ;-)
> + struct B {
> + unsigned bit0 : 1;
> + unsigned bit1 : 1;
> + };
> +
> + void
> + foo (struct B *b)
> + {
> + b->bit0 = b->bit0 | b->bit1;
> + }
> +
> + /* { dg-final { scan-tree-dump-not "\\\(unsigned char\\\)" "optimized" } } */
Perhaps test for only '\\\(unsigned' ? Because I'm not sure if some
targets don't extend to "unsigned int", after all that's the base type of
the bitfields.
Ciao,
Michael.