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Re: Unreviewed^2 patches - bootstrap failure
- From: "Zack Weinberg" <zack at codesourcery dot com>
- To: "Ulrich Weigand" <weigand at i1 dot informatik dot uni-erlangen dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 25 Aug 2003 14:05:58 -0700
- Subject: Re: Unreviewed^2 patches - bootstrap failure
- References: <200308252002.h7PK2uQ07678@faui1g.informatik.uni-erlangen.de>
"Ulrich Weigand" <weigand@i1.informatik.uni-erlangen.de> writes:
>> It is not clear to me why the change in this patch enables the
>> optimization only for non-paradoxical subregs. Could you please
>> clarify?
>
> Maybe it's seen most clearly by looking at the full expressions
> before and after the patch:
...
> The overall effect is simply that the test GET_CODE (SUBREG_REG (op0)) == REG
> is moved from the outer if, where it affects both the paraxocical and the
> non-paradoxical case, to a location inside the first inner if, where it
> affects only the paradoxical case.
>
> This means that the optimization in the paradoxical case is done only
> for REG subregs, as before, while in the non-paradoxical case it is
> now done for both REG and MEM subregs.
Okay, I get it now, thanks for explaining. (I did look at the code
but it didn't fit together without your explanation.) The patch is
OK, then.
zw