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Re: [patch tree-ssa-forwprop]: Improve binary and/or/xor folding
2011/6/27 Richard Guenther <richard.guenther@gmail.com>:
> On Wed, Jun 22, 2011 at 3:09 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>> Hello,
>>
>> This patch improves via type-sinking folding of binary and, or, and
>> xor operations.
>> First we do sinking also for compatible types with same precision, as
>> those don't need to be preserved for these operations.
>> Additional try to fold patterns (TYPE) X bin-op (Y CMP Z) and (TYPE) X
>> bin-op !Y, if type of X is
>> compatible to Y.
>>
>> ChangeLog gcc
>>
>> 2011-06-22 ?Kai Tietz ?<ktietz@redhat.com>
>>
>> ? ? ? ?* tree-ssa-forwprop.c (simplify_bitwise_binary):
>> ? ? ? ?Improve binary folding regarding casts.
>>
>>
>> ChangeLog gcc/testsuite
>>
>> 2011-06-22 ?Kai Tietz ?<ktietz@redhat.com>
>>
>> ? ? ? ?* gcc.dg/binop-notand1a.c: New test.
>> ? ? ? ?* gcc.dg/binop-notand2a.c: New test.
>> ? ? ? ?* gcc.dg/binop-notand3a.c: New test.
>> ? ? ? ?* gcc.dg/binop-notand4a.c: New test.
>> ? ? ? ?* gcc.dg/binop-notand5a.c: New test.
>> ? ? ? ?* gcc.dg/binop-notand6a.c: New test.
>>
>> Bootstrapped and regression tested for all standard languages, Ada,
>> and Obj-C++. Ok for apply?
>
> The first hunk is ok, the 2nd not - please don't use fold here. ?Also
> your comment says what it tries to match, but not what it tries
> to produce. ?So - what is the transformation you are trying to do?
> The code is also two duplicates of exactly the same stuff.
>
> Btw, I see TRUTH_NOT_EXPR is still around, why's that so?
>
> Thanks,
> Richard.
Ok, I will sent first hunk as separate patch. The second hunk shall
try to do simple simple folding like X & !X -> 0 (which is handled by
fold-const, too). As special case we have here also (type) X & !X,
and for case X & (type) !X. Later case can happen as soon as we
preserve casts from boolean-type.
I was thinking about implementing here the optimizations for all
binary and/or/xor the foldings to constant directly in
forward-propagate. This might be the better choice. Should I put this
into a separate function in forward-propagation, or should I put this
folding function into a different file?
Regards,
Kai