>>> Ingo Molnar <[email protected]> 17.12.07 14:26 >>>
>
>* Jan Beulich <[email protected]> wrote:
>
>> This generally allows better code to be generated, since the zero-
>> extension during 32-bit operations comes for free (needed when the
>> result is used as array index or similar), whereas sign extension must
>> be done explicitly and frequently requires a one byte larger
>> instruction due to the necessary rex64 prefix.
>
>good catch! Applied your patch to x86.git - queued it up for v2.6.25. I
>bet there are tons of other instances where we use signed instead of
>unsigned and get worse code generation.
Yes, definitely. This patch was kind of a testing one whether this is a
welcome change. As it appears to be, I'll probably produce more as I
run into respective cases.
Jan
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