RFR: JDK-8287288: Fix some typos in C1

[Zhuojun Miao]

On Thu, 26 May 2022 02:47:54 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> According to the definitions of `Opr_kind` and `kind_mask` below, it can be seen that `opr-kind` uses the lowest 3 bits, and if the lowest bit is 0, it means that this is a pointer.
>
> I was reading:
> 
> enum OprBits {
>       pointer_bits   = 1
>     , kind_bits      = 3
>     , type_bits      = 4
>     , size_bits      = 2
>     , destroys_bits  = 1
> 
> as a bitfield description so 1 pointer bit followed by 3 kind bits, followed by 4 type bits etc. But I agree the later mask value only does a shift of 3 not 4.
> 
> Also the code indicates there are a lot more non-data bits before we get to the data so the diagram is incomplete in other ways.

I don't think `pointer_bits` should be added to `non_data_bits`:


    , non_data_bits  = pointer_bits + kind_bits + type_bits + size_bits + destroys_bits + virtual_bits
                       + is_xmm_bits + last_use_bits + is_fpu_stack_offset_bits
    , data_bits      = BitsPerInt - non_data_bits
    , reg_bits       = data_bits / 2      // for two registers in one value encoding

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PR: https://git.openjdk.java.net/jdk/pull/8880