RFR: 8311847: Fix -Wconversion for assembler.hpp emit_int8,16 callers

[Dean Long]

On Tue, 11 Jul 2023 02:14:37 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Please review changes to fix -Wconversion warnings that come from assembler_<cpu>.cpp by adding narrow_casts to the emit_int8,16,24, and 32 functions.  And some other fixups with checked_cast.
>> 
>> Ran tier1 on Oracle platforms, and tier1-4 on linux-x64-debug, linux-aarch64-debug, windows-x64-debug.
>
> src/hotspot/cpu/aarch64/assembler_aarch64.hpp line 265:
> 
>> 263:     int64_t chk = val >> (nbits - 1);
>> 264:     guarantee (chk == -1 || chk == 0, "Field too big for insn");
>> 265:     uint64_t uval = val;
> 
> Suggestion:
> 
>     int32_t val32 = checked_cast<int32_t>(val);
>     unsigned uval = checked_cast<unsigned>(val32);

uint64_t uval64 = val;
    unsigned uval = checked_cast<unsigned>(uval64);
This won't work for negative values, right?

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PR Review Comment: https://git.openjdk.org/jdk/pull/14822#discussion_r1259106251