RFR: 8300800: UB: Shift exponent 32 is too large for 32-bit type 'int' [v2]

[Kim Barrett]

On Mon, 12 Aug 2024 08:19:44 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> The operand of shift which is a constant `0` changed to `unsigned long`.
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Used UCONST64(0) instead of UL.

src/hotspot/cpu/aarch64/immediate_aarch64.cpp line 298:

> 296:     uint64_t or_bits_sub = replicate(or_bit, 1, nbits);
> 297:     uint64_t and_bits_top = (and_bits_sub << nbits) | ones(nbits);
> 298:     uint64_t or_bits_top = (UCONST64(0) << nbits) | or_bits_sub;

I focused on the UL suffix earlier, and didn't really think about what this is doing.  Why are we shifting
a zero value at all?  This equivalent to `uint64_t or_bits_top = or_bits_sub;`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20530#discussion_r1713423493