RFR: 8309405: RISC-V: is_deopt may produce unaligned memory read

[Fei Yang]

On Sat, 3 Jun 2023 12:34:20 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

> Please review this simple fix, a continuation of JDK-8291550.
> 
> Doing some profiling for trp_lam event (misaligned load emulation) on fpga I've found some more misaligned loads, pretty rare but still happens.
> Here, is_deopt directly dereferences memory address, but with RVC enabled, a single 4-byte intruction could be 2-bytes, but not 4-bytes aligned.
> So is_deopt should use ld_instr to be on safe side.
> 
> Testing: tier1 on hifive clean.

Looks fine.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14299#pullrequestreview-1461471102