RFR: 8294087: RISC-V: RVC: Fix a potential alignment issue and add more alignment assertions for the patchable calls/nops [v3]

[Xiaolin Zheng]

On Wed, 21 Sep 2022 10:48:32 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> I think `static void assert_alignment(address pc, int alignment = NativeInstruction::instruction_size);` is cleaner, even though it requires a new include in `macroAssembler_riscv.hpp`.

Thanks for the determination. I have reverted the revertible one.

> src/hotspot/cpu/riscv/macroAssembler_riscv.cpp line 2850:
> 
>> 2848: 
>> 2849:   address call_pc = pc();
>> 2850:   assert(entry.rspec().type() == relocInfo::runtime_call_type || is_aligned(call_pc, 4), "bad alignment for patchable calls");
> 
> "4" is still here?

Nice catch, modified.

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PR: https://git.openjdk.org/jdk/pull/10370