RFR: 8332689: RISC-V: Use load instead of trampolines [v19]

[Dean Long]

On Fri, 28 Jun 2024 07:02:03 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/macroAssembler_riscv.hpp line 1275:
>> 
>>> 1273:   //
>>> 1274:   // Return: the call PC or null if CodeCache is full.
>>> 1275:   address patchable_far_call(Address entry) {
>> 
>> For runtime_call_type, I don't think we ever update the target/destination, so the name "patchable" seems not quite right for them.  Also, for runtime_call_type, since they never change, we can decide early if a near call is possible when the destination is always reachable (based on the bounds of code cache), which is what aarch64 does for trampoline_call.
>
> Yes. My thinking was, the site is still patachable, even if some sites don't need that capability.
> The reason why this patch ignores near calls is because the short reach of JAL +-1MB (so normally only a few stubs can be reach from a few nmethods).
> But it is on the enhancement list.
> 
> I don't mind changing the name, feel free to suggest something!

The key things seems to be that they are typed with a relocInfo, so maybe `reloc_call`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/19453#discussion_r1659486646