RFR: 8364150: RISC-V: Leftover for JDK-8343430 removing old trampoline call [v3]

[Hamlin Li]

On Mon, 28 Jul 2025 13:09:42 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/nativeInst_riscv.cpp line 116:
>> 
>>> 114:   if (code->is_nmethod()) {
>>> 115:     assert(dest != nullptr, "Sanity");
>>> 116:     MacroAssembler::pd_patch_instruction_size(call_addr, dest);
>> 
>> `dest` here is the reloc call desitnation, ie. the dest stored in the stub, and it should be able to reach anywhere in the address space.
>> The patch here should patch the `auipc + jalr` to the address of this stub, rather than `dest`?
>
> Yes, the `dest` param here holds the address of this stub.
> In `CallRelocation::fix_relocation_after_move`, we first get the `callee` address by calling `pd_call_destination` which delegates work to `NativeCall::reloc_destination` for a NativeCall. And we have modified `NativeCall::reloc_destination` to return the stub address in this PR at the same time. So `callee` will hold the stub address. Immediatedly after that, `callee` is passed to `pd_set_call_destination` which delegates work to `NativeCall::reloc_set_destination`. Make sense?
> 
> 
> void CallRelocation::fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
>   // Usually a self-relative reference to an external routine.
>   // On some platforms, the reference is absolute (not self-relative).
>   // The enhanced use of pd_call_destination sorts this all out.
>   address orig_addr = old_addr_for(addr(), src, dest);
>   address callee    = pd_call_destination(orig_addr);              <=========== callee is stub address
>   // Reassert the callee address, this time in the new copy of the code.
>   pd_set_call_destination(callee);                                 <=========== callee passed as param
> }

There is another call of `Relocation::pd_set_call_destination(address x)` from `CallRelocation::set_destination(address x)`, not sure if this `x` passed in from set_destination is also the stub addr?

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/26495#discussion_r2236501965