RFR: 8316694: Implement relocation of nmethod within CodeCache [v32]

[Evgeny Astigeevich]

On Tue, 1 Jul 2025 09:49:08 GMT, Evgeny Astigeevich <eastigeevich at openjdk.org> wrote:

>> Chad Rakoczy has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 90 commits:
>> 
>>  - Merge remote-tracking branch 'origin/master' into JDK-8316694-Final
>>  - Update how call sites are fixed
>>  - Merge remote-tracking branch 'origin/master' into JDK-8316694-Final
>>  - Fix pointer printing
>>  - Use set_destination_mt_safe
>>  - Print address as pointer
>>  - Use new _metadata_size instead of _jvmci_data_size
>>  - Merge remote-tracking branch 'origin/master' into JDK-8316694-Final
>>  - Only check branch distance for aarch64 and riscv
>>  - Move far branch fix to fix_relocation_after_move
>>  - ... and 80 more: https://git.openjdk.org/jdk/compare/f799cf18...70e4164e
>
> src/hotspot/share/code/nmethod.cpp line 1547:
> 
>> 1545:   CodeBuffer dst(nm_copy);
>> 1546:   while (iter.next()) {
>> 1547:     iter.reloc()->fix_relocation_after_move(&src, &dst, true);
> 
> What if, instead of a bool parameter we introduce a function `fix_relocation_after_copy`:
> ```c++
> virtual void Relocation::fix_relocation_after_copy(const CodeBuffer* src, CodeBuffer* dest) {
>   fix_relocation_after_move(src, dest);
> }
> 
> void CallRelocation::fix_relocation_after_copy(const CodeBuffer* src, CodeBuffer* dest) {
>    address orig_addr = old_addr_for(addr(), src, dest);
>    address callee    = pd_call_destination(orig_addr);
> 
>     if (src->contains(callee)) {
>       // If the original call is to an address in the src CodeBuffer (such as a stub call)
>       // the updated call should be to the corresponding address in dest CodeBuffer
>       ptrdiff_t offset = callee - orig_addr;
>       callee = addr() + offset;
>     }
> 
>     pd_set_call_destination(callee);
> }
> 
> 
> With this change we don't need to modify `relocInfo_*.cpp` files.

IMO, we might consider moving `pd_set_call_destination` to `CallRelocation` because only CallRelocation uses it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23573#discussion_r2177119955