RFR: 8316694: Implement relocation of nmethod within CodeCache [v48]

[Richard Reingruber]

On Mon, 6 Oct 2025 15:31:02 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> We also see assertions on PPC64 in the new test `DeoptimizeRelocatedNMethod`:
> 
> ```
> #  Internal Error (jdk/src/hotspot/cpu/ppc/nativeInst_ppc.cpp:405)
> #  assert(!decode(i1, i2)) failed: already patched
> 
> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
> V  [libjvm.so+0x1701784]  NativePostCallNop::patch(int, int)+0xf4  (nativeInst_ppc.cpp:405)
> V  [libjvm.so+0x1718414]  nmethod::finalize_relocations()+0x6f4  (nmethod.cpp:2059)
> V  [libjvm.so+0x171891c]  nmethod::post_init()+0x5c  (nmethod.cpp:1252)
> V  [libjvm.so+0x171a8dc]  nmethod::relocate(CodeBlobType)+0x1ec  (nmethod.cpp:1515)
> V  [libjvm.so+0x200b598]  WB_RelocateNMethodFromMethod+0x388  (whitebox.cpp:1653)
> j  jdk.test.whitebox.WhiteBox.relocateNMethodFromMethod0(Ljava/lang/reflect/Executable;I)V+0
> j  jdk.test.whitebox.WhiteBox.relocateNMethodFromMethod(Ljava/lang/reflect/Executable;I)V+8
> j  compiler.whitebox.DeoptimizeRelocatedNMethod.main([Ljava/lang/String;)V+50
> ```
> 
> @reinrich: I assume this assertion is no longer valid.

Yeah, I reckon it needs to be adapted/removed. Would be nice, though, if we could keep it.

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PR Comment: https://git.openjdk.org/jdk/pull/23573#issuecomment-3372392382