RFR: 8317257: RISC-V: llvm build broken

[Fei Yang]

On Thu, 28 Sep 2023 15:37:54 GMT, Vladimir Kempik <vkempik at openjdk.org> wrote:

> Please review this small fix to make hotspot compilable with clang on risc-v.
> It supposed to fix next error:
> 
> /home/user/openjdk/jdk/src/hotspot/cpu/riscv/c1_LIRAssembler_riscv.cpp:1518:10: error: call to member function 'null_check' is ambiguous
>       __ null_check(obj);
>       ~~~^~~~~~~~~~
> /home/user/openjdk/jdk/src/hotspot/cpu/riscv/macroAssembler_riscv.hpp:238:16: note: candidate function
>   virtual void null_check(Register reg, int offset = -1);
>                ^
> /home/user/openjdk/jdk/src/hotspot/cpu/riscv/c1_MacroAssembler_riscv.hpp:109:8: note: candidate function
>   void null_check(Register r, Label *Lnull = nullptr) { MacroAssembler::null_check(r); }
>        ^
> 1 error generated.

I see this was once introduced by https://bugs.openjdk.org/browse/JDK-8278479.
Maybe align with aarch64 by calling: `__ null_check(obj, -1);` directly?

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PR Comment: https://git.openjdk.org/jdk/pull/15965#issuecomment-1739622635