8285436: riscv: Fix broken MacroAssembler::debug64

[zhengxiaolinX]

MacroAssembler::stop()[1] and StubGenerator::generate_verify_oop()[2] would first push all regs (calling MacroAssembler::pusha()[3]) onto the stack and then call MacroAssembler::debug64()[4] to print the pushed regs. But MacroAssembler::pusha()[3] won't push x0~x4 so the result of MacroAssembler::debug64() is broken.

Tested by manually adding a __ verify_oop(x1) and option -XX:+VerifyOops -XX:+ShowMessageBoxOnError to deliberately crash the VM to make sure the new result matches the fact. Also a hotspot tier1.

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp#L533
[2] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp#L581
[3] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp#L1126-L1130
[4] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/riscv/macroAssembler_riscv.cpp#L473-L503

Thanks,
Xiaolin

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Issue

• JDK-8285436: riscv: Fix broken MacroAssembler::debug64

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[bridgekeeper]

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[openjdk]

@zhengxiaolinX The following label will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 00: Full (43675ed6)

[zhengxiaolinX]

/label hotspot-compiler
/label remove hotspot
/cc hotspot-compiler

[openjdk]

@zhengxiaolinX
The hotspot-compiler label was successfully added.

[openjdk]

@zhengxiaolinX
The hotspot label was successfully removed.

[openjdk]

@zhengxiaolinX The hotspot-compiler label was already applied.

[yadongw]

Good catch, Xiaolin. But I plan to follow JDK-8245986 to use a specific instruction which will raise a SIGILL according to riscv spec. The patch will remove all these push/pop(s).

[zhengxiaolinX]

Thank you for the explanation, Yadong. That would be better if you have future plans for this part, and I feel fine to retract this one as well because it might be not so important.

[TobiHartmann]

@zhengxiaolinX Should we close the JBS issue then?

[zhengxiaolinX]

@zhengxiaolinX Should we close the JBS issue then?

Thank you! Closed.