RFR: 8257794: Zero: assert(istate->_stack_limit == istate->_thread->last_Java_sp() + 1) failed: wrong on Linux/x86_32

[Aleksey Shipilev]

On Sat, 5 Dec 2020 03:25:10 GMT, Jie Fu <jiefu at openjdk.org> wrote:

> Hi all,
> 
> Zero debug build on Linux/x86_32 is broken due to an incorrect assert [1].
> 
> 'istate->_stack_limit' is set here [2] as 'stack->sp() - 1'.
> 'istate->_thread->last_Java_sp()' is set here [3], which is actually 'stack->sp()' according to [4].
> 
> So the correct assert should be:
>   assert(istate->_stack_limit == istate->_thread->last_Java_sp() - 1)
> 
> It would be better to fix it.
> 
> Testing:
>    - Zero fastdebug build passed on Linux/x86_32
> 
> Thanks.
> Best regards,
> Jie
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/interpreter/zero/bytecodeInterpreter.cpp#L422
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/zero/zeroInterpreter_zero.cpp#L819
> [3] https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/zero/zeroInterpreter_zero.cpp#L194
> [4] https://github.com/openjdk/jdk/blob/master/src/hotspot/os_cpu/linux_zero/thread_linux_zero.hpp#L65

@DamonFool, I don't think `/test` works here, or even makes sense: no current testing runs `Zero`. Please try to `make bootcycle-images` on platforms you can reach.

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PR: https://git.openjdk.java.net/jdk/pull/1637