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

[Jie Fu]

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

-------------

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

Changes: https://git.openjdk.java.net/jdk/pull/1637/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1637&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257794
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1637.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1637/head:pull/1637

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