RFR: 8256726: Zero: print proper message in ArrayIndexOutOfBoundException

[Severin Gehwolf]

On Fri, 20 Nov 2020 09:14:13 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Manifests on tier1 test:
> 
> $ CONF=linux-x86_64-zero-fastdebug make run-test TEST=runtime/exceptionMsgs/ArrayIndexOutOfBoundsException/
> test ArrayIndexOutOfBoundsExceptionTest.testAIOOBMessages(): failure
> java.lang.AssertionError: expected [Index -5 out of bounds for length 0] but found [-5]
> 
> Fix does similar thing to what `Runtime1::throw_range_check_exception` does, but using a safer `jio_snprintf`.
> 
> Additional testing:
>  - [x] AIOBB tests on Linux x86_64 Zero fastdebug

src/hotspot/share/interpreter/zero/bytecodeInterpreter.cpp line 1504:

> 1502:       arrayOop arrObj = (arrayOop)STACK_OBJECT(arrayOff);                      \
> 1503:       jint     index  = STACK_INT(arrayOff + 1);                               \
> 1504:       char message[2 * jintAsStringSize + 35];                                 \

What's this magic `35` here? `strlen("Index A out of bounds for length B") + 1 == 35`. Isn't this counting the integers twice?

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PR: https://git.openjdk.java.net/jdk/pull/1341