RFR: 8244307: Improve assertions against taskqueue underflow

[stefan.johansson at oracle.com]

On 2020-05-05 04:46, Kim Barrett wrote:
> Please review this change to the assertions in the taskqueue code that
> are checking for unexpected underflow of the buffer.  Temporary
> underflow is possible in some situations, but it should always be
> "quickly" resolved.  There were a number of different assertions of
> this.  This change introduces an assert_not_underflow() operation,
> giving them all a common name that makes the intent clearer.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8244307
> 
> Webrev:
> https://cr.openjdk.java.net/~kbarrett/8244307/open.00/
Nice cleanup, looks good,
Stefan

> 
> Testing:
> mach5 tier1-5, in combination with fix for JDK-8243325.
> Locally (linux-x64) hotspot:tier1 without JDK-8243325.
>