RFR: 8259228: Zero: rewrite (put|get)field from if-else chains to switches

[Coleen Phillimore]

On Tue, 5 Jan 2021 10:44:50 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Current handling for (put|get)field uses if-else chain to select the access type. This can be made more uniform by using switches, like accessor_entry code already does.
> 
> Additional testing:
>   - [x] Ad-hoc Zero performance tests

src/hotspot/share/interpreter/zero/bytecodeInterpreter.cpp line 1669:

> 1667:               }
> 1668:               default:
> 1669:                 ShouldNotReachHere();

Rather than having a 3000 line case statement in BytecodeInterpreter::run(), can you make these into separate functions?  I've always wondered how the C++ optimizer possibly does a good job on this function.  And it would be easier to read.

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PR: https://git.openjdk.java.net/jdk/pull/1943