[jdk17] RFR: 8267610: NPE at at jdk.compiler/com.sun.tools.javac.jvm.Code.emitop [v2]

[Guoxiong Li]

> Hi all,
> 
> Currently, the class TransPatterns sometimes doesn't transform the `pattern variables` and `pattern symbols` to the normal variables and symbols, especially the places where the pattern variables are used.
> The following phases, such as LambdaToMethod, Lower and Gen, may crash or generate some wrong results.
> 
> The known issues are [JDK-8267610](https://bugs.openjdk.java.net/browse/JDK-8267610) and [JDK-8268748](https://bugs.openjdk.java.net/browse/JDK-8268748).
> 
> **JDK-8267610 is an issue that pattern symbol causes the compiler to crash.**
> 
> During transforming the InstanceOfTree (JCInstanceOf) , the `BindingSymbol`  instead of the `VarSymbol` is used to make the new `JCIdent` and `JCBinary` trees. At the phase LambdaToMethod, the compiler can't capture this variable so that the lambda method has uncorrect parameters. So at the phase Gen, the compiler crashes because of NPE.
> 
> **JDK-8268748 is an issue that pattern symbol causes that the compiler generates wrong bytecodes.**
> 
> When transforming the BindingPatternTree (JCBindingPattern), the `BindingSymbol` is also handled uncorrectly and used to make the new `JCIdent` and `JCAssign` trees. At the phase Gen, the compiler find the wrong variables, so that the wrong bytecodes are generated.
> 
> These two issues are similar and influence each other. So I solve them at one patch.
> The lines 208-212 are to solve JDK-8267610 with the test `LambdaCannotCapturePatternVariables`. 
> The lines 233-239 are to solve JDK-8268748 with the test `NestedPatternVariablesBytecode`.
> 
> If lines 208-212 are not included, the test  `NestedPatternVariablesBytecode` can't pass. 
> If lines 233-239 are not included, the test `LambdaCannotCapturePatternVariables` can't pass. 
> So I put them together.
> 
> Thanks for taking the time to review.
> 
> Best Regards,
> -- Guoxiong.

Guoxiong Li has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into JDK-8267610
 - Set currentValue after translating tree.expr
 - JDK-8267610 and JDK-8268748

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/59/files
  - new: https://git.openjdk.java.net/jdk17/pull/59/files/3c303236..2ce9bcb6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=59&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=59&range=00-01

  Stats: 18076 lines in 301 files changed: 10232 ins; 7037 del; 807 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/59.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/59/head:pull/59

PR: https://git.openjdk.java.net/jdk17/pull/59