RFR: 8279219: [REDO] C2 crash when allocating array of size too large [v3]

[Roland Westrelin]

> The new fix is largely similar to the previous one. 3 bugs were filed
> because of the previous change but there are only really 2 issues:
> 
> - attaching the valid length condition at expansion time to the new
>   array runtime call causes issues. With Shenandoah, passes of loop
>   opts are executed after macro expansion but precedence edges are
>   ignored when assigning controls to nodes which causes loop opts to
>   incorrectly attempt to eliminate the node pointed to by the
>   precedence edge. A similar issue occurs when the runtime call ends
>   up in a subgraph that dies after macro expansion because the
>   precedence edge is not cleared by dead code elimination which causes
>   the runtime call to still be reachable. In the new patch, this is
>   fixed by appending an extra input to the runtime call instead of
>   using a precedence edge.
> 
> - In the previous patch, a top valid length input is used when there's
>   no valid length input that needs to be recorded. That can cause an
>   assert failure during CCP. If valid length initially has type top,
>   the CatchNode out of the AllocateArray then have type (control,
>   control). If next, the valid length input becomes constant 0, the
>   CatchNode has type (top, control). An assert catches that the type
>   of the CatchNode doesn't widen. This fixed by using 1 by default as
>   valid length input and tweaking CatchNode::Value.
> 
> The new patch includes test cases for both issues.

Roland Westrelin 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 five additional commits since the last revision:

 - review
 - Merge branch 'master' into JDK-8279219
 - review
 - tests & fix
 - Revert "8279204: [BACKOUT] JDK-8278413: C2 crash when allocating array of size too large"
   
   This reverts commit 04ad668921abbd71dfbc474eed6f1760f7a541b1.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6952/files
  - new: https://git.openjdk.java.net/jdk/pull/6952/files/b3cafb1d..541aa4ea

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6952&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6952&range=01-02

  Stats: 31286 lines in 1169 files changed: 20818 ins; 5776 del; 4692 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6952.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6952/head:pull/6952

PR: https://git.openjdk.java.net/jdk/pull/6952