[jdk17] RFR: 8269775: compiler/codegen/ClearArrayTest.java failed with "assert(false) failed: bad AD file" [v2]

[Sandhya Viswanathan]

> The following test failed in JDK17 
> compiler/codegen/ClearArrayTest.java
> with assert(false) failed: bad AD file
> 
> The problem is that no match is found for platforms not supporting avx512vlbw for constant input.
> 
> Per analysis from Dean Long and Vladimir Kozlov:
> This is due to rep_stos rules for small clear array which use !n->in(2)->bottom_type()->is_long()->is_con(). 
> This prevents the rule from matching with a constant --> register conversion. 
> Removing !is_con() from rep_stos for small clear array fixes the issue.
> We also add appropriate "ins_cost" to all ClearArray rules, so that in the case of multiple matches, we break the tie based on ins_cost.
> 
> Best Regards,
> Sandhya

Sandhya Viswanathan has updated the pull request incrementally with one additional commit since the last revision:

  Implement review comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/199/files
  - new: https://git.openjdk.java.net/jdk17/pull/199/files/f3380586..e8671b0b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=199&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=199&range=00-01

  Stats: 16 lines in 2 files changed: 2 ins; 5 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/199.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/199/head:pull/199

PR: https://git.openjdk.java.net/jdk17/pull/199