RFR: 8310524: C2: record parser-generated LoadN nodes for IGVN [v2]

[Daniel Lundén]

On Tue, 5 Dec 2023 10:31:16 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> Daniel Lundén has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Address comments
>
> src/hotspot/share/opto/graphKit.cpp line 1567:
> 
>> 1565:     record_for_igvn(ld);
>> 1566:     if (ld->is_DecodeN()) {
>> 1567:       // Also record the actual load (LoadN) in case ld is DecodeN
> 
> Maybe add an assertion here checking that `ld->in(1)` is indeed a LoadN node.

Good idea, added

> test/hotspot/jtreg/compiler/c2/irTests/igvn/TestLoadNIdeal.java line 48:
> 
>> 46: 
>> 47:     @Test
>> 48:     @IR(counts = {IRNode.LOAD_N, "1"})
> 
> Maybe add a precondition here testing that `UseCompressedOops` is enabled. Currently the test passes when running with  `-XX:-UseCompressedOops` because `UseCompressedOops` is not whitelisted by the IR framework and hence the IR check is disabled, but better to be explicit I think.

Thanks, now added. I also switched to `TestFramework.runWithFlags("-XX:+UseCompressedOops");` to ensure that the test runs with compressed oops enabled (if, for some reason, that is not the default at some point in the future).

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PR Review Comment: https://git.openjdk.org/jdk/pull/16967#discussion_r1415471606
PR Review Comment: https://git.openjdk.org/jdk/pull/16967#discussion_r1415471474