RFR: 8322694: C1: Handle Constant and IfOp in NullCheckEliminator [v2]

[Aleksey Shipilev]

On Wed, 3 Jan 2024 13:32:32 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> src/hotspot/share/c1/c1_Optimizer.cpp line 888:
>> 
>>> 886:     mark_visitable(instr);
>>> 887:     if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != nullptr)
>>> 888:         || (instr->as_Constant() != nullptr && instr->as_Constant()->type()->is_object())) {
>> 
>> Is this just `instr->as_ObjectConstant() != nullptr`?
>
> Do you mean `insr->type()->as_ObjectConstant() != nullptr`?
> But we should include other Constants (e.g. `ArrayConstant`, `InstanceConstant`), and those classes don't implement `as_ObjectConstant`

Ah, OK then. Yes, I thought ObjectConstant includes ArrayConstant and InstanceConstant.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17191#discussion_r1441479817