RFR: 8278079: C2: expand_dtrace_alloc_probe doesn't take effect in macro.cpp

[Vladimir Kozlov]

On Thu, 2 Dec 2021 13:22:45 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> Hi,
>> 
>> Could I have a review of this small fix that makes expand_dtrace_alloc_probe take effect?
>> 
>> Thanks,
>> Denghui
>
> src/hotspot/share/opto/macro.cpp line 1633:
> 
>> 1631: void PhaseMacroExpand::expand_dtrace_alloc_probe(AllocateNode* alloc, Node* oop,
>> 1632:                                                 Node*& ctrl, Node*& rawmem) {
>> 1633:   if (C->env()->dtrace_alloc_probes()) {
> 
> IIUC, this probe is related to object allocation, so it should be expanded when ciEnv::dtrace_alloc_probes() returns true, just like the implementation in C1(see C1_MacroAssembler::initialize_object().

Originally it checked `ExtendedDTraceProbes` flag here. But I think it was missing change when `DTraceAllocProbes` flag was introduced by
https://bugs.openjdk.java.net/browse/JDK-6346964

So I agree with this change.

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PR: https://git.openjdk.java.net/jdk/pull/6639