[jdk17] RFR: 8269771: assert(tmp == _callprojs.fallthrough_catchproj) failed: allocation control projection [v2]

[Vladimir Kozlov]

On Thu, 1 Jul 2021 21:11:26 GMT, Nils Eliasson <neliasso at openjdk.org> wrote:

>> When I investigated this bug I found out it was already fixed by JDK-8268405, or at least - it didn't happen any more. Since I had a good reproducer I took a look at why it happened and found two issues.
>> 
>> The noteable thing about the test case is that there are still allocations that isn't used. The initalizeNode lead to HaltNodes. This looks like a temporary state while the graph is simplified.
>> 
>> 1) In macro.cpp - process_users_of_allocation - there was an assert that was wrong. We must assert before the replace_node - otherwise tmp will always be NULL and fail. Why this hasn't happened before is a mystery.
>> 
>> 2) memnode.cpp - MemBarNode::remove - returns without doing anything if there are not exactly 2 outs. In this case there is a InitalizeNode that leads to a HaltNode. The memory uses has been removed - so the memory projection from the InitalizeNode is already removed.
>> 
>> If you want to check if this patch fixes the issue - you need to sync to jdk-17+26 - or before the fix for JDK-8268405.
>> 
>> Please review,
>> Nils Eliasson
>
> Nils Eliasson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix assert

Good.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk17/pull/193