[11] RFR(XS): 8202179: Compilation fails with assert(n->is_expensive()) failed: expensive nodes with non-null control here only

Tobias Hartmann tobias.hartmann at oracle.com
Thu Apr 26 15:59:24 UTC 2018

Hi Vladimir,

On 26.04.2018 17:47, Vladimir Kozlov wrote:
> Should we also check in(0) for NULL in Node::is_unreachable() ? I know that is called only for
> expensive nodes *now* but still it should check for 0.

Okay, let's do that:


> On 4/26/18 12:05 AM, Tobias Hartmann wrote:
>> Hi,
>> please review the following patch:
>> https://bugs.openjdk.java.net/browse/JDK-8202179
>> http://cr.openjdk.java.net/~thartmann/8202179/webrev.00/
>> Expensive nodes have control inputs to prevent GVN from commoning them which may cause more frequent
>> execution (see comment of PhaseIdealLoop::process_expensive_nodes()).
>> Compile::cleanup_expensive_nodes() assumes no expensive nodes are added after parsing and removes
>> the control input if there's only a single copy of a node. ConvD2FNode::Ideal() then creates a new
>> SqrtFNode with the control of the input SqrtDNode (which is NULL).
>> We should only treat the SqrtFNode as expensive if the control input is not NULL.
>> I was only able to reproduce this with replay compilation and a customer application.
>> All tests pass.
>> Thanks,
>> Tobias

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