[lworld] Initial C1 support for value types

[Frederic Parain]

> On Nov 20, 2018, at 04:13, Tobias Hartmann <tobias.hartmann at oracle.com> wrote:
> 
> Hi Ioi,
> 
> thanks for sending this for review!
> 
> Two minor things I've noticed in c1_GraphBuilder.cpp:
> - "is_flattened() can return true for fields that are not value types". This should not happen and I
> haven't seen this with C2 (which also uses the CI). We should add a "TODO" here to look at this later.

This is a behavior I’ve observed while tracing execution during a bug investigation.
Analyzing the ciField code, there’re some paths where the constructor returns before
initializing the _is_flattened field. The fix is quite obvious but I wrote the c1_GraphBuilder
code before I had time to fully analyzed the ciField code.

> - I don't understand this comment "// Only load those fields who are not modified". I think it only
> makes sense in the withfield context but not for putfield/getfield, right?

Right, the copy/past needed some clean up that have not been done :-(

Fred

> 
> No need for another webrev, please go ahead and push this.
> 
> Thanks,
> Tobias
> 
> On 19.11.18 05:01, Ioi Lam wrote:
>> Hi,
>> 
>> Here's a webrev for initial C1 support. Most of the work is done by Fred. I added support for
>> aaload/aastore.
>> 
>> http://cr.openjdk.java.net/~iklam/valhalla/c1-initial-checkin.v01/
>> 
>> C1 is disabled by default. To enable it, specify -XX:+EnableValhallaC1. When this flag is specified,
>> C2 is disabled.
>> 
>> To run the regression tests, use this:
>> 
>>    cd test/hotspot/jtreg/compiler/valhalla/valuetypes
>>    jtreg -Dtest.c1=true TestBasicFunctionality.java
>> 
>> Currently only tests derived from ValueTypeTest are supported this way. Other tests won't work,
>> especially if they try to parse C2 output.
>> 
>> TestBasicFunctionality can run a bunch of test cases but will fail at test27().
>> 
>> My plan is to work on acmp, and then gradually make all the test cases pass with
>> TestBasicFunctionality.
>> 
>> Thanks
>> 
>> - Ioi
>> 
>> 
>> 
>> 
>>