RFR(M): 8213528: fp registers should not need to be saved around a CallLeafNoFP

Vladimir Kozlov vladimir.kozlov at oracle.com
Mon Nov 12 18:02:10 UTC 2018

Hi, Roland

First, please explain your comment:

"That stuff is for parse time. We emit our CallLeafNoFP after parse
time. So we don't need that stuff."

Do you intent to add new CallLeafNoFP for Shenandoah?  Or you can use normal CallLeaf since there are no difference 
(except 32-bit x86).

Do you still need additional parameter exclude_fp in add_call_kills()?

And, please, file new RFE to remove NO_FP code.


On 11/12/18 1:01 AM, Roland Westrelin wrote:
>> Looking on all .ad files I see difference only for x86_32:
> I missed that.
>> http://hg.openjdk.java.net/jdk/jdk/file/13266dac5fdb/src/hotspot/cpu/x86/x86_32.ad#l13326
>> And I surprise we don't have difference for SPARC.
>> Your change make code in x86_32 be unused. The only drawback to always use CallLeaf there is empty_FPU_stack() when cpu
>> does not have SSE2 (such CPUs should disappear already) and reset FPU control word when it is in special 24BitFPMode
>> mode. The 24bit mode most likely is not used any more (requires not presence SSE and other conditions):
>> http://hg.openjdk.java.net/jdk/jdk/file/13266dac5fdb/src/hotspot/share/opto/compile.cpp#l3678
>> Based on this I think we need purge all this vary outdated code as separate RFE.
>> Lets first push your changes.
> Ok. Thanks. So you're ok with this?
> Roland.

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