On Tue, 25 Oct 2022 13:16:19 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> Ioi Lam has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> @JornVernee comments
>
> src/java.base/share/classes/java/lang/invoke/CallSite.java line 179:
>
>> 177: target.type(); // null check
>> 178: this.target = target;
>> 179: if (MethodHandleStatics.TRACE_CALLSITE) {
>
> This doesn't seem like the right place to put this. Anyone can indirectly
> extend CallSite, by extending e.g. MutableCallSite, but this code seems to
> assume that the call is going through `MethodHandleNatives.linkCallSite`? I
> suggest putting any tracing around that area. Both the target method handle,
> and the BSM are available at that point in the code as well.
>
> I also note that there's already a `TRACE_METHOD_LINKAGE` flag as well, which
> does some tracing of call site linking. Maybe that option could be enhanced
> instead of adding a new one?
Thanks for the suggestion! I removed the new property and just piggyback on
`TRACE_METHOD_LINKAGE`. I also moved the tracing code into
`MethodHandleNatives.linkCallSiteXXX`, and improved the existing code a bit to
print out the line number of the call site.
Here's what it looks like now:
$ java -Djava.lang.invoke.MethodHandle.TRACE_METHOD_LINKAGE=true -cp . StrConcat
[...]
linkCallSite StrConcat.main(StrConcat.java:6)
java.lang.invoke.StringConcatFactory.makeConcatWithConstants(Lookup,String,MethodType,String,Object[])CallSite/invokeStatic
makeConcatWithConstants(String)String/BSA1=World
linkCallSite target class => java.lang.invoke.BoundMethodHandle$Species_LL
linkCallSite target => (String)String :
invoke001_LL_L=Lambda(a0:L/SpeciesData[LL =>
BoundMethodHandle$Species_LL],a1:L)=>{
t2:L=BoundMethodHandle$Species_LL.argL1(a0:L);
t3:L=BoundMethodHandle$Species_LL.argL0(a0:L);
t4:L=MethodHandle.invokeBasic(t3:L,a1:L,t2:L);t4:L}
& BMH=[
0: MethodHandle = {(Object,Object)String :
DMH.invokeStatic000_LLL_L=Lambda(a0:L,a1:L,a2:L)=>{
t3:L=DirectMethodHandle.internalMemberName(a0:L);
t4:L=MethodHandle.linkToStatic(a1:L,a2:L,t3:L);t4:L}
&
DMH.MN=java.lang.StringConcatHelper.simpleConcat(Object,Object)String/invokeStatic
}
1: ( World )
]
linkCallSite linkage =>
java.lang.invoke.Invokers$Holder.linkToTargetMethod(Object,Object)Object/invokeStatic
+ MethodHandle(String)String
HelloWorld
-------------
PR: https://git.openjdk.org/jdk/pull/10842
