On Mon, 24 Oct 2022 22:15:49 GMT, Ioi Lam <ik...@openjdk.org> wrote:
> Improve the handling of the
> `java.lang.invoke.MethodHandle.TRACE_METHOD_LINKAGE` property to print out
> the full graph of MethodHandles that are used at a CallSite. This helps us
> understand how invokedynamic call sites are resolved. For example:
>
>
> public class StrConcat {
> static String hello = "Hello";
> static String world = "World";
> public static void main(String args[]) {
> System.out.println(hello + world);
> System.out.println(hello + "World");
> }
> }
>
> $ java -Djava.lang.invoke.MethodHandle.TRACE_METHOD_LINKAGE=true -cp .
> StrConcat
> linkCallSite StrConcat.main(StrConcat.java:5)
> java.lang.invoke.StringConcatFactory.makeConcatWithConstants(Lookup,String,MethodType,String,Object[])CallSite/invokeStatic
> makeConcatWithConstants(String,String)String/BSA1=
> linkMethod
> java.lang.invoke.MethodHandle.invokeExact(Lookup,String,MethodType,String,Object[])CallSite/5
> linkMethod =>
> java.lang.invoke.Invokers$Holder.invokeExact_MT(Object,Object,Object,Object,Object,Object,Object)Object/invokeStatic
> + (Lookup,String,MethodType,String,Object[])CallSite
> linkCallSite target class => java.lang.invoke.BoundMethodHandle$Species_L
> linkCallSite target => (String,String)String :
> BMH.reinvoke000_LLL_L=Lambda(a0:L/SpeciesData[L => Species_L],a1:L,a2:L)=>{
> t3:L=Species_L.argL0(a0:L);
> t4:L=MethodHandle.invokeBasic(t3:L,a1:L,a2: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
> }
> ]
> linkCallSite linkage =>
> java.lang.invoke.Invokers$Holder.linkToTargetMethod(Object,Object,Object)Object/invokeStatic
> + MethodHandle(String,String)String
> HelloWorld
> linkCallSite StrConcat.main(StrConcat.java:6)
> java.lang.invoke.StringConcatFactory.makeConcatWithConstants(Lookup,String,MethodType,String,Object[])CallSite/invokeStatic
> makeConcatWithConstants(String)String/BSA1=World
> linkCallSite target class => java.lang.invoke.BoundMethodHandle$Species_LL
> linkCallSite target => (String)String :
> invoke000_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
>
>
> More complex examples are in the JBS bug report
> - https://bugs.openjdk.org/secure/attachment/101202/eclipse-ide-log.txt
> - https://bugs.openjdk.org/secure/attachment/101203/lambda-expression.txt
> -
> https://bugs.openjdk.org/secure/attachment/101205/pattern-matching-switch.txt
> - https://bugs.openjdk.org/secure/attachment/101204/str-concat.txt
This pull request has now been integrated.
Changeset: fd668dc4
Author: Ioi Lam <ik...@openjdk.org>
URL:
https://git.openjdk.org/jdk/commit/fd668dc44f54274518d2bb46c5e22318a872c02e
Stats: 75 lines in 5 files changed: 61 ins; 0 del; 14 mod
8295537: Enhance TRACE_METHOD_LINKAGE to show the target MethodHandle
Reviewed-by: jvernee, redestad, mchung
-------------
PR: https://git.openjdk.org/jdk/pull/10842
