8257164: Share LambdaForms for VH linkers/invokers

Reviewed-by: redestad, kvn, psandoz

Author: Vladimir Ivanov

src/java.base/share/classes/java/lang/invoke/Invokers.java

@@ -139,7 +139,7 @@ private MethodHandle makeVarHandleMethodInvoker(VarHandle.AccessMode ak, boolean
         MethodType mtype = targetType;
         MethodType invokerType = mtype.insertParameterTypes(0, VarHandle.class);
 
-        LambdaForm lform = varHandleMethodInvokerHandleForm(ak, mtype, isExact);
+        LambdaForm lform = varHandleMethodInvokerHandleForm(mtype, isExact);
         VarHandle.AccessDescriptor ad = new VarHandle.AccessDescriptor(mtype, ak.at.ordinal(), ak.ordinal());
         MethodHandle invoker = BoundMethodHandle.bindSingle(invokerType, lform, ad);
 
@@ -346,20 +346,22 @@ static LambdaForm invokeHandleForm(MethodType mtype, boolean customized, int whi
     }
 
 
-    static MemberName varHandleInvokeLinkerMethod(VarHandle.AccessMode ak, MethodType mtype) {
-        LambdaForm lform;
-        if (mtype.parameterSlotCount() <= MethodType.MAX_MH_ARITY - MH_LINKER_ARG_APPENDED) {
-            lform = varHandleMethodGenericLinkerHandleForm(ak, mtype);
-        } else {
-            // TODO
+    static MemberName varHandleInvokeLinkerMethod(MethodType mtype) {
+        if (mtype.parameterSlotCount() > MethodType.MAX_MH_ARITY - MH_LINKER_ARG_APPENDED) {
             throw newInternalError("Unsupported parameter slot count " + mtype.parameterSlotCount());
         }
+        LambdaForm lform = varHandleMethodGenericLinkerHandleForm(mtype);
         return lform.vmentry;
     }
 
-    private static LambdaForm varHandleMethodGenericLinkerHandleForm(VarHandle.AccessMode ak,
-            MethodType mtype) {
-        // TODO Cache form?
+    private static LambdaForm varHandleMethodGenericLinkerHandleForm(MethodType mtype) {
+        mtype = mtype.basicType();  // normalize Z to I, String to Object, etc.
+
+        int which = MethodTypeForm.LF_VH_GEN_LINKER;
+        LambdaForm lform = mtype.form().cachedLambdaForm(which);
+        if (lform != null) {
+            return lform;
+        }
 
         final int THIS_VH      = 0;
         final int ARG_BASE     = THIS_VH + 1;
@@ -396,19 +398,26 @@ private static LambdaForm varHandleMethodGenericLinkerHandleForm(VarHandle.Acces
         MethodType outCallType = mtype.insertParameterTypes(0, VarHandle.class)
                 .basicType();
         names[LINKER_CALL] = new Name(outCallType, outArgs);
-        LambdaForm lform = new LambdaForm(ARG_LIMIT + 1, names, VARHANDLE_LINKER);
+        lform = new LambdaForm(ARG_LIMIT + 1, names, VARHANDLE_LINKER);
         if (LambdaForm.debugNames()) {
-            String name = ak.methodName() + ":VarHandle_invoke_MT_" +
-                    shortenSignature(basicTypeSignature(mtype));
+            String name = "VarHandle_invoke_MT_" + shortenSignature(basicTypeSignature(mtype));
             LambdaForm.associateWithDebugName(lform, name);
         }
         lform.compileToBytecode();
+
+        lform = mtype.form().setCachedLambdaForm(which, lform);
+
         return lform;
     }
 
-    private static LambdaForm varHandleMethodInvokerHandleForm(VarHandle.AccessMode ak,
-            MethodType mtype, boolean isExact) {
-        // TODO Cache form?
+    private static LambdaForm varHandleMethodInvokerHandleForm(MethodType mtype, boolean isExact) {
+        mtype = mtype.basicType();  // normalize Z to I, String to Object, etc.
+
+        int which = (isExact ? MethodTypeForm.LF_VH_EX_INVOKER : MethodTypeForm.LF_VH_GEN_INVOKER);
+        LambdaForm lform = mtype.form().cachedLambdaForm(which);
+        if (lform != null) {
+            return lform;
+        }
 
         final int THIS_MH      = 0;
         final int CALL_VH      = THIS_MH + 1;
@@ -448,17 +457,18 @@ private static LambdaForm varHandleMethodInvokerHandleForm(VarHandle.AccessMode
         }
 
         MethodType outCallType = mtype.insertParameterTypes(0, VarHandle.class)
-                .basicType();
+                                      .basicType();
         names[LINKER_CALL] = new Name(outCallType, outArgs);
         Kind kind = isExact ? VARHANDLE_EXACT_INVOKER : VARHANDLE_INVOKER;
-        LambdaForm lform = new LambdaForm(ARG_LIMIT, names, kind);
+        lform = new LambdaForm(ARG_LIMIT, names, kind);
         if (LambdaForm.debugNames()) {
-            String name = ak.methodName() +
-                    (isExact ? ":VarHandle_exactInvoker_" : ":VarHandle_invoker_") +
-                    shortenSignature(basicTypeSignature(mtype));
+            String name = (isExact ? "VarHandle_exactInvoker_" : "VarHandle_invoker_") + shortenSignature(basicTypeSignature(mtype));
             LambdaForm.associateWithDebugName(lform, name);
         }
         lform.prepare();
+
+        lform = mtype.form().setCachedLambdaForm(which, lform);
+
         return lform;
     }
 
@@ -473,12 +483,10 @@ static MethodHandle checkVarHandleGenericType(VarHandle handle, VarHandle.Access
         // Test for exact match on invoker types
         // TODO match with erased types and add cast of return value to lambda form
         MethodHandle mh = handle.getMethodHandle(ad.mode);
-        if (mh.type() == ad.symbolicMethodTypeInvoker) {
-            return mh;
-        }
-        else {
+        if (mh.type() != ad.symbolicMethodTypeInvoker) {
             return mh.asType(ad.symbolicMethodTypeInvoker);
         }
+        return mh;
     }
 
     @ForceInline

src/java.base/share/classes/java/lang/invoke/MethodHandleNatives.java

@@ -578,7 +578,7 @@ VarHandleGuards.class, getVarHandleGuardMethodName(guardType),
             // Fall back to lambda form linkage if guard method is not available
             // TODO Optionally log fallback ?
         }
-        return Invokers.varHandleInvokeLinkerMethod(ak, mtype);
+        return Invokers.varHandleInvokeLinkerMethod(mtype);
     }
     static String getVarHandleGuardMethodName(MethodType guardType) {
         String prefix = "guard_";

src/java.base/share/classes/java/lang/invoke/MethodTypeForm.java

@@ -87,7 +87,10 @@ final class MethodTypeForm {
             LF_LOOP                    = 19,  // loop
             LF_INVSPECIAL_IFC          = 20,  // DMH invokeSpecial of (private) interface method
             LF_INVNATIVE               = 21,  // NMH invokeNative
-            LF_LIMIT                   = 22;
+            LF_VH_EX_INVOKER           = 22,  // VarHandle exact invoker
+            LF_VH_GEN_INVOKER          = 23,  // VarHandle generic invoker
+            LF_VH_GEN_LINKER           = 24,  // VarHandle generic linker
+            LF_LIMIT                   = 25;
 
     /** Return the type corresponding uniquely (1-1) to this MT-form.
      *  It might have any primitive returns or arguments, but will have no references except Object.