Prevent recursive initialization, and fix topological sort during lin…

…king.

wasm/src/org.graalvm.wasm.test/src/test/linker/import_export_memory.opts

@@ -0,0 +1,5 @@
+zero-memory = false
+interpreter-iterations = 1
+sync-noinline-iterations = 1
+sync-inline-iterations = 1
+async-iterations = 0

wasm/src/org.graalvm.wasm.test/src/test/linker/import_export_memory.result

@@ -1 +1 @@
-int 0
+int 12

wasm/src/org.graalvm.wasm.test/src/test/linker/import_export_memory/man-in-the-middle.wat

@@ -39,6 +39,13 @@
 ;; SOFTWARE.
 ;;
 (module
+  (type (;0;) (func))
   (import "memory" "memory" (memory (;0;) 4))
   (export "memory" (memory 0))
+  (func $init (type 0)
+    i32.const 0
+    i32.const 12
+    i32.store
+  )
+  (start $init)
 )

wasm/src/org.graalvm.wasm/src/org/graalvm/wasm/ImportDescriptor.java

@@ -60,6 +60,6 @@ public boolean equals(Object object) {
             return false;
         }
         final ImportDescriptor that = (ImportDescriptor) object;
-        return that.moduleName.equals(this.memberName) && that.memberName.equals(this.memberName);
+        return that.moduleName.equals(this.moduleName) && that.memberName.equals(this.memberName);
     }
 }

wasm/src/org.graalvm.wasm/src/org/graalvm/wasm/Linker.java

@@ -59,13 +59,20 @@
 import java.util.function.Consumer;
 
 public class Linker {
+    private enum LinkState {
+        notLinked,
+        inProgress,
+        linked
+    }
+
     private final WasmLanguage language;
     private final ResolutionDag resolutionDag;
-    private @CompilerDirectives.CompilationFinal boolean linked;
+    private @CompilerDirectives.CompilationFinal LinkState linkState;
 
     public Linker(WasmLanguage language) {
         this.language = language;
         this.resolutionDag = new ResolutionDag();
+        this.linkState = LinkState.notLinked;
     }
 
     // TODO: Many of the following methods should work on all the modules in the context, instead of
@@ -79,7 +86,7 @@ public void tryLink() {
         // compilation, and this check will fold away.
         // If the code is compiled synchronously, then this check will persist in the compiled code.
         // We nevertheless invalidate the compiled code that reaches this point.
-        if (!linked) {
+        if (linkState == LinkState.notLinked) {
             // TODO: Once we support multi-threading, add adequate synchronization here.
             tryLinkOutsidePartialEvaluation();
             CompilerDirectives.transferToInterpreterAndInvalidate();
@@ -90,7 +97,8 @@ public void tryLink() {
     private void tryLinkOutsidePartialEvaluation() {
         // Some Truffle configurations allow that the code gets compiled before executing the code.
         // We therefore check the link state again.
-        if (!linked) {
+        if (linkState == LinkState.notLinked) {
+            linkState = LinkState.inProgress;
             Map<String, WasmModule> modules = WasmContext.getCurrent().modules();
             for (WasmModule module : modules.values()) {
                 linkFunctions(module);
@@ -106,7 +114,7 @@ private void tryLinkOutsidePartialEvaluation() {
                 }
             }
             resolutionDag.clear();
-            linked = true;
+            linkState = LinkState.linked;
         }
     }
 
@@ -364,6 +372,11 @@ static class DataDecl extends Decl {
                 this.dataSectionId = dataSectionId;
             }
 
+            @Override
+            public String toString() {
+                return String.format("data %d in %s", dataSectionId, moduleName);
+            }
+
             @Override
             public int hashCode() {
                 return moduleName.hashCode() ^ dataSectionId;
@@ -380,13 +393,20 @@ public boolean equals(Object object) {
         }
 
         static class Resolver {
+            final Decl element;
             final Decl[] dependencies;
             final Runnable action;
 
-            Resolver(Decl[] dependencies, Runnable action) {
+            Resolver(Decl element, Decl[] dependencies, Runnable action) {
+                this.element = element;
                 this.dependencies = dependencies;
                 this.action = action;
             }
+
+            @Override
+            public String toString() {
+                return "Resolver(" + element + ")";
+            }
         }
 
         private final Map<Decl, Resolver> resolutions;
@@ -396,7 +416,7 @@ static class Resolver {
         }
 
         void resolveLater(Decl element, Decl[] dependencies, Runnable action) {
-            resolutions.put(element, new Resolver(dependencies, action));
+            resolutions.put(element, new Resolver(element, dependencies, action));
         }
 
         void clear() {