load bootstrap classes in findInterfaceMethod

In afbd4ff, I made a low-risk, but very specific fix for a more
general problem: "bootstrap" classes (i.e. classes which the VM has
built-in knowledge of) need to be loaded from the classpath before any
of their methods are called.  Based on recent testing, I found there were
more cases than I previously thought where the VM tries to call methods on
"unloaded" bootstrap classes, so we needed a more general solution to
the problem.

This commit addresses it by closing the last (known) loophole by which
methods might be called on bootstrap classes: invokeinterface, and its
helper method findInterfaceMethod.  The fix is to check for bootstrap
classes in findInterfaceMethod and load the full versions if
necessary.  This process may lead to garbage collection and/or thrown
exceptions, which made me nervous about cases of direct or indirect
calls to findInterfaceMethod not expecting those events, which is why
I hadn't used that approach earlier.  However, it turns out there were
only a few places that made non-GC-safe calls to findInterfaceMethod,
and a bit of code rearrangement fixed that.

src/avian/machine.h

@@ -2675,7 +2675,12 @@ inline GcMethod* findInterfaceMethod(Thread* t,
                                      GcMethod* method,
                                      GcClass* class_)
 {
-  assertT(t, (class_->vmFlags() & BootstrapFlag) == 0);
+  if (UNLIKELY(class_->vmFlags() & BootstrapFlag)) {
+    PROTECT(t, method);
+    PROTECT(t, class_);
+
+    resolveSystemClass(t, roots(t)->bootLoader(), class_->name());
+  }
 
   GcClass* interface = method->class_();
   GcArray* itable = cast<GcArray>(t, class_->interfaceTable());

src/classpath-openjdk.cpp

@@ -2452,19 +2452,10 @@ object makeJconstructor(Thread* t,
 }
 #endif  // HAVE_JexecutableHasRealParameterData
 
-void resolveBootstrap(Thread* t, Gc::Type type)
-{
-  if (vm::type(t, type)->vmFlags() & BootstrapFlag) {
-    resolveSystemClass(t, roots(t)->bootLoader(), vm::type(t, type)->name());
-  }
-}
-
 object makeJmethod(Thread* t, GcMethod* vmMethod, int index)
 {
   PROTECT(t, vmMethod);
 
-  resolveBootstrap(t, GcJmethod::Type);
-
   object name
       = intern(t,
                t->m->classpath->makeString(
@@ -2567,8 +2558,6 @@ object makeJconstructor(Thread* t, GcMethod* vmMethod, int index)
 {
   PROTECT(t, vmMethod);
 
-  resolveBootstrap(t, GcJconstructor::Type);
-
   unsigned parameterCount;
   unsigned returnTypeSpec;
   object parameterTypes = resolveParameterJTypes(t,
@@ -2649,8 +2638,6 @@ object makeJfield(Thread* t, GcField* vmField, int index)
 {
   PROTECT(t, vmField);
 
-  resolveBootstrap(t, GcJfield::Type);
-
   object name
       = intern(t,
                t->m->classpath->makeString(

src/compile.cpp

@@ -8639,8 +8639,6 @@ class MyProcessor : public Processor {
 
     assertT(t, ((method->flags() & ACC_STATIC) == 0) xor (this_ == 0));
 
-    method = findMethod(t, method, this_);
-
     const char* spec = reinterpret_cast<char*>(method->spec()->body().begin());
 
     unsigned size = method->parameterFootprint();
@@ -8656,6 +8654,8 @@ class MyProcessor : public Processor {
 
     PROTECT(t, method);
 
+    method = findMethod(t, method, this_);
+
     compile(static_cast<MyThread*>(t),
             local::codeAllocator(static_cast<MyThread*>(t)),
             0,
@@ -8677,8 +8677,6 @@ class MyProcessor : public Processor {
 
     assertT(t, ((method->flags() & ACC_STATIC) == 0) xor (this_ == 0));
 
-    method = findMethod(t, method, this_);
-
     const char* spec = reinterpret_cast<char*>(method->spec()->body().begin());
 
     unsigned size = method->parameterFootprint();
@@ -8694,6 +8692,8 @@ class MyProcessor : public Processor {
 
     PROTECT(t, method);
 
+    method = findMethod(t, method, this_);
+
     compile(static_cast<MyThread*>(t),
             local::codeAllocator(static_cast<MyThread*>(t)),
             0,
@@ -8716,8 +8716,6 @@ class MyProcessor : public Processor {
 
     assertT(t, ((method->flags() & ACC_STATIC) == 0) xor (this_ == 0));
 
-    method = findMethod(t, method, this_);
-
     const char* spec = reinterpret_cast<char*>(method->spec()->body().begin());
 
     unsigned size = method->parameterFootprint();
@@ -8734,6 +8732,8 @@ class MyProcessor : public Processor {
 
     PROTECT(t, method);
 
+    method = findMethod(t, method, this_);
+
     compile(static_cast<MyThread*>(t),
             local::codeAllocator(static_cast<MyThread*>(t)),
             0,

test/Threads.java

@@ -1,4 +1,4 @@
-public class Threads implements Runnable {  
+public class Threads implements Runnable {
   private static boolean success = false;
 
   private static void expect(boolean v) {
@@ -6,6 +6,9 @@ public class Threads implements Runnable {
   }
 
   public static void main(String[] args) throws Exception {
+    ((Thread.UncaughtExceptionHandler) Thread.currentThread().getThreadGroup())
+      .uncaughtException(Thread.currentThread(), new Exception());
+
     { Threads test = new Threads();
       Thread thread = new Thread(test);
 
@@ -41,7 +44,7 @@ public class Threads implements Runnable {
           // do nothing
         }
       };
-    
+
       thread.start();
       thread.join();
     }