Fix an off-by-one error in the stack frame iteration.

runtime/vm/code_descriptors_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
 
 #include "vm/ast.h"
 #include "vm/assembler.h"
@@ skipping 174 matching lines @@
       Function::Handle(cls.LookupStaticFunction(function_moo_name));
   EXPECT(CompilerTest::TestCompileFunction(function_moo));
   EXPECT(function_moo.HasCode());
 
   String& function_foo_name = String::Handle(String::New("foo"));
   Function& function_foo =
       Function::Handle(cls.LookupStaticFunction(function_foo_name));
   EXPECT(CompilerTest::TestCompileFunction(function_foo));
   EXPECT(function_foo.HasCode());
 
-  // Build and setup a stackmap for function 'A.foo' in order to test the
-  // traversal of stack maps when a GC happens.
+  // Build and setup a stackmap for the call to 'func' in 'A.foo' in order
+  // to test the traversal of stack maps when a GC happens.
   StackmapBuilder* builder = new StackmapBuilder();
   EXPECT(builder != NULL);
   builder->SetSlotAsValue(0);  // var i.
   builder->SetSlotAsObject(1);  // var s1.
   builder->SetSlotAsValue(2);  // var k.
   builder->SetSlotAsObject(3);  // var s2.
   builder->SetSlotAsObject(4);  // var s3.
+  builder->SetSlotAsObject(5);  // First argument to func(i, k).
+  builder->SetSlotAsObject(6);  // Second argument to func(i, k).
   const Code& code = Code::Handle(function_foo.unoptimized_code());
   // Search for the pc of the call to 'func'.
   const PcDescriptors& descriptors =
       PcDescriptors::Handle(code.pc_descriptors());
+  int call_count = 0;
   for (int i = 0; i < descriptors.Length(); ++i) {
     if (descriptors.DescriptorKind(i) == PcDescriptors::kFuncCall) {
       builder->AddEntry(descriptors.PC(i) - code.EntryPoint());
+      ++call_count;
     }
   }
+  // We can't easily check that we put the stackmap at the correct pc, but
+  // we did if there was exactly one call seen.
+  EXPECT(call_count == 1);
   const Array& stack_maps = Array::Handle(builder->FinalizeStackmaps(code));
   code.set_stackmaps(stack_maps);
 
   // Now invoke 'A.moo' and it will trigger a GC when the native function
   // is called, this should then cause the stack map of function 'A.foo'
   // to be traversed and the appropriate objects visited.
   GrowableArray<const Object*> arguments;
   const Array& kNoArgumentNames = Array::Handle();
   Object& result = Object::Handle();
   result = DartEntry::InvokeStatic(function_foo, arguments, kNoArgumentNames);
   EXPECT(!result.IsError());
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32 || defined(TARGET_ARCH_X64)