Implement a -trace command line option and a trace option in the interpreter.

llvm-svn: 989
diff --git a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
index a7ded5b..1d7ec7a 100644
--- a/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
+++ b/llvm/lib/ExecutionEngine/Interpreter/Execution.cpp
@@ -834,6 +834,9 @@
   ExecutionContext &SF = ECStack.back();  // Current stack frame
   Instruction *I = *SF.CurInst++;         // Increment before execute
 
+  if (Trace)
+    cout << "Run:" << I;
+
   if (I->isBinaryOp()) {
     executeBinaryInst((BinaryOperator*)I, SF);
   } else {