Deal with error handling better.

llvm-svn: 34887
diff --git a/llvm/lib/ExecutionEngine/JIT/JIT.h b/llvm/lib/ExecutionEngine/JIT/JIT.h
index c8c8987..95105c9 100644
--- a/llvm/lib/ExecutionEngine/JIT/JIT.h
+++ b/llvm/lib/ExecutionEngine/JIT/JIT.h
@@ -71,7 +71,7 @@
   /// create - Create an return a new JIT compiler if there is one available
   /// for the current target.  Otherwise, return null.
   ///
-  static ExecutionEngine *create(ModuleProvider *MP);
+  static ExecutionEngine *create(ModuleProvider *MP, std::string* = 0);
 
   /// run - Start execution with the specified function and arguments.
   ///
diff --git a/llvm/lib/ExecutionEngine/JIT/TargetSelect.cpp b/llvm/lib/ExecutionEngine/JIT/TargetSelect.cpp
index c30f88c..30fd2fa 100644
--- a/llvm/lib/ExecutionEngine/JIT/TargetSelect.cpp
+++ b/llvm/lib/ExecutionEngine/JIT/TargetSelect.cpp
@@ -38,11 +38,15 @@
 /// create - Create an return a new JIT compiler if there is one available
 /// for the current target.  Otherwise, return null.
 ///
-ExecutionEngine *JIT::create(ModuleProvider *MP) {
+ExecutionEngine *JIT::create(ModuleProvider *MP, std::string *ErrorStr) {
   if (MArch == 0) {
     std::string Error;
     MArch = TargetMachineRegistry::getClosestTargetForJIT(Error);
-    if (MArch == 0) return 0;
+    if (MArch == 0) {
+      if (ErrorStr)
+        *ErrorStr = Error;
+      return 0;
+    }
   } else if (MArch->JITMatchQualityFn() == 0) {
     cerr << "WARNING: This target JIT is not designed for the host you are"
          << " running.  If bad things happen, please choose a different "
@@ -66,5 +70,8 @@
   // If the target supports JIT code generation, return a new JIT now.
   if (TargetJITInfo *TJ = Target->getJITInfo())
     return new JIT(MP, *Target, *TJ);
+
+  if (ErrorStr)
+    *ErrorStr = "target does not support JIT code generation";
   return 0;
 }