Index: lib/CodeGen/PPCGCodeGeneration.cpp
===================================================================
--- lib/CodeGen/PPCGCodeGeneration.cpp
+++ lib/CodeGen/PPCGCodeGeneration.cpp
@@ -1383,15 +1383,47 @@
 
 /// A list of functions that are available in NVIDIA's libdevice.
 const std::set<std::string> CUDALibDeviceFunctions = {
-    "exp",   "expf",     "expl",      "cos",       "cosf", "sqrt",
-    "sqrtf", "copysign", "copysignf", "copysignl", "log",  "logf"};
+    "exp",      "expf",      "expl",      "cos", "cosf", "sqrt", "sqrtf",
+    "copysign", "copysignf", "copysignl", "log", "logf", "powi"};
+
+/// A list of intrinsics that are unsupported by the NVPTX backend.
+const std::set<std::string> NVPTXUnsupportedIntrinsics = {"exp", "powi"};
+
+/// Return <intrinsicname> from the full  "llvm.<intrinsicname>.<ty>" name.
+///
+/// Return "" if function is not an intrinsic.
+std::string getStrippedIntrinsicName(const Function *F) {
+  assert(F && "invalid function pointer");
+  const StringRef FnName = F->getName();
+
+  if (F->isIntrinsic() && FnName.startswith("llvm.")) {
+    const size_t BeginSeparator = FnName.find(".");
+    const size_t EndSeparator = FnName.rfind(".");
+    return std::string(FnName.slice(BeginSeparator + 1, EndSeparator));
+  }
+  return "";
+}
 
 /// Return the corresponding CUDA libdevice function name for @p F.
+/// Note that this function will try to convert instrinsics in the list
+/// NVPTXUnsupportedIntrinsics into libdevice functions.
+/// This is because some intrinsics such as `exp`
+/// are not supported by the NVPTX backend.
+/// If this restriction of the backend is lifted, we should refactor our code
+/// so that we use intrinsics whenever possible.
 ///
 /// Return "" if we are not compiling for CUDA.
 std::string getCUDALibDeviceFuntion(Function *F) {
-  if (CUDALibDeviceFunctions.count(F->getName()))
-    return std::string("__nv_") + std::string(F->getName());
+  const std::string FnName = [&] {
+    const std::string IntrinsicName = getStrippedIntrinsicName(F);
+    if (NVPTXUnsupportedIntrinsics.count(IntrinsicName))
+      return IntrinsicName;
+
+    return std::string(F->getName());
+  }();
+
+  if (CUDALibDeviceFunctions.count(FnName))
+    return "__nv_" + FnName;
 
   return "";
 }
@@ -1409,7 +1441,7 @@
 
   return F->isIntrinsic() &&
          (Name.startswith("llvm.sqrt") || Name.startswith("llvm.fabs") ||
-          Name.startswith("llvm.copysign") || Name.startswith("llvm.powi"));
+          Name.startswith("llvm.copysign"));
 }
 
 /// Do not take `Function` as a subtree value.