Vendor import of llvm trunk r130700:

http://llvm.org/svn/llvm-project/llvm/trunk@130700

1 files changed, 7 insertions, 3 deletions

diff --git a/include/llvm/Target/TargetInstrItineraries.h b/include/llvm/Target/TargetInstrItineraries.h
index a95b70f..198d585 100644
--- a/include/llvm/Target/TargetInstrItineraries.h
+++ b/include/llvm/Target/TargetInstrItineraries.h
@@ -155,9 +155,13 @@ public:
   /// in the itinerary.
   ///
   unsigned getStageLatency(unsigned ItinClassIndx) const {
-    // If the target doesn't provide itinerary information, use a
-    // simple non-zero default value for all instructions.
-    if (isEmpty())
+    // If the target doesn't provide itinerary information, use a simple
+    // non-zero default value for all instructions.  Some target's provide a
+    // dummy (Generic) itinerary which should be handled as if it's itinerary is
+    // empty. We identify this by looking for a reference to stage zero (invalid
+    // stage). This is different from beginStage == endState != 0, which could
+    // be used for zero-latency pseudo ops.
+    if (isEmpty() || Itineraries[ItinClassIndx].FirstStage == 0)
       return 1;
 
     // Calculate the maximum completion time for any stage.