Renumber subroutines after removing unreachable code.

Author: pratikashar

visa/FlowGraph.cpp

@@ -1751,6 +1751,7 @@ void FlowGraph::removeUnreachableBlocks(FuncInfoHashTable& funcInfoHT)
     }
     reassignBlockIDs();
     setPhysicalPredSucc();
+    reassignFuncIds(funcInfoHT);
 }
 
 // prevent overwriting dump file and indicate compilation order with dump serial number
@@ -2385,6 +2386,18 @@ void FlowGraph::linkDummyBB()
     }
 }
 
+//
+// Re-assign function ids as implementation expects them to be consecutive.
+//
+void FlowGraph::reassignFuncIds(FuncInfoHashTable& funcInfoHT)
+{
+    unsigned int index = 0;
+    for (auto& item : funcInfoHT)
+    {
+        item.second->setId(index++);
+    }
+}
+
 //
 // Re-assign block ID so that we can use id to determine the ordering of two blocks in the code layout
 //

visa/FlowGraph.h

@@ -1106,11 +1106,20 @@ class FlowGraph
     // Add a dummy BB for multiple-exit flow graph
     //
     void linkDummyBB();
+
+    //
+    // Reassign function ids in case some functions were optimized away as dead code.
+    // Implementation uses function id to index in to std::vector so there shouldnt
+    // be holds in function ids.
+    //
+    void reassignFuncIds(FuncInfoHashTable& funcInfoHT);
+
     //
     // Re-assign block ID so that we can use id to determine the ordering of two blocks in
     // the code layout
     //
     void reassignBlockIDs();
+
     //
     // Remove blocks that are unreachable via control flow of program
     //