Switch lowering: use uint32_t for weights everywhere

I previously thought switch clusters would need to use uint64_t in case
the weights of multiple cases overflowed a 32-bit int. It turns
out that the weights on a terminator instruction are capped to allow for
being added together, so using a uint32_t should be safe.

llvm-svn: 235945
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 7c2cef6..ba6d974 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -153,7 +153,7 @@
       unsigned JTCasesIndex;
       unsigned BTCasesIndex;
     };
-    uint64_t Weight;
+    uint32_t Weight;
 
     static CaseCluster range(const ConstantInt *Low, const ConstantInt *High,
                              MachineBasicBlock *MBB, uint32_t Weight) {