Use back() instead of [size()-1].

llvm-svn: 52600
diff --git a/llvm/lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp b/llvm/lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp
index 3b10a95..7f01536 100644
--- a/llvm/lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp
+++ b/llvm/lib/ExecutionEngine/JIT/JITDwarfEmitter.cpp
@@ -364,7 +364,7 @@
 
       // Try to merge with the previous call-site.
       if (CallSites.size()) {
-        CallSiteEntry &Prev = CallSites[CallSites.size()-1];
+        CallSiteEntry &Prev = CallSites.back();
         if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
           // Extend the range of the previous entry.
           Prev.EndLabel = Site.EndLabel;
@@ -979,7 +979,7 @@
 
       // Try to merge with the previous call-site.
       if (CallSites.size()) {
-        CallSiteEntry &Prev = CallSites[CallSites.size()-1];
+        CallSiteEntry &Prev = CallSites.back();
         if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
           // Extend the range of the previous entry.
           Prev.EndLabel = Site.EndLabel;