Use a temporary variable, rather then a series of redundant calls.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150538 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index 13e20f4..952cd60 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -1576,10 +1576,11 @@
   SmallVector<unsigned, 8> Args;
   SmallVector<MVT, 8> ArgVTs;
   SmallVector<ISD::ArgFlagsTy, 8> ArgFlags;
-  Args.reserve(CS.arg_size());
-  ArgVals.reserve(CS.arg_size());
-  ArgVTs.reserve(CS.arg_size());
-  ArgFlags.reserve(CS.arg_size());
+  unsigned arg_size = CS.arg_size();
+  Args.reserve(arg_size);
+  ArgVals.reserve(arg_size);
+  ArgVTs.reserve(arg_size);
+  ArgFlags.reserve(arg_size);
   for (ImmutableCallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
        i != e; ++i) {
     // If we're lowering a mem intrinsic instead of a regular call, skip the