[InstCombine] recognizeBSwapOrBitReverseIdiom - use ArrayRef::back() helper. NFCI.

Post-commit feedback on D88316

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 463c6f1..a76dc65 100644 (file)
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -3027,7 +3027,7 @@ bool llvm::recognizeBSwapOrBitReverseIdiom(
          "Illegal bit provenance index");
 
   // If the upper bits are zero, then attempt to perform as a truncated op.
-  if (BitProvenance[BitProvenance.size() - 1] == BitPart::Unset) {
+  if (BitProvenance.back() == BitPart::Unset) {
     while (!BitProvenance.empty() && BitProvenance.back() == BitPart::Unset)
       BitProvenance = BitProvenance.drop_back();
     if (BitProvenance.empty())