Avoid copies of std::strings and APInt/APFloats where we only read from it

As suggested by clang-tidy's performance-unnecessary-copy-initialization.
This can easily hit lifetime issues, so I audited every change and ran the
tests under asan, which came back clean.

llvm-svn: 272126

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c7f6621..d735448 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1120,7 +1120,7 @@ static void computeKnownBitsFromOperator(Operator *I, APInt &KnownZero,
     break;
   case Instruction::URem: {
     if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
-      APInt RA = Rem->getValue();
+      const APInt &RA = Rem->getValue();
       if (RA.isPowerOf2()) {
         APInt LowBits = (RA - 1);
         computeKnownBits(I->getOperand(0), KnownZero, KnownOne, Depth + 1, Q);