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, 2 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index fb6ec5feb53..618bfb15718 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1615,7 +1615,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
       for (unsigned Idx = 0; Idx < NumElements; ++Idx) {
         if (ConstantInt *Elt =
                 dyn_cast<ConstantInt>(ConstArg->getAggregateElement(Idx))) {
-          APInt V = Elt->getValue();
+          const APInt &V = Elt->getValue();
           APInt V2 = APInt(V.getBitWidth(), 1) << V.countTrailingZeros();
           Elements.push_back(ConstantInt::get(EltTy, V2));
         } else {
@@ -1625,7 +1625,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
       ShadowMul = ConstantVector::get(Elements);
     } else {
       if (ConstantInt *Elt = dyn_cast<ConstantInt>(ConstArg)) {
-        APInt V = Elt->getValue();
+        const APInt &V = Elt->getValue();
         APInt V2 = APInt(V.getBitWidth(), 1) << V.countTrailingZeros();
         ShadowMul = ConstantInt::get(Ty, V2);
       } else {