[MC] Avoid useless triple copy (#103026)

Copying a triple is cheap, but not free, so let's not do that if there's
no reason to do so. Trivial cleanup.

Author: aengelke

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -525,7 +525,7 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
         TM.getCodeModel() == CodeModel::Large)
       return false;
 
-    Triple TargetTriple = TM.getTargetTriple();
+    const Triple &TargetTriple = TM.getTargetTriple();
     if (!TargetTriple.isArch64Bit())
       return false;
 

llvm/lib/MC/MCObjectFileInfo.cpp

@@ -1024,7 +1024,7 @@ void MCObjectFileInfo::initMCObjectFileInfo(MCContext &MCCtx, bool PIC,
   DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
   DwarfAccelTypesSection = nullptr;     // Used only by selected targets.
 
-  Triple TheTriple = Ctx->getTargetTriple();
+  const Triple &TheTriple = Ctx->getTargetTriple();
   switch (Ctx->getObjectFileType()) {
   case MCContext::IsMachO:
     initMachOMCObjectFileInfo(TheTriple);