[LV] Return debug loc directly from getDebugLocFromInstrOrOps (NFCI)

The return value of the function is only used to get the debug location.
Directly return the debug location, as this avoids an extra null
check in the caller.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -932,21 +932,21 @@ class EpilogueVectorizerEpilogueLoop : public InnerLoopAndEpilogueVectorizer {
 
 /// Look for a meaningful debug location on the instruction or it's
 /// operands.
-static Instruction *getDebugLocFromInstOrOperands(Instruction *I) {
+static DebugLoc getDebugLocFromInstOrOperands(Instruction *I) {
   if (!I)
-    return I;
+    return DebugLoc();
 
   DebugLoc Empty;
   if (I->getDebugLoc() != Empty)
-    return I;
+    return I->getDebugLoc();
 
   for (Use &Op : I->operands()) {
     if (Instruction *OpInst = dyn_cast<Instruction>(Op))
       if (OpInst->getDebugLoc() != Empty)
-        return OpInst;
+        return OpInst->getDebugLoc();
   }
 
-  return I;
+  return I->getDebugLoc();
 }
 
 /// Write a \p DebugMsg about vectorization to the debug output stream. If \p I
@@ -8814,10 +8814,8 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
   for (ElementCount VF : Range)
     IVUpdateMayOverflow |= !isIndvarOverflowCheckKnownFalse(&CM, VF);
 
-  Instruction *DLInst =
-      getDebugLocFromInstOrOperands(Legal->getPrimaryInduction());
-  addCanonicalIVRecipes(*Plan, Legal->getWidestInductionType(),
-                        DLInst ? DLInst->getDebugLoc() : DebugLoc(),
+  DebugLoc DL = getDebugLocFromInstOrOperands(Legal->getPrimaryInduction());
+  addCanonicalIVRecipes(*Plan, Legal->getWidestInductionType(), DL,
                         CM.getTailFoldingStyle(IVUpdateMayOverflow));
 
   // Proactively create header mask. Masks for other blocks are created on