[MSan] Introduce insertWarningFn(). NFC

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Summary

This is a step towards the upcoming KMSAN implementation patch.
KMSAN is going to use a different warning function, __msan_warning_32(uptr origin), so we'd better create the warning calls in one place.

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Formatted the diff with clang-format

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Finally attached the formatted version.

lib/Transforms/Instrumentation/MemorySanitizer.cpp

for (StoreInst *SI : StoreList) {
         SI->setOrdering(addReleaseOrdering(SI->getOrdering()));
 
       if (MS.TrackOrigins && !SI->isAtomic())
         storeOrigin(IRB, Addr, Shadow, getOrigin(Val), OriginPtr,
                     OriginAlignment, InstrumentWithCalls);
     }
   }
 
+/// \brief Helper function to insert a warning at IRB's current insert point.
+void insertWarningFn(IRBuilder<> &IRB, Value *Origin) {
+  if (!Origin) Origin = (Value *)IRB.getInt32(0);
+  if (MS.TrackOrigins) {
+    IRB.CreateStore(Origin, MS.OriginTLS);
+  }
+  IRB.CreateCall(MS.WarningFn, {});
+  IRB.CreateCall(MS.EmptyAsm, {});
+  // FIXME: Insert UnreachableInst if !MS.Recover?
+  // This may invalidate some of the following checks and needs to be done
+  // at the very end.
+}
+
   void materializeOneCheck(Instruction *OrigIns, Value *Shadow, Value *Origin,
                            bool AsCall) {
     IRBuilder<> IRB(OrigIns);
     DEBUG(dbgs() << "  SHAD0 : " << *Shadow << "\n");
     Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
     DEBUG(dbgs() << "  SHAD1 : " << *ConvertedShadow << "\n");
 
     Constant *ConstantShadow = dyn_cast_or_null<Constant>(ConvertedShadow);
     if (ConstantShadow) {
       if (ClCheckConstantShadow && !ConstantShadow->isZeroValue()) {
-        if (MS.TrackOrigins) {
-          IRB.CreateStore(Origin ? (Value *)Origin : (Value *)IRB.getInt32(0),
-                          MS.OriginTLS);
-        }
-        IRB.CreateCall(MS.WarningFn, {});
-        IRB.CreateCall(MS.EmptyAsm, {});
-        // FIXME: Insert UnreachableInst if !MS.Recover?
-        // This may invalidate some of the following checks and needs to be done
-        // at the very end.
+        insertWarningFn(IRB, Origin);
       }
       return;
     }
 
     const DataLayout &DL = OrigIns->getModule()->getDataLayout();
 
     unsigned TypeSizeInBits = DL.getTypeSizeInBits(ConvertedShadow->getType());
     unsigned SizeIndex = TypeSizeToSizeIndex(TypeSizeInBits);
     if (AsCall && SizeIndex < kNumberOfAccessSizes) {
       Value *Fn = MS.MaybeWarningFn[SizeIndex];
       Value *ConvertedShadow2 =
           IRB.CreateZExt(ConvertedShadow, IRB.getIntNTy(8 * (1 << SizeIndex)));
       IRB.CreateCall(Fn, {ConvertedShadow2, MS.TrackOrigins && Origin
                                                 ? Origin
                                                 : (Value *)IRB.getInt32(0)});
     } else {
       Value *Cmp = IRB.CreateICmpNE(ConvertedShadow,
                                     getCleanShadow(ConvertedShadow), "_mscmp");
       Instruction *CheckTerm = SplitBlockAndInsertIfThen(
           Cmp, OrigIns,
           /* Unreachable */ !MS.Recover, MS.ColdCallWeights);
 
       IRB.SetInsertPoint(CheckTerm);
-      if (MS.TrackOrigins) {
-        IRB.CreateStore(Origin ? (Value *)Origin : (Value *)IRB.getInt32(0),
-                        MS.OriginTLS);
-      }
-      IRB.CreateCall(MS.WarningFn, {});
-      IRB.CreateCall(MS.EmptyAsm, {});
+      insertWarningFn(IRB, Origin);
       DEBUG(dbgs() << "  CHECK: " << *Cmp << "\n");
     }
   }
 
   void materializeChecks(bool InstrumentWithCalls) {
     for (const auto &ShadowData : InstrumentationList) {
       Instruction *OrigIns = ShadowData.OrigIns;
       Value *Shadow = ShadowData.Shadow;