Remove a unnecessary hasLoopInvariantOperands check in loop sink.

[trentxintong]

Summary

Preheader instruction's operands will always be invariant w.r.t. the loop which its the preheader
for.

Memory aliases are handled in canSinkOrHoistInst.

[trentxintong]

Friendly ping.

[sanjoy]

llvm/trunk/lib/Transforms/Scalar/LoopSink.cpp

286

Did you consider asserting on hasLoopInvariantOperands instead? That kind of checking tends to make things easier to debug.

[trentxintong]

Thats a good idea.

llvm/trunk/lib/Transforms/Scalar/LoopSink.cpp

std::stable_sort(ColdLoopBBs.begin(), ColdLoopBBs.end(),
                      return BFI.getBlockFreq(A) < BFI.getBlockFreq(B);
                    });
 
   // Traverse preheader's instructions in reverse order becaue if A depends
   // on B (A appears after B), A needs to be sinked first before B can be
   // sinked.
   for (auto II = Preheader->rbegin(), E = Preheader->rend(); II != E;) {
     Instruction *I = &*II++;
-    if (!L.hasLoopInvariantOperands(I) ||
-        !canSinkOrHoistInst(*I, &AA, &DT, &L, &CurAST, nullptr))
+    if (!canSinkOrHoistInst(*I, &AA, &DT, &L, &CurAST, nullptr))
       continue;
     if (sinkInstruction(L, *I, ColdLoopBBs, LoopBlockNumber, LI, DT, BFI))
       Changed = true;
   }
 
   if (Changed && SE)
     SE->forgetLoopDispositions(&L);
   return Changed;