message: Fix loop iterations
  Exit condition in loop header was always True
diff: @@ -106,11 +106,13 @@ MemoryCoalescing::BasePtrInfo MemoryCoalescing::analyseVarOffsetGEP(llvm::GetEle
  // Find the last constant idxs: we may be able to use them as constant offset for
  // several GEPs with common pre-constant part
  auto FirstConstIdx = GEP->getNumOperands();
  - for (unsigned i = FirstConstIdx - 1; i >= 0; --i) {
  + Assert(FirstConstIdx);
  + unsigned i = FirstConstIdx - 1;
  + do {
  if (!llvm::isa<llvm::ConstantInt>(GEP->getOperand(i)))
  break;
  FirstConstIdx = i;
  - }
  + } while (i--);
  // Early return in case when no constant offset was found:
  // further actions are useless.
  if (GEP->getNumOperands() == FirstConstIdx) {
  