Demote this opt remark to DEBUG.

From a random opt-stat output:

Top 10 remarks:
  tailcallelim/tailcall          53%
  inline/AlwaysInline            13%
  gvn/LoadClobbered              13%
  inline/Inlined                  8%
  inline/TooCostly                2%
  inline/NoDefinition             2%
  licm/LoadWithLoopInvariantAddressInvalidated  2%
  licm/Hoisted                    1%
  asm-printer/InstructionCount    1%
  prologepilog/StackSize          1%

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319235 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/TailRecursionElimination.cpp

@@ -303,10 +303,7 @@ static bool markTails(Function &F, bool &AllCallsAreTailCalls,
     if (Visited[CI->getParent()] != ESCAPED) {
       // If the escape point was part way through the block, calls after the
       // escape point wouldn't have been put into DeferredTails.
-      ORE->emit([&]() {
-        return OptimizationRemark(DEBUG_TYPE, "tailcall", CI)
-               << "marked as tail call candidate";
-      });
+      DEBUG(dbgs() << "Marked as tail call candidate: " << *CI << "\n");
       CI->setTailCall();
       Modified = true;
     } else {

test/Transforms/TailCallElim/opt-remarks-recursion.ll

@@ -1,7 +1,6 @@
 ; RUN: opt %s -tailcallelim -pass-remarks=tailcallelim -o /dev/null 2>&1 | FileCheck %s
 ; RUN: opt %s -o /dev/null -passes='require<opt-remark-emit>,tailcallelim' -pass-remarks=tailcallelim 2>&1 | FileCheck %s
 
-; CHECK: /home/davide/pat.c:2:20: marked as tail call candidate
 ; CHECK: /home/davide/pat.c:2:20: transforming tail recursion into loop
 define i32 @fib(i32 %n) nounwind ssp {
 entry: