[llvm] [PGO] Gracefully handle zero entry-count in `fixFuncEntryCount` (PR #112029)

[via llvm-commits]

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@@ -1972,11 +1972,9 @@ static void fixFuncEntryCount(PGOUseFunc &Func, LoopInfo &LI,
                               BranchProbabilityInfo &NBPI) {
   Function &F = Func.getFunc();
   BlockFrequencyInfo NBFI(F, NBPI, LI);
-#ifndef NDEBUG
   auto BFIEntryCount = F.getEntryCount();
-  assert(BFIEntryCount && (BFIEntryCount->getCount() > 0) &&
-         "Invalid BFI Entrycount");
-#endif
+  if (!BFIEntryCount || BFIEntryCount->getCount() == 0)
----------------
WenleiHe wrote:

Yeah, given we're doing that already, I think it makes sense to fix it in `populateCounters` -- that code below should be close. Entry should not be zero if there is any count in the function. 

```
  // Fix the obviously inconsistent entry count.
  if (FuncMaxCount > 0 && FuncEntryCount == 0)
    FuncEntryCount = 1;
```

https://github.com/llvm/llvm-project/pull/112029