[llvm-branch-commits] [ubsan] Improve lowering of @llvm.allow.ubsan.check (PR #119013)

[Vitaly Buka via llvm-branch-commits]

https://github.com/vitalybuka created https://github.com/llvm/llvm-project/pull/119013

This fix the case, when single hot inlined callsite, prevent
checks for all other. This helps to reduce number of removed checks up to 50% (deppedes on `cutoff-hot` value) .

`ScalarOptimizerLateEPCallback` was happening during
CGSCC walk, after each inlining, but this is effectively
after inlining.

Example, order in comments:

```
static void overflow() {
  // 1. Inline get/set if possible
  // 2. Simplify
  // 3. LowerAllowCheckPass
  set(get() + get());
}

void test() {
  // 4. Inline
  // 5. Nothing for LowerAllowCheckPass
  overflow();
}
```

With this patch it will look like:
```
static void overflow() {
  // 1. Inline get/set if possible
  // 2. Simplify
  set(get() + get());
}

void test() {
  // 3. Inline
  // 4. Simplify
  overflow();
}

// Later, after inliner CGSCC walk complete:
// 5. LowerAllowCheckPass for `overflow`
// 6. LowerAllowCheckPass for `test`
```