[AbstractCallSite] Handle Indirect Calls Properly (#163003)

AbstractCallSite handles three types of calls (direct, indirect, and
callback).

This patch fixes the handling of indirect calls in some methods, which
incorrectly assumed that non-direct calls are always callback calls.

Moreover, this PR adds 2 unit tests for direct call type and indirect
call type.

The aforementioned misassumption leads to the following problem:

---
## Problem

When the underlying call is **indirect**, some APIs of
`AbstractCallSite` behave unexpectedly.
E.g., `AbstractCallSite::getCalledFunction()` currently triggers an
**assertion failure**, instead of returning `nullptr` as documented:

```cpp
/// Return the function being called if this is a direct call, otherwise
/// return null (if it's an indirect call).
Function *getCalledFunction() const;
```

Actual unexpected assertion failure:
```
AbstractCallSite.h:197: int llvm::AbstractCallSite::getCallArgOperandNoForCallee() const: Assertion `isCallbackCall()' failed.
```

This is because `AbstractCallSite` mistakenly entered the branch that
handles Callback Calls as its guard condition (`!isDirectCall()`) does
not take into account the case of indirect calls

0 files changed, 0 insertions, 0 deletions