[llvm] [InstCombine] Remove transformation on call instruction where return value need void to non-void conversion (PR #98536)

[Nikita Popov via llvm-commits]

================
@@ -4071,9 +4071,7 @@ bool InstCombinerImpl::transformConstExprCastCall(CallBase &Call) {
       if (Callee->isDeclaration())
         return false;   // Cannot transform this return value.
 
-      if (!Caller->use_empty() &&
-          // void -> non-void is handled specially
-          !NewRetTy->isVoidTy())
+      if (!Caller->use_empty() || NewRetTy->isVoidTy())
----------------
nikic wrote:

```suggestion
      if (!Caller->use_empty())
```
A more conservative change would be this. In that case we'd still allow changing the return type to void as long as the return value is not used. That may be more consistent with the overall handling?

https://github.com/llvm/llvm-project/pull/98536