[llvm] [FuncAttrs] Relax norecurse attribute inference (PR #139943)

[Usha Gupta via llvm-commits]

================
@@ -2071,24 +2072,36 @@ static void addNoRecurseAttrs(const SCCNodeSet &SCCNodes,
   if (!F || !F->hasExactDefinition() || F->doesNotRecurse())
     return;
 
-  // If all of the calls in F are identifiable and are to norecurse functions, F
-  // is norecurse. This check also detects self-recursion as F is not currently
-  // marked norecurse, so any called from F to F will not be marked norecurse.
-  for (auto &BB : *F)
-    for (auto &I : BB.instructionsWithoutDebug())
+  if (F->hasAddressTaken())
----------------
usha1830 wrote:

Thanks for the review @david-arm.

> ```
> foo() -> bar() -> moo() -> foo()
> ```
> 
> or
> 
> ```
> boo() -> foo() -> bar() -> moo() -> boo()
> ```
These cases should be covered with an earlier check in the function as the SCC for foo will have more than 1 node

` if (SCCNodes.size() != 1) return;`

I have added a test in this PR for multi-SCC cases like this.


https://github.com/llvm/llvm-project/pull/139943