[llvm] [ArgPromotion] Handle pointer arguments of recursive calls (PR #78735)

[Vedant Paranjape via llvm-commits]

================
@@ -422,13 +422,16 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
 
 /// Return true if we can prove that all callees pass in a valid pointer for the
 /// specified function argument.
-static bool allCallersPassValidPointerForArgument(Argument *Arg,
-                                                  Align NeededAlign,
-                                                  uint64_t NeededDerefBytes) {
+static bool allCallersPassValidPointerForArgument(
+    Argument *Arg, SmallPtrSet<CallBase *, 4> &RecursiveCalls,
+    Align NeededAlign, uint64_t NeededDerefBytes) {
   Function *Callee = Arg->getParent();
   const DataLayout &DL = Callee->getParent()->getDataLayout();
   APInt Bytes(64, NeededDerefBytes);
 
+  if (RecursiveCalls.size())
+    return true;
----------------
vedantparanjape-amd wrote:

> The code currently only looks for dereferenceable attributes on the caller (i.e. bar()), not the function itself.

Even this doesn't seem to work or manually adding a load i32 on ptr %x

```
define i32 @bar(ptr dereferenceable(32) %x, i32 %n, i32 %m) {
entry:
  %tmp3 = call i32 @foo(ptr %x, i32 %n, i32 %m)
  br label %return

return:                                           ; preds = %entry
  ret i32 %tmp3
}
```

https://github.com/llvm/llvm-project/pull/78735