[llvm] [AMDGPU] Avoid resource propagation for recursion through multiple functions (PR #111004)

[Matt Arsenault via llvm-commits]

================
@@ -91,8 +91,17 @@ MCSymbol *MCResourceInfo::getMaxSGPRSymbol(MCContext &OutContext) {
   return OutContext.getOrCreateSymbol("amdgpu.max_num_sgpr");
 }
 
+// The (partially complete) expression should have no recursion in it. After
+// all, we're trying to avoid recursion using this codepath.
 static bool findSymbolInExpr(MCSymbol *Sym, const MCExpr *Expr,
-                             SmallVectorImpl<const MCExpr *> &Exprs) {
+                             SmallVectorImpl<const MCExpr *> &Exprs,
+                             SmallPtrSetImpl<const MCExpr *> &Visited) {
+  // Assert if any of the expressions is already visited (i.e., there is
+  // existing recursion).
+  assert(!Visited.contains(Expr) &&
+         "Expr should not exist in Visited as we're avoiding recursion");
+  Visited.insert(Expr);
----------------
arsenm wrote:

```suggestion
  if (!Visited.insert(Expr).second)
    llvm_unreachable("already visited expression");
```

https://github.com/llvm/llvm-project/pull/111004