[llvm] [Analysis]: Allow inlining recursive call IF recursion depth is 1. (PR #119677)

[David Green via llvm-commits]

================
@@ -1666,6 +1670,78 @@ bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
   return isGEPFree(I);
 }
 
+/// Simplify \p Cmp if RHS is const and we can ValueTrack LHS,
+// This handles the case when the Cmp instruction is guarded a recursive call
+// that will cause the Cmp to fail/succeed for the next iteration.
+bool CallAnalyzer::simplifyCmpInst(Function *F, CmpInst &Cmp) {
+  // Bail out if the RHS is NOT const:
+  if (!isa<Constant>(Cmp.getOperand(1)))
----------------
davemgreen wrote:

Can we check here that Cmp.getOperand(0) is a function argument? It is checked below too but this will allow it to early exit for a lot of icmp's.

https://github.com/llvm/llvm-project/pull/119677