third_party/llvm-7.0/llvm/test/Analysis/CFLAliasAnalysis/Steensgaard/interproc-ret-ref-arg.ll

; This testcase ensures that CFL AA answers queries soundly when callee tries 
; to return the reference of one of its parameters

; RUN: opt < %s -disable-basicaa -cfl-steens-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
; RUN: opt < %s -aa-pipeline=cfl-steens-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s

declare noalias i8* @malloc(i64)

define i32** @return_ref_arg_callee(i32* %arg1) {
	%ptr = call noalias i8* @malloc(i64 8)
	%ptr_cast = bitcast i8* %ptr to i32**
	store i32* %arg1, i32** %ptr_cast
	ret i32** %ptr_cast
}
; CHECK-LABEL: Function: test_return_ref_arg
; CHECK: MayAlias: i32* %a, i32* %lb
; CHECK: NoAlias: i32* %lb, i32** %p
; CHECK: NoAlias: i32* %lb, i32** %b
; CHECK: NoAlias: i32* %lp, i32** %p
; CHECK: NoAlias: i32* %lp, i32** %b
; CHECK: MayAlias: i32* %lb, i32* %lp

; We could've proven the following facts if the analysis were inclusion-based:
; NoAlias: i32** %b, i32** %p
define void @test_return_ref_arg() {
  %a = alloca i32, align 4
  %p = alloca i32*, align 8

  store i32* %a, i32** %p
  %b = call i32** @return_ref_arg_callee(i32* %a)

  %lb = load i32*, i32** %b
  %lp = load i32*, i32** %p

  ret void
}