llvm/test/Transforms/GVN/volatile-nonvolatile.ll

; RUN: opt -passes=gvn -S < %s | FileCheck %s

%struct.t = type { ptr }

; The loaded address and the location of the address itself are not aliased,
; so the second reload is not necessary. Check that it can be eliminated.
; CHECK-LABEL: test1
; CHECK: load
; CHECK-NOT: load
define void @test1(ptr nocapture readonly %p, i32 %v) #0 {
entry:
  %0 = load ptr, ptr %p, align 4, !tbaa !1
  store volatile i32 %v, ptr %0, align 4, !tbaa !6
  %1 = load ptr, ptr %p, align 4, !tbaa !1
  store volatile i32 %v, ptr %1, align 4, !tbaa !6
  ret void
}

; The store via the loaded address may overwrite the address itself.
; Make sure that both loads remain.
; CHECK-LABEL: test2
; CHECK: load
; CHECK: store
; CHECK: load
define void @test2(ptr nocapture readonly %p, i32 %v) #0 {
entry:
  %0 = load ptr, ptr %p, align 4, !tbaa !1
  store volatile i32 %v, ptr %0, align 4, !tbaa !1
  %1 = load ptr, ptr %p, align 4, !tbaa !1
  store volatile i32 %v, ptr %1, align 4, !tbaa !1
  ret void
}

; The loads are ordered and non-monotonic. Although they are not aliased to
; the stores, make sure both are preserved.
; CHECK-LABEL: test3
; CHECK: load
; CHECK: store
; CHECK: load
define void @test3(ptr nocapture readonly %p, i32 %v) #0 {
entry:
  %0 = load atomic ptr, ptr %p acquire, align 4, !tbaa !1
  store volatile i32 %v, ptr %0, align 4, !tbaa !6
  %1 = load atomic ptr, ptr %p acquire, align 4, !tbaa !1
  store volatile i32 %v, ptr %1, align 4, !tbaa !6
  ret void
}

attributes #0 = { norecurse nounwind }

!1 = !{!2, !3, i64 0}
!2 = !{!"", !3, i64 0}
!3 = !{!"any pointer", !4, i64 0}
!4 = !{!"omnipotent char", !5, i64 0}
!5 = !{!"Simple C/C++ TBAA"}
!6 = !{!7, !7, i64 0}
!7 = !{!"int", !4, i64 0}