; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; Verify that strnlen calls that aren't folded into constants are annotated
; with noundef, nonnull, and dereferenceable only when maxlen is known to
; to be nonzero.
;
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

declare i64 @strnlen(i8*, i64)

@ecp = external global i8*, align 8


; Annotate strnlen(ecp, 3) call with noundef, nonnull, and dereferenceable
; based on the access to *ecp.

define i64 @deref_strnlen_ecp_3() {
; CHECK-LABEL: @deref_strnlen_ecp_3(
; CHECK-NEXT:    [[PTR:%.*]] = load i8*, i8** @ecp, align 8
; CHECK-NEXT:    [[LEN:%.*]] = call i64 @strnlen(i8* noundef nonnull dereferenceable(1) [[PTR]], i64 3)
; CHECK-NEXT:    ret i64 [[LEN]]
;
  %ptr = load i8*, i8** @ecp
  %len = call i64 @strnlen(i8* %ptr, i64 3)
  ret i64 %len
}


; Annotate strnlen(ecp, %n) call with nonzero %n with noundef, nonnull, and
; dereferenceable based on the access to *ecp.

define i64 @deref_strnlen_ecp_nz(i64 %n) {
; CHECK-LABEL: @deref_strnlen_ecp_nz(
; CHECK-NEXT:    [[NONZERO:%.*]] = or i64 [[N:%.*]], 1
; CHECK-NEXT:    [[PTR:%.*]] = load i8*, i8** @ecp, align 8
; CHECK-NEXT:    [[LEN:%.*]] = call i64 @strnlen(i8* noundef nonnull dereferenceable(1) [[PTR]], i64 [[NONZERO]])
; CHECK-NEXT:    ret i64 [[LEN]]
;
  %nonzero = or i64 %n, 1
  %ptr = load i8*, i8** @ecp
  %len = call i64 @strnlen(i8* %ptr, i64 %nonzero)
  ret i64 %len
}



; Do not annotate strnlen(ecp, %n) call with nonnull etc. because it need
; not access *ecp.  (Strictly, every pointer function argument must be
; noundef, so this is overly conservative.)


define i64 @noderef_strnlen_ecp_n(i64 %n) {
; CHECK-LABEL: @noderef_strnlen_ecp_n(
; CHECK-NEXT:    [[PTR:%.*]] = load i8*, i8** @ecp, align 8
; CHECK-NEXT:    [[LEN:%.*]] = call i64 @strnlen(i8* [[PTR]], i64 [[N:%.*]])
; CHECK-NEXT:    ret i64 [[LEN]]
;
  %ptr = load i8*, i8** @ecp
  %len = call i64 @strnlen(i8* %ptr, i64 %n)
  ret i64 %len
}