bad instcombine

instcombine.ll

; ModuleID = 'test.cgu-0.rs'
source_filename = "test.cgu-0.rs"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: readonly uwtable
define i32 @dot_ref_s(i32** noalias nocapture readonly dereferenceable(8)) {
entry-block:
  %loadedptr = load i32*, i32** %0, align 8, !nonnull !0
  %ptrtoint = ptrtoint i32* %loadedptr to i64
  %inttoptr = inttoptr i64 %ptrtoint to i32*
  %switchtmp = icmp eq i32* %inttoptr, null
  br i1 %switchtmp, label %bb6, label %bb7

bb6:
  ret i32 0

bb7:
  ret i32 42
}

!0 = !{}