text: ; RUN: opt -S -jump-threading %s | FileCheck %s
  ; When simplify a branch based on LVI predicates, we should replace the 
  ; comparison itself with a constant (when possible) in case it's otherwise used.
  
  define i32 @test(i32* %p) {
  ; CHECK-LABEL: @test
  ; CHECK: icmp eq
  ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
  ; CHECK-NOT: icmp ne
  entry:
    %cmp = icmp eq i32* %p, null
    br i1 %cmp, label %is_null, label %not_null
  is_null:
    %cmp2 = icmp ne i32* %p, null
    br i1 %cmp2, label %exit1, label %exit2
  not_null:
    %cmp3 = icmp ne i32* %p, null
    br i1 %cmp3, label %exit1, label %exit2
  exit1:
    ret i32 0
  exit2:
    ret i32 1
  }
  
  declare void @use(i1)
  
  ; It would not be legal to replace %cmp2 (well, in this case it actually is, 
  ; but that's a CSE problem, not a LVI/jump threading problem)
  define i32 @test_negative(i32* %p) {
  ; CHECK-LABEL: @test
  ; CHECK: icmp ne
  ; CHECK: icmp eq
  ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
  ; CHECK-NOT: icmp ne
  entry:
    %cmp2 = icmp ne i32* %p, null
    call void @use(i1 %cmp2)
    %cmp = icmp eq i32* %p, null
    br i1 %cmp, label %is_null, label %not_null
  is_null:
    br i1 %cmp2, label %exit1, label %exit2
  not_null:
    br i1 %cmp2, label %exit1, label %exit2
  exit1:
    ret i32 0
  exit2:
    ret i32 1
  }
  
  ; In this case, we can remove cmp2 because it's otherwise unused
  define i32 @test2(i32* %p) {
  ; CHECK-LABEL: @test
  ; CHECK-LABEL: entry:
  ; CHECK-NEXT: icmp eq
  ; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
  ; CHECK-NOT: icmp ne
  entry:
    %cmp2 = icmp ne i32* %p, null
    %cmp = icmp eq i32* %p, null
    br i1 %cmp, label %is_null, label %not_null
  is_null:
    br i1 %cmp2, label %exit1, label %exit2
  not_null:
    br i1 %cmp2, label %exit1, label %exit2
  exit1:
    ret i32 0
  exit2:
    ret i32 1
  }
  