1; RUN: llc -mtriple=x86_64-apple-macosx -O3 -debug-only=faultmaps -enable-implicit-null-checks < %s 2>&1 | FileCheck %s
2; REQUIRES: asserts
3
4; List cases where we should *not* be emitting implicit null checks.
5
6; CHECK-NOT: Fault Map Output
7
8define i32 @imp_null_check_load(i32* %x, i32* %y) {
9 entry:
10  %c = icmp eq i32* %x, null
11; It isn't legal to move the load from %x from "not_null" to here --
12; the store to %y could be aliasing it.
13  br i1 %c, label %is_null, label %not_null, !make.implicit !0
14
15 is_null:
16  ret i32 42
17
18 not_null:
19  store i32 0, i32* %y
20  %t = load i32, i32* %x
21  ret i32 %t
22}
23
24define i32 @imp_null_check_gep_load(i32* %x) {
25 entry:
26  %c = icmp eq i32* %x, null
27  br i1 %c, label %is_null, label %not_null, !make.implicit !0
28
29 is_null:
30  ret i32 42
31
32 not_null:
33; null + 5000 * sizeof(i32) lies outside the null page and hence the
34; load to %t cannot be assumed to be reliably faulting.
35  %x.gep = getelementptr i32, i32* %x, i32 5000
36  %t = load i32, i32* %x.gep
37  ret i32 %t
38}
39
40define i32 @imp_null_check_load_no_md(i32* %x) {
41; This is fine, except it is missing the !make.implicit metadata.
42 entry:
43  %c = icmp eq i32* %x, null
44  br i1 %c, label %is_null, label %not_null
45
46 is_null:
47  ret i32 42
48
49 not_null:
50  %t = load i32, i32* %x
51  ret i32 %t
52}
53
54define i32 @imp_null_check_no_hoist_over_acquire_load(i32* %x, i32* %y) {
55; We cannot hoist %t1 over %t0 since %t0 is an acquire load
56 entry:
57  %c = icmp eq i32* %x, null
58  br i1 %c, label %is_null, label %not_null, !make.implicit !0
59
60 is_null:
61  ret i32 42
62
63 not_null:
64  %t0 = load atomic i32, i32* %y acquire, align 4
65  %t1 = load i32, i32* %x
66  %p = add i32 %t0, %t1
67  ret i32 %p
68}
69
70define i32 @imp_null_check_add_result(i32* %x, i32* %y) {
71; This will codegen to:
72;
73;   movl    (%rsi), %eax
74;   addl    (%rdi), %eax
75;
76; The load instruction we wish to hoist is the addl, but there is a
77; write-after-write hazard preventing that from happening.  We could
78; get fancy here and exploit the commutativity of addition, but right
79; now -implicit-null-checks isn't that smart.
80;
81
82 entry:
83  %c = icmp eq i32* %x, null
84  br i1 %c, label %is_null, label %not_null, !make.implicit !0
85
86 is_null:
87  ret i32 42
88
89 not_null:
90  %t0 = load i32, i32* %y
91  %t1 = load i32, i32* %x
92  %p = add i32 %t0, %t1
93  ret i32 %p
94}
95
96!0 = !{}
97