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1; RUN: opt -S -globalopt < %s | FileCheck %s
2
3; This test is hint, what could globalOpt optimize and what it can't
4; FIXME: @tmp and @tmp2 can be safely set to 42
5; CHECK: @tmp = local_unnamed_addr global i32 0
6; CHECK: @tmp2 = local_unnamed_addr global i32 0
7; CHECK: @tmp3 = global i32 0
8
9@tmp = global i32 0
10@tmp2 = global i32 0
11@tmp3 = global i32 0
12@ptrToTmp3 = global i32* null
13
14@llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @_GLOBAL__I_a }]
15
16define i32 @TheAnswerToLifeTheUniverseAndEverything() {
17  ret i32 42
18}
19
20define void @_GLOBAL__I_a() {
21enter:
22  call void @_optimizable()
23  call void @_not_optimizable()
24  ret void
25}
26
27define void @_optimizable() {
28enter:
29  %valptr = alloca i32
30
31  %val = call i32 @TheAnswerToLifeTheUniverseAndEverything()
32  store i32 %val, i32* @tmp
33  store i32 %val, i32* %valptr
34
35  %0 = bitcast i32* %valptr to i8*
36  %barr = call i8* @llvm.invariant.group.barrier(i8* %0)
37  %1 = bitcast i8* %barr to i32*
38
39  %val2 = load i32, i32* %1
40  store i32 %val2, i32* @tmp2
41  ret void
42}
43
44; We can't step through invariant.group.barrier here, because that would change
45; this load in @usage_of_globals()
46; val = load i32, i32* %ptrVal, !invariant.group !0
47; into
48; %val = load i32, i32* @tmp3, !invariant.group !0
49; and then we could assume that %val and %val2 to be the same, which coud be
50; false, because @changeTmp3ValAndCallBarrierInside() may change the value
51; of @tmp3.
52define void @_not_optimizable() {
53enter:
54  store i32 13, i32* @tmp3, !invariant.group !0
55
56  %0 = bitcast i32* @tmp3 to i8*
57  %barr = call i8* @llvm.invariant.group.barrier(i8* %0)
58  %1 = bitcast i8* %barr to i32*
59
60  store i32* %1, i32** @ptrToTmp3
61  store i32 42, i32* %1, !invariant.group !0
62
63  ret void
64}
65define void @usage_of_globals() {
66entry:
67  %ptrVal = load i32*, i32** @ptrToTmp3
68  %val = load i32, i32* %ptrVal, !invariant.group !0
69
70  call void @changeTmp3ValAndCallBarrierInside()
71  %val2 = load i32, i32* @tmp3, !invariant.group !0
72  ret void;
73}
74
75declare void @changeTmp3ValAndCallBarrierInside()
76
77declare i8* @llvm.invariant.group.barrier(i8*)
78
79!0 = !{!"something"}
80