1; RUN: opt < %s -instcombine -S | FileCheck %s
2
3; With left shift, the comparison should not be modified.
4; CHECK-LABEL: @test_shift_and_cmp_not_changed1(
5; CHECK: icmp slt i8 %andp, 32
6define i1 @test_shift_and_cmp_not_changed1(i8 %p) #0 {
7entry:
8  %shlp = shl i8 %p, 5
9  %andp = and i8 %shlp, -64
10  %cmp = icmp slt i8 %andp, 32
11  ret i1 %cmp
12}
13
14; With arithmetic right shift, the comparison should not be modified.
15; CHECK-LABEL: @test_shift_and_cmp_not_changed2(
16; CHECK: icmp slt i8 %andp, 32
17define i1 @test_shift_and_cmp_not_changed2(i8 %p) #0 {
18entry:
19  %shlp = ashr i8 %p, 5
20  %andp = and i8 %shlp, -64
21  %cmp = icmp slt i8 %andp, 32
22  ret i1 %cmp
23}
24
25; This should simplify functionally to the left shift case.
26; The extra input parameter should be optimized away.
27; CHECK-LABEL: @test_shift_and_cmp_changed1(
28; CHECK:  %andp = shl i8 %p, 5
29; CHECK-NEXT: %shl = and i8 %andp, -64
30; CHECK-NEXT:  %cmp = icmp slt i8 %shl, 32
31define i1 @test_shift_and_cmp_changed1(i8 %p, i8 %q) #0 {
32entry:
33  %andp = and i8 %p, 6
34  %andq = and i8 %q, 8
35  %or = or i8 %andq, %andp
36  %shl = shl i8 %or, 5
37  %ashr = ashr i8 %shl, 5
38  %cmp = icmp slt i8 %ashr, 1
39  ret i1 %cmp
40}
41
42; Unsigned compare allows a transformation to compare against 0.
43; CHECK-LABEL: @test_shift_and_cmp_changed2(
44; CHECK: icmp eq i8 %andp, 0
45define i1 @test_shift_and_cmp_changed2(i8 %p) #0 {
46entry:
47  %shlp = shl i8 %p, 5
48  %andp = and i8 %shlp, -64
49  %cmp = icmp ult i8 %andp, 32
50  ret i1 %cmp
51}
52
53; nsw on the shift should not affect the comparison.
54; CHECK-LABEL: @test_shift_and_cmp_changed3(
55; CHECK: icmp slt i8 %andp, 32
56define i1 @test_shift_and_cmp_changed3(i8 %p) #0 {
57entry:
58  %shlp = shl nsw i8 %p, 5
59  %andp = and i8 %shlp, -64
60  %cmp = icmp slt i8 %andp, 32
61  ret i1 %cmp
62}
63
64; Logical shift right allows a return true because the 'and' guarantees no bits are set.
65; CHECK-LABEL: @test_shift_and_cmp_changed4(
66; CHECK: ret i1 true
67define i1 @test_shift_and_cmp_changed4(i8 %p) #0 {
68entry:
69  %shlp = lshr i8 %p, 5
70  %andp = and i8 %shlp, -64
71  %cmp = icmp slt i8 %andp, 32
72  ret i1 %cmp
73}
74
75