1; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
2; RUN: opt < %s -instsimplify -S | FileCheck %s
3
4; %ret = add nuw i8 %x, C
5; nuw means no unsigned wrap, from -1 to 0.
6; So if C is -1, %x can only be 0, and the result is always -1.
7
8define i8 @add_nuw (i8 %x) {
9; CHECK-LABEL: @add_nuw(
10; CHECK-NEXT:    ret i8 -1
11;
12  %ret = add nuw i8 %x, -1
13  ; nuw here means that %x can only be 0
14  ret i8 %ret
15}
16
17define i8 @add_nuw_nsw (i8 %x) {
18; CHECK-LABEL: @add_nuw_nsw(
19; CHECK-NEXT:    ret i8 -1
20;
21  %ret = add nuw nsw i8 %x, -1
22  ; nuw here means that %x can only be 0
23  ret i8 %ret
24}
25
26define i8 @add_nuw_commute (i8 %x) {
27; CHECK-LABEL: @add_nuw_commute(
28; CHECK-NEXT:    ret i8 -1
29;
30  %ret = add nuw i8 -1, %x ; swapped
31  ; nuw here means that %x can only be 0
32  ret i8 %ret
33}
34
35; ============================================================================ ;
36; Positive tests with value range known
37; ============================================================================ ;
38
39declare void @llvm.assume(i1 %cond);
40
41define i8 @knownbits_allones(i8 %x, i8 %y) {
42; CHECK-LABEL: @knownbits_allones(
43; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[Y:%.*]], -2
44; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
45; CHECK-NEXT:    [[RET:%.*]] = add nuw i8 [[X:%.*]], [[Y]]
46; CHECK-NEXT:    ret i8 [[RET]]
47;
48  %cmp = icmp slt i8 %y, 254
49  tail call void @llvm.assume(i1 %cmp)
50  %ret = add nuw i8 %x, %y
51  ret i8 %ret
52}
53
54; ============================================================================ ;
55; Vectors
56; ============================================================================ ;
57
58define <2 x i8> @add_vec(<2 x i8> %x) {
59; CHECK-LABEL: @add_vec(
60; CHECK-NEXT:    ret <2 x i8> <i8 -1, i8 -1>
61;
62  %ret = add nuw <2 x i8> %x, <i8 -1, i8 -1>
63  ret <2 x i8> %ret
64}
65
66define <3 x i8> @add_vec_undef(<3 x i8> %x) {
67; CHECK-LABEL: @add_vec_undef(
68; CHECK-NEXT:    ret <3 x i8> <i8 -1, i8 undef, i8 -1>
69;
70  %ret = add nuw <3 x i8> %x, <i8 -1, i8 undef, i8 -1>
71  ret <3 x i8> %ret
72}
73
74; ============================================================================ ;
75; Negative tests. Should not be folded.
76; ============================================================================ ;
77
78define i8 @bad_add (i8 %x) {
79; CHECK-LABEL: @bad_add(
80; CHECK-NEXT:    [[RET:%.*]] = add i8 [[X:%.*]], -1
81; CHECK-NEXT:    ret i8 [[RET]]
82;
83  %ret = add i8 %x, -1 ; need nuw
84  ret i8 %ret
85}
86
87define i8 @bad_add_nsw (i8 %x) {
88; CHECK-LABEL: @bad_add_nsw(
89; CHECK-NEXT:    [[RET:%.*]] = add nsw i8 [[X:%.*]], -1
90; CHECK-NEXT:    ret i8 [[RET]]
91;
92  %ret = add nsw i8 %x, -1 ; need nuw
93  ret i8 %ret
94}
95
96; Second `add` operand is not `-1` constant
97
98define i8 @bad_add0(i8 %x, i8 %addop2) {
99; CHECK-LABEL: @bad_add0(
100; CHECK-NEXT:    [[RET:%.*]] = add nuw i8 [[X:%.*]], [[ADDOP2:%.*]]
101; CHECK-NEXT:    ret i8 [[RET]]
102;
103  %ret = add nuw i8 %x, %addop2
104  ret i8 %ret
105}
106
107; Bad constant
108
109define i8 @bad_add1(i8 %x) {
110; CHECK-LABEL: @bad_add1(
111; CHECK-NEXT:    [[RET:%.*]] = add nuw i8 [[X:%.*]], 1
112; CHECK-NEXT:    ret i8 [[RET]]
113;
114  %ret = add nuw i8 %x, 1 ; not -1
115  ret i8 %ret
116}
117
118define <2 x i8> @bad_add_vec_nonsplat(<2 x i8> %x) {
119; CHECK-LABEL: @bad_add_vec_nonsplat(
120; CHECK-NEXT:    [[RET:%.*]] = add nuw <2 x i8> [[X:%.*]], <i8 -1, i8 1>
121; CHECK-NEXT:    ret <2 x i8> [[RET]]
122;
123  %ret = add nuw <2 x i8> %x, <i8 -1, i8 1>
124  ret <2 x i8> %ret
125}
126
127; Bad known bits
128
129define i8 @bad_knownbits(i8 %x, i8 %y) {
130; CHECK-LABEL: @bad_knownbits(
131; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i8 [[X:%.*]], -3
132; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
133; CHECK-NEXT:    [[RET:%.*]] = add nuw i8 [[X]], [[Y:%.*]]
134; CHECK-NEXT:    ret i8 [[RET]]
135;
136  %cmp = icmp slt i8 %x, 253
137  tail call void @llvm.assume(i1 %cmp)
138  %ret = add nuw i8 %x, %y
139  ret i8 %ret
140}
141