align-down.ll
4.3 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
; Fold
; ptr - (ptr & (alignment-1))
; To
; ptr & (0 - alignment)
;
; This needs to be a backend-level fold because only by now pointers
; are just registers; in middle-end IR this can only be done via @llvm.ptrmask()
; intrinsic which is not sufficiently widely-spread yet.
;
; https://bugs.llvm.org/show_bug.cgi?id=44448
; The basic positive tests
define i32 @t0_32(i32 %ptr, i32 %alignment) nounwind {
; CHECK-LABEL: t0_32:
; CHECK: // %bb.0:
; CHECK-NEXT: neg w8, w1
; CHECK-NEXT: and w0, w0, w8
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %ptr, %mask
%r = sub i32 %ptr, %bias
ret i32 %r
}
define i64 @t1_64(i64 %ptr, i64 %alignment) nounwind {
; CHECK-LABEL: t1_64:
; CHECK: // %bb.0:
; CHECK-NEXT: neg x8, x1
; CHECK-NEXT: and x0, x0, x8
; CHECK-NEXT: ret
%mask = add i64 %alignment, -1
%bias = and i64 %ptr, %mask
%r = sub i64 %ptr, %bias
ret i64 %r
}
define i32 @t2_commutative(i32 %ptr, i32 %alignment) nounwind {
; CHECK-LABEL: t2_commutative:
; CHECK: // %bb.0:
; CHECK-NEXT: neg w8, w1
; CHECK-NEXT: and w0, w0, w8
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %mask, %ptr ; swapped
%r = sub i32 %ptr, %bias
ret i32 %r
}
; Extra use tests
define i32 @t3_extrause0(i32 %ptr, i32 %alignment, i32* %mask_storage) nounwind {
; CHECK-LABEL: t3_extrause0:
; CHECK: // %bb.0:
; CHECK-NEXT: neg w9, w1
; CHECK-NEXT: sub w8, w1, #1 // =1
; CHECK-NEXT: and w0, w0, w9
; CHECK-NEXT: str w8, [x2]
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
store i32 %mask, i32* %mask_storage
%bias = and i32 %ptr, %mask
%r = sub i32 %ptr, %bias
ret i32 %r
}
define i32 @n4_extrause1(i32 %ptr, i32 %alignment, i32* %bias_storage) nounwind {
; CHECK-LABEL: n4_extrause1:
; CHECK: // %bb.0:
; CHECK-NEXT: sub w8, w1, #1 // =1
; CHECK-NEXT: and w8, w0, w8
; CHECK-NEXT: sub w0, w0, w8
; CHECK-NEXT: str w8, [x2]
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %ptr, %mask ; has extra uses, can't fold
store i32 %bias, i32* %bias_storage
%r = sub i32 %ptr, %bias
ret i32 %r
}
define i32 @n5_extrause2(i32 %ptr, i32 %alignment, i32* %mask_storage, i32* %bias_storage) nounwind {
; CHECK-LABEL: n5_extrause2:
; CHECK: // %bb.0:
; CHECK-NEXT: sub w8, w1, #1 // =1
; CHECK-NEXT: str w8, [x2]
; CHECK-NEXT: and w8, w0, w8
; CHECK-NEXT: sub w0, w0, w8
; CHECK-NEXT: str w8, [x3]
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
store i32 %mask, i32* %mask_storage
%bias = and i32 %ptr, %mask ; has extra uses, can't fold
store i32 %bias, i32* %bias_storage
%r = sub i32 %ptr, %bias
ret i32 %r
}
; Negative tests
define i32 @n6_different_ptrs(i32 %ptr0, i32 %ptr1, i32 %alignment) nounwind {
; CHECK-LABEL: n6_different_ptrs:
; CHECK: // %bb.0:
; CHECK-NEXT: sub w8, w2, #1 // =1
; CHECK-NEXT: and w8, w1, w8
; CHECK-NEXT: sub w0, w0, w8
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %ptr1, %mask ; not %ptr0
%r = sub i32 %ptr0, %bias ; not %ptr1
ret i32 %r
}
define i32 @n7_different_ptrs_commutative(i32 %ptr0, i32 %ptr1, i32 %alignment) nounwind {
; CHECK-LABEL: n7_different_ptrs_commutative:
; CHECK: // %bb.0:
; CHECK-NEXT: sub w8, w2, #1 // =1
; CHECK-NEXT: and w8, w8, w1
; CHECK-NEXT: sub w0, w0, w8
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %mask, %ptr1 ; swapped, not %ptr0
%r = sub i32 %ptr0, %bias ; not %ptr1
ret i32 %r
}
define i32 @n8_not_lowbit_mask(i32 %ptr, i32 %alignment) nounwind {
; CHECK-LABEL: n8_not_lowbit_mask:
; CHECK: // %bb.0:
; CHECK-NEXT: add w8, w1, #1 // =1
; CHECK-NEXT: bic w0, w0, w8
; CHECK-NEXT: ret
%mask = add i32 %alignment, 1 ; not -1
%bias = and i32 %ptr, %mask
%r = sub i32 %ptr, %bias
ret i32 %r
}
define i32 @n9_sub_is_not_commutative(i32 %ptr, i32 %alignment) nounwind {
; CHECK-LABEL: n9_sub_is_not_commutative:
; CHECK: // %bb.0:
; CHECK-NEXT: sub w8, w1, #1 // =1
; CHECK-NEXT: and w8, w0, w8
; CHECK-NEXT: sub w0, w8, w0
; CHECK-NEXT: ret
%mask = add i32 %alignment, -1
%bias = and i32 %ptr, %mask
%r = sub i32 %bias, %ptr ; wrong order
ret i32 %r
}