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
| # RUN: llc -mtriple=thumbv8.1m.main -run-pass=arm-low-overhead-loops %s -verify-machineinstrs -o - | FileCheck %s
# CHECK: $lr = t2DLS $r0
# CHECK: $lr = tMOVr $r0, 14
# CHECK: $lr = t2LEUpdate renamable $lr, %bb.2
# TODO: Explore the preheader to remove the redundant tMOVr
--- |
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv8.1m.main"
define i32 @do_copy(i32 %n, i32* nocapture %p, i32* nocapture readonly %q) {
entry:
%scevgep = getelementptr i32, i32* %q, i32 -1
%scevgep3 = getelementptr i32, i32* %p, i32 -1
call void @llvm.set.loop.iterations.i32(i32 %n)
br label %preheader
preheader:
br label %while.body
while.body: ; preds = %while.body, %entry
%lsr.iv4 = phi i32* [ %scevgep5, %while.body ], [ %scevgep3, %preheader ]
%lsr.iv = phi i32* [ %scevgep1, %while.body ], [ %scevgep, %preheader ]
%0 = phi i32 [ %n, %preheader ], [ %2, %while.body ]
%scevgep6 = getelementptr i32, i32* %lsr.iv, i32 1
%scevgep2 = getelementptr i32, i32* %lsr.iv4, i32 1
%1 = load i32, i32* %scevgep6, align 4
store i32 %1, i32* %scevgep2, align 4
%scevgep1 = getelementptr i32, i32* %lsr.iv, i32 1
%scevgep5 = getelementptr i32, i32* %lsr.iv4, i32 1
%2 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %0, i32 1)
%3 = icmp ne i32 %2, 0
br i1 %3, label %while.body, label %while.end
while.end: ; preds = %while.body
ret i32 0
}
declare void @llvm.set.loop.iterations.i32(i32) #0
declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) #0
attributes #0 = { noduplicate nounwind }
attributes #1 = { nounwind }
...
---
name: do_copy
alignment: 2
exposesReturnsTwice: false
legalized: false
regBankSelected: false
selected: false
failedISel: false
tracksRegLiveness: true
hasWinCFI: false
registers: []
liveins:
- { reg: '$r0', virtual-reg: '' }
- { reg: '$r1', virtual-reg: '' }
- { reg: '$r2', virtual-reg: '' }
frameInfo:
isFrameAddressTaken: false
isReturnAddressTaken: false
hasStackMap: false
hasPatchPoint: false
stackSize: 8
offsetAdjustment: 0
maxAlignment: 4
adjustsStack: false
hasCalls: false
stackProtector: ''
maxCallFrameSize: 0
cvBytesOfCalleeSavedRegisters: 0
hasOpaqueSPAdjustment: false
hasVAStart: false
hasMustTailInVarArgFunc: false
localFrameSize: 0
savePoint: ''
restorePoint: ''
fixedStack: []
stack:
- { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
stack-id: default, callee-saved-register: '$lr', callee-saved-restored: false,
debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
- { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
stack-id: default, callee-saved-register: '$r7', callee-saved-restored: true,
debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
callSites: []
constants: []
machineFunctionInfo: {}
body: |
bb.0.entry:
successors: %bb.1(0x80000000)
liveins: $r0, $r1, $r2, $r7, $lr
frame-setup tPUSH 14, $noreg, killed $r7, killed $lr, implicit-def $sp, implicit $sp
frame-setup CFI_INSTRUCTION def_cfa_offset 8
frame-setup CFI_INSTRUCTION offset $lr, -4
frame-setup CFI_INSTRUCTION offset $r7, -8
t2DoLoopStart $r0
renamable $r0, dead $cpsr = tSUBi3 killed renamable $r1, 4, 14, $noreg
renamable $r1, dead $cpsr = tSUBi3 killed renamable $r2, 4, 14, $noreg
bb.1.preheader:
successors: %bb.2(0x80000000)
liveins: $r0
$lr = tMOVr $r0, 14, $noreg
bb.2.while.body:
successors: %bb.2(0x7c000000), %bb.3(0x04000000)
liveins: $lr, $r0, $r1
renamable $r2, renamable $r1 = t2LDR_PRE killed renamable $r1, 4, 14, $noreg :: (load 4 from %ir.scevgep6)
early-clobber renamable $r0 = t2STR_PRE killed renamable $r2, killed renamable $r0, 4, 14, $noreg :: (store 4 into %ir.scevgep2)
renamable $lr = t2LoopDec killed renamable $lr, 1
t2LoopEnd renamable $lr, %bb.2, implicit-def dead $cpsr
tB %bb.3, 14, $noreg
bb.3.while.end:
$r0, dead $cpsr = tMOVi8 0, 14, $noreg
tPOP_RET 14, $noreg, def $r7, def $pc, implicit killed $r0
...
|