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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
using ARMeilleure.IntermediateRepresentation;
using System;
using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
namespace ARMeilleure.CodeGen.Optimizations
{
static class Simplification
{
public static void RunPass(Operation operation)
{
switch (operation.Instruction)
{
case Instruction.Add:
if (operation.GetSource(0).Relocatable ||
operation.GetSource(1).Relocatable)
{
break;
}
TryEliminateBinaryOpComutative(operation, 0);
break;
case Instruction.BitwiseAnd:
TryEliminateBitwiseAnd(operation);
break;
case Instruction.BitwiseOr:
TryEliminateBitwiseOr(operation);
break;
case Instruction.BitwiseExclusiveOr:
TryEliminateBitwiseExclusiveOr(operation);
break;
case Instruction.ConditionalSelect:
TryEliminateConditionalSelect(operation);
break;
case Instruction.Divide:
TryEliminateBinaryOpY(operation, 1);
break;
case Instruction.Multiply:
TryEliminateBinaryOpComutative(operation, 1);
break;
case Instruction.ShiftLeft:
case Instruction.ShiftRightSI:
case Instruction.ShiftRightUI:
case Instruction.Subtract:
TryEliminateBinaryOpY(operation, 0);
break;
}
}
private static void TryEliminateBitwiseAnd(Operation operation)
{
// Try to recognize and optimize those 3 patterns (in order):
// x & 0xFFFFFFFF == x, 0xFFFFFFFF & y == y,
// x & 0x00000000 == 0x00000000, 0x00000000 & y == 0x00000000
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, AllOnes(x.Type)))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, AllOnes(y.Type)))
{
operation.TurnIntoCopy(x);
}
else if (IsConstEqual(x, 0) || IsConstEqual(y, 0))
{
operation.TurnIntoCopy(Const(x.Type, 0));
}
}
private static void TryEliminateBitwiseOr(Operation operation)
{
// Try to recognize and optimize those 3 patterns (in order):
// x | 0x00000000 == x, 0x00000000 | y == y,
// x | 0xFFFFFFFF == 0xFFFFFFFF, 0xFFFFFFFF | y == 0xFFFFFFFF
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, 0))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, 0))
{
operation.TurnIntoCopy(x);
}
else if (IsConstEqual(x, AllOnes(x.Type)) || IsConstEqual(y, AllOnes(y.Type)))
{
operation.TurnIntoCopy(Const(AllOnes(x.Type)));
}
}
private static void TryEliminateBitwiseExclusiveOr(Operation operation)
{
// Try to recognize and optimize those 2 patterns (in order):
// x ^ y == 0x00000000 when x == y
// 0x00000000 ^ y == y, x ^ 0x00000000 == x
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (x == y && x.Type.IsInteger())
{
operation.TurnIntoCopy(Const(x.Type, 0));
}
else
{
TryEliminateBinaryOpComutative(operation, 0);
}
}
private static void TryEliminateBinaryOpY(Operation operation, ulong comparand)
{
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(y, comparand))
{
operation.TurnIntoCopy(x);
}
}
private static void TryEliminateBinaryOpComutative(Operation operation, ulong comparand)
{
Operand x = operation.GetSource(0);
Operand y = operation.GetSource(1);
if (IsConstEqual(x, comparand))
{
operation.TurnIntoCopy(y);
}
else if (IsConstEqual(y, comparand))
{
operation.TurnIntoCopy(x);
}
}
private static void TryEliminateConditionalSelect(Operation operation)
{
Operand cond = operation.GetSource(0);
if (cond.Kind != OperandKind.Constant)
{
return;
}
// The condition is constant, we can turn it into a copy, and select
// the source based on the condition value.
int srcIndex = cond.Value != 0 ? 1 : 2;
Operand source = operation.GetSource(srcIndex);
operation.TurnIntoCopy(source);
}
private static bool IsConstEqual(Operand operand, ulong comparand)
{
if (operand.Kind != OperandKind.Constant || !operand.Type.IsInteger())
{
return false;
}
return operand.Value == comparand;
}
private static ulong AllOnes(OperandType type)
{
switch (type)
{
case OperandType.I32: return ~0U;
case OperandType.I64: return ~0UL;
}
throw new ArgumentException("Invalid operand type \"" + type + "\".");
}
}
}
|
