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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
|
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ssa
import (
"cmd/internal/obj"
"fmt"
)
// An Op encodes the specific operation that a Value performs.
// Opcodes' semantics can be modified by the type and aux fields of the Value.
// For instance, OpAdd can be 32 or 64 bit, signed or unsigned, float or complex, depending on Value.Type.
// Semantics of each op are described in the opcode files in gen/*Ops.go.
// There is one file for generic (architecture-independent) ops and one file
// for each architecture.
type Op int32
type opInfo struct {
name string
reg regInfo
auxType auxType
argLen int32 // the number of arguments, -1 if variable length
asm obj.As
generic bool // this is a generic (arch-independent) opcode
rematerializeable bool // this op is rematerializeable
commutative bool // this operation is commutative (e.g. addition)
resultInArg0 bool // (first, if a tuple) output of v and v.Args[0] must be allocated to the same register
resultNotInArgs bool // outputs must not be allocated to the same registers as inputs
clobberFlags bool // this op clobbers flags register
call bool // is a function call
nilCheck bool // this op is a nil check on arg0
faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset)
faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset)
usesScratch bool // this op requires scratch memory space
hasSideEffects bool // for "reasons", not to be eliminated. E.g., atomic store, #19182.
zeroWidth bool // op never translates into any machine code. example: copy, which may sometimes translate to machine code, is not zero-width.
unsafePoint bool // this op is an unsafe point, i.e. not safe for async preemption
symEffect SymEffect // effect this op has on symbol in aux
scale uint8 // amd64/386 indexed load scale
}
type inputInfo struct {
idx int // index in Args array
regs regMask // allowed input registers
}
type outputInfo struct {
idx int // index in output tuple
regs regMask // allowed output registers
}
type regInfo struct {
// inputs encodes the register restrictions for an instruction's inputs.
// Each entry specifies an allowed register set for a particular input.
// They are listed in the order in which regalloc should pick a register
// from the register set (most constrained first).
// Inputs which do not need registers are not listed.
inputs []inputInfo
// clobbers encodes the set of registers that are overwritten by
// the instruction (other than the output registers).
clobbers regMask
// outputs is the same as inputs, but for the outputs of the instruction.
outputs []outputInfo
}
type auxType int8
const (
auxNone auxType = iota
auxBool // auxInt is 0/1 for false/true
auxInt8 // auxInt is an 8-bit integer
auxInt16 // auxInt is a 16-bit integer
auxInt32 // auxInt is a 32-bit integer
auxInt64 // auxInt is a 64-bit integer
auxInt128 // auxInt represents a 128-bit integer. Always 0.
auxFloat32 // auxInt is a float32 (encoded with math.Float64bits)
auxFloat64 // auxInt is a float64 (encoded with math.Float64bits)
auxFlagConstant // auxInt is a flagConstant
auxString // aux is a string
auxSym // aux is a symbol (a *gc.Node for locals, an *obj.LSym for globals, or nil for none)
auxSymOff // aux is a symbol, auxInt is an offset
auxSymValAndOff // aux is a symbol, auxInt is a ValAndOff
auxTyp // aux is a type
auxTypSize // aux is a type, auxInt is a size, must have Aux.(Type).Size() == AuxInt
auxCCop // aux is a ssa.Op that represents a flags-to-bool conversion (e.g. LessThan)
// architecture specific aux types
auxARM64BitField // aux is an arm64 bitfield lsb and width packed into auxInt
auxS390XRotateParams // aux is a s390x rotate parameters object encoding start bit, end bit and rotate amount
auxS390XCCMask // aux is a s390x 4-bit condition code mask
auxS390XCCMaskInt8 // aux is a s390x 4-bit condition code mask, auxInt is a int8 immediate
auxS390XCCMaskUint8 // aux is a s390x 4-bit condition code mask, auxInt is a uint8 immediate
)
// A SymEffect describes the effect that an SSA Value has on the variable
// identified by the symbol in its Aux field.
type SymEffect int8
const (
SymRead SymEffect = 1 << iota
SymWrite
SymAddr
SymRdWr = SymRead | SymWrite
SymNone SymEffect = 0
)
// A Sym represents a symbolic offset from a base register.
// Currently a Sym can be one of 3 things:
// - a *gc.Node, for an offset from SP (the stack pointer)
// - a *obj.LSym, for an offset from SB (the global pointer)
// - nil, for no offset
type Sym interface {
String() string
CanBeAnSSASym()
}
// A ValAndOff is used by the several opcodes. It holds
// both a value and a pointer offset.
// A ValAndOff is intended to be encoded into an AuxInt field.
// The zero ValAndOff encodes a value of 0 and an offset of 0.
// The high 32 bits hold a value.
// The low 32 bits hold a pointer offset.
type ValAndOff int64
func (x ValAndOff) Val() int64 { return int64(x) >> 32 }
func (x ValAndOff) Val32() int32 { return int32(int64(x) >> 32) }
func (x ValAndOff) Val16() int16 { return int16(int64(x) >> 32) }
func (x ValAndOff) Val8() int8 { return int8(int64(x) >> 32) }
func (x ValAndOff) Off() int64 { return int64(int32(x)) }
func (x ValAndOff) Off32() int32 { return int32(x) }
func (x ValAndOff) Int64() int64 {
return int64(x)
}
func (x ValAndOff) String() string {
return fmt.Sprintf("val=%d,off=%d", x.Val(), x.Off())
}
// validVal reports whether the value can be used
// as an argument to makeValAndOff.
func validVal(val int64) bool {
return val == int64(int32(val))
}
// validOff reports whether the offset can be used
// as an argument to makeValAndOff.
func validOff(off int64) bool {
return off == int64(int32(off))
}
// validValAndOff reports whether we can fit the value and offset into
// a ValAndOff value.
func validValAndOff(val, off int64) bool {
if !validVal(val) {
return false
}
if !validOff(off) {
return false
}
return true
}
// makeValAndOff encodes a ValAndOff into an int64 suitable for storing in an AuxInt field.
func makeValAndOff(val, off int64) int64 {
if !validValAndOff(val, off) {
panic("invalid makeValAndOff")
}
return ValAndOff(val<<32 + int64(uint32(off))).Int64()
}
func makeValAndOff32(val, off int32) ValAndOff {
return ValAndOff(int64(val)<<32 + int64(uint32(off)))
}
func (x ValAndOff) canAdd(off int64) bool {
newoff := x.Off() + off
return newoff == int64(int32(newoff))
}
func (x ValAndOff) canAdd32(off int32) bool {
newoff := x.Off() + int64(off)
return newoff == int64(int32(newoff))
}
func (x ValAndOff) add(off int64) int64 {
if !x.canAdd(off) {
panic("invalid ValAndOff.add")
}
return makeValAndOff(x.Val(), x.Off()+off)
}
func (x ValAndOff) addOffset32(off int32) ValAndOff {
if !x.canAdd32(off) {
panic("invalid ValAndOff.add")
}
return ValAndOff(makeValAndOff(x.Val(), x.Off()+int64(off)))
}
func (x ValAndOff) addOffset64(off int64) ValAndOff {
if !x.canAdd(off) {
panic("invalid ValAndOff.add")
}
return ValAndOff(makeValAndOff(x.Val(), x.Off()+off))
}
// int128 is a type that stores a 128-bit constant.
// The only allowed constant right now is 0, so we can cheat quite a bit.
type int128 int64
type BoundsKind uint8
const (
BoundsIndex BoundsKind = iota // indexing operation, 0 <= idx < len failed
BoundsIndexU // ... with unsigned idx
BoundsSliceAlen // 2-arg slicing operation, 0 <= high <= len failed
BoundsSliceAlenU // ... with unsigned high
BoundsSliceAcap // 2-arg slicing operation, 0 <= high <= cap failed
BoundsSliceAcapU // ... with unsigned high
BoundsSliceB // 2-arg slicing operation, 0 <= low <= high failed
BoundsSliceBU // ... with unsigned low
BoundsSlice3Alen // 3-arg slicing operation, 0 <= max <= len failed
BoundsSlice3AlenU // ... with unsigned max
BoundsSlice3Acap // 3-arg slicing operation, 0 <= max <= cap failed
BoundsSlice3AcapU // ... with unsigned max
BoundsSlice3B // 3-arg slicing operation, 0 <= high <= max failed
BoundsSlice3BU // ... with unsigned high
BoundsSlice3C // 3-arg slicing operation, 0 <= low <= high failed
BoundsSlice3CU // ... with unsigned low
BoundsKindCount
)
// boundsAPI determines which register arguments a bounds check call should use. For an [a:b:c] slice, we do:
// CMPQ c, cap
// JA fail1
// CMPQ b, c
// JA fail2
// CMPQ a, b
// JA fail3
//
// fail1: CALL panicSlice3Acap (c, cap)
// fail2: CALL panicSlice3B (b, c)
// fail3: CALL panicSlice3C (a, b)
//
// When we register allocate that code, we want the same register to be used for
// the first arg of panicSlice3Acap and the second arg to panicSlice3B. That way,
// initializing that register once will satisfy both calls.
// That desire ends up dividing the set of bounds check calls into 3 sets. This function
// determines which set to use for a given panic call.
// The first arg for set 0 should be the second arg for set 1.
// The first arg for set 1 should be the second arg for set 2.
func boundsABI(b int64) int {
switch BoundsKind(b) {
case BoundsSlice3Alen,
BoundsSlice3AlenU,
BoundsSlice3Acap,
BoundsSlice3AcapU:
return 0
case BoundsSliceAlen,
BoundsSliceAlenU,
BoundsSliceAcap,
BoundsSliceAcapU,
BoundsSlice3B,
BoundsSlice3BU:
return 1
case BoundsIndex,
BoundsIndexU,
BoundsSliceB,
BoundsSliceBU,
BoundsSlice3C,
BoundsSlice3CU:
return 2
default:
panic("bad BoundsKind")
}
}
|