100 lines
2.5 KiB
Go
100 lines
2.5 KiB
Go
/**
|
|
* Copyright 2023 ByteDance Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
package loader
|
|
|
|
const (
|
|
_N_PCDATA = 4
|
|
|
|
_PCDATA_UnsafePoint = 0
|
|
_PCDATA_StackMapIndex = 1
|
|
_PCDATA_InlTreeIndex = 2
|
|
_PCDATA_ArgLiveIndex = 3
|
|
|
|
_PCDATA_INVALID_OFFSET = 0
|
|
)
|
|
|
|
const (
|
|
// PCDATA_UnsafePoint values.
|
|
PCDATA_UnsafePointSafe = -1 // Safe for async preemption
|
|
PCDATA_UnsafePointUnsafe = -2 // Unsafe for async preemption
|
|
|
|
// PCDATA_Restart1(2) apply on a sequence of instructions, within
|
|
// which if an async preemption happens, we should back off the PC
|
|
// to the start of the sequence when resume.
|
|
// We need two so we can distinguish the start/end of the sequence
|
|
// in case that two sequences are next to each other.
|
|
PCDATA_Restart1 = -3
|
|
PCDATA_Restart2 = -4
|
|
|
|
// Like PCDATA_RestartAtEntry, but back to function entry if async
|
|
// preempted.
|
|
PCDATA_RestartAtEntry = -5
|
|
|
|
_PCDATA_START_VAL = -1
|
|
)
|
|
|
|
var emptyByte byte
|
|
|
|
func encodeValue(v int) []byte {
|
|
return encodeVariant(toZigzag(v))
|
|
}
|
|
|
|
func toZigzag(v int) int {
|
|
return (v << 1) ^ (v >> 31)
|
|
}
|
|
|
|
func encodeVariant(v int) []byte {
|
|
var u int
|
|
var r []byte
|
|
|
|
/* split every 7 bits */
|
|
for v > 127 {
|
|
u = v & 0x7f
|
|
v = v >> 7
|
|
r = append(r, byte(u) | 0x80)
|
|
}
|
|
|
|
/* check for last one */
|
|
if v == 0 {
|
|
return r
|
|
}
|
|
|
|
/* add the last one */
|
|
r = append(r, byte(v))
|
|
return r
|
|
}
|
|
|
|
type Pcvalue struct {
|
|
PC uint32 // PC offset from func entry
|
|
Val int32
|
|
}
|
|
|
|
type Pcdata []Pcvalue
|
|
|
|
// see https://docs.google.com/document/d/1lyPIbmsYbXnpNj57a261hgOYVpNRcgydurVQIyZOz_o/pub
|
|
func (self Pcdata) MarshalBinary() (data []byte, err error) {
|
|
// delta value always starts from -1
|
|
sv := int32(_PCDATA_START_VAL)
|
|
sp := uint32(0)
|
|
for _, v := range self {
|
|
data = append(data, encodeVariant(toZigzag(int(v.Val - sv)))...)
|
|
data = append(data, encodeVariant(int(v.PC - sp))...)
|
|
sp = v.PC
|
|
sv = v.Val
|
|
}
|
|
return
|
|
} |