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core/vm: faster code analysis (#23381)

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* core/vm: more detailed benchmark for jumpdest analysis

* core/vm: make jd analysis benchmark alloc free

* core/vm: improve jumpdest analysis

* core/vm: improve worst-case

* core/vm: further improvements in analysis

* core/vm: improve jumpdest analysis >PUSH15

* core/vm: make jd analysis ref by value

* core/vm: fix misspell

* core/vm: improve set8 and set16 a bit

* core/vm: reduce amount of code

* core/vm: optimize byte copying
This commit is contained in:
Martin Holst Swende
2021-08-24 09:00:10 +02:00
committed by GitHub
parent f38abc55f1
commit 1d99573192
4 changed files with 105 additions and 19 deletions
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94
core/vm/analysis.go
View File

@ -16,17 +16,49 @@
package vm
const (
set2BitsMask = uint16(0b1100_0000_0000_0000)
set3BitsMask = uint16(0b1110_0000_0000_0000)
set4BitsMask = uint16(0b1111_0000_0000_0000)
set5BitsMask = uint16(0b1111_1000_0000_0000)
set6BitsMask = uint16(0b1111_1100_0000_0000)
set7BitsMask = uint16(0b1111_1110_0000_0000)
)
// bitvec is a bit vector which maps bytes in a program.
// An unset bit means the byte is an opcode, a set bit means
// it's data (i.e. argument of PUSHxx).
type bitvec []byte
func (bits *bitvec) set(pos uint64) {
(*bits)[pos/8] |= 0x80 >> (pos % 8)
var lookup = [8]byte{
0x80, 0x40, 0x20, 0x10, 0x8, 0x4, 0x2, 0x1,
}
func (bits *bitvec) set8(pos uint64) {
(*bits)[pos/8] |= 0xFF >> (pos % 8)
(*bits)[pos/8+1] |= ^(0xFF >> (pos % 8))
func (bits bitvec) set1(pos uint64) {
bits[pos/8] |= lookup[pos%8]
}
func (bits bitvec) setN(flag uint16, pos uint64) {
a := flag >> (pos % 8)
bits[pos/8] |= byte(a >> 8)
if b := byte(a); b != 0 {
// If the bit-setting affects the neighbouring byte, we can assign - no need to OR it,
// since it's the first write to that byte
bits[pos/8+1] = b
}
}
func (bits bitvec) set8(pos uint64) {
a := byte(0xFF >> (pos % 8))
bits[pos/8] |= a
bits[pos/8+1] = ^a
}
func (bits bitvec) set16(pos uint64) {
a := byte(0xFF >> (pos % 8))
bits[pos/8] |= a
bits[pos/8+1] = 0xFF
bits[pos/8+2] = ^a
}
// codeSegment checks if the position is in a code segment.
@ -40,22 +72,52 @@ func codeBitmap(code []byte) bitvec {
// ends with a PUSH32, the algorithm will push zeroes onto the
// bitvector outside the bounds of the actual code.
bits := make(bitvec, len(code)/8+1+4)
return codeBitmapInternal(code, bits)
}
// codeBitmapInternal is the internal implementation of codeBitmap.
// It exists for the purpose of being able to run benchmark tests
// without dynamic allocations affecting the results.
func codeBitmapInternal(code, bits bitvec) bitvec {
for pc := uint64(0); pc < uint64(len(code)); {
op := OpCode(code[pc])
if op >= PUSH1 && op <= PUSH32 {
numbits := op - PUSH1 + 1
pc++
pc++
if op < PUSH1 || op > PUSH32 {
continue
}
numbits := op - PUSH1 + 1
if numbits >= 8 {
for ; numbits >= 16; numbits -= 16 {
bits.set16(pc)
pc += 16
}
for ; numbits >= 8; numbits -= 8 {
bits.set8(pc) // 8
bits.set8(pc)
pc += 8
}
for ; numbits > 0; numbits-- {
bits.set(pc)
pc++
}
} else {
pc++
}
switch numbits {
case 1:
bits.set1(pc)
pc += 1
case 2:
bits.setN(set2BitsMask, pc)
pc += 2
case 3:
bits.setN(set3BitsMask, pc)
pc += 3
case 4:
bits.setN(set4BitsMask, pc)
pc += 4
case 5:
bits.setN(set5BitsMask, pc)
pc += 5
case 6:
bits.setN(set6BitsMask, pc)
pc += 6
case 7:
bits.setN(set7BitsMask, pc)
pc += 7
}
}
return bits