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compiler: use uint16 for label numbers

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As noted in #687 this will make compiler a bit more predictable.
This commit is contained in:
Evgenii Stratonikov 2020-02-21 11:50:03 +03:00
parent 56f87cd44e
commit 5e229d84d4
3 changed files with 33 additions and 27 deletions
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50
pkg/compiler/codegen.go
View file

@ -8,6 +8,7 @@ import (
"go/constant"
"go/token"
"go/types"
"math"
"sort"
"strconv"
"strings"
@ -39,7 +40,7 @@ type codegen struct {
scope *funcScope
// A mapping from label's names to their ids.
labels map[labelWithType]int
labels map[labelWithType]uint16
// A label for the for-loop being currently visited.
currentFor string
@ -66,21 +67,26 @@ type labelWithType struct {
}
// newLabel creates a new label to jump to
func (c *codegen) newLabel() (l int) {
l = len(c.l)
func (c *codegen) newLabel() (l uint16) {
li := len(c.l)
if li > math.MaxUint16 {
c.prog.Err = errors.New("label number is too big")
return
}
l = uint16(li)
c.l = append(c.l, -1)
return
}
// newNamedLabel creates a new label with a specified name.
func (c *codegen) newNamedLabel(typ labelOffsetType, name string) (l int) {
func (c *codegen) newNamedLabel(typ labelOffsetType, name string) (l uint16) {
l = c.newLabel()
lt := labelWithType{name: name, typ: typ}
c.labels[lt] = l
return
}
func (c *codegen) setLabel(l int) {
func (c *codegen) setLabel(l uint16) {
c.l[l] = c.pc() + 1
}
@ -384,13 +390,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
if n.Cond != nil {
ast.Walk(c, n.Cond)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(lElse))
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, lElse)
}
c.setLabel(lIf)
ast.Walk(c, n.Body)
if n.Else != nil {
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(lElseEnd))
emit.Jmp(c.prog.BinWriter, opcode.JMP, lElseEnd)
}
c.setLabel(lElse)
@ -421,9 +427,9 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
ast.Walk(c, cc.List[j])
emit.Opcode(c.prog.BinWriter, eqOpcode)
if j == l-1 {
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(lEnd))
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, lEnd)
} else {
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(lStart))
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, lStart)
}
}
}
@ -432,7 +438,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
for _, stmt := range cc.Body {
ast.Walk(c, stmt)
}
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(switchEnd))
emit.Jmp(c.prog.BinWriter, opcode.JMP, switchEnd)
c.setLabel(lEnd)
}
@ -500,13 +506,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
switch n.Op {
case token.LAND:
ast.Walk(c, n.X)
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(len(c.l)-1))
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, uint16(len(c.l)-1))
ast.Walk(c, n.Y)
return nil
case token.LOR:
ast.Walk(c, n.X)
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(len(c.l)-3))
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, uint16(len(c.l)-3))
ast.Walk(c, n.Y)
return nil
@ -612,7 +618,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
case isSyscall(f):
c.convertSyscall(f.selector.Name, f.name)
default:
emit.Call(c.prog.BinWriter, opcode.CALL, int16(f.label))
emit.Call(c.prog.BinWriter, opcode.CALL, f.label)
}
return nil
@ -702,10 +708,10 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
switch n.Tok {
case token.BREAK:
end := c.getLabelOffset(labelEnd, label)
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(end))
emit.Jmp(c.prog.BinWriter, opcode.JMP, end)
case token.CONTINUE:
post := c.getLabelOffset(labelPost, label)
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(post))
emit.Jmp(c.prog.BinWriter, opcode.JMP, post)
}
return nil
@ -737,7 +743,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
ast.Walk(c, n.Cond)
// Jump if the condition is false
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(fend))
emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, fend)
// Walk body followed by the iterator (post stmt).
ast.Walk(c, n.Body)
@ -747,7 +753,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
}
// Jump back to condition.
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(fstart))
emit.Jmp(c.prog.BinWriter, opcode.JMP, fstart)
c.setLabel(fend)
c.currentFor = lastLabel
@ -782,7 +788,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.OVER)
emit.Opcode(c.prog.BinWriter, opcode.LTE) // finish if len <= i
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(end))
emit.Jmp(c.prog.BinWriter, opcode.JMPIF, end)
if n.Key != nil {
emit.Opcode(c.prog.BinWriter, opcode.DUP)
@ -796,7 +802,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
c.setLabel(post)
emit.Opcode(c.prog.BinWriter, opcode.INC)
emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(start))
emit.Jmp(c.prog.BinWriter, opcode.JMP, start)
c.setLabel(end)
@ -833,7 +839,7 @@ func (c *codegen) emitReverse(num int) {
}
// generateLabel returns a new label.
func (c *codegen) generateLabel(typ labelOffsetType) (int, string) {
func (c *codegen) generateLabel(typ labelOffsetType) (uint16, string) {
name := c.nextLabel
if name == "" {
name = fmt.Sprintf("@%d", len(c.l))
@ -843,7 +849,7 @@ func (c *codegen) generateLabel(typ labelOffsetType) (int, string) {
return c.newNamedLabel(typ, name), name
}
func (c *codegen) getLabelOffset(typ labelOffsetType, name string) int {
func (c *codegen) getLabelOffset(typ labelOffsetType, name string) uint16 {
return c.labels[labelWithType{name: name, typ: typ}]
}
@ -1144,7 +1150,7 @@ func CodeGen(info *buildInfo) ([]byte, error) {
prog: io.NewBufBinWriter(),
l: []int{},
funcs: map[string]*funcScope{},
labels: map[labelWithType]int{},
labels: map[labelWithType]uint16{},
typeInfo: &pkg.Info,
}

4
pkg/compiler/func_scope.go
View file

@ -18,7 +18,7 @@ type funcScope struct {
decl *ast.FuncDecl
// Program label of the scope
label int
label uint16
// Local variables
locals map[string]int
@ -35,7 +35,7 @@ type funcScope struct {
i int
}
func newFuncScope(decl *ast.FuncDecl, label int) *funcScope {
func newFuncScope(decl *ast.FuncDecl, label uint16) *funcScope {
return &funcScope{
name: decl.Name.Name,
decl: decl,

6
pkg/vm/emit/emit.go
View file

@ -91,12 +91,12 @@ func Syscall(w *io.BinWriter, api string) {
}
// Call emits a call Instruction with label to the given buffer.
func Call(w *io.BinWriter, op opcode.Opcode, label int16) {
func Call(w *io.BinWriter, op opcode.Opcode, label uint16) {
Jmp(w, op, label)
}
// Jmp emits a jump Instruction along with label to the given buffer.
func Jmp(w *io.BinWriter, op opcode.Opcode, label int16) {
func Jmp(w *io.BinWriter, op opcode.Opcode, label uint16) {
if w.Err != nil {
return
} else if !isInstructionJmp(op) {
@ -104,7 +104,7 @@ func Jmp(w *io.BinWriter, op opcode.Opcode, label int16) {
return
}
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(label))
binary.LittleEndian.PutUint16(buf, label)
Instruction(w, op, buf)
}