Merge pull request #688 from nspcc-dev/fix/jmplabels
compiler: use uint16 for labels
This commit is contained in:
Roman Khimov
GitHub
commit
71a18b1727
3 changed files with 49 additions and 35 deletions
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@ -8,6 +8,7 @@ import (
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"go/constant"
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"go/token"
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"go/types"
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"math"
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"sort"
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"strconv"
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"strings"
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@ -39,7 +40,7 @@ type codegen struct {
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scope *funcScope
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// A mapping from label's names to their ids.
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labels map[labelWithType]int
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labels map[labelWithType]uint16
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// A label for the for-loop being currently visited.
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currentFor string
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@ -66,21 +67,26 @@ type labelWithType struct {
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}
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// newLabel creates a new label to jump to
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func (c *codegen) newLabel() (l int) {
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l = len(c.l)
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func (c *codegen) newLabel() (l uint16) {
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li := len(c.l)
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if li > math.MaxUint16 {
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c.prog.Err = errors.New("label number is too big")
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return
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}
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l = uint16(li)
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c.l = append(c.l, -1)
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return
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}
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// newNamedLabel creates a new label with a specified name.
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func (c *codegen) newNamedLabel(typ labelOffsetType, name string) (l int) {
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func (c *codegen) newNamedLabel(typ labelOffsetType, name string) (l uint16) {
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l = c.newLabel()
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lt := labelWithType{name: name, typ: typ}
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c.labels[lt] = l
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return
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}
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func (c *codegen) setLabel(l int) {
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func (c *codegen) setLabel(l uint16) {
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c.l[l] = c.pc() + 1
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}
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@ -384,13 +390,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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if n.Cond != nil {
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ast.Walk(c, n.Cond)
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(lElse))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, lElse)
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}
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c.setLabel(lIf)
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ast.Walk(c, n.Body)
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if n.Else != nil {
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(lElseEnd))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, lElseEnd)
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}
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c.setLabel(lElse)
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@ -421,9 +427,9 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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ast.Walk(c, cc.List[j])
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emit.Opcode(c.prog.BinWriter, eqOpcode)
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if j == l-1 {
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(lEnd))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, lEnd)
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} else {
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(lStart))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, lStart)
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}
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}
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}
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@ -432,7 +438,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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for _, stmt := range cc.Body {
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ast.Walk(c, stmt)
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}
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(switchEnd))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, switchEnd)
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c.setLabel(lEnd)
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}
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@ -500,13 +506,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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switch n.Op {
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case token.LAND:
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ast.Walk(c, n.X)
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(len(c.l)-1))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, uint16(len(c.l)-1))
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ast.Walk(c, n.Y)
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return nil
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case token.LOR:
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ast.Walk(c, n.X)
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(len(c.l)-3))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, uint16(len(c.l)-3))
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ast.Walk(c, n.Y)
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return nil
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@ -612,7 +618,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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case isSyscall(f):
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c.convertSyscall(f.selector.Name, f.name)
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default:
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emit.Call(c.prog.BinWriter, opcode.CALL, int16(f.label))
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emit.Call(c.prog.BinWriter, opcode.CALL, f.label)
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}
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return nil
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@ -702,10 +708,10 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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switch n.Tok {
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case token.BREAK:
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end := c.getLabelOffset(labelEnd, label)
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(end))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, end)
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case token.CONTINUE:
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post := c.getLabelOffset(labelPost, label)
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(post))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, post)
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}
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return nil
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@ -737,7 +743,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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ast.Walk(c, n.Cond)
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// Jump if the condition is false
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(fend))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIFNOT, fend)
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// Walk body followed by the iterator (post stmt).
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ast.Walk(c, n.Body)
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@ -747,7 +753,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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}
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// Jump back to condition.
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(fstart))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, fstart)
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c.setLabel(fend)
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c.currentFor = lastLabel
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@ -782,7 +788,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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emit.Opcode(c.prog.BinWriter, opcode.OVER)
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emit.Opcode(c.prog.BinWriter, opcode.OVER)
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emit.Opcode(c.prog.BinWriter, opcode.LTE) // finish if len <= i
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, int16(end))
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emit.Jmp(c.prog.BinWriter, opcode.JMPIF, end)
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if n.Key != nil {
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emit.Opcode(c.prog.BinWriter, opcode.DUP)
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@ -796,7 +802,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
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c.setLabel(post)
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emit.Opcode(c.prog.BinWriter, opcode.INC)
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emit.Jmp(c.prog.BinWriter, opcode.JMP, int16(start))
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emit.Jmp(c.prog.BinWriter, opcode.JMP, start)
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c.setLabel(end)
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@ -833,7 +839,7 @@ func (c *codegen) emitReverse(num int) {
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}
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// generateLabel returns a new label.
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func (c *codegen) generateLabel(typ labelOffsetType) (int, string) {
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func (c *codegen) generateLabel(typ labelOffsetType) (uint16, string) {
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name := c.nextLabel
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if name == "" {
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name = fmt.Sprintf("@%d", len(c.l))
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@ -843,7 +849,7 @@ func (c *codegen) generateLabel(typ labelOffsetType) (int, string) {
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return c.newNamedLabel(typ, name), name
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}
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func (c *codegen) getLabelOffset(typ labelOffsetType, name string) int {
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func (c *codegen) getLabelOffset(typ labelOffsetType, name string) uint16 {
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return c.labels[labelWithType{name: name, typ: typ}]
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}
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@ -1144,7 +1150,7 @@ func CodeGen(info *buildInfo) ([]byte, error) {
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prog: io.NewBufBinWriter(),
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l: []int{},
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funcs: map[string]*funcScope{},
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labels: map[labelWithType]int{},
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labels: map[labelWithType]uint16{},
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typeInfo: &pkg.Info,
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}
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@ -1197,7 +1203,9 @@ func CodeGen(info *buildInfo) ([]byte, error) {
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return nil, c.prog.Err
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}
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buf := c.prog.Bytes()
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c.writeJumps(buf)
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if err := c.writeJumps(buf); err != nil {
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return nil, err
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}
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return buf, nil
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}
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@ -1212,20 +1220,26 @@ func (c *codegen) resolveFuncDecls(f *ast.File) {
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}
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}
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func (c *codegen) writeJumps(b []byte) {
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func (c *codegen) writeJumps(b []byte) error {
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ctx := vm.NewContext(b)
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for op, _, err := ctx.Next(); err == nil && ctx.NextIP() < len(b); op, _, err = ctx.Next() {
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switch op {
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case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL:
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// we can't use arg returned by ctx.Next() because it is copied
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arg := b[ctx.NextIP()-2:]
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nextIP := ctx.NextIP()
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arg := b[nextIP-2:]
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index := int16(binary.LittleEndian.Uint16(arg))
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if int(index) > len(c.l) || int(index) < 0 {
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continue
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index := binary.LittleEndian.Uint16(arg)
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if int(index) > len(c.l) {
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return fmt.Errorf("unexpected label number: %d (max %d)", index, len(c.l))
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}
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offset := uint16(c.l[index] - ctx.NextIP() + 3)
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binary.LittleEndian.PutUint16(arg, offset)
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offset := c.l[index] - nextIP + 3
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if offset > math.MaxUint16 {
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return fmt.Errorf("label offset is too big at the instruction %d: %d (max %d)",
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nextIP-3, offset, math.MaxUint16)
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}
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binary.LittleEndian.PutUint16(arg, uint16(offset))
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}
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}
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return nil
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}
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@ -18,7 +18,7 @@ type funcScope struct {
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decl *ast.FuncDecl
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// Program label of the scope
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label int
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label uint16
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// Local variables
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locals map[string]int
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@ -35,7 +35,7 @@ type funcScope struct {
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i int
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}
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func newFuncScope(decl *ast.FuncDecl, label int) *funcScope {
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func newFuncScope(decl *ast.FuncDecl, label uint16) *funcScope {
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return &funcScope{
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name: decl.Name.Name,
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decl: decl,
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@ -91,12 +91,12 @@ func Syscall(w *io.BinWriter, api string) {
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}
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// Call emits a call Instruction with label to the given buffer.
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func Call(w *io.BinWriter, op opcode.Opcode, label int16) {
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func Call(w *io.BinWriter, op opcode.Opcode, label uint16) {
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Jmp(w, op, label)
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}
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// Jmp emits a jump Instruction along with label to the given buffer.
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func Jmp(w *io.BinWriter, op opcode.Opcode, label int16) {
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func Jmp(w *io.BinWriter, op opcode.Opcode, label uint16) {
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if w.Err != nil {
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return
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} else if !isInstructionJmp(op) {
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@ -104,7 +104,7 @@ func Jmp(w *io.BinWriter, op opcode.Opcode, label int16) {
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return
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}
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buf := make([]byte, 2)
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binary.LittleEndian.PutUint16(buf, uint16(label))
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binary.LittleEndian.PutUint16(buf, label)
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Instruction(w, op, buf)
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}
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