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cmd/compile/internal/types: remove Sym.Link field
The dclstack is now a proper stack and thus we can implement it using a slice rather than a linked list. Change-Id: I200e85621ff76c111bdeb7eb382fd82da438f3ba Reviewed-on: https://go-review.googlesource.com/41135 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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@ -4,10 +4,7 @@
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package types
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import (
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"cmd/internal/src"
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"fmt"
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)
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import "cmd/internal/src"
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// Declaration stack & operations
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@ -16,17 +13,11 @@ var Block int32 // current block number
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// dclstack maintains a stack of shadowed symbol declarations so that
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// popdcl can restore their declarations when a block scope ends.
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// The stack is maintained as a linked list, using Sym's Link field.
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//
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// In practice, the "stack" actually ends up forming a tree: goto and label
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// statements record the current state of dclstack so that checkgoto can
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// validate that a goto statement does not jump over any declarations or
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// into a new block scope.
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//
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// Finally, the Syms in this list are not "real" Syms as they don't actually
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// The Syms on this stack are not "real" Syms as they don't actually
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// represent object names. Sym is just a convenient type for saving shadowed
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// Sym definitions, and only a subset of its fields are actually used.
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var dclstack *Sym
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var dclstack []*Sym
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func dcopy(a, b *Sym) {
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a.Pkg = b.Pkg
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@ -39,8 +30,7 @@ func dcopy(a, b *Sym) {
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func push(pos src.XPos) *Sym {
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d := new(Sym)
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d.Lastlineno = pos
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d.Link = dclstack
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dclstack = d
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dclstack = append(dclstack, d)
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return d
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}
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@ -54,48 +44,38 @@ func Pushdcl(s *Sym, pos src.XPos) {
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// Popdcl pops the innermost block scope and restores all symbol declarations
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// to their previous state.
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func Popdcl() {
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d := dclstack
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for ; d != nil && d.Name != ""; d = d.Link {
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i := len(dclstack)
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for ; i > 0; i-- {
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d := dclstack[i-1]
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if d.Name == "" {
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break
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}
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s := d.Pkg.Lookup(d.Name)
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lno := s.Lastlineno
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dcopy(s, d)
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d.Lastlineno = lno
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}
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if d == nil {
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if i == 0 {
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Fatalf("popdcl: no mark")
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}
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dclstack = d.Link // pop mark
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Block = d.Block
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Block = dclstack[i-1].Block
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dclstack = dclstack[:i-1] // pop mark
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}
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// Markdcl records the start of a new block scope for declarations.
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func Markdcl(lineno src.XPos) {
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d := push(lineno)
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d.Name = "" // used as a mark in fifo
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d.Name = "" // used as stack mark
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d.Block = Block
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blockgen++
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Block = blockgen
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}
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// keep around for debugging
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func DumpDclstack() {
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i := 0
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for d := dclstack; d != nil; d = d.Link {
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fmt.Printf("%6d %p", i, d)
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if d.Name != "" {
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fmt.Printf(" '%s' %v\n", d.Name, d.Pkg.Lookup(d.Name))
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} else {
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fmt.Printf(" ---\n")
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}
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i++
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}
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}
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func IsDclstackValid() bool {
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for d := dclstack; d != nil; d = d.Link {
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for _, d := range dclstack {
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if d.Name == "" {
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return false
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}
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@ -22,7 +22,7 @@ func TestSizeof(t *testing.T) {
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_32bit uintptr // size on 32bit platforms
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_64bit uintptr // size on 64bit platforms
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}{
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{Sym{}, 60, 104},
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{Sym{}, 56, 96},
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{Type{}, 52, 88},
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{Map{}, 20, 40},
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{Forward{}, 20, 32},
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@ -18,7 +18,6 @@ import (
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// allows using Sym pointer equality to test for Go identifier uniqueness when
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// handling selector expressions.
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type Sym struct {
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Link *Sym
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Importdef *Pkg // where imported definition was found
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Linkname string // link name
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