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mirror of https://github.com/golang/go synced 2024-11-23 16:30:06 -07:00

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>
This commit is contained in:
Robert Griesemer 2017-04-19 15:15:49 -07:00
parent 33fd319cbc
commit 1368977a08
3 changed files with 16 additions and 37 deletions

View File

@ -4,10 +4,7 @@
package types
import (
"cmd/internal/src"
"fmt"
)
import "cmd/internal/src"
// Declaration stack & operations
@ -16,17 +13,11 @@ var Block int32 // current block number
// dclstack maintains a stack of shadowed symbol declarations so that
// popdcl can restore their declarations when a block scope ends.
// The stack is maintained as a linked list, using Sym's Link field.
//
// In practice, the "stack" actually ends up forming a tree: goto and label
// statements record the current state of dclstack so that checkgoto can
// validate that a goto statement does not jump over any declarations or
// into a new block scope.
//
// Finally, the Syms in this list are not "real" Syms as they don't actually
// The Syms on this stack are not "real" Syms as they don't actually
// represent object names. Sym is just a convenient type for saving shadowed
// Sym definitions, and only a subset of its fields are actually used.
var dclstack *Sym
var dclstack []*Sym
func dcopy(a, b *Sym) {
a.Pkg = b.Pkg
@ -39,8 +30,7 @@ func dcopy(a, b *Sym) {
func push(pos src.XPos) *Sym {
d := new(Sym)
d.Lastlineno = pos
d.Link = dclstack
dclstack = d
dclstack = append(dclstack, d)
return d
}
@ -54,48 +44,38 @@ func Pushdcl(s *Sym, pos src.XPos) {
// Popdcl pops the innermost block scope and restores all symbol declarations
// to their previous state.
func Popdcl() {
d := dclstack
for ; d != nil && d.Name != ""; d = d.Link {
i := len(dclstack)
for ; i > 0; i-- {
d := dclstack[i-1]
if d.Name == "" {
break
}
s := d.Pkg.Lookup(d.Name)
lno := s.Lastlineno
dcopy(s, d)
d.Lastlineno = lno
}
if d == nil {
if i == 0 {
Fatalf("popdcl: no mark")
}
dclstack = d.Link // pop mark
Block = d.Block
Block = dclstack[i-1].Block
dclstack = dclstack[:i-1] // pop mark
}
// Markdcl records the start of a new block scope for declarations.
func Markdcl(lineno src.XPos) {
d := push(lineno)
d.Name = "" // used as a mark in fifo
d.Name = "" // used as stack mark
d.Block = Block
blockgen++
Block = blockgen
}
// keep around for debugging
func DumpDclstack() {
i := 0
for d := dclstack; d != nil; d = d.Link {
fmt.Printf("%6d %p", i, d)
if d.Name != "" {
fmt.Printf(" '%s' %v\n", d.Name, d.Pkg.Lookup(d.Name))
} else {
fmt.Printf(" ---\n")
}
i++
}
}
func IsDclstackValid() bool {
for d := dclstack; d != nil; d = d.Link {
for _, d := range dclstack {
if d.Name == "" {
return false
}

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@ -22,7 +22,7 @@ func TestSizeof(t *testing.T) {
_32bit uintptr // size on 32bit platforms
_64bit uintptr // size on 64bit platforms
}{
{Sym{}, 60, 104},
{Sym{}, 56, 96},
{Type{}, 52, 88},
{Map{}, 20, 40},
{Forward{}, 20, 32},

View File

@ -18,7 +18,6 @@ import (
// allows using Sym pointer equality to test for Go identifier uniqueness when
// handling selector expressions.
type Sym struct {
Link *Sym
Importdef *Pkg // where imported definition was found
Linkname string // link name