cmd/compile/internal/types: remove Markdcl/Pushdcl/Popdcl

Sym.Def used to be used for symbol resolution during the
old (pre-types2) typechecker. But since moving to types2-based IR
construction, we haven't really had a need for Sym.Def to ever refer
to anything but the package-scope definition, because types2 handles
symbol resolution for us.

This CL finally removes the Markdcl/Pushdcl/Popdcl functions that have
been a recurring source of issues in the past.

Change-Id: I2b012a0f17203efdd724ebd1e9314bd128cc2d61
Reviewed-on: https://go-review.googlesource.com/c/go/+/458625
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>

diff --git a/src/cmd/compile/internal/base/debug.go b/src/cmd/compile/internal/base/debug.go
index f9debd55064510b9303f6200daf49b7be6c782d1..d1b095ad3552f17ff3c52cf1ca51a0f25d64f5e4 100644 (file)
--- a/src/cmd/compile/internal/base/debug.go
+++ b/src/cmd/compile/internal/base/debug.go
@@ -19,7 +19,6 @@ type DebugFlags struct {
        Append                int    `help:"print information about append compilation"`
        Checkptr              int    `help:"instrument unsafe pointer conversions\n0: instrumentation disabled\n1: conversions involving unsafe.Pointer are instrumented\n2: conversions to unsafe.Pointer force heap allocation" concurrent:"ok"`
        Closure               int    `help:"print information about closure compilation"`
-       DclStack              int    `help:"run internal dclstack check"`
        Defer                 int    `help:"print information about defer compilation"`
        DisableNil            int    `help:"disable nil checks" concurrent:"ok"`
        DumpPtrs              int    `help:"show Node pointers values in dump output"`

diff --git a/src/cmd/compile/internal/reflectdata/alg.go b/src/cmd/compile/internal/reflectdata/alg.go
index 2f2f986df0b883a154340b018b032551716c3d9a..c04de83f67280f1bdd6c5fe657cc8b69be94a389 100644 (file)
--- a/src/cmd/compile/internal/reflectdata/alg.go
+++ b/src/cmd/compile/internal/reflectdata/alg.go
@@ -224,10 +224,6 @@ func genhash(t *types.Type) *obj.LSym {
        typecheck.Stmts(fn.Body)
        ir.CurFunc = nil
 
-       if base.Debug.DclStack != 0 {
-               types.CheckDclstack()
-       }
-
        fn.SetNilCheckDisabled(true)
        typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
 
@@ -552,10 +548,6 @@ func geneq(t *types.Type) *obj.LSym {
        typecheck.Stmts(fn.Body)
        ir.CurFunc = nil
 
-       if base.Debug.DclStack != 0 {
-               types.CheckDclstack()
-       }
-
        // Disable checknils while compiling this code.
        // We are comparing a struct or an array,
        // neither of which can be nil, and our comparisons

diff --git a/src/cmd/compile/internal/ssagen/abi.go b/src/cmd/compile/internal/ssagen/abi.go
index 84d5b5951c2faa161ec878b2f347f0f1ec2dbcf7..fa26ae1f06d788f88cb4552176506c98f58ea901 100644 (file)
--- a/src/cmd/compile/internal/ssagen/abi.go
+++ b/src/cmd/compile/internal/ssagen/abi.go
@@ -324,9 +324,6 @@ func makeABIWrapper(f *ir.Func, wrapperABI obj.ABI) {
        fn.Body.Append(tail)
 
        typecheck.FinishFuncBody()
-       if base.Debug.DclStack != 0 {
-               types.CheckDclstack()
-       }
 
        typecheck.Func(fn)
        ir.CurFunc = fn

diff --git a/src/cmd/compile/internal/typecheck/dcl.go b/src/cmd/compile/internal/typecheck/dcl.go
index 5ea15937a257a6e9409082c5a1e836d328f52f49..fcac52a17cba4b14d979a8d3c9b663f281aa5a3f 100644 (file)
--- a/src/cmd/compile/internal/typecheck/dcl.go
+++ b/src/cmd/compile/internal/typecheck/dcl.go
@@ -59,6 +59,7 @@ func Declare(n *ir.Name, ctxt ir.Class) {
                        base.ErrorfAt(n.Pos(), "cannot declare main - must be func")
                }
                Target.Externs = append(Target.Externs, n)
+               s.Def = n
        } else {
                if ir.CurFunc == nil && ctxt == ir.PAUTO {
                        base.Pos = n.Pos()
@@ -67,7 +68,6 @@ func Declare(n *ir.Name, ctxt ir.Class) {
                if ir.CurFunc != nil && ctxt != ir.PFUNC && n.Op() == ir.ONAME {
                        ir.CurFunc.Dcl = append(ir.CurFunc.Dcl, n)
                }
-               types.Pushdcl(s)
                n.Curfn = ir.CurFunc
        }
 
@@ -75,7 +75,6 @@ func Declare(n *ir.Name, ctxt ir.Class) {
                n.SetFrameOffset(0)
        }
 
-       s.Def = n
        n.Class = ctxt
        if ctxt == ir.PFUNC {
                n.Sym().SetFunc(true)
@@ -107,8 +106,6 @@ func StartFuncBody(fn *ir.Func) {
        funcStack = append(funcStack, funcStackEnt{ir.CurFunc, DeclContext})
        ir.CurFunc = fn
        DeclContext = ir.PAUTO
-
-       types.Markdcl()
 }
 
 // finish the body.
@@ -116,7 +113,6 @@ func StartFuncBody(fn *ir.Func) {
 // returns in extern-declaration context.
 func FinishFuncBody() {
        // change the declaration context from auto to previous context
-       types.Popdcl()
        var e funcStackEnt
        funcStack, e = funcStack[:len(funcStack)-1], funcStack[len(funcStack)-1]
        ir.CurFunc, DeclContext = e.curfn, e.dclcontext

diff --git a/src/cmd/compile/internal/types/scope.go b/src/cmd/compile/internal/types/scope.go
index e577b7aa532cb1915d7844a700dab580a459efdf..438a3f9a474a889039b89355ad41a0238aabea82 100644 (file)
--- a/src/cmd/compile/internal/types/scope.go
+++ b/src/cmd/compile/internal/types/scope.go
@@ -4,96 +4,8 @@
 
 package types
 
-import (
-       "cmd/compile/internal/base"
-)
-
-// Declaration stack & operations
-
-// A dsym stores a symbol's shadowed declaration so that it can be
-// restored once the block scope ends.
-type dsym struct {
-       sym *Sym // sym == nil indicates stack mark
-       def Object
-}
-
-// dclstack maintains a stack of shadowed symbol declarations so that
-// Popdcl can restore their declarations when a block scope ends.
-var dclstack []dsym
-
-// Pushdcl pushes the current declaration for symbol s (if any) so that
-// it can be shadowed by a new declaration within a nested block scope.
-func Pushdcl(s *Sym) {
-       dclstack = append(dclstack, dsym{
-               sym: s,
-               def: s.Def,
-       })
-}
-
-// Popdcl pops the innermost block scope and restores all symbol declarations
-// to their previous state.
-func Popdcl() {
-       for i := len(dclstack); i > 0; i-- {
-               d := &dclstack[i-1]
-               s := d.sym
-               if s == nil {
-                       // pop stack mark
-                       dclstack = dclstack[:i-1]
-                       return
-               }
-
-               s.Def = d.def
-
-               // Clear dead pointer fields.
-               d.sym = nil
-               d.def = nil
-       }
-       base.Fatalf("popdcl: no stack mark")
-}
-
-// Markdcl records the start of a new block scope for declarations.
-func Markdcl() {
-       dclstack = append(dclstack, dsym{
-               sym: nil, // stack mark
-       })
-}
-
-func isDclstackValid() bool {
-       for _, d := range dclstack {
-               if d.sym == nil {
-                       return false
-               }
-       }
-       return true
-}
-
 // PkgDef returns the definition associated with s at package scope.
-func (s *Sym) PkgDef() Object {
-       return *s.pkgDefPtr()
-}
+func (s *Sym) PkgDef() Object { return s.Def }
 
 // SetPkgDef sets the definition associated with s at package scope.
-func (s *Sym) SetPkgDef(n Object) {
-       *s.pkgDefPtr() = n
-}
-
-func (s *Sym) pkgDefPtr() *Object {
-       // Look for outermost saved declaration, which must be the
-       // package scope definition, if present.
-       for i := range dclstack {
-               d := &dclstack[i]
-               if s == d.sym {
-                       return &d.def
-               }
-       }
-
-       // Otherwise, the declaration hasn't been shadowed within a
-       // function scope.
-       return &s.Def
-}
-
-func CheckDclstack() {
-       if !isDclstackValid() {
-               base.Fatalf("mark left on the dclstack")
-       }
-}
+func (s *Sym) SetPkgDef(n Object) { s.Def = n }

diff --git a/src/cmd/compile/internal/types/sym.go b/src/cmd/compile/internal/types/sym.go
index 9d8707befa594b15080eb77b2969c4e49d572456..67fa6bb1d0c1cc4a450ecf14f4cbd74e53113bdf 100644 (file)
--- a/src/cmd/compile/internal/types/sym.go
+++ b/src/cmd/compile/internal/types/sym.go
@@ -35,8 +35,6 @@ type Sym struct {
        // bound to within the current scope. (Most parts of the compiler should
        // prefer passing the Node directly, rather than relying on this field.)
        //
-       // Def is saved and restored by Pushdcl/Popdcl.
-       //
        // Deprecated: New code should avoid depending on Sym.Def. Add
        // mdempsky@ as a reviewer for any CLs involving Sym.Def.
        Def Object