cmd/link: remove reading/processing of function Autom records

Remove linker reading and processing of automs (no longer needed, now
that the compiler is emitting R_USETYPE relocations on functions). So
as to avoid changing the object file format, the object still contains
a count of automs, but this count is required to be zero.

Updates #34554.

Change-Id: I10230e191057c5c5705541eeb06f747d5f73c42d
Reviewed-on: https://go-review.googlesource.com/c/go/+/197500
Reviewed-by: Jeremy Faller <jeremy@golang.org>

diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 418703cb2f695e20bef4906a803ec057586637a7..c880c0da01ac9d66d53399e27ead558237a5b95b 100644 (file)
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -270,12 +270,6 @@ func (d *deadcodepass) flood() {
                        if d.ctxt.Debugvlog > 1 {
                                d.ctxt.Logf("marktext %s\n", s.Name)
                        }
-                       if s.FuncInfo != nil {
-                               for _, a := range s.FuncInfo.Autom {
-                                       d.mark(a.Gotype, s)
-                               }
-                       }
-
                }
 
                if strings.HasPrefix(s.Name, "type.") && s.Name[5] != '.' {

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 3739838bcee8ea40584669d94377d32292c78289..182e5b0769eae38652bf6f9bf37a747add5bd9b6 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -2366,7 +2366,6 @@ func genasmsym(ctxt *Link, put func(*Link, *sym.Symbol, string, SymbolType, int6
                }
        }
 
-       var off int32
        for _, s := range ctxt.Textp {
                put(ctxt, s, s.Name, TextSym, s.Value, s.Gotype)
 
@@ -2380,39 +2379,6 @@ func genasmsym(ctxt *Link, put func(*Link, *sym.Symbol, string, SymbolType, int6
                if s.FuncInfo == nil {
                        continue
                }
-               for _, a := range s.FuncInfo.Autom {
-                       if a.Name == objabi.A_DELETED_AUTO {
-                               put(ctxt, nil, "", DeletedAutoSym, 0, a.Gotype)
-                               continue
-                       }
-
-                       // Emit a or p according to actual offset, even if label is wrong.
-                       // This avoids negative offsets, which cannot be encoded.
-                       if a.Name != objabi.A_AUTO && a.Name != objabi.A_PARAM {
-                               continue
-                       }
-
-                       // compute offset relative to FP
-                       if a.Name == objabi.A_PARAM {
-                               off = a.Aoffset
-                       } else {
-                               off = a.Aoffset - int32(ctxt.Arch.PtrSize)
-                       }
-
-                       // FP
-                       if off >= 0 {
-                               put(ctxt, nil, a.Asym.Name, ParamSym, int64(off), a.Gotype)
-                               continue
-                       }
-
-                       // SP
-                       if off <= int32(-ctxt.Arch.PtrSize) {
-                               put(ctxt, nil, a.Asym.Name, AutoSym, -(int64(off) + int64(ctxt.Arch.PtrSize)), a.Gotype)
-                               continue
-                       }
-                       // Otherwise, off is addressing the saved program counter.
-                       // Something underhanded is going on. Say nothing.
-               }
        }
 
        if ctxt.Debugvlog != 0 || *flagN {

diff --git a/src/cmd/link/internal/objfile/objfile.go b/src/cmd/link/internal/objfile/objfile.go
index da9a38a6d49d6fe129efcd29c24031624c4f2a9c..3a4ba8224c1d1fcb03e8ab07b9f53692cb2404c4 100644 (file)
--- a/src/cmd/link/internal/objfile/objfile.go
+++ b/src/cmd/link/internal/objfile/objfile.go
@@ -55,7 +55,6 @@ type objReader struct {
        data        []byte
        reloc       []sym.Reloc
        pcdata      []sym.Pcdata
-       autom       []sym.Auto
        funcdata    []*sym.Symbol
        funcdataoff []int64
        file        []*sym.Symbol
@@ -193,8 +192,7 @@ func (r *objReader) readSlices() {
        r.reloc = make([]sym.Reloc, n)
        n = r.readInt()
        r.pcdata = make([]sym.Pcdata, n)
-       n = r.readInt()
-       r.autom = make([]sym.Auto, n)
+       _ = r.readInt() // TODO: remove on next object file rev (autom count)
        n = r.readInt()
        r.funcdata = make([]*sym.Symbol, n)
        r.funcdataoff = make([]int64, n)
@@ -328,24 +326,10 @@ overwrite:
                        s.Attr |= sym.AttrTopFrame
                }
                n := r.readInt()
-               pc.Autom = r.autom[:n:n]
-               if !isdup {
-                       r.autom = r.autom[n:]
+               if n != 0 {
+                       log.Fatalf("stale object file: autom count nonzero")
                }
 
-               for i := 0; i < n; i++ {
-                       pc.Autom[i] = sym.Auto{
-                               Asym:    r.readSymIndex(),
-                               Aoffset: r.readInt32(),
-                               Name:    r.readInt16(),
-                               Gotype:  r.readSymIndex(),
-                       }
-               }
-
-               // Temporary: zero out the autom list after we've read it.
-               // In a subsequent patch we'll remove autom handling more completely.
-               pc.Autom = nil
-
                pc.Pcsp.P = r.readData()
                pc.Pcfile.P = r.readData()
                pc.Pcline.P = r.readData()

diff --git a/src/cmd/link/internal/sym/symbol.go b/src/cmd/link/internal/sym/symbol.go
index da06b08ebd090503e1474254cfb5e84cd36c3837..698f8ee653bdbd180eaf03e5a0b28ca93e5c17cc 100644 (file)
--- a/src/cmd/link/internal/sym/symbol.go
+++ b/src/cmd/link/internal/sym/symbol.go
@@ -518,7 +518,6 @@ func SortSub(l *Symbol) *Symbol {
 type FuncInfo struct {
        Args        int32
        Locals      int32
-       Autom       []Auto
        Pcsp        Pcdata
        Pcfile      Pcdata
        Pcline      Pcdata
@@ -542,10 +541,3 @@ type InlinedCall struct {
 type Pcdata struct {
        P []byte
 }
-
-type Auto struct {
-       Asym    *Symbol
-       Gotype  *Symbol
-       Aoffset int32
-       Name    int16
-}