cmd/internal/goobj, cmd/link: remove funcdataoff

FUNCDATA is always a symbol reference with 0 offset. Assert the
offset is 0 and remove funcdataoff.

Change-Id: I326815365c9db5aeef6b869df5d78a9957bc16a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/352894
Trust: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

4 files changed, 21 insertions, 46 deletions

diff --git a/src/cmd/internal/goobj/funcinfo.go b/src/cmd/internal/goobj/funcinfo.go
index 6e7970fb74..59cb957fa7 100644
--- a/src/cmd/internal/goobj/funcinfo.go
+++ b/src/cmd/internal/goobj/funcinfo.go
@@ -21,11 +21,8 @@ type FuncInfo struct {
 	Locals   uint32
 	FuncID   objabi.FuncID
 	FuncFlag objabi.FuncFlag
-
-	Funcdataoff []uint32
-	File        []CUFileIndex
-
-	InlTree []InlTreeNode
+	File     []CUFileIndex
+	InlTree  []InlTreeNode
 }
 
 func (a *FuncInfo) Write(w *bytes.Buffer) {
@@ -45,10 +42,6 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
 	writeUint8(0) // pad to uint32 boundary
 	writeUint8(0)
 
-	writeUint32(uint32(len(a.Funcdataoff)))
-	for _, x := range a.Funcdataoff {
-		writeUint32(x)
-	}
 	writeUint32(uint32(len(a.File)))
 	for _, f := range a.File {
 		writeUint32(uint32(f))
@@ -65,25 +58,19 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
 // corresponding "off" field stores the byte offset of the start of
 // the items in question.
 type FuncInfoLengths struct {
-	NumFuncdataoff uint32
-	FuncdataoffOff uint32
-	NumFile        uint32
-	FileOff        uint32
-	NumInlTree     uint32
-	InlTreeOff     uint32
-	Initialized    bool
+	NumFile     uint32
+	FileOff     uint32
+	NumInlTree  uint32
+	InlTreeOff  uint32
+	Initialized bool
 }
 
 func (*FuncInfo) ReadFuncInfoLengths(b []byte) FuncInfoLengths {
 	var result FuncInfoLengths
 
-	// Offset to the number of funcdataoff values. This value is determined by counting
+	// Offset to the number of the file table. This value is determined by counting
 	// the number of bytes until we write funcdataoff to the file.
-	const numfuncdataoffOff = 12
-	result.NumFuncdataoff = binary.LittleEndian.Uint32(b[numfuncdataoffOff:])
-	result.FuncdataoffOff = numfuncdataoffOff + 4
-
-	numfileOff := result.FuncdataoffOff + 4*result.NumFuncdataoff
+	const numfileOff = 12
 	result.NumFile = binary.LittleEndian.Uint32(b[numfileOff:])
 	result.FileOff = numfileOff + 4
 
@@ -104,10 +91,6 @@ func (*FuncInfo) ReadFuncID(b []byte) objabi.FuncID { return objabi.FuncID(b[8])
 
 func (*FuncInfo) ReadFuncFlag(b []byte) objabi.FuncFlag { return objabi.FuncFlag(b[9]) }
 
-func (*FuncInfo) ReadFuncdataoff(b []byte, funcdataofffoff uint32, k uint32) int64 {
-	return int64(binary.LittleEndian.Uint32(b[funcdataofffoff+4*k:]))
-}
-
 func (*FuncInfo) ReadFile(b []byte, filesoff uint32, k uint32) CUFileIndex {
 	return CUFileIndex(binary.LittleEndian.Uint32(b[filesoff+4*k:]))
 }
diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
index 82ff5994d1..abb37416cc 100644
--- a/src/cmd/internal/obj/link.go
+++ b/src/cmd/internal/obj/link.go
@@ -830,15 +830,14 @@ func (*LSym) CanBeAnSSAAux() {}
 
 type Pcln struct {
 	// Aux symbols for pcln
-	Pcsp        *LSym
-	Pcfile      *LSym
-	Pcline      *LSym
-	Pcinline    *LSym
-	Pcdata      []*LSym
-	Funcdata    []*LSym
-	Funcdataoff []int64
-	UsedFiles   map[goobj.CUFileIndex]struct{} // file indices used while generating pcfile
-	InlTree     InlTree                        // per-function inlining tree extracted from the global tree
+	Pcsp      *LSym
+	Pcfile    *LSym
+	Pcline    *LSym
+	Pcinline  *LSym
+	Pcdata    []*LSym
+	Funcdata  []*LSym
+	UsedFiles map[goobj.CUFileIndex]struct{} // file indices used while generating pcfile
+	InlTree   InlTree                        // per-function inlining tree extracted from the global tree
 }
 
 type Reloc struct {
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index bed32198d7..3d8d69f069 100644
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -671,10 +671,6 @@ func genFuncInfoSyms(ctxt *Link) {
 			FuncFlag: fn.FuncFlag,
 		}
 		pc := &fn.Pcln
-		o.Funcdataoff = make([]uint32, len(pc.Funcdataoff))
-		for i, x := range pc.Funcdataoff {
-			o.Funcdataoff[i] = uint32(x)
-		}
 		i := 0
 		o.File = make([]goobj.CUFileIndex, len(pc.UsedFiles))
 		for f := range pc.UsedFiles {
diff --git a/src/cmd/internal/obj/pcln.go b/src/cmd/internal/obj/pcln.go
index 42c4a2a9d9..49b425b124 100644
--- a/src/cmd/internal/obj/pcln.go
+++ b/src/cmd/internal/obj/pcln.go
@@ -8,6 +8,7 @@ import (
 	"cmd/internal/goobj"
 	"cmd/internal/objabi"
 	"encoding/binary"
+	"fmt"
 	"log"
 )
 
@@ -280,8 +281,6 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 
 	pcln.Pcdata = make([]*LSym, npcdata)
 	pcln.Funcdata = make([]*LSym, nfuncdata)
-	pcln.Funcdataoff = make([]int64, nfuncdata)
-	pcln.Funcdataoff = pcln.Funcdataoff[:nfuncdata]
 
 	pcln.Pcsp = funcpctab(ctxt, cursym, "pctospadj", pctospadj, nil)
 	pcln.Pcfile = funcpctab(ctxt, cursym, "pctofile", pctofileline, pcln)
@@ -351,12 +350,10 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 				continue
 			}
 			i := int(p.From.Offset)
-			pcln.Funcdataoff[i] = p.To.Offset
-			if p.To.Type != TYPE_CONST {
-				// TODO: Dedup.
-				//funcdata_bytes += p->to.sym->size;
-				pcln.Funcdata[i] = p.To.Sym
+			if p.To.Type != TYPE_MEM || p.To.Offset != 0 {
+				panic(fmt.Sprintf("bad funcdata: %v", p))
 			}
+			pcln.Funcdata[i] = p.To.Sym
 		}
 	}
 }