cmd/link: access pcdata via aux symbols

Pcdata are now separate aux symbols. Read them from aux, instead
of using funcinfo.

Now we can remove pcdata fields from funcinfo.

Change-Id: Ie65e3962edecc0f39127a5f6963dc59d1f141e67
Reviewed-on: https://go-review.googlesource.com/c/go/+/352893
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

2 files changed, 3 insertions, 60 deletions

diff --git a/src/cmd/internal/goobj/funcinfo.go b/src/cmd/internal/goobj/funcinfo.go
index 6d33a10a51..6e7970fb74 100644
--- a/src/cmd/internal/goobj/funcinfo.go
+++ b/src/cmd/internal/goobj/funcinfo.go
@@ -16,19 +16,12 @@ type CUFileIndex uint32
 
 // FuncInfo is serialized as a symbol (aux symbol). The symbol data is
 // the binary encoding of the struct below.
-//
-// TODO: make each pcdata a separate symbol?
 type FuncInfo struct {
 	Args     uint32
 	Locals   uint32
 	FuncID   objabi.FuncID
 	FuncFlag objabi.FuncFlag
 
-	Pcsp        SymRef
-	Pcfile      SymRef
-	Pcline      SymRef
-	Pcinline    SymRef
-	Pcdata      []SymRef
 	Funcdataoff []uint32
 	File        []CUFileIndex
 
@@ -44,10 +37,6 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
 		binary.LittleEndian.PutUint32(b[:], x)
 		w.Write(b[:])
 	}
-	writeSymRef := func(s SymRef) {
-		writeUint32(s.PkgIdx)
-		writeUint32(s.SymIdx)
-	}
 
 	writeUint32(a.Args)
 	writeUint32(a.Locals)
@@ -55,14 +44,6 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
 	writeUint8(uint8(a.FuncFlag))
 	writeUint8(0) // pad to uint32 boundary
 	writeUint8(0)
-	writeSymRef(a.Pcsp)
-	writeSymRef(a.Pcfile)
-	writeSymRef(a.Pcline)
-	writeSymRef(a.Pcinline)
-	writeUint32(uint32(len(a.Pcdata)))
-	for _, sym := range a.Pcdata {
-		writeSymRef(sym)
-	}
 
 	writeUint32(uint32(len(a.Funcdataoff)))
 	for _, x := range a.Funcdataoff {
@@ -84,8 +65,6 @@ 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 {
-	NumPcdata      uint32
-	PcdataOff      uint32
 	NumFuncdataoff uint32
 	FuncdataoffOff uint32
 	NumFile        uint32
@@ -98,13 +77,9 @@ type FuncInfoLengths struct {
 func (*FuncInfo) ReadFuncInfoLengths(b []byte) FuncInfoLengths {
 	var result FuncInfoLengths
 
-	// Offset to the number of pcdata values. This value is determined by counting
-	// the number of bytes until we write pcdata to the file.
-	const numpcdataOff = 44
-	result.NumPcdata = binary.LittleEndian.Uint32(b[numpcdataOff:])
-	result.PcdataOff = numpcdataOff + 4
-
-	numfuncdataoffOff := result.PcdataOff + 8*result.NumPcdata
+	// Offset to the number of funcdataoff values. 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
 
@@ -129,30 +104,6 @@ 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) ReadPcsp(b []byte) SymRef {
-	return SymRef{binary.LittleEndian.Uint32(b[12:]), binary.LittleEndian.Uint32(b[16:])}
-}
-
-func (*FuncInfo) ReadPcfile(b []byte) SymRef {
-	return SymRef{binary.LittleEndian.Uint32(b[20:]), binary.LittleEndian.Uint32(b[24:])}
-}
-
-func (*FuncInfo) ReadPcline(b []byte) SymRef {
-	return SymRef{binary.LittleEndian.Uint32(b[28:]), binary.LittleEndian.Uint32(b[32:])}
-}
-
-func (*FuncInfo) ReadPcinline(b []byte) SymRef {
-	return SymRef{binary.LittleEndian.Uint32(b[36:]), binary.LittleEndian.Uint32(b[40:])}
-}
-
-func (*FuncInfo) ReadPcdata(b []byte) []SymRef {
-	syms := make([]SymRef, binary.LittleEndian.Uint32(b[44:]))
-	for i := range syms {
-		syms[i] = SymRef{binary.LittleEndian.Uint32(b[48+i*8:]), binary.LittleEndian.Uint32(b[52+i*8:])}
-	}
-	return syms
-}
-
 func (*FuncInfo) ReadFuncdataoff(b []byte, funcdataofffoff uint32, k uint32) int64 {
 	return int64(binary.LittleEndian.Uint32(b[funcdataofffoff+4*k:]))
 }
diff --git a/src/cmd/internal/obj/objfile.go b/src/cmd/internal/obj/objfile.go
index 030a02b499..bed32198d7 100644
--- a/src/cmd/internal/obj/objfile.go
+++ b/src/cmd/internal/obj/objfile.go
@@ -671,14 +671,6 @@ func genFuncInfoSyms(ctxt *Link) {
 			FuncFlag: fn.FuncFlag,
 		}
 		pc := &fn.Pcln
-		o.Pcsp = makeSymRef(pc.Pcsp)
-		o.Pcfile = makeSymRef(pc.Pcfile)
-		o.Pcline = makeSymRef(pc.Pcline)
-		o.Pcinline = makeSymRef(pc.Pcinline)
-		o.Pcdata = make([]goobj.SymRef, len(pc.Pcdata))
-		for i, pcSym := range pc.Pcdata {
-			o.Pcdata[i] = makeSymRef(pcSym)
-		}
 		o.Funcdataoff = make([]uint32, len(pc.Funcdataoff))
 		for i, x := range pc.Funcdataoff {
 			o.Funcdataoff[i] = uint32(x)