Revert "cmd/compile,cmd/asm: simplify recording of branch targets"

This reverts CL 243318.

Reason for revert: Seems to be crashing some builders.

Change-Id: I2ffc59bc5535be60b884b281c8d0eff4647dc756
Reviewed-on: https://go-review.googlesource.com/c/go/+/251169
Reviewed-by: Bryan C. Mills <[email protected]>

Author: randall77

src/cmd/compile/internal/amd64/ssa.go

@@ -319,8 +319,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 			// TODO(khr): issue only the -1 fixup code we need.
 			// For instance, if only the quotient is used, no point in zeroing the remainder.
 
-			j1.To.SetTarget(n1)
-			j2.To.SetTarget(s.Pc())
+			j1.To.Val = n1
+			j2.To.Val = s.Pc()
 		}
 
 	case ssa.OpAMD64HMULQ, ssa.OpAMD64HMULL, ssa.OpAMD64HMULQU, ssa.OpAMD64HMULLU:

src/cmd/compile/internal/gc/gsubr.go

@@ -342,6 +342,6 @@ func Patch(p *obj.Prog, to *obj.Prog) {
 	if p.To.Type != obj.TYPE_BRANCH {
 		Fatalf("patch: not a branch")
 	}
-	p.To.SetTarget(to)
+	p.To.Val = to
 	p.To.Offset = to.Pc
 }

src/cmd/compile/internal/gc/ssa.go

@@ -6182,7 +6182,7 @@ func genssa(f *ssa.Func, pp *Progs) {
 
 	// Resolve branches, and relax DefaultStmt into NotStmt
 	for _, br := range s.Branches {
-		br.P.To.SetTarget(s.bstart[br.B.ID])
+		br.P.To.Val = s.bstart[br.B.ID]
 		if br.P.Pos.IsStmt() != src.PosIsStmt {
 			br.P.Pos = br.P.Pos.WithNotStmt()
 		} else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {

src/cmd/compile/internal/s390x/ssa.go

@@ -338,8 +338,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 				n.To.Reg = dividend
 			}
 
-			j.To.SetTarget(n)
-			j2.To.SetTarget(s.Pc())
+			j.To.Val = n
+			j2.To.Val = s.Pc()
 		}
 	case ssa.OpS390XADDconst, ssa.OpS390XADDWconst:
 		opregregimm(s, v.Op.Asm(), v.Reg(), v.Args[0].Reg(), v.AuxInt)

src/cmd/compile/internal/x86/ssa.go

@@ -261,8 +261,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 				n.To.Reg = x86.REG_DX
 			}
 
-			j.To.SetTarget(n)
-			j2.To.SetTarget(s.Pc())
+			j.To.Val = n
+			j2.To.Val = s.Pc()
 		}
 
 	case ssa.Op386HMULL, ssa.Op386HMULLU:

src/cmd/internal/obj/arm/asm5.go

@@ -644,7 +644,7 @@ func (c *ctxt5) flushpool(p *obj.Prog, skip int, force int) bool {
 			q := c.newprog()
 			q.As = AB
 			q.To.Type = obj.TYPE_BRANCH
-			q.To.SetTarget(p.Link)
+			q.Pcond = p.Link
 			q.Link = c.blitrl
 			q.Pos = p.Pos
 			c.blitrl = q
@@ -705,7 +705,7 @@ func (c *ctxt5) addpool(p *obj.Prog, a *obj.Addr) {
 	if t.Rel == nil {
 		for q := c.blitrl; q != nil; q = q.Link { /* could hash on t.t0.offset */
 			if q.Rel == nil && q.To == t.To {
-				p.Pool = q
+				p.Pcond = q
 				return
 			}
 		}
@@ -724,8 +724,8 @@ func (c *ctxt5) addpool(p *obj.Prog, a *obj.Addr) {
 	c.elitrl = q
 	c.pool.size += 4
 
-	// Store the link to the pool entry in Pool.
-	p.Pool = q
+	// Store the link to the pool entry in Pcond.
+	p.Pcond = q
 }
 
 func (c *ctxt5) regoff(a *obj.Addr) int32 {
@@ -1584,8 +1584,8 @@ func (c *ctxt5) asmout(p *obj.Prog, o *Optab, out []uint32) {
 			break
 		}
 
-		if p.To.Target() != nil {
-			v = int32((p.To.Target().Pc - c.pc) - 8)
+		if p.Pcond != nil {
+			v = int32((p.Pcond.Pc - c.pc) - 8)
 		}
 		o1 |= (uint32(v) >> 2) & 0xffffff
 
@@ -3023,7 +3023,7 @@ func (c *ctxt5) omvr(p *obj.Prog, a *obj.Addr, dr int) uint32 {
 
 func (c *ctxt5) omvl(p *obj.Prog, a *obj.Addr, dr int) uint32 {
 	var o1 uint32
-	if p.Pool == nil {
+	if p.Pcond == nil {
 		c.aclass(a)
 		v := immrot(^uint32(c.instoffset))
 		if v == 0 {
@@ -3035,7 +3035,7 @@ func (c *ctxt5) omvl(p *obj.Prog, a *obj.Addr, dr int) uint32 {
 		o1 |= uint32(v)
 		o1 |= (uint32(dr) & 15) << 12
 	} else {
-		v := int32(p.Pool.Pc - p.Pc - 8)
+		v := int32(p.Pcond.Pc - p.Pc - 8)
 		o1 = c.olr(v, REGPC, dr, int(p.Scond)&C_SCOND)
 	}
 

src/cmd/internal/obj/arm/obj5.go

@@ -406,7 +406,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				mov.To.Reg = REG_R2
 
 				// B.NE branch target is MOVW above
-				bne.To.SetTarget(mov)
+				bne.Pcond = mov
 
 				// ADD $(autosize+4), R13, R3
 				p = obj.Appendp(mov, newprog)
@@ -428,7 +428,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				p = obj.Appendp(p, newprog)
 				p.As = ABNE
 				p.To.Type = obj.TYPE_BRANCH
-				p.To.SetTarget(end)
+				p.Pcond = end
 
 				// ADD $4, R13, R4
 				p = obj.Appendp(p, newprog)
@@ -452,7 +452,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				p = obj.Appendp(p, newprog)
 				p.As = AB
 				p.To.Type = obj.TYPE_BRANCH
-				p.To.SetTarget(end)
+				p.Pcond = end
 
 				// reset for subsequent passes
 				p = end
@@ -741,7 +741,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	movw.To.Type = obj.TYPE_REG
 	movw.To.Reg = REG_R3
 
-	bls.To.SetTarget(movw)
+	bls.Pcond = movw
 
 	// BL runtime.morestack
 	call := obj.Appendp(movw, c.newprog)
@@ -762,7 +762,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	b := obj.Appendp(pcdata, c.newprog)
 	b.As = obj.AJMP
 	b.To.Type = obj.TYPE_BRANCH
-	b.To.SetTarget(c.cursym.Func.Text.Link)
+	b.Pcond = c.cursym.Func.Text.Link
 	b.Spadj = +framesize
 
 	return end

src/cmd/internal/obj/arm64/asm7.go

@@ -977,8 +977,8 @@ func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			o = c.oplook(p)
 
 			/* very large branches */
-			if (o.type_ == 7 || o.type_ == 39 || o.type_ == 40) && p.To.Target() != nil { // 7: BEQ and like, 39: CBZ and like, 40: TBZ and like
-				otxt := p.To.Target().Pc - pc
+			if (o.type_ == 7 || o.type_ == 39 || o.type_ == 40) && p.Pcond != nil { // 7: BEQ and like, 39: CBZ and like, 40: TBZ and like
+				otxt := p.Pcond.Pc - pc
 				var toofar bool
 				switch o.type_ {
 				case 7, 39: // branch instruction encodes 19 bits
@@ -992,14 +992,14 @@ func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 					p.Link = q
 					q.As = AB
 					q.To.Type = obj.TYPE_BRANCH
-					q.To.SetTarget(p.To.Target())
-					p.To.SetTarget(q)
+					q.Pcond = p.Pcond
+					p.Pcond = q
 					q = c.newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AB
 					q.To.Type = obj.TYPE_BRANCH
-					q.To.SetTarget(q.Link.Link)
+					q.Pcond = q.Link.Link
 					bflag = 1
 				}
 			}
@@ -1123,7 +1123,7 @@ func (c *ctxt7) flushpool(p *obj.Prog, skip int) {
 			q := c.newprog()
 			q.As = AB
 			q.To.Type = obj.TYPE_BRANCH
-			q.To.SetTarget(p.Link)
+			q.Pcond = p.Link
 			q.Link = c.blitrl
 			q.Pos = p.Pos
 			c.blitrl = q
@@ -1249,7 +1249,7 @@ func (c *ctxt7) addpool(p *obj.Prog, a *obj.Addr) {
 
 	for q := c.blitrl; q != nil; q = q.Link { /* could hash on t.t0.offset */
 		if q.To == t.To {
-			p.Pool = q
+			p.Pcond = q
 			return
 		}
 	}
@@ -1266,7 +1266,7 @@ func (c *ctxt7) addpool(p *obj.Prog, a *obj.Addr) {
 	c.elitrl = q
 	c.pool.size = -c.pool.size & (funcAlign - 1)
 	c.pool.size += uint32(sz)
-	p.Pool = q
+	p.Pcond = q
 }
 
 func (c *ctxt7) regoff(a *obj.Addr) uint32 {
@@ -6042,15 +6042,15 @@ func (c *ctxt7) opimm(p *obj.Prog, a obj.As) uint32 {
 func (c *ctxt7) brdist(p *obj.Prog, preshift int, flen int, shift int) int64 {
 	v := int64(0)
 	t := int64(0)
-	if p.To.Target() != nil {
-		v = (p.To.Target().Pc >> uint(preshift)) - (c.pc >> uint(preshift))
+	if p.Pcond != nil {
+		v = (p.Pcond.Pc >> uint(preshift)) - (c.pc >> uint(preshift))
 		if (v & ((1 << uint(shift)) - 1)) != 0 {
 			c.ctxt.Diag("misaligned label\n%v", p)
 		}
 		v >>= uint(shift)
 		t = int64(1) << uint(flen-1)
 		if v < -t || v >= t {
-			c.ctxt.Diag("branch too far %#x vs %#x [%p]\n%v\n%v", v, t, c.blitrl, p, p.To.Target())
+			c.ctxt.Diag("branch too far %#x vs %#x [%p]\n%v\n%v", v, t, c.blitrl, p, p.Pcond)
 			panic("branch too far")
 		}
 	}
@@ -6526,7 +6526,7 @@ func (c *ctxt7) oaddi(p *obj.Prog, o1 int32, v int32, r int, rt int) uint32 {
  */
 func (c *ctxt7) omovlit(as obj.As, p *obj.Prog, a *obj.Addr, dr int) uint32 {
 	var o1 int32
-	if p.Pool == nil { /* not in literal pool */
+	if p.Pcond == nil { /* not in literal pool */
 		c.aclass(a)
 		c.ctxt.Logf("omovlit add %d (%#x)\n", c.instoffset, uint64(c.instoffset))
 
@@ -6552,11 +6552,11 @@ func (c *ctxt7) omovlit(as obj.As, p *obj.Prog, a *obj.Addr, dr int) uint32 {
 			w = 1 /* 64-bit SIMD/FP */
 
 		case AMOVD:
-			if p.Pool.As == ADWORD {
+			if p.Pcond.As == ADWORD {
 				w = 1 /* 64-bit */
-			} else if p.Pool.To.Offset < 0 {
+			} else if p.Pcond.To.Offset < 0 {
 				w = 2 /* 32-bit, sign-extended to 64-bit */
-			} else if p.Pool.To.Offset >= 0 {
+			} else if p.Pcond.To.Offset >= 0 {
 				w = 0 /* 32-bit, zero-extended to 64-bit */
 			} else {
 				c.ctxt.Diag("invalid operand %v in %v", a, p)

src/cmd/internal/obj/arm64/obj7.go

@@ -187,9 +187,9 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	movlr.To.Type = obj.TYPE_REG
 	movlr.To.Reg = REG_R3
 	if q != nil {
-		q.To.SetTarget(movlr)
+		q.Pcond = movlr
 	}
-	bls.To.SetTarget(movlr)
+	bls.Pcond = movlr
 
 	debug := movlr
 	if false {
@@ -220,7 +220,7 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	jmp := obj.Appendp(pcdata, c.newprog)
 	jmp.As = AB
 	jmp.To.Type = obj.TYPE_BRANCH
-	jmp.To.SetTarget(c.cursym.Func.Text.Link)
+	jmp.Pcond = c.cursym.Func.Text.Link
 	jmp.Spadj = +framesize
 
 	return end
@@ -697,7 +697,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				mov.To.Reg = REG_R2
 
 				// CBNZ branches to the MOV above
-				cbnz.To.SetTarget(mov)
+				cbnz.Pcond = mov
 
 				// ADD $(autosize+8), SP, R3
 				q = obj.Appendp(mov, c.newprog)
@@ -719,7 +719,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q = obj.Appendp(q, c.newprog)
 				q.As = ABNE
 				q.To.Type = obj.TYPE_BRANCH
-				q.To.SetTarget(end)
+				q.Pcond = end
 
 				// ADD $8, SP, R4
 				q = obj.Appendp(q, c.newprog)
@@ -743,7 +743,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q = obj.Appendp(q, c.newprog)
 				q.As = AB
 				q.To.Type = obj.TYPE_BRANCH
-				q.To.SetTarget(end)
+				q.Pcond = end
 			}
 
 		case obj.ARET:
@@ -913,7 +913,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q5.Reg = REGSP
 				q5.To.Type = obj.TYPE_REG
 				q5.To.Reg = REGFP
-				q1.From.SetTarget(q5)
+				q1.Pcond = q5
 				p = q5
 			}
 
@@ -966,7 +966,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q5.Reg = REGSP
 				q5.To.Type = obj.TYPE_REG
 				q5.To.Reg = REGFP
-				q1.From.SetTarget(q5)
+				q1.Pcond = q5
 				p = q5
 			}
 		}

src/cmd/internal/obj/link.go

@@ -237,19 +237,6 @@ const (
 	TYPE_REGLIST
 )
 
-func (a *Addr) Target() *Prog {
-	if a.Type == TYPE_BRANCH && a.Val != nil {
-		return a.Val.(*Prog)
-	}
-	return nil
-}
-func (a *Addr) SetTarget(t *Prog) {
-	if a.Type != TYPE_BRANCH {
-		panic("setting branch target when type is not TYPE_BRANCH")
-	}
-	a.Val = t
-}
-
 // Prog describes a single machine instruction.
 //
 // The general instruction form is:
@@ -268,7 +255,7 @@ func (a *Addr) SetTarget(t *Prog) {
 // to avoid too much changes in a single swing.
 // (1) scheme is enough to express any kind of operand combination.
 //
-// Jump instructions use the To.Val field to point to the target *Prog,
+// Jump instructions use the Pcond field to point to the target instruction,
 // which must be in the same linked list as the jump instruction.
 //
 // The Progs for a given function are arranged in a list linked through the Link field.
@@ -287,7 +274,7 @@ type Prog struct {
 	From     Addr     // first source operand
 	RestArgs []Addr   // can pack any operands that not fit into {Prog.From, Prog.To}
 	To       Addr     // destination operand (second is RegTo2 below)
-	Pool     *Prog    // constant pool entry, for arm,arm64 back ends
+	Pcond    *Prog    // target of conditional jump
 	Forwd    *Prog    // for x86 back end
 	Rel      *Prog    // for x86, arm back ends
 	Pc       int64    // for back ends or assembler: virtual or actual program counter, depending on phase