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

We currently use two fields to store the targets of branches.
Some phases use p.To.Val, some use p.Pcond. Rewrite so that
every branch instruction uses p.To.Val.
p.From.Val is also used in rare instances.
Introduce a Pool link for use by arm/arm64, instead of
repurposing Pcond.

This is a cleanup CL in preparation for some stack frame CLs.

Change-Id: I9055bf0a1d986aff421e47951a1dedc301c846f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/243318
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

2 files changed, 23 insertions, 23 deletions

diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index 7a5a8ff38c..0fa0c20b6a 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/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.Pcond != nil { // 7: BEQ and like, 39: CBZ and like, 40: TBZ and like
-				otxt := p.Pcond.Pc - pc
+			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
 				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.Pcond = p.Pcond
-					p.Pcond = q
+					q.To.SetTarget(p.To.Target())
+					p.To.SetTarget(q)
 					q = c.newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AB
 					q.To.Type = obj.TYPE_BRANCH
-					q.Pcond = q.Link.Link
+					q.To.SetTarget(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.Pcond = p.Link
+			q.To.SetTarget(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.Pcond = q
+			p.Pool = 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.Pcond = q
+	p.Pool = 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.Pcond != nil {
-		v = (p.Pcond.Pc >> uint(preshift)) - (c.pc >> uint(preshift))
+	if p.To.Target() != nil {
+		v = (p.To.Target().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.Pcond)
+			c.ctxt.Diag("branch too far %#x vs %#x [%p]\n%v\n%v", v, t, c.blitrl, p, p.To.Target())
 			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.Pcond == nil { /* not in literal pool */
+	if p.Pool == 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.Pcond.As == ADWORD {
+			if p.Pool.As == ADWORD {
 				w = 1 /* 64-bit */
-			} else if p.Pcond.To.Offset < 0 {
+			} else if p.Pool.To.Offset < 0 {
 				w = 2 /* 32-bit, sign-extended to 64-bit */
-			} else if p.Pcond.To.Offset >= 0 {
+			} else if p.Pool.To.Offset >= 0 {
 				w = 0 /* 32-bit, zero-extended to 64-bit */
 			} else {
 				c.ctxt.Diag("invalid operand %v in %v", a, p)
diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go
index f54429fabe..56da854f16 100644
--- a/src/cmd/internal/obj/arm64/obj7.go
+++ b/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.Pcond = movlr
+		q.To.SetTarget(movlr)
 	}
-	bls.Pcond = movlr
+	bls.To.SetTarget(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.Pcond = c.cursym.Func.Text.Link
+	jmp.To.SetTarget(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.Pcond = mov
+				cbnz.To.SetTarget(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.Pcond = end
+				q.To.SetTarget(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.Pcond = end
+				q.To.SetTarget(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.Pcond = q5
+				q1.From.SetTarget(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.Pcond = q5
+				q1.From.SetTarget(q5)
 				p = q5
 			}
 		}