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, 19 insertions, 19 deletions

diff --git a/src/cmd/internal/obj/mips/asm0.go b/src/cmd/internal/obj/mips/asm0.go
index faa827da9f..6107974745 100644
--- a/src/cmd/internal/obj/mips/asm0.go
+++ b/src/cmd/internal/obj/mips/asm0.go
@@ -460,8 +460,8 @@ func span0(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			o = c.oplook(p)
 
 			// very large conditional branches
-			if o.type_ == 6 && p.Pcond != nil {
-				otxt = p.Pcond.Pc - pc
+			if o.type_ == 6 && p.To.Target() != nil {
+				otxt = p.To.Target().Pc - pc
 				if otxt < -(1<<17)+10 || otxt >= (1<<17)-10 {
 					q = c.newprog()
 					q.Link = p.Link
@@ -469,15 +469,15 @@ func span0(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 					q.As = AJMP
 					q.Pos = p.Pos
 					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 = AJMP
 					q.Pos = p.Pos
 					q.To.Type = obj.TYPE_BRANCH
-					q.Pcond = q.Link.Link
+					q.To.SetTarget(q.Link.Link)
 
 					c.addnop(p.Link)
 					c.addnop(p)
@@ -1230,10 +1230,10 @@ func (c *ctxt0) asmout(p *obj.Prog, o *Optab, out []uint32) {
 
 	case 6: /* beq r1,[r2],sbra */
 		v := int32(0)
-		if p.Pcond == nil {
+		if p.To.Target() == nil {
 			v = int32(-4) >> 2
 		} else {
-			v = int32(p.Pcond.Pc-p.Pc-4) >> 2
+			v = int32(p.To.Target().Pc-p.Pc-4) >> 2
 		}
 		if (v<<16)>>16 != v {
 			c.ctxt.Diag("short branch too far\n%v", p)
@@ -1285,25 +1285,25 @@ func (c *ctxt0) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		if c.aclass(&p.To) == C_SBRA && p.To.Sym == nil && p.As == AJMP {
 			// use PC-relative branch for short branches
 			// BEQ	R0, R0, sbra
-			if p.Pcond == nil {
+			if p.To.Target() == nil {
 				v = int32(-4) >> 2
 			} else {
-				v = int32(p.Pcond.Pc-p.Pc-4) >> 2
+				v = int32(p.To.Target().Pc-p.Pc-4) >> 2
 			}
 			if (v<<16)>>16 == v {
 				o1 = OP_IRR(c.opirr(ABEQ), uint32(v), uint32(REGZERO), uint32(REGZERO))
 				break
 			}
 		}
-		if p.Pcond == nil {
+		if p.To.Target() == nil {
 			v = int32(p.Pc) >> 2
 		} else {
-			v = int32(p.Pcond.Pc) >> 2
+			v = int32(p.To.Target().Pc) >> 2
 		}
 		o1 = OP_JMP(c.opirr(p.As), uint32(v))
 		if p.To.Sym == nil {
 			p.To.Sym = c.cursym.Func.Text.From.Sym
-			p.To.Offset = p.Pcond.Pc
+			p.To.Offset = p.To.Target().Pc
 		}
 		rel := obj.Addrel(c.cursym)
 		rel.Off = int32(c.pc)
diff --git a/src/cmd/internal/obj/mips/obj0.go b/src/cmd/internal/obj/mips/obj0.go
index 77cad979a6..f19facc00c 100644
--- a/src/cmd/internal/obj/mips/obj0.go
+++ b/src/cmd/internal/obj/mips/obj0.go
@@ -227,11 +227,11 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			} else {
 				p.Mark |= BRANCH
 			}
-			q1 := p.Pcond
+			q1 := p.To.Target()
 			if q1 != nil {
 				for q1.As == obj.ANOP {
 					q1 = q1.Link
-					p.Pcond = q1
+					p.To.SetTarget(q1)
 				}
 
 				if q1.Mark&LEAF == 0 {
@@ -424,8 +424,8 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				q = obj.Appendp(q, newprog)
 
 				q.As = obj.ANOP
-				p1.Pcond = q
-				p2.Pcond = q
+				p1.To.SetTarget(q)
+				p2.To.SetTarget(q)
 			}
 
 		case ARET:
@@ -778,7 +778,7 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	p.To.Type = obj.TYPE_REG
 	p.To.Reg = REG_R3
 	if q != nil {
-		q.Pcond = p
+		q.To.SetTarget(p)
 		p.Mark |= LABEL
 	}
 
@@ -805,14 +805,14 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 
 	p.As = AJMP
 	p.To.Type = obj.TYPE_BRANCH
-	p.Pcond = c.cursym.Func.Text.Link
+	p.To.SetTarget(c.cursym.Func.Text.Link)
 	p.Mark |= BRANCH
 
 	// placeholder for q1's jump target
 	p = obj.Appendp(p, c.newprog)
 
 	p.As = obj.ANOP // zero-width place holder
-	q1.Pcond = p
+	q1.To.SetTarget(p)
 
 	return p
 }