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 <bcmills@google.com>

1 files changed, 10 insertions, 7 deletions

diff --git a/src/cmd/internal/obj/pass.go b/src/cmd/internal/obj/pass.go
index 09d520b4e9..4f156d969b 100644
--- a/src/cmd/internal/obj/pass.go
+++ b/src/cmd/internal/obj/pass.go
@@ -36,8 +36,8 @@ package obj
 // In the case of an infinite loop, brloop returns nil.
 func brloop(p *Prog) *Prog {
 	c := 0
-	for q := p; q != nil; q = q.To.Target() {
-		if q.As != AJMP || q.To.Target() == nil {
+	for q := p; q != nil; q = q.Pcond {
+		if q.As != AJMP || q.Pcond == nil {
 			return q
 		}
 		c++
@@ -132,6 +132,8 @@ func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 			continue
 		}
 		if p.To.Val != nil {
+			// TODO: Remove To.Val.(*Prog) in favor of p->pcond.
+			p.Pcond = p.To.Val.(*Prog)
 			continue
 		}
 
@@ -156,7 +158,8 @@ func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 			p.To.Type = TYPE_NONE
 		}
 
-		p.To.SetTarget(q)
+		p.To.Val = q
+		p.Pcond = q
 	}
 
 	if !ctxt.Flag_optimize {
@@ -165,12 +168,12 @@ func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 
 	// Collapse series of jumps to jumps.
 	for p := sym.Func.Text; p != nil; p = p.Link {
-		if p.To.Target() == nil {
+		if p.Pcond == nil {
 			continue
 		}
-		p.To.SetTarget(brloop(p.To.Target()))
-		if p.To.Target() != nil && p.To.Type == TYPE_BRANCH {
-			p.To.Offset = p.To.Target().Pc
+		p.Pcond = brloop(p.Pcond)
+		if p.Pcond != nil && p.To.Type == TYPE_BRANCH {
+			p.To.Offset = p.Pcond.Pc
 		}
 	}
 }