cmd/internal/obj: fix PCSP table at runtime.morestack calls

Fixes #13346.

Change-Id: Ic903ee90575e8dbe23905d0678d3295745d1d47f
Reviewed-on: https://go-review.googlesource.com/18154
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Russ Cox <rsc@golang.org>

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

@@ -803,8 +803,12 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 	for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
 	}
 
+	spfix := obj.Appendp(ctxt, last)
+	spfix.As = obj.ANOP
+	spfix.Spadj = -framesize
+
 	// MOVW	LR, R3
-	movw := obj.Appendp(ctxt, last)
+	movw := obj.Appendp(ctxt, spfix)
 	movw.As = AMOVW
 	movw.From.Type = obj.TYPE_REG
 	movw.From.Reg = REGLINK
@@ -831,6 +835,7 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 	b.As = obj.AJMP
 	b.To.Type = obj.TYPE_BRANCH
 	b.Pcond = ctxt.Cursym.Text.Link
+	b.Spadj = +framesize
 
 	return bls
 }

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

@@ -161,8 +161,12 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 	for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
 	}
 
+	spfix := obj.Appendp(ctxt, last)
+	spfix.As = obj.ANOP
+	spfix.Spadj = -framesize
+
 	// MOV	LR, R3
-	movlr := obj.Appendp(ctxt, last)
+	movlr := obj.Appendp(ctxt, spfix)
 	movlr.As = AMOVD
 	movlr.From.Type = obj.TYPE_REG
 	movlr.From.Reg = REGLINK
@@ -201,6 +205,7 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
 	jmp.As = AB
 	jmp.To.Type = obj.TYPE_BRANCH
 	jmp.Pcond = ctxt.Cursym.Text.Link
+	jmp.Spadj = +framesize
 
 	// placeholder for bls's jump target
 	// p = obj.Appendp(ctxt, p)

src/cmd/internal/obj/x86/obj6.go

@@ -1080,7 +1080,11 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, textarg int32) *ob
 	for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
 	}
 
-	call := obj.Appendp(ctxt, last)
+	spfix := obj.Appendp(ctxt, last)
+	spfix.As = obj.ANOP
+	spfix.Spadj = -framesize
+
+	call := obj.Appendp(ctxt, spfix)
 	call.Lineno = ctxt.Cursym.Text.Lineno
 	call.Mode = ctxt.Cursym.Text.Mode
 	call.As = obj.ACALL
@@ -1098,6 +1102,7 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, textarg int32) *ob
 	jmp.As = obj.AJMP
 	jmp.To.Type = obj.TYPE_BRANCH
 	jmp.Pcond = ctxt.Cursym.Text.Link
+	jmp.Spadj = +framesize
 
 	jls.Pcond = call
 	if q1 != nil {