cmd/internal/obj/s390x: cleanup objz.go

This CL deletes some unnecessary code in objz.go that existed to
support instruction scheduling. It's likely instruction scheduling
will never be done in this part of the backend so this code can
just be deleted.

This file can probably be cleaned up a bit more, but I think this
is a good start.

Passes: go build -toolexec 'toolstash -cmp' -a std.

Change-Id: I1645632ac551a90a4f4be418045c046b488e9469
Reviewed-on: https://go-review.googlesource.com/38394
Run-TryBot: Michael Munday <munday@ca.ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/internal/obj/s390x/a.out.go

@@ -159,16 +159,8 @@ const (
 
 const (
 	// mark flags
-	LABEL   = 1 << 0
-	LEAF    = 1 << 1
-	FLOAT   = 1 << 2
-	BRANCH  = 1 << 3
-	LOAD    = 1 << 4
-	FCMP    = 1 << 5
-	SYNC    = 1 << 6
-	LIST    = 1 << 7
-	FOLL    = 1 << 8
-	NOSCHED = 1 << 9
+	LEAF = 1 << iota
+	BRANCH
 )
 
 const ( // comments from func aclass in asmz.go

src/cmd/internal/obj/s390x/objz.go

@@ -239,60 +239,20 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 	 * find leaf subroutines
 	 * strip NOPs
 	 * expand RET
-	 * expand BECOME pseudo
 	 */
 	if ctxt.Debugvlog != 0 {
 		ctxt.Logf("%5.2f noops\n", obj.Cputime())
 	}
 
 	var q *obj.Prog
-	var q1 *obj.Prog
 	for p := cursym.Text; p != nil; p = p.Link {
 		switch p.As {
-		/* too hard, just leave alone */
 		case obj.ATEXT:
 			q = p
+			p.Mark |= LEAF
 
-			p.Mark |= LABEL | LEAF | SYNC
-			if p.Link != nil {
-				p.Link.Mark |= LABEL
-			}
-
-		case ASYNC,
-			AWORD:
-			q = p
-			p.Mark |= LABEL | SYNC
-			continue
-
-		case AMOVW, AMOVWZ, AMOVD:
+		case ABL, ABCL:
 			q = p
-			if p.From.Reg >= REG_RESERVED || p.To.Reg >= REG_RESERVED {
-				p.Mark |= LABEL | SYNC
-			}
-			continue
-
-		case AFABS,
-			AFADD,
-			AFDIV,
-			AFMADD,
-			AFMOVD,
-			AFMOVS,
-			AFMSUB,
-			AFMUL,
-			AFNABS,
-			AFNEG,
-			ALEDBR,
-			ALDEBR,
-			AFSUB:
-			q = p
-
-			p.Mark |= FLOAT
-			continue
-
-		case ABL,
-			ABCL,
-			obj.ADUFFZERO,
-			obj.ADUFFCOPY:
 			cursym.Text.Mark &^= LEAF
 			fallthrough
 
@@ -320,54 +280,26 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 			ACMPUBLE,
 			ACMPUBLT,
 			ACMPUBNE:
-			p.Mark |= BRANCH
 			q = p
-			q1 = p.Pcond
-			if q1 != nil {
-				for q1.As == obj.ANOP {
-					q1 = q1.Link
-					p.Pcond = q1
-				}
-
-				if q1.Mark&LEAF == 0 {
-					q1.Mark |= LABEL
+			p.Mark |= BRANCH
+			if p.Pcond != nil {
+				q := p.Pcond
+				for q.As == obj.ANOP {
+					q = q.Link
+					p.Pcond = q
 				}
-			} else {
-				p.Mark |= LABEL
-			}
-			q1 = p.Link
-			if q1 != nil {
-				q1.Mark |= LABEL
 			}
-			continue
-
-		case AFCMPO, AFCMPU:
-			q = p
-			p.Mark |= FCMP | FLOAT
-			continue
-
-		case obj.ARET:
-			q = p
-			if p.Link != nil {
-				p.Link.Mark |= LABEL
-			}
-			continue
 
 		case obj.ANOP:
-			q1 = p.Link
-			q.Link = q1 /* q is non-nop */
-			q1.Mark |= p.Mark
-			continue
+			q.Link = p.Link /* q is non-nop */
+			p.Link.Mark |= p.Mark
 
 		default:
 			q = p
-			continue
 		}
 	}
 
 	autosize := int32(0)
-	var p1 *obj.Prog
-	var p2 *obj.Prog
 	var pLast *obj.Prog
 	var pPre *obj.Prog
 	var pPreempt *obj.Prog
@@ -397,7 +329,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 
 			p.To.Offset = int64(autosize)
 
-			q = p
+			q := p
 
 			if p.From3.Offset&obj.NOSPLIT == 0 {
 				p, pPreempt = stacksplitPre(ctxt, p, autosize) // emit pre part of split check
@@ -476,7 +408,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				q = obj.Appendp(ctxt, q)
 				q.As = ABEQ
 				q.To.Type = obj.TYPE_BRANCH
-				p1 = q
+				p1 := q
 
 				q = obj.Appendp(ctxt, q)
 				q.As = AMOVD
@@ -504,7 +436,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 				q = obj.Appendp(ctxt, q)
 				q.As = ABNE
 				q.To.Type = obj.TYPE_BRANCH
-				p2 = q
+				p2 := q
 
 				q = obj.Appendp(ctxt, q)
 				q.As = AADD
@@ -530,11 +462,6 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 			}
 
 		case obj.ARET:
-			if p.From.Type == obj.TYPE_CONST {
-				ctxt.Diag("using BECOME (%v) is not supported!", p)
-				break
-			}
-
 			retTarget := p.To.Sym
 
 			if cursym.Text.Mark&LEAF != 0 {
@@ -608,55 +535,10 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
 		}
 	}
 	if wasSplit {
-		pLast = stacksplitPost(ctxt, pLast, pPre, pPreempt, autosize) // emit post part of split check
+		stacksplitPost(ctxt, pLast, pPre, pPreempt, autosize) // emit post part of split check
 	}
 }
 
-/*
-// instruction scheduling
-	if(debug['Q'] == 0)
-		return;
-
-	curtext = nil;
-	q = nil;	// p - 1
-	q1 = firstp;	// top of block
-	o = 0;		// count of instructions
-	for(p = firstp; p != nil; p = p1) {
-		p1 = p->link;
-		o++;
-		if(p->mark & NOSCHED){
-			if(q1 != p){
-				sched(q1, q);
-			}
-			for(; p != nil; p = p->link){
-				if(!(p->mark & NOSCHED))
-					break;
-				q = p;
-			}
-			p1 = p;
-			q1 = p;
-			o = 0;
-			continue;
-		}
-		if(p->mark & (LABEL|SYNC)) {
-			if(q1 != p)
-				sched(q1, q);
-			q1 = p;
-			o = 1;
-		}
-		if(p->mark & (BRANCH|SYNC)) {
-			sched(q1, p);
-			q1 = p1;
-			o = 0;
-		}
-		if(o >= NSCHED) {
-			sched(q1, p);
-			q1 = p1;
-			o = 0;
-		}
-		q = p;
-	}
-*/
 func stacksplitPre(ctxt *obj.Link, p *obj.Prog, framesize int32) (*obj.Prog, *obj.Prog) {
 	var q *obj.Prog