gc: frame compaction for arm.

Required moving some parts of gc/pgen.c to ?g/ggen.c

on linux tests pass for all 3 architectures, and
frames are actually compacted (diagnostic code for
that has been removed from the CL).

R=rsc
CC=golang-dev
https://golang.org/cl/4571071

src/cmd/5g/ggen.c

@@ -22,6 +22,32 @@ defframe(Prog *ptxt)
 	maxstksize = 0;
 }
 
+// Sweep the prog list to mark any used nodes.
+void
+markautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.name == D_AUTO && p->from.node)
+			p->from.node->used++;
+
+		if (p->to.name == D_AUTO && p->to.node)
+			p->to.node->used++;
+	}
+}
+
+// Fixup instructions after compactframe has moved all autos around.
+void
+fixautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.name == D_AUTO && p->from.node)
+			p->from.offset += p->from.node->stkdelta;
+
+		if (p->to.name == D_AUTO && p->to.node)
+			p->to.offset += p->to.node->stkdelta;
+	}
+}
+
 /*
  * generate:
  *	call f

src/cmd/6g/ggen.c

@@ -18,6 +18,32 @@ defframe(Prog *ptxt)
 	ptxt->to.offset |= rnd(stksize+maxarg, widthptr);
 }
 
+// Sweep the prog list to mark any used nodes.
+void
+markautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.type == D_AUTO && p->from.node)
+			p->from.node->used++;
+
+		if (p->to.type == D_AUTO && p->to.node)
+			p->to.node->used++;
+	}
+}
+
+// Fixup instructions after compactframe has moved all autos around.
+void
+fixautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.type == D_AUTO && p->from.node)
+			p->from.offset += p->from.node->stkdelta;
+
+		if (p->to.type == D_AUTO && p->to.node)
+			p->to.offset += p->to.node->stkdelta;
+	}
+}
+
 
 /*
  * generate:

src/cmd/8g/ggen.c

@@ -20,6 +20,32 @@ defframe(Prog *ptxt)
 	maxstksize = 0;
 }
 
+// Sweep the prog list to mark any used nodes.
+void
+markautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.type == D_AUTO && p->from.node)
+			p->from.node->used++;
+
+		if (p->to.type == D_AUTO && p->to.node)
+			p->to.node->used++;
+	}
+}
+
+// Fixup instructions after compactframe has moved all autos around.
+void
+fixautoused(Prog* p)
+{
+	for (; p; p = p->link) {
+		if (p->from.type == D_AUTO && p->from.node)
+			p->from.offset += p->from.node->stkdelta;
+
+		if (p->to.type == D_AUTO && p->to.node)
+			p->to.offset += p->to.node->stkdelta;
+	}
+}
+
 void
 clearfat(Node *nl)
 {

src/cmd/gc/go.h

@@ -1195,7 +1195,7 @@ void	walkstmt(Node **np);
 void	walkstmtlist(NodeList *l);
 
 /*
- *	arch-specific ggen.c/gsubr.c/gobj.c
+ *	arch-specific ggen.c/gsubr.c/gobj.c/pgen.c
  */
 #define	P	((Prog*)0)
 
@@ -1237,6 +1237,7 @@ int	dsymptr(Sym *s, int off, Sym *x, int xoff);
 int	duintxx(Sym *s, int off, uint64 v, int wid);
 void	dumpdata(void);
 void	dumpfuncs(void);
+void	fixautoused(Prog*);
 void	gdata(Node*, Node*, int);
 void	gdatacomplex(Node*, Mpcplx*);
 void	gdatastring(Node*, Strlit*);
@@ -1246,6 +1247,7 @@ void	ggloblsym(Sym *s, int32 width, int dupok);
 Prog*	gjmp(Prog*);
 void	gused(Node*);
 int	isfat(Type*);
+void	markautoused(Prog*);
 Plist*	newplist(void);
 Node*	nodarg(Type*, int);
 void	nopout(Prog*);

src/cmd/gc/pgen.c

@@ -111,7 +111,6 @@ compile(Node *fn)
 	}
 
 	oldstksize = stksize;
-	if(thechar != '5')
 	compactframe(ptxt);
 	if(0)
 		print("compactframe: %ld to %ld\n", oldstksize, stksize);
@@ -142,12 +141,12 @@ cmpstackvar(Node *a, Node *b)
 
 }
 
+// TODO(lvd) find out where the PAUTO/OLITERAL nodes come from.
 static void
 compactframe(Prog* ptxt)
 {
 	NodeList *ll;
 	Node* n;
-	Prog *p;
 	uint32 w;
 
 	if (stksize == 0)
@@ -155,17 +154,10 @@ compactframe(Prog* ptxt)
 
 	// Mark the PAUTO's unused.
 	for(ll=curfn->dcl; ll != nil; ll=ll->next)
-		if (ll->n->class == PAUTO && ll->n->op == ONAME)
+		if (ll->n->class == PAUTO)
 			ll->n->used = 0;
 
-	// Sweep the prog list to mark any used nodes.
-	for (p = ptxt; p; p = p->link) {
-		if (p->from.type == D_AUTO && p->from.node)
-			p->from.node->used++;
-
-		if (p->to.type == D_AUTO && p->to.node)
-			p->to.node->used++;
-	}
+	markautoused(ptxt);
 
 	listsort(&curfn->dcl, cmpstackvar);
 
@@ -191,7 +183,6 @@ compactframe(Prog* ptxt)
 	stksize = 0;
 	for(ll = curfn->dcl; ll != nil; ll=ll->next) {
 		n = ll->n;
-		// TODO find out where the literal autos come from
 		if (n->class != PAUTO || n->op != ONAME)
 			continue;
 
@@ -205,14 +196,7 @@ compactframe(Prog* ptxt)
 		n->stkdelta = -stksize - n->xoffset;
 	}
 
-	// Fixup instructions.
-	for (p = ptxt; p; p = p->link) {
-		if (p->from.type == D_AUTO && p->from.node)
-			p->from.offset += p->from.node->stkdelta;
-
-		if (p->to.type == D_AUTO && p->to.node)
-			p->to.offset += p->to.node->stkdelta;
-	}
+	fixautoused(ptxt);
 
 	// The debug information needs accurate offsets on the symbols.
 	for(ll = curfn->dcl ;ll != nil; ll=ll->next) {