arm reg bug with SP adjust

after call to deferproc

R=r
CC=golang-dev
https://golang.org/cl/4059041

src/cmd/5g/opt.h

@@ -69,6 +69,7 @@ struct	Reg
 
 	uint16	loop;		// x5 for every loop
 	uchar	refset;		// diagnostic generated
+	uchar	nomove;		// funny mov instruction
 
 	Reg*	p1;
 	Reg*	p2;
@@ -128,7 +129,7 @@ Reg*	rega(void);
 int	rcmp(const void*, const void*);
 void	regopt(Prog*);
 void	addmove(Reg*, int, int, int);
-Bits	mkvar(Reg *r, Adr *a, int);
+Bits	mkvar(Reg *r, Adr *a);
 void	prop(Reg*, Bits, Bits);
 void	loopit(Reg*, int32);
 void	synch(Reg*, Bits);

src/cmd/5g/peep.c

@@ -983,7 +983,7 @@ copyu(Prog *p, Adr *v, Adr *s)
 					return 2;
 			} else {
 		  		if(p->to.reg == v->reg)
-				return 2;
+					return 2;
 			}
 		}
 		if(s != A) {

src/cmd/5g/reg.c

@@ -83,7 +83,7 @@ setoutvar(void)
 		n = nodarg(t, 1);
 		a = zprog.from;
 		naddr(n, &a, 0);
-		bit = mkvar(R, &a, 0);
+		bit = mkvar(R, &a);
 		for(z=0; z<BITS; z++)
 			ovar.b[z] |= bit.b[z];
 		t = structnext(&save);
@@ -143,7 +143,7 @@ regopt(Prog *firstp)
 	first++;
 
 	if(debug['K']) {
-		if(first != 1)
+		if(first != 4)
 			return;
 //		debug['R'] = 2;
 //		debug['P'] = 2;
@@ -165,7 +165,7 @@ regopt(Prog *firstp)
 	firstr = R;
 	lastr = R;
 	nvar = 0;
-	regbits = 0;
+	regbits = RtoB(REGSP)|RtoB(REGLINK)|RtoB(REGPC);
 	for(z=0; z<BITS; z++) {
 		externs.b[z] = 0;
 		params.b[z] = 0;
@@ -191,6 +191,21 @@ regopt(Prog *firstp)
 		case ANAME:
 		case ASIGNAME:
 			continue;
+
+		case AMOVW:
+			// mark instructions that set SP
+			if(p->to.type == D_REG) {
+				switch(p->to.reg) {
+				case REGSP:
+				case REGLINK:
+				case REGPC:
+					r->nomove = 1;
+					break;
+				}
+			}
+			if(p->scond != C_SCOND_NONE)
+				r->nomove = 1;
+			break;
 		}
 		r = rega();
 		nr++;
@@ -220,14 +235,14 @@ regopt(Prog *firstp)
 		/*
 		 * left side always read
 		 */
-		bit = mkvar(r, &p->from, p->as==AMOVW);
+		bit = mkvar(r, &p->from);
 		for(z=0; z<BITS; z++)
 			r->use1.b[z] |= bit.b[z];
 
 		/*
 		 * right side depends on opcode
 		 */
-		bit = mkvar(r, &p->to, 0);
+		bit = mkvar(r, &p->to);
 		if(bany(&bit))
 		switch(p->as) {
 		default:
@@ -567,6 +582,9 @@ addmove(Reg *r, int bn, int rn, int f)
 	if(a->etype == TARRAY || a->sym == S)
 		a->type = D_CONST;
 
+	if(v->addr)
+		fatal("addmove: shouldnt be doing this %A\n", a);
+
 	switch(v->etype) {
 	default:
 		print("What is this %E\n", v->etype);
@@ -636,7 +654,7 @@ overlap(int32 o1, int w1, int32 o2, int w2)
 }
 
 Bits
-mkvar(Reg *r, Adr *a, int docon)
+mkvar(Reg *r, Adr *a)
 {
 	Var *v;
 	int i, t, n, et, z, w, flag;
@@ -1190,8 +1208,15 @@ paint3(Reg *r, int bn, int32 rb, int rn)
 		r = r1;
 	}
 
+	// horrible hack to prevent loading a
+	// variable after a call (to defer) but
+	// before popping the SP.
+	if(r->prog->as == ABL && r->nomove)
+		r = r->p1;
+
 	if(LOAD(r) & ~(r->set.b[z] & ~(r->use1.b[z]|r->use2.b[z])) & bb)
 		addmove(r, bn, rn, 0);
+
 	for(;;) {
 		r->act.b[z] |= bb;
 		p = r->prog;
@@ -1240,6 +1265,9 @@ void
 addreg(Adr *a, int rn)
 {
 
+	if(a->type == D_CONST)
+		fatal("addreg: cant do this %D %d\n", a, rn);
+
 	a->sym = 0;
 	a->name = D_NONE;
 	a->type = D_REG;