nacl:

add jmp to constant pc.
	generate HLT for INT $3
	do not insert NOPs between REP/REPN and subsequent instruction.
	allow very long time for convergence.

R=ken
OCL=34879
CL=34879

src/cmd/8l/l.h

@@ -201,6 +201,7 @@ enum
 	Zil_rp,
 	Zilo_m,
 	Zjmp,
+	Zjmpcon,
 	Zloop,
 	Zm_o,
 	Zm_r,

src/cmd/8l/optab.c

@@ -267,7 +267,8 @@ uchar	ycall[] =
 uchar	yjmp[] =
 {
 	Ynone,	Yml,	Zo_m,	2,
-	Ynone,	Ybr,	Zjmp,	1,
+	Ynone,	Ybr,	Zjmp,	0,
+	Ynone,	Yi32,	Zjmpcon,	1,
 	0
 };
 

src/cmd/8l/pass.c

@@ -464,7 +464,6 @@ dostkoff(void)
 	int a, f, curframe, curbecome, maxbecome;
 	Prog *pmorestack;
 	Sym *symmorestack;
-	static int fsreg;
 
 	pmorestack = P;
 	symmorestack = lookup("sys·morestack", 0);

src/cmd/8l/span.c

@@ -72,8 +72,9 @@ start:
 		if(debug['v'])
 			Bprint(&bso, "%5.2f span %d\n", cputime(), n);
 		Bflush(&bso);
-		if(n > 50) {
-			print("span must be looping\n");
+		if(n > 500) {
+			// TODO(rsc): figure out why nacl takes so long to converge.
+			print("span must be looping - %d\n", textsize);
 			errorexit();
 		}
 		c = INITTEXT;
@@ -1045,6 +1046,12 @@ found:
 	case Z_ib:
 		v = vaddr(&p->to);
 	case Zib_:
+		if(HEADTYPE == 8 && p->as == AINT && v == 3) {
+			// native client disallows all INT instructions.
+			// translate INT $3 to HLT.
+			*andptr++ = 0xf4;
+			break;
+		}
 		*andptr++ = op;
 		*andptr++ = v;
 		break;
@@ -1194,6 +1201,15 @@ found:
 		}
 		break;
 
+	case Zjmpcon:
+		v = p->to.offset - p->pc - 5;
+		*andptr++ = o->op[z+1];
+		*andptr++ = v;
+		*andptr++ = v>>8;
+		*andptr++ = v>>16;
+		*andptr++ = v>>24;
+		break;
+
 	case Zloop:
 		q = p->pcond;
 		if(q) {
@@ -1371,6 +1387,7 @@ asmins(Prog *p)
 {
 	if(HEADTYPE == 8) {
 		ulong npc;
+		static Prog *prefix;
 
 		// native client
 		// - pad indirect jump targets (aka ATEXT) to 32-byte boundary
@@ -1386,15 +1403,27 @@ asmins(Prog *p)
 			npc = p->pc + (andptr - and);
 			p->pc += 31 & -npc;
 		}
+		if(p->as == AREP || p->as == AREPN) {
+			// save prefix for next instruction,
+			// so that inserted NOPs do not split (e.g.) REP / MOVSL sequence.
+			prefix = p;
 			andptr = and;
+			return;
+		}
+		andptr = and;
+		if(prefix)
+			doasm(prefix);
 		doasm(p);
 		npc = p->pc + (andptr - and);
-		if((p->pc&~31) != ((npc-1)&~31)) {
+		if(andptr > and && (p->pc&~31) != ((npc-1)&~31)) {
 			// crossed 32-byte boundary; pad to boundary and try again
 			p->pc += 31 & -p->pc;
 			andptr = and;
+			if(prefix)
+				doasm(prefix);
 			doasm(p);
 		}
+		prefix = nil;
 	} else {
 		andptr = and;
 		doasm(p);