1 got rid if static 'fn wo return' test

2 added dynamic calls to throw for array bounds
  and 'fn wo return'
3 small optimization on index[constant]

R=r
OCL=15281
CL=15281

src/cmd/6g/cgen.c

@@ -301,6 +301,7 @@ agen(Node *n, Node *res)
 	Node n1, n2, n3, tmp;
 	Prog *p1;
 	uint32 w;
+	uint64 v;
 	Type *t;
 
 	if(debug['g']) {
@@ -344,6 +345,12 @@ agen(Node *n, Node *res)
 		cgen_aret(n, res);
 		break;
 
+	case OS2I:
+	case OI2I:
+	case OI2S:
+		agen_inter(n, res);
+		break;
+
 	case OINDEXPTR:
 		w = n->type->width;
 		if(nr->addable)
@@ -364,12 +371,6 @@ agen(Node *n, Node *res)
 		cgen(nr, &n1);
 		goto index;
 
-	case OS2I:
-	case OI2I:
-	case OI2S:
-		agen_inter(n, res);
-		break;
-
 	case OINDEX:
 		w = n->type->width;
 		if(nr->addable)
@@ -409,8 +410,7 @@ agen(Node *n, Node *res)
 
 				p1 = gbranch(optoas(OLT, types[TUINT32]), T);
 
-				nodconst(&n3, types[TUINT8], 5); // 5 is range trap
-				gins(AINT, &n3, N);
+				gins(ACALL, N, throwindex);
 				patch(p1, pc);
 			}
 
@@ -431,12 +431,18 @@ agen(Node *n, Node *res)
 				gins(optoas(OCMP, types[TUINT32]), &n1, &n3);
 
 				p1 = gbranch(optoas(OLT, types[TUINT32]), T);
-
-				nodconst(&n3, types[TUINT8], 5); // 5 is range trap
-				gins(AINT, &n3, N);
+				gins(ACALL, N, throwindex);
 				patch(p1, pc);
 			}
 
+		if(whatis(nr) == Wlitint) {
+			regfree(&n1);
+			v = mpgetfix(nr->val.u.xval);
+			nodconst(&n2, types[tptr], v*w);
+			gins(optoas(OADD, types[tptr]), &n2, res);
+			break;
+		}
+
 		t = types[TUINT64];
 		if(issigned[n1.type->etype])
 			t = types[TINT64];

src/cmd/6g/gen.c

@@ -13,9 +13,6 @@ enum
 	AJMPX	= AADDPD,
 };
 
-static	Node*	curfn;
-static	Node*	newproc;
-
 void
 compile(Node *fn)
 {
@@ -26,14 +23,28 @@ compile(Node *fn)
 
 if(newproc == N) {
 	newproc = nod(ONAME, N, N);
-	memset(newproc, 0, sizeof(*newproc));
-	newproc->op = ONAME;
 	newproc->sym = pkglookup("newproc", "sys");
 	newproc->class = PEXTERN;
 	newproc->addable = 1;
 	newproc->ullman = 0;
 }
 
+if(throwindex == N) {
+	throwindex = nod(ONAME, N, N);
+	throwindex->sym = pkglookup("throwindex", "sys");
+	throwindex->class = PEXTERN;
+	throwindex->addable = 1;
+	throwindex->ullman = 0;
+}
+
+if(throwreturn == N) {
+	throwreturn = nod(ONAME, N, N);
+	throwreturn->sym = pkglookup("throwreturn", "sys");
+	throwreturn->class = PEXTERN;
+	throwreturn->addable = 1;
+	throwreturn->ullman = 0;
+}
+
 	if(fn->nbody == N)
 		return;
 
@@ -69,8 +80,7 @@ if(newproc == N) {
 	checklabels();
 
 	if(curfn->type->outtuple != 0) {
-		nodconst(&nod1, types[TUINT8], 6); // 6 is opcode trap
-		gins(AINT, &nod1, N);
+		gins(ACALL, N, throwreturn);
 	}
 
 	pc->as = ARET;	// overwrite AEND

src/cmd/6g/gg.h

@@ -113,6 +113,10 @@ EXTERN	Hist*	hist;
 EXTERN	Prog	zprog;
 EXTERN	Label*	labellist;
 EXTERN	Label*	findlab(Sym*);
+EXTERN	Node*	curfn;
+EXTERN	Node*	newproc;
+EXTERN	Node*	throwindex;
+EXTERN	Node*	throwreturn;
 
 /*
  * gen.c

src/cmd/gc/sys.go

@@ -7,6 +7,8 @@ package foop	// rename to avoid redeclaration
 
 func	mal(uint32) *any;
 func	breakpoint();
+func	throwindex();
+func	throwreturn();
 func	panicl(int32);
 
 func	printbool(bool);
@@ -75,6 +77,8 @@ func	exit(int32);
 export
 	mal
 	breakpoint
+	throwindex
+	throwreturn
 
 	// print panic
 	panicl

src/cmd/gc/walk.c

@@ -17,6 +17,10 @@ int
 walkret(Node *n)
 {
 
+	// until gri gets rid
+	// of the bugs on this
+	return 0;
+
 loop:
 	if(n != N)
 	switch(n->op) {

src/runtime/runtime.c

@@ -25,6 +25,18 @@ sys·panicl(int32 lno)
 	sys·exit(2);
 }
 
+void
+sys·throwindex(void)
+{
+	throw("index out of range");
+}
+
+void
+sys·throwreturn(void)
+{
+	throw("no return at end of a typed function");
+}
+
 enum
 {
 	NHUNK		= 20<<20,