5g, 6g, 8g: generate code for string index

instead of calling function.

R=ken2
CC=golang-dev
https://golang.org/cl/2762041

14 files changed, 117 insertions, 69 deletions

diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index bbe5b9c0b7..1328f4be64 100644
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -558,9 +558,11 @@ agen(Node *n, Node *res)
 		p2 = nil;  // to be patched to panicindex.
 		w = n->type->width;
 		if(nr->addable) {
-			agenr(nl, &n3, res);
-			if(!isconst(nr, CTINT)) {
+			if(!isconst(nr, CTINT))
 				tempname(&tmp, types[TINT32]);
+			if(!isconst(nl, CTSTR))
+				agenr(nl, &n3, res);
+			if(!isconst(nr, CTINT)) {
 				p2 = cgenindex(nr, &tmp);
 				regalloc(&n1, tmp.type, N);
 				gmove(&tmp, &n1);
@@ -572,13 +574,16 @@ agen(Node *n, Node *res)
 				regalloc(&n1, tmp.type, N);
 				gmove(&tmp, &n1);
 			}
-			regalloc(&n3, types[tptr], res);
-			agen(nl, &n3);
+			if(!isconst(nl, CTSTR)) {
+				regalloc(&n3, types[tptr], res);
+				agen(nl, &n3);
+			}
 		} else {
 			tempname(&tmp, types[TINT32]);
 			p2 = cgenindex(nr, &tmp);
 			nr = &tmp;
-			agenr(nl, &n3, res);
+			if(!isconst(nl, CTSTR))
+				agenr(nl, &n3, res);
 			regalloc(&n1, tmp.type, N);
 			gins(optoas(OAS, tmp.type), &tmp, &n1);
 		}
@@ -592,9 +597,10 @@ agen(Node *n, Node *res)
 
 		// constant index
 		if(isconst(nr, CTINT)) {
+			if(isconst(nl, CTSTR))
+				fatal("constant string constant index");
 			v = mpgetfix(nr->val.u.xval);
-			if(isslice(nl->type)) {
-
+			if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				if(!debug['B'] && !n->etype) {
 					n1 = n3;
 					n1.op = OINDREG;
@@ -638,7 +644,10 @@ agen(Node *n, Node *res)
 		if(!debug['B'] && !n->etype) {
 			// check bounds
 			regalloc(&n4, types[TUINT32], N);
-			if(isslice(nl->type)) {
+			if(isconst(nl, CTSTR)) {
+				nodconst(&n1, types[TUINT32], nl->val.u.sval->len);
+				gmove(&n1, &n4);
+			} else if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				n1 = n3;
 				n1.op = OINDREG;
 				n1.type = types[tptr];
@@ -656,8 +665,13 @@ agen(Node *n, Node *res)
 			ginscall(panicindex, 0);
 			patch(p1, pc);
 		}
-
-		if(isslice(nl->type)) {
+		
+		if(isconst(nl, CTSTR)) {
+			regalloc(&n3, types[tptr], res);
+			p1 = gins(AMOVW, N, &n3);
+			datastring(nl->val.u.sval->s, nl->val.u.sval->len, &p1->from);
+			p1->from.type = D_CONST;
+		} else if(isslice(nl->type) || nl->type->etype == TSTRING) {
 			n1 = n3;
 			n1.op = OINDREG;
 			n1.type = types[tptr];
@@ -795,12 +809,8 @@ igen(Node *n, Node *a, Node *res)
 void
 agenr(Node *n, Node *a, Node *res)
 {
-	Node n1;
-
-	tempname(&n1, types[tptr]);
-	agen(n, &n1);
 	regalloc(a, types[tptr], res);
-	gmove(&n1, a);
+	agen(n, a);
 }
 
 /*
diff --git a/src/cmd/5g/gsubr.c b/src/cmd/5g/gsubr.c
index 7089b71850..260a9d3f6a 100644
--- a/src/cmd/5g/gsubr.c
+++ b/src/cmd/5g/gsubr.c
@@ -1678,6 +1678,8 @@ sudoaddable(int as, Node *n, Addr *a, int *w)
 		goto odot;
 
 	case OINDEX:
+		if(n->left->type->etype == TSTRING)
+			return 0;
 		cleani += 2;
 		reg = &clean[cleani-1];
 		reg1 = &clean[cleani-2];
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 1df6b25dd2..d4d22fd610 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -477,8 +477,10 @@ agen(Node *n, Node *res)
 				regalloc(&n1, nr->type, N);
 				cgen(nr, &n1);
 			}
-			regalloc(&n3, types[tptr], res);
-			agen(nl, &n3);
+			if(!isconst(nl, CTSTR)) {
+				regalloc(&n3, types[tptr], res);
+				agen(nl, &n3);
+			}
 			goto index;
 		}
 		tempname(&tmp, nr->type);
@@ -486,8 +488,10 @@ agen(Node *n, Node *res)
 		nr = &tmp;
 
 	irad:
-		regalloc(&n3, types[tptr], res);
-		agen(nl, &n3);
+		if(!isconst(nl, CTSTR)) {
+			regalloc(&n3, types[tptr], res);
+			agen(nl, &n3);
+		}
 		if(!isconst(nr, CTINT)) {
 			regalloc(&n1, nr->type, N);
 			cgen(nr, &n1);
@@ -501,7 +505,7 @@ agen(Node *n, Node *res)
 
 		// explicit check for nil if array is large enough
 		// that we might derive too big a pointer.
-		if(!isslice(nl->type) && nl->type->width >= unmappedzero) {
+		if(isfixedarray(nl->type) && nl->type->width >= unmappedzero) {
 			regalloc(&n4, types[tptr], &n3);
 			gmove(&n3, &n4);
 			n4.op = OINDREG;
@@ -516,8 +520,10 @@ agen(Node *n, Node *res)
 
 		// constant index
 		if(isconst(nr, CTINT)) {
+			if(isconst(nl, CTSTR))
+				fatal("constant string constant index");	// front end should handle
 			v = mpgetfix(nr->val.u.xval);
-			if(isslice(nl->type)) {
+			if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				if(!debug['B'] && !n->etype) {
 					n1 = n3;
 					n1.op = OINDREG;
@@ -556,20 +562,21 @@ agen(Node *n, Node *res)
 			// check bounds
 			n5.op = OXXX;
 			t = types[TUINT32];
-			if(isslice(nl->type)) {
+			if(is64(nr->type))
+				t = types[TUINT64];
+			if(isconst(nl, CTSTR)) {
+				nodconst(&n1, t, nl->val.u.sval->len);
+			} else if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				n1 = n3;
 				n1.op = OINDREG;
 				n1.type = types[TUINT32];
 				n1.xoffset = Array_nel;
 				if(is64(nr->type)) {
-					t = types[TUINT64];
 					regalloc(&n5, t, N);
 					gmove(&n1, &n5);
 					n1 = n5;
 				}
 			} else {
-				if(is64(nr->type))
-					t = types[TUINT64];
 				nodconst(&n1, t, nl->type->bound);
 			}
 			gins(optoas(OCMP, t), &n2, &n1);
@@ -580,7 +587,16 @@ agen(Node *n, Node *res)
 			patch(p1, pc);
 		}
 
-		if(isslice(nl->type)) {
+		if(isconst(nl, CTSTR)) {
+			regalloc(&n3, types[tptr], res);
+			p1 = gins(ALEAQ, N, &n3);
+			datastring(nl->val.u.sval->s, nl->val.u.sval->len, &p1->from);
+			p1->from.scale = 1;
+			p1->from.index = n2.val.u.reg;
+			goto indexdone;
+		}
+
+		if(isslice(nl->type) || nl->type->etype == TSTRING) {
 			n1 = n3;
 			n1.op = OINDREG;
 			n1.type = types[tptr];
@@ -599,6 +615,7 @@ agen(Node *n, Node *res)
 			gmove(&n3, res);
 		}
 
+	indexdone:
 		gmove(&n3, res);
 		regfree(&n2);
 		regfree(&n3);
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index 1cd5c650bd..ebb61ea945 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -1784,6 +1784,8 @@ sudoaddable(int as, Node *n, Addr *a)
 		goto odot;
 
 	case OINDEX:
+		if(n->left->type->etype == TSTRING)
+			return 0;
 		goto oindex;
 	}
 	return 0;
diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c
index 810ad4da64..875d434fa7 100644
--- a/src/cmd/8g/cgen.c
+++ b/src/cmd/8g/cgen.c
@@ -230,8 +230,8 @@ cgen(Node *n, Node *res)
 			cgen(nl, res);
 			break;
 		}
-		mgen(nl, &n1, res);
 		tempname(&n2, n->type);
+		mgen(nl, &n1, res);
 		gmove(&n1, &n2);
 		gmove(&n2, res);
 		mfree(&n1);
@@ -518,9 +518,11 @@ agen(Node *n, Node *res)
 		p2 = nil;  // to be patched to panicindex.
 		w = n->type->width;
 		if(nr->addable) {
-			agenr(nl, &n3, res);
-			if(!isconst(nr, CTINT)) {
+			if(!isconst(nr, CTINT))
 				tempname(&tmp, types[TINT32]);
+			if(!isconst(nl, CTSTR))
+				agenr(nl, &n3, res);
+			if(!isconst(nr, CTINT)) {
 				p2 = cgenindex(nr, &tmp);
 				regalloc(&n1, tmp.type, N);
 				gmove(&tmp, &n1);
@@ -532,13 +534,16 @@ agen(Node *n, Node *res)
 				regalloc(&n1, tmp.type, N);
 				gmove(&tmp, &n1);
 			}
-			regalloc(&n3, types[tptr], res);
-			agen(nl, &n3);
+			if(!isconst(nl, CTSTR)) {
+				regalloc(&n3, types[tptr], res);
+				agen(nl, &n3);
+			}
 		} else {
 			tempname(&tmp, types[TINT32]);
 			p2 = cgenindex(nr, &tmp);
 			nr = &tmp;
-			agenr(nl, &n3, res);
+			if(!isconst(nl, CTSTR))
+				agenr(nl, &n3, res);
 			regalloc(&n1, tmp.type, N);
 			gins(optoas(OAS, tmp.type), &tmp, &n1);
 		}
@@ -549,7 +554,7 @@ agen(Node *n, Node *res)
 
 		// explicit check for nil if array is large enough
 		// that we might derive too big a pointer.
-		if(!isslice(nl->type) && nl->type->width >= unmappedzero) {
+		if(isfixedarray(nl->type) && nl->type->width >= unmappedzero) {
 			regalloc(&n4, types[tptr], &n3);
 			gmove(&n3, &n4);
 			n4.op = OINDREG;
@@ -564,9 +569,10 @@ agen(Node *n, Node *res)
 
 		// constant index
 		if(isconst(nr, CTINT)) {
+			if(isconst(nl, CTSTR))
+				fatal("constant string constant index");
 			v = mpgetfix(nr->val.u.xval);
-			if(isslice(nl->type)) {
-
+			if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				if(!debug['B'] && !n->etype) {
 					n1 = n3;
 					n1.op = OINDREG;
@@ -600,7 +606,9 @@ agen(Node *n, Node *res)
 
 		if(!debug['B'] && !n->etype) {
 			// check bounds
-			if(isslice(nl->type)) {
+			if(isconst(nl, CTSTR))
+				nodconst(&n1, types[TUINT32], nl->val.u.sval->len);
+			else if(isslice(nl->type) || nl->type->etype == TSTRING) {
 				n1 = n3;
 				n1.op = OINDREG;
 				n1.type = types[tptr];
@@ -614,8 +622,17 @@ agen(Node *n, Node *res)
 			ginscall(panicindex, 0);
 			patch(p1, pc);
 		}
+		
+		if(isconst(nl, CTSTR)) {
+			regalloc(&n3, types[tptr], res);
+			p1 = gins(ALEAL, N, &n3);
+			datastring(nl->val.u.sval->s, nl->val.u.sval->len, &p1->from);
+			p1->from.scale = 1;
+			p1->from.index = n2.val.u.reg;
+			goto indexdone;
+		}
 
-		if(isslice(nl->type)) {
+		if(isslice(nl->type) || nl->type->etype == TSTRING) {
 			n1 = n3;
 			n1.op = OINDREG;
 			n1.type = types[tptr];
@@ -635,6 +652,7 @@ agen(Node *n, Node *res)
 			gmove(&n3, res);
 		}
 
+	indexdone:
 		gmove(&n3, res);
 		regfree(&n2);
 		regfree(&n3);
@@ -710,8 +728,14 @@ igen(Node *n, Node *a, Node *res)
 {
 	Node n1;
 
+	// release register for now, to avoid
+	// confusing tempname.
+	if(res != N && res->op == OREGISTER)
+		reg[res->val.u.reg]--;
 	tempname(&n1, types[tptr]);
 	agen(n, &n1);
+	if(res != N && res->op == OREGISTER)
+		reg[res->val.u.reg]++;
 	regalloc(a, types[tptr], res);
 	gmove(&n1, a);
 	a->op = OINDREG;
diff --git a/src/cmd/8g/reg.c b/src/cmd/8g/reg.c
index ae9a5f2eaf..e1dacf55ad 100644
--- a/src/cmd/8g/reg.c
+++ b/src/cmd/8g/reg.c
@@ -789,6 +789,8 @@ mkvar(Reg *r, Adr *a)
 
 			// if they overlaps, disable both
 			if(overlap(v->offset, v->width, o, w)) {
+				if(debug['R'])
+					print("disable %s\n", v->sym->name);
 				v->addr = 1;
 				flag = 1;
 			}
@@ -821,7 +823,7 @@ mkvar(Reg *r, Adr *a)
 	v->addr = flag;		// funny punning
 
 	if(debug['R'])
-		print("bit=%2d et=%2d w=%d %S %D\n", i, et, w, s, a);
+		print("bit=%2d et=%2d w=%d %S %D flag=%d\n", i, et, w, s, a, v->addr);
 	ostats.nvar++;
 
 	bit = blsh(i);
diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index bb1a5f5fa6..10559a900f 100644
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -24,7 +24,6 @@ char *runtimeimport =
 	"func \"\".cmpstring (? string, ? string) int\n"
 	"func \"\".slicestring (? string, ? int, ? int) string\n"
 	"func \"\".slicestring1 (? string, ? int) string\n"
-	"func \"\".indexstring (? string, ? int) uint8\n"
 	"func \"\".intstring (? int64) string\n"
 	"func \"\".slicebytetostring (? []uint8) string\n"
 	"func \"\".sliceinttostring (? []int) string\n"
diff --git a/src/cmd/gc/gen.c b/src/cmd/gc/gen.c
index d2396aa09f..65861c7635 100644
--- a/src/cmd/gc/gen.c
+++ b/src/cmd/gc/gen.c
@@ -652,7 +652,6 @@ tempname(Node *n, Type *t)
 	snprint(namebuf, sizeof(namebuf), "autotmp_%.4d", statuniqgen);
 	statuniqgen++;
 	s = lookup(namebuf);
-
 	memset(n, 0, sizeof(*n));
 	n->op = ONAME;
 	n->sym = s;
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 78472d22eb..91a1562f75 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -369,7 +369,7 @@ enum
 	ODOTTYPE2,
 	OEQ, ONE, OLT, OLE, OGE, OGT,
 	OIND,
-	OINDEX, OINDEXSTR, OINDEXMAP,
+	OINDEX, OINDEXMAP,
 	OKEY, OPARAM,
 	OLEN,
 	OMAKE, OMAKECHAN, OMAKEMAP, OMAKESLICE,
diff --git a/src/cmd/gc/print.c b/src/cmd/gc/print.c
index 32e8b7de55..478aa84e3b 100644
--- a/src/cmd/gc/print.c
+++ b/src/cmd/gc/print.c
@@ -59,6 +59,9 @@ exprfmt(Fmt *f, Node *n, int prec)
 	case OPRINT:
 	case OPRINTN:
 	case OCALL:
+	case OCALLMETH:
+	case OCALLINTER:
+	case OCALLFUNC:
 	case OCONV:
 	case OCONVNOP:
 	case OMAKESLICE:
@@ -72,6 +75,8 @@ exprfmt(Fmt *f, Node *n, int prec)
 	case ORECV:
 	case OCONVIFACE:
 	case OTPAREN:
+	case OINDEX:
+	case OINDEXMAP:
 		nprec = 7;
 		break;
 
@@ -328,7 +333,6 @@ exprfmt(Fmt *f, Node *n, int prec)
 
 	case OINDEX:
 	case OINDEXMAP:
-	case OINDEXSTR:
 		exprfmt(f, n->left, 7);
 		fmtprint(f, "[");
 		exprfmt(f, n->right, 0);
diff --git a/src/cmd/gc/runtime.go b/src/cmd/gc/runtime.go
index 2279384473..1be706fa2f 100644
--- a/src/cmd/gc/runtime.go
+++ b/src/cmd/gc/runtime.go
@@ -39,7 +39,6 @@ func concatstring()
 func cmpstring(string, string) int
 func slicestring(string, int, int) string
 func slicestring1(string, int) string
-func indexstring(string, int) byte
 func intstring(int64) string
 func slicebytetostring([]byte) string
 func sliceinttostring([]int) string
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 614833740a..c4f082612c 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -614,7 +614,6 @@ reswitch:
 			if(n->right->type != T && !isint[n->right->type->etype])
 				yyerror("non-integer string index %#N", n->right);
 			n->type = types[TUINT8];
-			n->op = OINDEXSTR;
 			break;
 		}
 		goto ret;
@@ -2052,6 +2051,8 @@ islvalue(Node *n)
 	case OINDEX:
 		if(isfixedarray(n->left->type))
 			return islvalue(n->left);
+		if(n->left->type != T && n->left->type->etype == TSTRING)
+			return 0;
 		// fall through
 	case OIND:
 	case ODOTPTR:
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index bf20102c7d..757b6d93d6 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1033,22 +1033,35 @@ walkexpr(Node **np, NodeList **init)
 
 		// if range of type cannot exceed static array bound,
 		// disable bounds check
-		if(!isslice(n->left->type))
+		if(isfixedarray(n->left->type))
 		if(n->right->type->width < 4)
 		if((1<<(8*n->right->type->width)) <= n->left->type->bound)
 			n->etype = 1;
 
+		if(isconst(n->left, CTSTR))
+		if(n->right->type->width < 4)
+		if((1<<(8*n->right->type->width)) <= n->left->val.u.sval->len)
+			n->etype = 1;
+
 		// check for static out of bounds
 		if(isconst(n->right, CTINT) && !n->etype) {
 			v = mpgetfix(n->right->val.u.xval);
 			len = 1LL<<60;
 			t = n->left->type;
+			if(isconst(n->left, CTSTR))
+				len = n->left->val.u.sval->len;
 			if(t != T && isptr[t->etype])
 				t = t->type;
 			if(isfixedarray(t))
 				len = t->bound;
 			if(v < 0 || v >= (1LL<<31) || v >= len)
 				yyerror("index out of bounds");
+			else if(isconst(n->left, CTSTR)) {
+				// replace "abc"[2] with 'b'.
+				// delayed until now because "abc"[2] is not
+				// an ideal constant.
+				nodconst(n, n->type, n->left->val.u.sval->s[v]);
+			}
 		}
 		goto ret;
 
@@ -1252,14 +1265,6 @@ walkexpr(Node **np, NodeList **init)
 		}
 		goto ret;
 
-	case OINDEXSTR:
-		// TODO(rsc): should be done in back end
-		// sys_indexstring(s, i)
-		n = mkcall("indexstring", n->type, init,
-			conv(n->left, types[TSTRING]),
-			conv(n->right, types[TINT]));
-		goto ret;
-
 	case OCOPY:
 		if(n->right->type->etype == TSTRING)
 			fn = syslook("slicestringcopy", 1);
diff --git a/src/pkg/runtime/string.goc b/src/pkg/runtime/string.goc
index 7bf8f8b37c..1db1c2c2cb 100644
--- a/src/pkg/runtime/string.goc
+++ b/src/pkg/runtime/string.goc
@@ -200,10 +200,6 @@ func slicestring(si String, lindex int32, hindex int32) (so String) {
 	l = hindex-lindex;
 	so.str = si.str + lindex;
 	so.len = l;
-
-//	alternate to create a new string
-//	so = gostringsize(l);
-//	mcpy(so.str, si.str+lindex, l);
 }
 
 func slicestring1(si String, lindex int32) (so String) {
@@ -216,18 +212,6 @@ func slicestring1(si String, lindex int32) (so String) {
 	l = si.len-lindex;
 	so.str = si.str + lindex;
 	so.len = l;
-
-//	alternate to create a new string
-//	so = gostringsize(l);
-//	mcpy(so.str, si.str+lindex, l);
-}
-
-func indexstring(s String, i int32) (b byte) {
-	if(i < 0 || i >= s.len) {
-		·panicindex();
-	}
-
-	b = s.str[i];
 }
 
 func intstring(v int64) (s String) {