install copy predefined

did not test 386, but should work
shouldnt matter if copy is not used

R=rsc
https://golang.org/cl/156055

src/cmd/gc/builtin.c.boot

@@ -25,6 +25,7 @@ char *runtimeimport =
 	"func runtime.sliceinttostring (? []int) (? string)\n"
 	"func runtime.stringiter (? string, ? int) (? int)\n"
 	"func runtime.stringiter2 (? string, ? int) (retk int, retv int)\n"
+	"func runtime.slicecopy (to any, fr any, wid uint32) (? int)\n"
 	"func runtime.ifaceI2E (iface any) (ret any)\n"
 	"func runtime.ifaceE2I (typ *uint8, iface any) (ret any)\n"
 	"func runtime.ifaceT2E (typ *uint8, elem any) (ret any)\n"

src/cmd/gc/go.h

@@ -346,6 +346,7 @@ enum
 	OCMPIFACE, OCMPSTR,
 	OCOMPLIT, OMAPLIT, OSTRUCTLIT, OARRAYLIT,
 	OCONV, OCONVNOP, OCONVIFACE, OCONVSLICE,
+	OCOPY,
 	ODCL, ODCLFUNC, ODCLFIELD, ODCLCONST, ODCLTYPE,
 	ODOT, ODOTPTR, ODOTMETH, ODOTINTER, OXDOT,
 	ODOTTYPE,

src/cmd/gc/lex.c

@@ -1245,6 +1245,7 @@ static	struct
 	"cap",		LNAME,		Txxx,		OCAP,
 	"close",	LNAME,		Txxx,		OCLOSE,
 	"closed",	LNAME,		Txxx,		OCLOSED,
+	"copy",		LNAME,		Txxx,		OCOPY,
 	"len",		LNAME,		Txxx,		OLEN,
 	"make",		LNAME,		Txxx,		OMAKE,
 	"new",		LNAME,		Txxx,		ONEW,

src/cmd/gc/print.c

@@ -44,6 +44,7 @@ exprfmt(Fmt *f, Node *n, int prec)
 	case OCAP:
 	case OCLOSE:
 	case OCLOSED:
+	case OCOPY:
 	case OLEN:
 	case OMAKE:
 	case ONEW:
@@ -305,6 +306,7 @@ exprfmt(Fmt *f, Node *n, int prec)
 	case OCLOSE:
 	case OCLOSED:
 	case OLEN:
+	case OCOPY:
 	case OMAKE:
 	case ONEW:
 	case OPANIC:

src/cmd/gc/runtime.go

@@ -33,6 +33,7 @@ func slicebytetostring([]byte) string
 func sliceinttostring([]int) string
 func stringiter(string, int) int
 func stringiter2(string, int) (retk int, retv int)
+func slicecopy(to any, fr any, wid uint32) int
 
 func ifaceI2E(iface any) (ret any)
 func ifaceE2I(typ *byte, iface any) (ret any)

src/cmd/gc/subr.c

@@ -746,6 +746,7 @@ goopnames[] =
 	[OCLOSE]	= "close",
 	[OCOM]		= "^",
 	[OCONTINUE]	= "continue",
+	[OCOPY]		= "copy",
 	[ODEC]		= "--",
 	[ODEFER]	= "defer",
 	[ODIV]		= "/",

src/cmd/gc/typecheck.c

@@ -761,6 +761,32 @@ reswitch:
 			ok |= Etop;
 		goto ret;
 
+	case OCOPY:
+		ok |= Erv;
+		args = n->list;
+		if(args == nil || args->next == nil) {
+			yyerror("missing arguments to copy");
+			goto error;
+		}
+		if(args->next->next != nil) {
+			yyerror("too many arguments to copy");
+			goto error;
+		}
+		typecheck(&args->n, Erv);
+		typecheck(&args->next->n, Erv);
+		if(!isslice(args->n->type) || !isslice(args->next->n->type)) {
+			yyerror("arguments to copy must be slices");
+			goto error;
+		}
+		if(!eqtype(args->n->type, args->next->n->type)) {
+			yyerror("arguments to copy must be slices of the same type");
+			goto error;
+		}
+		n->left = args->n;
+		n->right = args->next->n;
+		n->type = types[TINT];
+		goto ret;
+
 	case OCONV:
 	doconv:
 		ok |= Erv;

src/cmd/gc/walk.c

@@ -307,6 +307,7 @@ walkstmt(Node **np)
 	case OAS2MAPR:
 	case OCLOSE:
 	case OCLOSED:
+	case OCOPY:
 	case OCALLMETH:
 	case OCALLINTER:
 	case OCALL:
@@ -904,6 +905,15 @@ walkexpr(Node **np, NodeList **init)
 			conv(n->right, types[TINT]));
 		goto ret;
 
+	case OCOPY:
+		fn = syslook("slicecopy", 1);
+		argtype(fn, n->left->type);
+		argtype(fn, n->right->type);
+		n = mkcall1(fn, n->type, init,
+			n->left, n->right,
+			nodintconst(n->left->type->width));
+		goto ret;
+
 	case OCLOSE:
 		// cannot use chanfn - closechan takes any, not chan any
 		fn = syslook("closechan", 1);
@@ -950,7 +960,8 @@ walkexpr(Node **np, NodeList **init)
 
 	case ORUNESTR:
 		// sys_intstring(v)
-		n = mkcall("intstring", n->type, init, conv(n->left, types[TINT64]));	// TODO(rsc): int64?!
+		n = mkcall("intstring", n->type, init,
+			conv(n->left, types[TINT64]));	// TODO(rsc): int64?!
 		goto ret;
 
 	case OARRAYBYTESTR:

src/pkg/runtime/Makefile

@@ -68,6 +68,7 @@ OFILES=\
 	sys.$O\
 	thread.$O\
 	traceback.$O\
+	memmove_$(GOARCH).$O\
 	$(OFILES_$(GOARCH))\
 
 HFILES=\

src/pkg/runtime/memmove_386.s

@@ -0,0 +1,65 @@
+	TEXT	memmove(SB), $0
+
+	MOVL	to+0(FP), DI
+	MOVL	fr+4(FP), SI
+	MOVL	n+8(FP), BX
+	JLT	fault
+
+/*
+ * check and set for backwards
+ * should we look closer for overlap?
+ */
+	CMPL	SI, DI
+	JLS	back
+
+/*
+ * foreward copy loop
+ */
+	MOVL	BX, CX
+	SHRL	$2, CX
+	ANDL	$3, BX
+
+	REP;	MOVSL
+	MOVL	BX, CX
+	REP;	MOVSB
+
+	MOVL	to+0(FP),AX
+	RET
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+back:
+	ADDL	BX, DI
+	ADDL	BX, SI
+	STD
+
+/*
+ * copy
+ */
+	MOVL	BX, CX
+	SHRL	$2, CX
+	ANDL	$3, BX
+
+	SUBL	$4, DI
+	SUBL	$4, SI
+	REP;	MOVSL
+
+	ADDL	$3, DI
+	ADDL	$3, SI
+	MOVL	BX, CX
+	REP;	MOVSB
+
+	CLD
+	MOVL	to+0(FP),AX
+	RET
+
+/*
+ * if called with negative count,
+ * treat as error rather than
+ * rotating all of memory
+ */
+fault:
+	MOVL	$0,SI
+	MOVL	0(SI), AX
+	RET

src/pkg/runtime/memmove_amd64.s

@@ -0,0 +1,65 @@
+	TEXT	memmove(SB), $0
+
+	MOVQ	to+0(FP), DI
+	MOVQ	fr+8(FP), SI
+	MOVLQSX	n+16(FP), BX
+	JLT	fault
+
+/*
+ * check and set for backwards
+ * should we look closer for overlap?
+ */
+	CMPQ	SI, DI
+	JLS	back
+
+/*
+ * foreward copy loop
+ */
+	MOVQ	BX, CX
+	SHRQ	$3, CX
+	ANDQ	$7, BX
+
+	REP;	MOVSQ
+	MOVQ	BX, CX
+	REP;	MOVSB
+
+	MOVQ	to+0(FP),AX
+	RET
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+back:
+	ADDQ	BX, DI
+	ADDQ	BX, SI
+	STD
+
+/*
+ * copy
+ */
+	MOVQ	BX, CX
+	SHRQ	$3, CX
+	ANDQ	$7, BX
+
+	SUBQ	$8, DI
+	SUBQ	$8, SI
+	REP;	MOVSQ
+
+	ADDQ	$7, DI
+	ADDQ	$7, SI
+	MOVQ	BX, CX
+	REP;	MOVSB
+
+	CLD
+	MOVQ	to+0(FP),AX
+	RET
+
+/*
+ * if called with negative count,
+ * treat as error rather than
+ * rotating all of memory
+ */
+fault:
+	MOVQ	$0,SI
+	MOVQ	0(SI), AX
+	RET

src/pkg/runtime/slice.c

@@ -177,6 +177,39 @@ runtime·arraytoslice(byte* old, uint32 nel, Slice ret)
 	}
 }
 
+// slicecopy(to any, fr any, wid uint32) int
+void
+runtime·slicecopy(Slice to, Slice fm, uintptr width, int32 ret)
+{
+	if(fm.array == nil || fm.len == 0 ||
+	   to.array == nil || to.len == 0 ||
+	   width == 0) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = fm.len;
+	if(to.len > ret)
+		ret = to.len;
+
+	memmove(to.array, fm.array, ret*width);
+
+out:
+	FLUSH(&ret);
+
+	if(debug) {
+		prints("main·copy: to=");
+		runtime·printslice(to);
+		prints("; fm=");
+		runtime·printslice(fm);
+		prints("; width=");
+		runtime·printint(width);
+		prints("; ret=");
+		runtime·printint(ret);
+		prints("\n");
+	}
+}
+
 void
 runtime·printslice(Slice a)
 {