From bc1d6791b9ac95dc0c6dfdab0ba057068b6c0744 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Thu, 9 Jul 2020 13:51:49 +0300
Subject: [PATCH] compiler: allow to append multiple elements

---
 pkg/compiler/codegen.go    | 28 ++++++++++++++++------------
 pkg/compiler/slice_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index c7d888a42..f51de0942 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -1176,25 +1176,29 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 	case "append":
 		arg := expr.Args[0]
 		typ := c.typeInfo.Types[arg].Type
-		emit.Opcode(c.prog.BinWriter, opcode.OVER)
+		c.emitReverse(len(expr.Args))
+		emit.Opcode(c.prog.BinWriter, opcode.DUP)
 		emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
-		emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 4})
+		emit.Instruction(c.prog.BinWriter, opcode.JMPIFNOT, []byte{2 + 3})
 		if isByteSlice(typ) {
-			emit.Opcode(c.prog.BinWriter, opcode.NIP)
+			emit.Opcode(c.prog.BinWriter, opcode.DROP)
 			emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
 			emit.Opcode(c.prog.BinWriter, opcode.NEWBUFFER)
-			emit.Opcode(c.prog.BinWriter, opcode.SWAP)
-			// Jump target.
-			emit.Opcode(c.prog.BinWriter, opcode.CAT)
 		} else {
-			emit.Opcode(c.prog.BinWriter, opcode.NIP)
+			emit.Opcode(c.prog.BinWriter, opcode.DROP)
 			emit.Opcode(c.prog.BinWriter, opcode.NEWARRAY0)
-			emit.Opcode(c.prog.BinWriter, opcode.SWAP)
 			emit.Opcode(c.prog.BinWriter, opcode.NOP)
-			// Jump target.
-			emit.Opcode(c.prog.BinWriter, opcode.OVER)
-			emit.Opcode(c.prog.BinWriter, opcode.SWAP)
-			emit.Opcode(c.prog.BinWriter, opcode.APPEND)
+		}
+		// Jump target.
+		for range expr.Args[1:] {
+			if isByteSlice(typ) {
+				emit.Opcode(c.prog.BinWriter, opcode.SWAP)
+				emit.Opcode(c.prog.BinWriter, opcode.CAT)
+			} else {
+				emit.Opcode(c.prog.BinWriter, opcode.DUP)
+				emit.Opcode(c.prog.BinWriter, opcode.ROT)
+				emit.Opcode(c.prog.BinWriter, opcode.APPEND)
+			}
 		}
 	case "panic":
 		arg := expr.Args[0]
diff --git a/pkg/compiler/slice_test.go b/pkg/compiler/slice_test.go
index f386beddf..20223fb04 100644
--- a/pkg/compiler/slice_test.go
+++ b/pkg/compiler/slice_test.go
@@ -151,6 +151,33 @@ var sliceTestCases = []testCase{
 		}`,
 		[]byte{1, 2},
 	},
+	{
+		"append multiple bytes to a slice",
+		`package foo
+		func Main() []byte {
+			var a []byte
+			a = append(a, 1, 2)
+			return a
+		}`,
+		[]byte{1, 2},
+	},
+	{
+		"append multiple ints to a slice",
+		`package foo
+		func Main() []int {
+			var a []int
+			a = append(a, 1, 2, 3)
+			a = append(a, 4, 5)
+			return a
+		}`,
+		[]stackitem.Item{
+			stackitem.NewBigInteger(big.NewInt(1)),
+			stackitem.NewBigInteger(big.NewInt(2)),
+			stackitem.NewBigInteger(big.NewInt(3)),
+			stackitem.NewBigInteger(big.NewInt(4)),
+			stackitem.NewBigInteger(big.NewInt(5)),
+		},
+	},
 	{
 		"declare compound slice",
 		`package foo