Add support for printing slices via print/println

With help from @aykevl.

compiler/compiler.go

@@ -1541,6 +1541,12 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 			case *types.Pointer:
 				ptrValue := b.CreatePtrToInt(value, b.uintptrType, "")
 				b.createRuntimeCall("printptr", []llvm.Value{ptrValue}, "")
+			case *types.Slice:
+				bufptr := b.CreateExtractValue(value, 0, "")
+				buflen := b.CreateExtractValue(value, 1, "")
+				bufcap := b.CreateExtractValue(value, 2, "")
+				ptrValue := b.CreatePtrToInt(bufptr, b.uintptrType, "")
+				b.createRuntimeCall("printslice", []llvm.Value{ptrValue, buflen, bufcap}, "")
 			default:
 				return llvm.Value{}, b.makeError(pos, "unknown arg type: "+typ.String())
 			}

src/runtime/print.go

@@ -39,6 +39,17 @@ func printint8(n int8) {
 	}
 }
 
+func printuint(n uintptr) {
+	switch unsafe.Sizeof(n) {
+	case 2:
+		printuint16(uint16(n))
+	case 4:
+		printuint32(uint32(n))
+	case 8:
+		printuint64(uint64(n))
+	}
+}
+
 func printuint16(n uint16) {
 	printuint32(uint32(n))
 }
@@ -323,14 +334,7 @@ func printitf(msg interface{}) {
 		// cast to underlying type
 		itf := *(*_interface)(unsafe.Pointer(&msg))
 		putchar('(')
-		switch unsafe.Sizeof(itf.typecode) {
-		case 2:
-			printuint16(uint16(itf.typecode))
-		case 4:
-			printuint32(uint32(itf.typecode))
-		case 8:
-			printuint64(uint64(itf.typecode))
-		}
+		printuint(uintptr(itf.typecode))
 		putchar(':')
 		print(itf.value)
 		putchar(')')
@@ -372,3 +376,12 @@ func printbool(b bool) {
 		printstring("false")
 	}
 }
+
+func printslice(ptr, len_, cap_ uintptr) {
+	putchar('[')
+	printuint(len_)
+	putchar('/')
+	printuint(cap_)
+	putchar(']')
+	printptr(ptr)
+}

testdata/print.go

@@ -45,4 +45,8 @@ func main() {
 
 	// print bool
 	println(true, false)
+
+	// print slice
+	println([]byte(nil))
+	println([]int(nil))
 }

testdata/print.txt

@@ -21,3 +21,5 @@ a b c
 (0:nil)
 map[2]
 true false
+[0/0]nil
+[0/0]nil