1 files changed, 59 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ir/bitset.go b/src/cmd/compile/internal/ir/bitset.go
new file mode 100644
index 0000000000..29f136296f
--- /dev/null
+++ b/src/cmd/compile/internal/ir/bitset.go
@@ -0,0 +1,59 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ir
+
+type bitset8 uint8
+
+func (f *bitset8) set(mask uint8, b bool) {
+	if b {
+		*(*uint8)(f) |= mask
+	} else {
+		*(*uint8)(f) &^= mask
+	}
+}
+
+type bitset16 uint16
+
+func (f *bitset16) set(mask uint16, b bool) {
+	if b {
+		*(*uint16)(f) |= mask
+	} else {
+		*(*uint16)(f) &^= mask
+	}
+}
+
+type bitset32 uint32
+
+func (f *bitset32) set(mask uint32, b bool) {
+	if b {
+		*(*uint32)(f) |= mask
+	} else {
+		*(*uint32)(f) &^= mask
+	}
+}
+
+func (f bitset32) get2(shift uint8) uint8 {
+	return uint8(f>>shift) & 3
+}
+
+// set2 sets two bits in f using the bottom two bits of b.
+func (f *bitset32) set2(shift uint8, b uint8) {
+	// Clear old bits.
+	*(*uint32)(f) &^= 3 << shift
+	// Set new bits.
+	*(*uint32)(f) |= uint32(b&3) << shift
+}
+
+func (f bitset32) get3(shift uint8) uint8 {
+	return uint8(f>>shift) & 7
+}
+
+// set3 sets three bits in f using the bottom three bits of b.
+func (f *bitset32) set3(shift uint8, b uint8) {
+	// Clear old bits.
+	*(*uint32)(f) &^= 7 << shift
+	// Set new bits.
+	*(*uint32)(f) |= uint32(b&7) << shift
+}