Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 79 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/sparseset.go b/src/cmd/compile/internal/ssa/sparseset.go
new file mode 100644
index 0000000..07d40dc
--- /dev/null
+++ b/src/cmd/compile/internal/ssa/sparseset.go
@@ -0,0 +1,79 @@
+// Copyright 2015 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 ssa
+
+// from https://research.swtch.com/sparse
+// in turn, from Briggs and Torczon
+
+type sparseSet struct {
+	dense  []ID
+	sparse []int32
+}
+
+// newSparseSet returns a sparseSet that can represent
+// integers between 0 and n-1.
+func newSparseSet(n int) *sparseSet {
+	return &sparseSet{dense: nil, sparse: make([]int32, n)}
+}
+
+func (s *sparseSet) cap() int {
+	return len(s.sparse)
+}
+
+func (s *sparseSet) size() int {
+	return len(s.dense)
+}
+
+func (s *sparseSet) contains(x ID) bool {
+	i := s.sparse[x]
+	return i < int32(len(s.dense)) && s.dense[i] == x
+}
+
+func (s *sparseSet) add(x ID) {
+	i := s.sparse[x]
+	if i < int32(len(s.dense)) && s.dense[i] == x {
+		return
+	}
+	s.dense = append(s.dense, x)
+	s.sparse[x] = int32(len(s.dense)) - 1
+}
+
+func (s *sparseSet) addAll(a []ID) {
+	for _, x := range a {
+		s.add(x)
+	}
+}
+
+func (s *sparseSet) addAllValues(a []*Value) {
+	for _, v := range a {
+		s.add(v.ID)
+	}
+}
+
+func (s *sparseSet) remove(x ID) {
+	i := s.sparse[x]
+	if i < int32(len(s.dense)) && s.dense[i] == x {
+		y := s.dense[len(s.dense)-1]
+		s.dense[i] = y
+		s.sparse[y] = i
+		s.dense = s.dense[:len(s.dense)-1]
+	}
+}
+
+// pop removes an arbitrary element from the set.
+// The set must be nonempty.
+func (s *sparseSet) pop() ID {
+	x := s.dense[len(s.dense)-1]
+	s.dense = s.dense[:len(s.dense)-1]
+	return x
+}
+
+func (s *sparseSet) clear() {
+	s.dense = s.dense[:0]
+}
+
+func (s *sparseSet) contents() []ID {
+	return s.dense
+}