Ch# Chapter 19: Instruction Selection and Portable Compilationlinear-chapter19

Co-authored-by: hadha <helsgithub15@gmail.com>
Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/main/java/com/seaofnodes/simple/RegMask.java b/src/main/java/com/seaofnodes/simple/RegMask.java
new file mode 100644
index 00000000..20be7157
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/RegMask.java
@@ -0,0 +1,39 @@
+package com.seaofnodes.simple;
+
+import java.util.BitSet;
+
+// A "register mask" - 1 bit set for each allowed register.  In addition "stack
+// slot" registers may be allowed, effectively making the set infinite.
+public class RegMask {
+
+    public static final RegMask EMPTY = new RegMask();
+
+    final BitSet _bits;
+
+    public RegMask(long   x ) { _bits = BitSet.valueOf(new long[]{x}); }
+    public RegMask(long[] xs) { _bits = BitSet.valueOf(           xs); }
+    // Internal constructor
+    RegMask() { _bits = new BitSet(); }
+    RegMask(BitSet bs) { _bits = bs; }
+
+    public boolean get(int r) { return _bits.get(r); }
+
+    // Defensive writable copy
+    public RegMaskRW copy() { return new RegMaskRW( (BitSet)_bits.clone() ); }
+
+    boolean size1() { return _bits.cardinality()==1; }
+}
+
+class RegMaskRW extends RegMask {
+    public RegMaskRW() { super(); }
+    public RegMaskRW(long x) { super(new long[]{x}); }
+    public RegMaskRW(long[] xs) { super(xs); }
+    public RegMaskRW(BitSet bs) { super(bs); }
+    public void set(int r) { _bits.set(r); }
+    public void clr(int r) { _bits.clear(r); }
+    public void set(int r, boolean b) { _bits.set(r,b); }
+    public RegMaskRW and( RegMask r ) {
+        _bits.and(r._bits);
+        return this;
+    }
+}