1 files changed, 21 insertions, 0 deletions
diff --git a/backend/lib/CodeGen/RegisterMask.cpp b/backend/lib/CodeGen/RegisterMask.cpp
new file mode 100644
index 0000000..027ee26
--- /dev/null
+++ b/backend/lib/CodeGen/RegisterMask.cpp
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/RegisterMask.h"
+
+namespace rcc {
+
+bool RegisterMask::preserves(PhysicalRegister PhysReg) const noexcept {
+  if (!PhysReg.isValid())
+    return false;
+
+  constexpr std::uint32_t BitsPerWord = 64;
+  const std::uint32_t RegisterNumber = PhysReg.number();
+  const std::size_t WordIndex = RegisterNumber / BitsPerWord;
+  if (WordIndex >= PreservedWords.size())
+    return false;
+
+  const std::uint32_t BitIndex = RegisterNumber % BitsPerWord;
+  return (PreservedWords[WordIndex] & (std::uint64_t{1} << BitIndex)) != 0;
+}
+
+} // namespace rcc