Add an AllocationOrder class that can iterate over the allocatable physical
registers for a given virtual register.
Reserved registers are filtered from the allocation order, and any valid hint is
returned as the first suggestion.
For target dependent hints, a number of arcane target hooks are invoked.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121497 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AllocationOrder.h b/lib/CodeGen/AllocationOrder.h
new file mode 100644
index 0000000..3db4b69
--- /dev/null
+++ b/lib/CodeGen/AllocationOrder.h
@@ -0,0 +1,54 @@
+//===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements an allocation order for virtual registers.
+//
+// The preferred allocation order for a virtual register depends on allocation
+// hints and target hooks. The AllocationOrder class encapsulates all of that.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_ALLOCATIONORDER_H
+#define LLVM_CODEGEN_ALLOCATIONORDER_H
+
+namespace llvm {
+
+class BitVector;
+class VirtRegMap;
+
+class AllocationOrder {
+ const unsigned *Begin;
+ const unsigned *End;
+ const unsigned *Pos;
+ const BitVector &Reserved;
+ unsigned Hint;
+public:
+
+ /// AllocationOrder - Create a new AllocationOrder for VirtReg.
+ /// @param VirtReg Virtual register to allocate for.
+ /// @param VRM Virtual register map for function.
+ /// @param ReservedRegs Set of reserved registers as returned by
+ /// TargetRegisterInfo::getReservedRegs().
+ AllocationOrder(unsigned VirtReg,
+ const VirtRegMap &VRM,
+ const BitVector &ReservedRegs);
+
+ /// next - Return the next physical register in the allocation order, or 0.
+ /// It is safe to call next again after it returned 0.
+ /// It will keep returning 0 until rewind() is called.
+ unsigned next();
+
+ /// rewind - Start over from the beginning.
+ void rewind() { Pos = 0; }
+
+};
+
+} // end namespace llvm
+
+#endif