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73 lines
2.1 KiB
C++
73 lines
2.1 KiB
C++
//===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements an allocation order for virtual registers.
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//
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// The preferred allocation order for a virtual register depends on allocation
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// hints and target hooks. The AllocationOrder class encapsulates all of that.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_ALLOCATIONORDER_H
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#define LLVM_CODEGEN_ALLOCATIONORDER_H
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namespace llvm {
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class RegisterClassInfo;
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class VirtRegMap;
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class AllocationOrder {
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const unsigned *Begin;
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const unsigned *End;
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const unsigned *Pos;
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const RegisterClassInfo &RCI;
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unsigned Hint;
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bool OwnedBegin;
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public:
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/// AllocationOrder - Create a new AllocationOrder for VirtReg.
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/// @param VirtReg Virtual register to allocate for.
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/// @param VRM Virtual register map for function.
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/// @param RegClassInfo Information about reserved and allocatable registers.
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AllocationOrder(unsigned VirtReg,
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const VirtRegMap &VRM,
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const RegisterClassInfo &RegClassInfo);
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~AllocationOrder();
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/// next - Return the next physical register in the allocation order, or 0.
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/// It is safe to call next again after it returned 0.
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/// It will keep returning 0 until rewind() is called.
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unsigned next() {
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// First take the hint.
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if (!Pos) {
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Pos = Begin;
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if (Hint)
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return Hint;
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}
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// Then look at the order from TRI.
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while (Pos != End) {
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unsigned Reg = *Pos++;
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if (Reg != Hint)
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return Reg;
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}
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return 0;
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}
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/// rewind - Start over from the beginning.
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void rewind() { Pos = 0; }
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/// isHint - Return true if PhysReg is a preferred register.
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bool isHint(unsigned PhysReg) const { return PhysReg == Hint; }
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};
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} // end namespace llvm
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#endif
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