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9b9861651f
Only target-dependent hints require callbacks. The RCI allocation order has CSR aliases last according to their order of appearance in the getCalleeSavedRegs list. This can depend on the calling convention. This way, AllocationOrder::next doesn't have to check for reserved registers, and CSRs are always allocated last, even with weird calling conventions. llvm-svn: 132690
74 lines
2.1 KiB
C++
74 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 ReservedRegs Set of reserved registers as returned by
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/// TargetRegisterInfo::getReservedRegs().
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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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