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6d6132986d
When tryEvict() is looking for a cheaper register in the allocation order, skip the tail of too expensive registers when possible. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172281 91177308-0d34-0410-b5e6-96231b3b80d8
86 lines
2.6 KiB
C++
86 lines
2.6 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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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/MC/MCRegisterInfo.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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SmallVector<MCPhysReg, 16> Hints;
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ArrayRef<MCPhysReg> Order;
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int Pos;
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public:
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/// 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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/// Get the allocation order without reordered hints.
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ArrayRef<MCPhysReg> getOrder() const { return Order; }
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/// 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, it will keep
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/// returning 0 until rewind() is called.
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unsigned next() {
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if (Pos < 0)
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return Hints.end()[Pos++];
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while (Pos < int(Order.size())) {
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unsigned Reg = Order[Pos++];
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if (!isHint(Reg))
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return Reg;
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}
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return 0;
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}
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/// As next(), but allow duplicates to be returned, and stop before the
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/// Limit'th register in the RegisterClassInfo allocation order.
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///
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/// This can produce more than Limit registers if there are hints.
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unsigned nextWithDups(unsigned Limit) {
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if (Pos < 0)
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return Hints.end()[Pos++];
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if (Pos < int(Limit))
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return Order[Pos++];
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return 0;
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}
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/// Start over from the beginning.
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void rewind() { Pos = -int(Hints.size()); }
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/// Return true if the last register returned from next() was a preferred register.
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bool isHint() const { return Pos <= 0; }
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/// Return true if PhysReg is a preferred register.
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bool isHint(unsigned PhysReg) const {
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return std::find(Hints.begin(), Hints.end(), PhysReg) != Hints.end();
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}
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};
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} // end namespace llvm
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#endif
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