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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
113 lines
4.0 KiB
C++
113 lines
4.0 KiB
C++
//===- RegisterCoalescer.h - Register Coalescing Interface ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the abstract interface for register coalescers,
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// allowing them to interact with and query register allocators.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_CODEGEN_REGISTERCOALESCER_H
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#define LLVM_LIB_CODEGEN_REGISTERCOALESCER_H
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namespace llvm {
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class MachineInstr;
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class TargetRegisterClass;
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class TargetRegisterInfo;
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/// A helper class for register coalescers. When deciding if
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/// two registers can be coalesced, CoalescerPair can determine if a copy
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/// instruction would become an identity copy after coalescing.
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class CoalescerPair {
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const TargetRegisterInfo &TRI;
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/// The register that will be left after coalescing. It can be a
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/// virtual or physical register.
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unsigned DstReg = 0;
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/// The virtual register that will be coalesced into dstReg.
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unsigned SrcReg = 0;
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/// The sub-register index of the old DstReg in the new coalesced register.
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unsigned DstIdx = 0;
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/// The sub-register index of the old SrcReg in the new coalesced register.
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unsigned SrcIdx = 0;
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/// True when the original copy was a partial subregister copy.
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bool Partial = false;
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/// True when both regs are virtual and newRC is constrained.
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bool CrossClass = false;
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/// True when DstReg and SrcReg are reversed from the original
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/// copy instruction.
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bool Flipped = false;
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/// The register class of the coalesced register, or NULL if DstReg
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/// is a physreg. This register class may be a super-register of both
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/// SrcReg and DstReg.
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const TargetRegisterClass *NewRC = nullptr;
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public:
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CoalescerPair(const TargetRegisterInfo &tri) : TRI(tri) {}
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/// Create a CoalescerPair representing a virtreg-to-physreg copy.
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/// No need to call setRegisters().
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CoalescerPair(unsigned VirtReg, unsigned PhysReg,
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const TargetRegisterInfo &tri)
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: TRI(tri), DstReg(PhysReg), SrcReg(VirtReg) {}
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/// Set registers to match the copy instruction MI. Return
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/// false if MI is not a coalescable copy instruction.
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bool setRegisters(const MachineInstr*);
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/// Swap SrcReg and DstReg. Return false if swapping is impossible
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/// because DstReg is a physical register, or SubIdx is set.
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bool flip();
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/// Return true if MI is a copy instruction that will become
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/// an identity copy after coalescing.
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bool isCoalescable(const MachineInstr*) const;
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/// Return true if DstReg is a physical register.
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bool isPhys() const { return !NewRC; }
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/// Return true if the original copy instruction did not copy
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/// the full register, but was a subreg operation.
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bool isPartial() const { return Partial; }
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/// Return true if DstReg is virtual and NewRC is a smaller
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/// register class than DstReg's.
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bool isCrossClass() const { return CrossClass; }
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/// Return true when getSrcReg is the register being defined by
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/// the original copy instruction.
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bool isFlipped() const { return Flipped; }
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/// Return the register (virtual or physical) that will remain
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/// after coalescing.
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unsigned getDstReg() const { return DstReg; }
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/// Return the virtual register that will be coalesced away.
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unsigned getSrcReg() const { return SrcReg; }
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/// Return the subregister index that DstReg will be coalesced into, or 0.
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unsigned getDstIdx() const { return DstIdx; }
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/// Return the subregister index that SrcReg will be coalesced into, or 0.
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unsigned getSrcIdx() const { return SrcIdx; }
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/// Return the register class of the coalesced register.
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const TargetRegisterClass *getNewRC() const { return NewRC; }
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};
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} // end namespace llvm
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#endif // LLVM_LIB_CODEGEN_REGISTERCOALESCER_H
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