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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
4.3 KiB
C++
113 lines
4.3 KiB
C++
//===- MachineSSAUpdater.h - Unstructured SSA Update Tool -------*- 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 declares the MachineSSAUpdater class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_MACHINESSAUPDATER_H
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#define LLVM_CODEGEN_MACHINESSAUPDATER_H
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namespace llvm {
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class MachineBasicBlock;
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class MachineFunction;
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class MachineInstr;
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class MachineOperand;
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class MachineRegisterInfo;
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class TargetInstrInfo;
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class TargetRegisterClass;
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template<typename T> class SmallVectorImpl;
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template<typename T> class SSAUpdaterTraits;
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/// MachineSSAUpdater - This class updates SSA form for a set of virtual
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/// registers defined in multiple blocks. This is used when code duplication
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/// or another unstructured transformation wants to rewrite a set of uses of one
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/// vreg with uses of a set of vregs.
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class MachineSSAUpdater {
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friend class SSAUpdaterTraits<MachineSSAUpdater>;
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private:
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/// AvailableVals - This keeps track of which value to use on a per-block
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/// basis. When we insert PHI nodes, we keep track of them here.
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//typedef DenseMap<MachineBasicBlock*, unsigned > AvailableValsTy;
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void *AV = nullptr;
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/// VR - Current virtual register whose uses are being updated.
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unsigned VR;
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/// VRC - Register class of the current virtual register.
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const TargetRegisterClass *VRC;
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/// InsertedPHIs - If this is non-null, the MachineSSAUpdater adds all PHI
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/// nodes that it creates to the vector.
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SmallVectorImpl<MachineInstr*> *InsertedPHIs;
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const TargetInstrInfo *TII;
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MachineRegisterInfo *MRI;
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public:
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/// MachineSSAUpdater constructor. If InsertedPHIs is specified, it will be
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/// filled in with all PHI Nodes created by rewriting.
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explicit MachineSSAUpdater(MachineFunction &MF,
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SmallVectorImpl<MachineInstr*> *NewPHI = nullptr);
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MachineSSAUpdater(const MachineSSAUpdater &) = delete;
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MachineSSAUpdater &operator=(const MachineSSAUpdater &) = delete;
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~MachineSSAUpdater();
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/// Initialize - Reset this object to get ready for a new set of SSA
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/// updates.
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void Initialize(unsigned V);
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/// AddAvailableValue - Indicate that a rewritten value is available at the
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/// end of the specified block with the specified value.
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void AddAvailableValue(MachineBasicBlock *BB, unsigned V);
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/// HasValueForBlock - Return true if the MachineSSAUpdater already has a
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/// value for the specified block.
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bool HasValueForBlock(MachineBasicBlock *BB) const;
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/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
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/// live at the end of the specified block.
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unsigned GetValueAtEndOfBlock(MachineBasicBlock *BB);
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/// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that
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/// is live in the middle of the specified block.
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///
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/// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one
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/// important case: if there is a definition of the rewritten value after the
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/// 'use' in BB. Consider code like this:
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///
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/// X1 = ...
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/// SomeBB:
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/// use(X)
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/// X2 = ...
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/// br Cond, SomeBB, OutBB
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///
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/// In this case, there are two values (X1 and X2) added to the AvailableVals
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/// set by the client of the rewriter, and those values are both live out of
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/// their respective blocks. However, the use of X happens in the *middle* of
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/// a block. Because of this, we need to insert a new PHI node in SomeBB to
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/// merge the appropriate values, and this value isn't live out of the block.
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unsigned GetValueInMiddleOfBlock(MachineBasicBlock *BB);
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/// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes,
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/// which use their value in the corresponding predecessor. Note that this
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/// will not work if the use is supposed to be rewritten to a value defined in
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/// the same block as the use, but above it. Any 'AddAvailableValue's added
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/// for the use's block will be considered to be below it.
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void RewriteUse(MachineOperand &U);
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private:
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unsigned GetValueAtEndOfBlockInternal(MachineBasicBlock *BB);
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};
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} // end namespace llvm
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#endif // LLVM_CODEGEN_MACHINESSAUPDATER_H
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