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fae02a2ab1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76688 91177308-0d34-0410-b5e6-96231b3b80d8
81 lines
2.9 KiB
C++
81 lines
2.9 KiB
C++
//===-- lib/CodeGen/PHIElimination.h ----------------------------*- 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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#ifndef LLVM_CODEGEN_PHIELIMINATION_HPP
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#define LLVM_CODEGEN_PHIELIMINATION_HPP
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include <map>
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namespace llvm {
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/// Lower PHI instructions to copies.
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class PHIElimination : public MachineFunctionPass {
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MachineRegisterInfo *MRI; // Machine register information
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public:
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static char ID; // Pass identification, replacement for typeid
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PHIElimination() : MachineFunctionPass(&ID) {}
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virtual bool runOnMachineFunction(MachineFunction &Fn);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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private:
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/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
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/// in predecessor basic blocks.
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///
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bool EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB);
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void LowerAtomicPHINode(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator AfterPHIsIt);
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/// analyzePHINodes - Gather information about the PHI nodes in
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/// here. In particular, we want to map the number of uses of a virtual
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/// register which is used in a PHI node. We map that to the BB the
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/// vreg is coming from. This is used later to determine when the vreg
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/// is killed in the BB.
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///
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void analyzePHINodes(const MachineFunction& Fn);
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// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
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// SrcReg. This needs to be after any def or uses of SrcReg, but before
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// any subsequent point where control flow might jump out of the basic
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// block.
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MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
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unsigned SrcReg);
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// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
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// also after any exception handling labels: in landing pads execution
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// starts at the label, so any copies placed before it won't be executed!
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MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) {
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// Rather than assuming that EH labels come before other kinds of labels,
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// just skip all labels.
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while (I != MBB.end() &&
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(I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
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++I;
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return I;
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}
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typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
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typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
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VRegPHIUse VRegPHIUseCount;
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// Defs of PHI sources which are implicit_def.
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SmallPtrSet<MachineInstr*, 4> ImpDefs;
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};
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}
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#endif /* PHIELIMINATION_H */
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