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must be called in the pass's constructor. This function uses static dependency declarations to recursively initialize the pass's dependencies. Clients that only create passes through the createFooPass() APIs will require no changes. Clients that want to use the CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h before parsing commandline arguments. I have tested this with all standard configurations of clang and llvm-gcc on Darwin. It is possible that there are problems with the static dependencies that will only be visible with non-standard options. If you encounter any crash in pass registration/creation, please send the testcase to me directly. llvm-svn: 116820
118 lines
4.5 KiB
C++
118 lines
4.5 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/DenseMap.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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namespace llvm {
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class LiveVariables;
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class MachineRegisterInfo;
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class MachineLoopInfo;
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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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initializePHIEliminationPass(*PassRegistry::getPassRegistry());
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}
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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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/// Split critical edges where necessary for good coalescer performance.
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bool SplitPHIEdges(MachineFunction &MF, MachineBasicBlock &MBB,
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LiveVariables &LV, MachineLoopInfo *MLI);
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/// SplitCriticalEdge - Split a critical edge from A to B by
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/// inserting a new MBB. Update branches in A and PHI instructions
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/// in B. Return the new block.
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MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *A,
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MachineBasicBlock *B);
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/// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
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/// SrcReg when following the CFG edge to SuccMBB. This needs to be after
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/// any def of SrcReg, but before any subsequent point where control flow
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/// might jump out of the basic block.
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MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
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MachineBasicBlock &SuccMBB,
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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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// We also deal with DBG_VALUEs, which are a bit tricky:
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// PHI
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// DBG_VALUE
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// LABEL
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// Here the DBG_VALUE needs to be skipped, and if it refers to a PHI it
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// needs to be annulled or, better, moved to follow the label, as well.
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// PHI
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// DBG_VALUE
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// no label
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// Here it is not a good idea to skip the DBG_VALUE.
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// FIXME: For now we skip and annul all DBG_VALUEs, maximally simple and
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// maximally stupid.
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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->isPHI() || I->isLabel() || I->isDebugValue())) {
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if (I->isDebugValue() && I->getNumOperands()==3 &&
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I->getOperand(0).isReg())
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I->getOperand(0).setReg(0U);
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++I;
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}
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return I;
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}
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typedef std::pair<unsigned, unsigned> BBVRegPair;
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typedef DenseMap<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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// Map reusable lowered PHI node -> incoming join register.
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typedef DenseMap<MachineInstr*, unsigned,
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MachineInstrExpressionTrait> LoweredPHIMap;
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LoweredPHIMap LoweredPHIs;
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};
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}
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#endif /* LLVM_CODEGEN_PHIELIMINATION_HPP */
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