127 lines
4.8 KiB
C++
127 lines
4.8 KiB
C++
//===- PHITransAddr.h - PHI Translation for Addresses -----------*- 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 PHITransAddr class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_PHITRANSADDR_H
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#define LLVM_ANALYSIS_PHITRANSADDR_H
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/IR/Instruction.h"
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namespace llvm {
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class AssumptionCache;
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class DominatorTree;
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class DataLayout;
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class TargetLibraryInfo;
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/// PHITransAddr - An address value which tracks and handles phi translation.
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/// As we walk "up" the CFG through predecessors, we need to ensure that the
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/// address we're tracking is kept up to date. For example, if we're analyzing
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/// an address of "&A[i]" and walk through the definition of 'i' which is a PHI
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/// node, we *must* phi translate i to get "&A[j]" or else we will analyze an
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/// incorrect pointer in the predecessor block.
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///
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/// This is designed to be a relatively small object that lives on the stack and
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/// is copyable.
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///
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class PHITransAddr {
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/// Addr - The actual address we're analyzing.
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Value *Addr;
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/// The DataLayout we are playing with.
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const DataLayout &DL;
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/// TLI - The target library info if known, otherwise null.
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const TargetLibraryInfo *TLI;
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/// A cache of \@llvm.assume calls used by SimplifyInstruction.
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AssumptionCache *AC;
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/// InstInputs - The inputs for our symbolic address.
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SmallVector<Instruction*, 4> InstInputs;
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public:
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PHITransAddr(Value *addr, const DataLayout &DL, AssumptionCache *AC)
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: Addr(addr), DL(DL), TLI(nullptr), AC(AC) {
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// If the address is an instruction, the whole thing is considered an input.
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if (Instruction *I = dyn_cast<Instruction>(Addr))
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InstInputs.push_back(I);
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}
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Value *getAddr() const { return Addr; }
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/// NeedsPHITranslationFromBlock - Return true if moving from the specified
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/// BasicBlock to its predecessors requires PHI translation.
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bool NeedsPHITranslationFromBlock(BasicBlock *BB) const {
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// We do need translation if one of our input instructions is defined in
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// this block.
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for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
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if (InstInputs[i]->getParent() == BB)
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return true;
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return false;
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}
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/// IsPotentiallyPHITranslatable - If this needs PHI translation, return true
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/// if we have some hope of doing it. This should be used as a filter to
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/// avoid calling PHITranslateValue in hopeless situations.
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bool IsPotentiallyPHITranslatable() const;
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/// PHITranslateValue - PHI translate the current address up the CFG from
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/// CurBB to Pred, updating our state to reflect any needed changes. If
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/// 'MustDominate' is true, the translated value must dominate
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/// PredBB. This returns true on failure and sets Addr to null.
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bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB,
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const DominatorTree *DT, bool MustDominate);
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/// PHITranslateWithInsertion - PHI translate this value into the specified
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/// predecessor block, inserting a computation of the value if it is
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/// unavailable.
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///
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/// All newly created instructions are added to the NewInsts list. This
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/// returns null on failure.
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///
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Value *PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB,
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const DominatorTree &DT,
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SmallVectorImpl<Instruction *> &NewInsts);
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void dump() const;
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/// Verify - Check internal consistency of this data structure. If the
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/// structure is valid, it returns true. If invalid, it prints errors and
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/// returns false.
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bool Verify() const;
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private:
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Value *PHITranslateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB,
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const DominatorTree *DT);
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/// InsertPHITranslatedSubExpr - Insert a computation of the PHI translated
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/// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
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/// block. All newly created instructions are added to the NewInsts list.
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/// This returns null on failure.
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///
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Value *InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
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BasicBlock *PredBB, const DominatorTree &DT,
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SmallVectorImpl<Instruction *> &NewInsts);
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/// AddAsInput - If the specified value is an instruction, add it as an input.
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Value *AddAsInput(Value *V) {
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// If V is an instruction, it is now an input.
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if (Instruction *VI = dyn_cast<Instruction>(V))
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InstInputs.push_back(VI);
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return V;
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}
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};
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} // end namespace llvm
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#endif
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