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//===- PHITransAddr.h - PHI Translation for Addresses -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file declares the PHITransAddr class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_PHITRANSADDR_H
#define LLVM_ANALYSIS_PHITRANSADDR_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Instruction.h"
namespace llvm {
class AssumptionCache;
class DominatorTree;
class DataLayout;
class TargetLibraryInfo;
/// PHITransAddr - An address value which tracks and handles phi translation.
/// As we walk "up" the CFG through predecessors, we need to ensure that the
/// address we're tracking is kept up to date. For example, if we're analyzing
/// an address of "&A[i]" and walk through the definition of 'i' which is a PHI
/// node, we *must* phi translate i to get "&A[j]" or else we will analyze an
/// incorrect pointer in the predecessor block.
///
/// This is designed to be a relatively small object that lives on the stack and
/// is copyable.
///
class PHITransAddr {
/// Addr - The actual address we're analyzing.
Value *Addr;
/// The DataLayout we are playing with.
const DataLayout &DL;
/// TLI - The target library info if known, otherwise null.
const TargetLibraryInfo *TLI = nullptr;
/// A cache of \@llvm.assume calls used by SimplifyInstruction.
AssumptionCache *AC;
/// InstInputs - The inputs for our symbolic address.
SmallVector<Instruction*, 4> InstInputs;
public:
PHITransAddr(Value *Addr, const DataLayout &DL, AssumptionCache *AC)
: Addr(Addr), DL(DL), AC(AC) {
// If the address is an instruction, the whole thing is considered an input.
addAsInput(Addr);
}
Value *getAddr() const { return Addr; }
/// needsPHITranslationFromBlock - Return true if moving from the specified
/// BasicBlock to its predecessors requires PHI translation.
bool needsPHITranslationFromBlock(BasicBlock *BB) const {
// We do need translation if one of our input instructions is defined in
// this block.
return any_of(InstInputs, [BB](const auto &InstInput) {
return InstInput->getParent() == BB;
});
}
/// isPotentiallyPHITranslatable - If this needs PHI translation, return true
/// if we have some hope of doing it. This should be used as a filter to
/// avoid calling PHITranslateValue in hopeless situations.
bool isPotentiallyPHITranslatable() const;
/// translateValue - PHI translate the current address up the CFG from
/// CurBB to Pred, updating our state to reflect any needed changes. If
/// 'MustDominate' is true, the translated value must dominate PredBB.
Value *translateValue(BasicBlock *CurBB, BasicBlock *PredBB,
const DominatorTree *DT, bool MustDominate);
/// translateWithInsertion - PHI translate this value into the specified
/// predecessor block, inserting a computation of the value if it is
/// unavailable.
///
/// All newly created instructions are added to the NewInsts list. This
/// returns null on failure.
///
Value *translateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB,
const DominatorTree &DT,
SmallVectorImpl<Instruction *> &NewInsts);
void dump() const;
/// verify - Check internal consistency of this data structure. If the
/// structure is valid, it returns true. If invalid, it prints errors and
/// returns false.
bool verify() const;
private:
Value *translateSubExpr(Value *V, BasicBlock *CurBB, BasicBlock *PredBB,
const DominatorTree *DT);
/// insertTranslatedSubExpr - Insert a computation of the PHI translated
/// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
/// block. All newly created instructions are added to the NewInsts list.
/// This returns null on failure.
///
Value *insertTranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
BasicBlock *PredBB, const DominatorTree &DT,
SmallVectorImpl<Instruction *> &NewInsts);
/// addAsInput - If the specified value is an instruction, add it as an input.
Value *addAsInput(Value *V) {
// If V is an instruction, it is now an input.
if (Instruction *VI = dyn_cast<Instruction>(V))
InstInputs.push_back(VI);
return V;
}
};
} // end namespace llvm
#endif
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