//===- llvm/PassAnalysisSupport.h - Analysis Pass Support code --*- 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 defines stuff that is used to define and "use" Analysis Passes.
// This file is automatically #included by Pass.h, so:
//
// NO .CPP FILES SHOULD INCLUDE THIS FILE DIRECTLY
//
// Instead, #include Pass.h
//
//===----------------------------------------------------------------------===//
#if !defined(LLVM_PASS_H) || defined(LLVM_PASSANALYSISSUPPORT_H)
#error "Do not include <PassAnalysisSupport.h>; include <Pass.h> instead"
#endif
#ifndef LLVM_PASSANALYSISSUPPORT_H
#define LLVM_PASSANALYSISSUPPORT_H
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include <cassert>
#include <tuple>
#include <utility>
#include <vector>
namespace llvm {
class Function;
class Pass;
class PMDataManager;
class StringRef;
//===----------------------------------------------------------------------===//
/// Represent the analysis usage information of a pass. This tracks analyses
/// that the pass REQUIRES (must be available when the pass runs), REQUIRES
/// TRANSITIVE (must be available throughout the lifetime of the pass), and
/// analyses that the pass PRESERVES (the pass does not invalidate the results
/// of these analyses). This information is provided by a pass to the Pass
/// infrastructure through the getAnalysisUsage virtual function.
///
class AnalysisUsage {
public:
using VectorType = SmallVectorImpl<AnalysisID>;
private:
/// Sets of analyses required and preserved by a pass
// TODO: It's not clear that SmallVector is an appropriate data structure for
// this usecase. The sizes were picked to minimize wasted space, but are
// otherwise fairly meaningless.
SmallVector<AnalysisID, 8> Required;
SmallVector<AnalysisID, 2> RequiredTransitive;
SmallVector<AnalysisID, 2> Preserved;
SmallVector<AnalysisID, 0> Used;
bool PreservesAll = false;
void pushUnique(VectorType &Set, AnalysisID ID) {
if (!llvm::is_contained(Set, ID))
Set.push_back(ID);
}
public:
AnalysisUsage() = default;
///@{
/// Add the specified ID to the required set of the usage info for a pass.
AnalysisUsage &addRequiredID(const void *ID);
AnalysisUsage &addRequiredID(char &ID);
template<class PassClass>
AnalysisUsage &addRequired() {
return addRequiredID(PassClass::ID);
}
AnalysisUsage &addRequiredTransitiveID(char &ID);
template<class PassClass>
AnalysisUsage &addRequiredTransitive() {
return addRequiredTransitiveID(PassClass::ID);
}
///@}
///@{
/// Add the specified ID to the set of analyses preserved by this pass.
AnalysisUsage &addPreservedID(const void *ID) {
pushUnique(Preserved, ID);
return *this;
}
AnalysisUsage &addPreservedID(char &ID) {
pushUnique(Preserved, &ID);
return *this;
}
/// Add the specified Pass class to the set of analyses preserved by this pass.
template<class PassClass>
AnalysisUsage &addPreserved() {
pushUnique(Preserved, &PassClass::ID);
return *this;
}
///@}
///@{
/// Add the specified ID to the set of analyses used by this pass if they are
/// available..
AnalysisUsage &addUsedIfAvailableID(const void *ID) {
pushUnique(Used, ID);
return *this;
}
AnalysisUsage &addUsedIfAvailableID(char &ID) {
pushUnique(Used, &ID);
return *this;
}
/// Add the specified Pass class to the set of analyses used by this pass.
template<class PassClass>
AnalysisUsage &addUsedIfAvailable() {
pushUnique(Used, &PassClass::ID);
return *this;
}
///@}
/// Add the Pass with the specified argument string to the set of analyses
/// preserved by this pass. If no such Pass exists, do nothing. This can be
/// useful when a pass is trivially preserved, but may not be linked in. Be
/// careful about spelling!
AnalysisUsage &addPreserved(StringRef Arg);
/// Set by analyses that do not transform their input at all
void setPreservesAll() { PreservesAll = true; }
/// Determine whether a pass said it does not transform its input at all
bool getPreservesAll() const { return PreservesAll; }
/// This function should be called by the pass, iff they do not:
///
/// 1. Add or remove basic blocks from the function
/// 2. Modify terminator instructions in any way.
///
/// This function annotates the AnalysisUsage info object to say that analyses
/// that only depend on the CFG are preserved by this pass.
void setPreservesCFG();
const VectorType &getRequiredSet() const { return Required; }
const VectorType &getRequiredTransitiveSet() const {
return RequiredTransitive;
}
const VectorType &getPreservedSet() const { return Preserved; }
const VectorType &getUsedSet() const { return Used; }
};
//===----------------------------------------------------------------------===//
/// AnalysisResolver - Simple interface used by Pass objects to pull all
/// analysis information out of pass manager that is responsible to manage
/// the pass.
///
class AnalysisResolver {
public:
AnalysisResolver() = delete;
explicit AnalysisResolver(PMDataManager &P) : PM(P) {}
PMDataManager &getPMDataManager() { return PM; }
/// Find pass that is implementing PI.
Pass *findImplPass(AnalysisID PI) {
Pass *ResultPass = nullptr;
for (const auto &AnalysisImpl : AnalysisImpls) {
if (AnalysisImpl.first == PI) {
ResultPass = AnalysisImpl.second;
break;
}
}
return ResultPass;
}
/// Find pass that is implementing PI. Initialize pass for Function F.
std::tuple<Pass *, bool> findImplPass(Pass *P, AnalysisID PI, Function &F);
void addAnalysisImplsPair(AnalysisID PI, Pass *P) {
if (findImplPass(PI) == P)
return;
std::pair<AnalysisID, Pass*> pir = std::make_pair(PI,P);
AnalysisImpls.push_back(pir);
}
/// Clear cache that is used to connect a pass to the analysis (PassInfo).
void clearAnalysisImpls() {
AnalysisImpls.clear();
}
/// Return analysis result or null if it doesn't exist.
Pass *getAnalysisIfAvailable(AnalysisID ID) const;
private:
/// This keeps track of which passes implements the interfaces that are
/// required by the current pass (to implement getAnalysis()).
std::vector<std::pair<AnalysisID, Pass *>> AnalysisImpls;
/// PassManager that is used to resolve analysis info
PMDataManager &PM;
};
/// getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to
/// get analysis information that might be around, for example to update it.
/// This is different than getAnalysis in that it can fail (if the analysis
/// results haven't been computed), so should only be used if you can handle
/// the case when the analysis is not available. This method is often used by
/// transformation APIs to update analysis results for a pass automatically as
/// the transform is performed.
template<typename AnalysisType>
AnalysisType *Pass::getAnalysisIfAvailable() const {
assert(Resolver && "Pass not resident in a PassManager object!");
const void *PI = &AnalysisType::ID;
Pass *ResultPass = Resolver->getAnalysisIfAvailable(PI);
if (!ResultPass) return nullptr;
// Because the AnalysisType may not be a subclass of pass (for
// AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
// adjust the return pointer (because the class may multiply inherit, once
// from pass, once from AnalysisType).
return (AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
}
/// getAnalysis<AnalysisType>() - This function is used by subclasses to get
/// to the analysis information that they claim to use by overriding the
/// getAnalysisUsage function.
template<typename AnalysisType>
AnalysisType &Pass::getAnalysis() const {
assert(Resolver && "Pass has not been inserted into a PassManager object!");
return getAnalysisID<AnalysisType>(&AnalysisType::ID);
}
template<typename AnalysisType>
AnalysisType &Pass::getAnalysisID(AnalysisID PI) const {
assert(PI && "getAnalysis for unregistered pass!");
assert(Resolver&&"Pass has not been inserted into a PassManager object!");
// PI *must* appear in AnalysisImpls. Because the number of passes used
// should be a small number, we just do a linear search over a (dense)
// vector.
Pass *ResultPass = Resolver->findImplPass(PI);
assert(ResultPass &&
"getAnalysis*() called on an analysis that was not "
"'required' by pass!");
// Because the AnalysisType may not be a subclass of pass (for
// AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
// adjust the return pointer (because the class may multiply inherit, once
// from pass, once from AnalysisType).
return *(AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
}
/// getAnalysis<AnalysisType>() - This function is used by subclasses to get
/// to the analysis information that they claim to use by overriding the
/// getAnalysisUsage function. If as part of the dependencies, an IR
/// transformation is triggered (e.g. because the analysis requires
/// BreakCriticalEdges), and Changed is non null, *Changed is updated.
template <typename AnalysisType>
AnalysisType &Pass::getAnalysis(Function &F, bool *Changed) {
assert(Resolver &&"Pass has not been inserted into a PassManager object!");
return getAnalysisID<AnalysisType>(&AnalysisType::ID, F, Changed);
}
template <typename AnalysisType>
AnalysisType &Pass::getAnalysisID(AnalysisID PI, Function &F, bool *Changed) {
assert(PI && "getAnalysis for unregistered pass!");
assert(Resolver && "Pass has not been inserted into a PassManager object!");
// PI *must* appear in AnalysisImpls. Because the number of passes used
// should be a small number, we just do a linear search over a (dense)
// vector.
Pass *ResultPass;
bool LocalChanged;
std::tie(ResultPass, LocalChanged) = Resolver->findImplPass(this, PI, F);
assert(ResultPass && "Unable to find requested analysis info");
if (Changed)
*Changed |= LocalChanged;
else
assert(!LocalChanged &&
"A pass trigged a code update but the update status is lost");
// Because the AnalysisType may not be a subclass of pass (for
// AnalysisGroups), we use getAdjustedAnalysisPointer here to potentially
// adjust the return pointer (because the class may multiply inherit, once
// from pass, once from AnalysisType).
return *(AnalysisType*)ResultPass->getAdjustedAnalysisPointer(PI);
}
} // end namespace llvm
#endif // LLVM_PASSANALYSISSUPPORT_H