//===- llvm/Pass.h - Base class for Passes ----------------------*- 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 a base class that indicates that a specified class is a
// transformation pass implementation.
//
// Passes are designed this way so that it is possible to run passes in a cache
// and organizationally optimal order without having to specify it at the front
// end. This allows arbitrary passes to be strung together and have them
// executed as efficiently as possible.
//
// Passes should extend one of the classes below, depending on the guarantees
// that it can make about what will be modified as it is run. For example, most
// global optimizations should derive from FunctionPass, because they do not add
// or delete functions, they operate on the internals of the function.
//
// Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the
// bottom), so the APIs exposed by these files are also automatically available
// to all users of this file.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_PASS_H
#define LLVM_PASS_H
#include <string>
namespace llvm {
class AnalysisResolver;
class AnalysisUsage;
class Function;
class ImmutablePass;
class Module;
class PassInfo;
class PMDataManager;
class PMStack;
class raw_ostream;
class StringRef;
// AnalysisID - Use the PassInfo to identify a pass...
using AnalysisID = const void *;
/// Different types of internal pass managers. External pass managers
/// (PassManager and FunctionPassManager) are not represented here.
/// Ordering of pass manager types is important here.
enum PassManagerType {
PMT_Unknown = 0,
PMT_ModulePassManager = 1, ///< MPPassManager
PMT_CallGraphPassManager, ///< CGPassManager
PMT_FunctionPassManager, ///< FPPassManager
PMT_LoopPassManager, ///< LPPassManager
PMT_RegionPassManager, ///< RGPassManager
PMT_Last
};
// Different types of passes.
enum PassKind {
PT_Region,
PT_Loop,
PT_Function,
PT_CallGraphSCC,
PT_Module,
PT_PassManager
};
/// This enumerates the LLVM full LTO or ThinLTO optimization phases.
enum class ThinOrFullLTOPhase {
/// No LTO/ThinLTO behavior needed.
None,
/// ThinLTO prelink (summary) phase.
ThinLTOPreLink,
/// ThinLTO postlink (backend compile) phase.
ThinLTOPostLink,
/// Full LTO prelink phase.
FullLTOPreLink,
/// Full LTO postlink (backend compile) phase.
FullLTOPostLink
};
//===----------------------------------------------------------------------===//
/// Pass interface - Implemented by all 'passes'. Subclass this if you are an
/// interprocedural optimization or you do not fit into any of the more
/// constrained passes described below.
///
class Pass {
AnalysisResolver *Resolver = nullptr; // Used to resolve analysis
const void *PassID;
PassKind Kind;
public:
explicit Pass(PassKind K, char &pid) : PassID(&pid), Kind(K) {}
Pass(const Pass &) = delete;
Pass &operator=(const Pass &) = delete;
virtual ~Pass();
PassKind getPassKind() const { return Kind; }
/// getPassName - Return a nice clean name for a pass. This usually
/// implemented in terms of the name that is registered by one of the
/// Registration templates, but can be overloaded directly.
virtual StringRef getPassName() const;
/// getPassID - Return the PassID number that corresponds to this pass.
AnalysisID getPassID() const {
return PassID;
}
/// doInitialization - Virtual method overridden by subclasses to do
/// any necessary initialization before any pass is run.
virtual bool doInitialization(Module &) { return false; }
/// doFinalization - Virtual method overriden by subclasses to do any
/// necessary clean up after all passes have run.
virtual bool doFinalization(Module &) { return false; }
/// print - Print out the internal state of the pass. This is called by
/// Analyze to print out the contents of an analysis. Otherwise it is not
/// necessary to implement this method. Beware that the module pointer MAY be
/// null. This automatically forwards to a virtual function that does not
/// provide the Module* in case the analysis doesn't need it it can just be
/// ignored.
virtual void print(raw_ostream &OS, const Module *M) const;
void dump() const; // dump - Print to stderr.
/// createPrinterPass - Get a Pass appropriate to print the IR this
/// pass operates on (Module, Function or MachineFunction).
virtual Pass *createPrinterPass(raw_ostream &OS,
const std::string &Banner) const = 0;
/// Each pass is responsible for assigning a pass manager to itself.
/// PMS is the stack of available pass manager.
virtual void assignPassManager(PMStack &,
PassManagerType) {}
/// Check if available pass managers are suitable for this pass or not.
virtual void preparePassManager(PMStack &);
/// Return what kind of Pass Manager can manage this pass.
virtual PassManagerType getPotentialPassManagerType() const;
// Access AnalysisResolver
void setResolver(AnalysisResolver *AR);
AnalysisResolver *getResolver() const { return Resolver; }
/// getAnalysisUsage - This function should be overriden by passes that need
/// analysis information to do their job. If a pass specifies that it uses a
/// particular analysis result to this function, it can then use the
/// getAnalysis<AnalysisType>() function, below.
virtual void getAnalysisUsage(AnalysisUsage &) const;
/// releaseMemory() - This member can be implemented by a pass if it wants to
/// be able to release its memory when it is no longer needed. The default
/// behavior of passes is to hold onto memory for the entire duration of their
/// lifetime (which is the entire compile time). For pipelined passes, this
/// is not a big deal because that memory gets recycled every time the pass is
/// invoked on another program unit. For IP passes, it is more important to
/// free memory when it is unused.
///
/// Optionally implement this function to release pass memory when it is no
/// longer used.
virtual void releaseMemory();
/// getAdjustedAnalysisPointer - This method is used when a pass implements
/// an analysis interface through multiple inheritance. If needed, it should
/// override this to adjust the this pointer as needed for the specified pass
/// info.
virtual void *getAdjustedAnalysisPointer(AnalysisID ID);
virtual ImmutablePass *getAsImmutablePass();
virtual PMDataManager *getAsPMDataManager();
/// verifyAnalysis() - This member can be implemented by a analysis pass to
/// check state of analysis information.
virtual void verifyAnalysis() const;
// dumpPassStructure - Implement the -debug-passes=PassStructure option
virtual void dumpPassStructure(unsigned Offset = 0);
// lookupPassInfo - Return the pass info object for the specified pass class,
// or null if it is not known.
static const PassInfo *lookupPassInfo(const void *TI);
// lookupPassInfo - Return the pass info object for the pass with the given
// argument string, or null if it is not known.
static const PassInfo *lookupPassInfo(StringRef Arg);
// createPass - Create a object for the specified pass class,
// or null if it is not known.
static Pass *createPass(AnalysisID ID);
/// 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 *
getAnalysisIfAvailable() const; // Defined in PassAnalysisSupport.h
/// mustPreserveAnalysisID - This method serves the same function as
/// getAnalysisIfAvailable, but works if you just have an AnalysisID. This
/// obviously cannot give you a properly typed instance of the class if you
/// don't have the class name available (use getAnalysisIfAvailable if you
/// do), but it can tell you if you need to preserve the pass at least.
bool mustPreserveAnalysisID(char &AID) const;
/// 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 &getAnalysis() const; // Defined in PassAnalysisSupport.h
template <typename AnalysisType>
AnalysisType &
getAnalysis(Function &F,
bool *Changed = nullptr); // Defined in PassAnalysisSupport.h
template<typename AnalysisType>
AnalysisType &getAnalysisID(AnalysisID PI) const;
template <typename AnalysisType>
AnalysisType &getAnalysisID(AnalysisID PI, Function &F,
bool *Changed = nullptr);
#ifdef EXPENSIVE_CHECKS
/// Hash a module in order to detect when a module (or more specific) pass has
/// modified it.
uint64_t structuralHash(Module &M) const;
/// Hash a function in order to detect when a function (or more specific) pass
/// has modified it.
virtual uint64_t structuralHash(Function &F) const;
#endif
};
//===----------------------------------------------------------------------===//
/// ModulePass class - This class is used to implement unstructured
/// interprocedural optimizations and analyses. ModulePasses may do anything
/// they want to the program.
///
class ModulePass : public Pass {
public:
explicit ModulePass(char &pid) : Pass(PT_Module, pid) {}
// Force out-of-line virtual method.
~ModulePass() override;
/// createPrinterPass - Get a module printer pass.
Pass *createPrinterPass(raw_ostream &OS,
const std::string &Banner) const override;
/// runOnModule - Virtual method overriden by subclasses to process the module
/// being operated on.
virtual bool runOnModule(Module &M) = 0;
void assignPassManager(PMStack &PMS, PassManagerType T) override;
/// Return what kind of Pass Manager can manage this pass.
PassManagerType getPotentialPassManagerType() const override;
protected:
/// Optional passes call this function to check whether the pass should be
/// skipped. This is the case when optimization bisect is over the limit.
bool skipModule(Module &M) const;
};
//===----------------------------------------------------------------------===//
/// ImmutablePass class - This class is used to provide information that does
/// not need to be run. This is useful for things like target information and
/// "basic" versions of AnalysisGroups.
///
class ImmutablePass : public ModulePass {
public:
explicit ImmutablePass(char &pid) : ModulePass(pid) {}
// Force out-of-line virtual method.
~ImmutablePass() override;
/// initializePass - This method may be overriden by immutable passes to allow
/// them to perform various initialization actions they require. This is
/// primarily because an ImmutablePass can "require" another ImmutablePass,
/// and if it does, the overloaded version of initializePass may get access to
/// these passes with getAnalysis<>.
virtual void initializePass();
ImmutablePass *getAsImmutablePass() override { return this; }
/// ImmutablePasses are never run.
bool runOnModule(Module &) override { return false; }
};
//===----------------------------------------------------------------------===//
/// FunctionPass class - This class is used to implement most global
/// optimizations. Optimizations should subclass this class if they meet the
/// following constraints:
///
/// 1. Optimizations are organized globally, i.e., a function at a time
/// 2. Optimizing a function does not cause the addition or removal of any
/// functions in the module
///
class FunctionPass : public Pass {
public:
explicit FunctionPass(char &pid) : Pass(PT_Function, pid) {}
/// createPrinterPass - Get a function printer pass.
Pass *createPrinterPass(raw_ostream &OS,
const std::string &Banner) const override;
/// runOnFunction - Virtual method overriden by subclasses to do the
/// per-function processing of the pass.
virtual bool runOnFunction(Function &F) = 0;
void assignPassManager(PMStack &PMS, PassManagerType T) override;
/// Return what kind of Pass Manager can manage this pass.
PassManagerType getPotentialPassManagerType() const override;
protected:
/// Optional passes call this function to check whether the pass should be
/// skipped. This is the case when Attribute::OptimizeNone is set or when
/// optimization bisect is over the limit.
bool skipFunction(const Function &F) const;
};
/// If the user specifies the -time-passes argument on an LLVM tool command line
/// then the value of this boolean will be true, otherwise false.
/// This is the storage for the -time-passes option.
extern bool TimePassesIsEnabled;
/// If TimePassesPerRun is true, there would be one line of report for
/// each pass invocation.
/// If TimePassesPerRun is false, there would be only one line of
/// report for each pass (even there are more than one pass objects).
/// (For new pass manager only)
extern bool TimePassesPerRun;
} // end namespace llvm
// Include support files that contain important APIs commonly used by Passes,
// but that we want to separate out to make it easier to read the header files.
#include "llvm/PassAnalysisSupport.h"
#include "llvm/PassSupport.h"
#endif // LLVM_PASS_H