llvm-6502/include/llvm/Pass.h
Chris Lattner 4445519fab Add support for passes to announce that they only depend on the CFG of a
function.  This is crude but effective


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2505 91177308-0d34-0410-b5e6-96231b3b80d8
2002-05-06 19:31:16 +00:00

330 lines
12 KiB
C++

//===- llvm/Pass.h - Base class for XForm Passes -----------------*- C++ -*--=//
//
// This file defines a base class that indicates that a specified class is a
// transformation pass implementation.
//
// Pass's 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 effeciently 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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_PASS_H
#define LLVM_PASS_H
#include <vector>
#include <map>
class Value;
class BasicBlock;
class Function;
class Module;
class AnalysisUsage;
class AnalysisID;
template<class UnitType> class PassManagerT;
struct AnalysisResolver;
//===----------------------------------------------------------------------===//
// 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 {
friend class AnalysisResolver;
AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
public:
inline Pass(AnalysisResolver *AR = 0) : Resolver(AR) {}
inline virtual ~Pass() {} // Destructor is virtual so we can be subclassed
// getPassName - Return a nice clean name for a pass. This should be
// overloaded by the pass, but if it is not, C++ RTTI will be consulted to get
// a SOMEWHAT intelligable name for the pass.
//
virtual const char *getPassName() const;
// run - Run this pass, returning true if a modification was made to the
// module argument. This should be implemented by all concrete subclasses.
//
virtual bool run(Module *M) = 0;
// 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 &Info) const {
// By default, no analysis results are used, all are invalidated.
}
// 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() {}
// dumpPassStructure - Implement the -debug-passes=PassStructure option
virtual void dumpPassStructure(unsigned Offset = 0);
protected:
// 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(AnalysisID AID = AnalysisType::ID) {
assert(Resolver && "Pass not resident in a PassManager object!");
return *(AnalysisType*)Resolver->getAnalysis(AID);
}
// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
// to get to the analysis information that might be around that needs to be
// updated. This is different than getAnalysis in that it can fail (ie the
// analysis results haven't been computed), so should only be used if you
// provide the capability to update an analysis that exists.
//
template<typename AnalysisType>
AnalysisType *getAnalysisToUpdate(AnalysisID AID = AnalysisType::ID) {
assert(Resolver && "Pass not resident in a PassManager object!");
return (AnalysisType*)Resolver->getAnalysisToUpdate(AID);
}
private:
friend class PassManagerT<Module>;
friend class PassManagerT<Function>;
friend class PassManagerT<BasicBlock>;
virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
};
//===----------------------------------------------------------------------===//
// 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, ie a function at a time
// 2. Optimizing a function does not cause the addition or removal of any
// functions in the module
//
struct FunctionPass : public Pass {
// doInitialization - Virtual method overridden by subclasses to do
// any neccesary per-module initialization.
//
virtual bool doInitialization(Module *M) { return false; }
// runOnFunction - Virtual method overriden by subclasses to do the
// per-function processing of the pass.
//
virtual bool runOnFunction(Function *F) = 0;
// doFinalization - Virtual method overriden by subclasses to do any post
// processing needed after all passes have run.
//
virtual bool doFinalization(Module *M) { return false; }
// run - On a module, we run this pass by initializing, ronOnFunction'ing once
// for every function in the module, then by finalizing.
//
virtual bool run(Module *M);
// run - On a function, we simply initialize, run the function, then finalize.
//
bool run(Function *F);
private:
friend class PassManagerT<Module>;
friend class PassManagerT<Function>;
friend class PassManagerT<BasicBlock>;
virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
};
//===----------------------------------------------------------------------===//
// BasicBlockPass class - This class is used to implement most local
// optimizations. Optimizations should subclass this class if they
// meet the following constraints:
// 1. Optimizations are local, operating on either a basic block or
// instruction at a time.
// 2. Optimizations do not modify the CFG of the contained function, or any
// other basic block in the function.
// 3. Optimizations conform to all of the contstraints of FunctionPass's.
//
struct BasicBlockPass : public FunctionPass {
// runOnBasicBlock - Virtual method overriden by subclasses to do the
// per-basicblock processing of the pass.
//
virtual bool runOnBasicBlock(BasicBlock *M) = 0;
// To run this pass on a function, we simply call runOnBasicBlock once for
// each function.
//
virtual bool runOnFunction(Function *F);
// To run directly on the basic block, we initialize, runOnBasicBlock, then
// finalize.
//
bool run(BasicBlock *BB);
private:
friend class PassManagerT<Function>;
friend class PassManagerT<BasicBlock>;
virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU);
};
// CreatePass - Helper template to invoke the constructor for the AnalysisID
// class. Note that this should be a template internal to AnalysisID, but
// GCC 2.95.3 crashes if we do that, doh.
//
template<class AnalysisType>
static Pass *CreatePass(AnalysisID ID) { return new AnalysisType(ID); }
//===----------------------------------------------------------------------===//
// AnalysisID - This class is used to uniquely identify an analysis pass that
// is referenced by a transformation.
//
class AnalysisID {
static unsigned NextID; // Next ID # to deal out...
unsigned ID; // Unique ID for this analysis
Pass *(*Constructor)(AnalysisID); // Constructor to return the Analysis
AnalysisID(); // Disable default ctor
AnalysisID(unsigned id, Pass *(*Ct)(AnalysisID)) : ID(id), Constructor(Ct) {}
public:
// create - the only way to define a new AnalysisID. This static method is
// supposed to be used to define the class static AnalysisID's that are
// provided by analysis passes. In the implementation (.cpp) file for the
// class, there should be a line that looks like this (using CallGraph as an
// example):
//
// AnalysisID CallGraph::ID(AnalysisID::create<CallGraph>());
//
template<class AnalysisType>
static AnalysisID create() {
return AnalysisID(NextID++, CreatePass<AnalysisType>);
}
// Special Copy Constructor - This is how analysis passes declare that they
// only depend on the CFG of the function they are working on, so they are not
// invalidated by other passes that do not modify the CFG. This should be
// used like this:
// AnalysisID DominatorSet::ID(AnalysisID::create<DominatorSet>(), true);
//
AnalysisID(const AnalysisID &AID, bool DependsOnlyOnCFG = false);
inline Pass *createPass() const { return Constructor(*this); }
inline bool operator==(const AnalysisID &A) const {
return A.ID == ID;
}
inline bool operator!=(const AnalysisID &A) const {
return A.ID != ID;
}
inline bool operator<(const AnalysisID &A) const {
return ID < A.ID;
}
};
//===----------------------------------------------------------------------===//
// AnalysisUsage - Represent the analysis usage information of a pass. This
// tracks analyses that the pass REQUIRES (must available when the pass runs),
// 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 {
// Sets of analyses required and preserved by a pass
std::vector<AnalysisID> Required, Preserved, Provided;
bool PreservesAll;
public:
AnalysisUsage() : PreservesAll(false) {}
// addRequires - Add the specified ID to the required set of the usage info
// for a pass.
//
AnalysisUsage &addRequired(AnalysisID ID) {
Required.push_back(ID);
return *this;
}
// addPreserves - Add the specified ID to the set of analyses preserved by
// this pass
//
AnalysisUsage &addPreserved(AnalysisID ID) {
Preserved.push_back(ID);
return *this;
}
void addProvided(AnalysisID ID) {
Provided.push_back(ID);
}
// PreservesAll - Set by analyses that do not transform their input at all
void setPreservesAll() { PreservesAll = true; }
bool preservesAll() const { return PreservesAll; }
// preservesCFG - This function should be called to 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 preservesCFG();
const std::vector<AnalysisID> &getRequiredSet() const { return Required; }
const std::vector<AnalysisID> &getPreservedSet() const { return Preserved; }
const std::vector<AnalysisID> &getProvidedSet() const { return Provided; }
};
//===----------------------------------------------------------------------===//
// AnalysisResolver - Simple interface implemented by PassManagers objects that
// is used to pull analysis information out of them.
//
struct AnalysisResolver {
virtual Pass *getAnalysisOrNullUp(AnalysisID ID) const = 0;
virtual Pass *getAnalysisOrNullDown(AnalysisID ID) const = 0;
Pass *getAnalysis(AnalysisID ID) {
Pass *Result = getAnalysisOrNullUp(ID);
assert(Result && "Pass has an incorrect analysis uses set!");
return Result;
}
// getAnalysisToUpdate - Return an analysis result or null if it doesn't exist
Pass *getAnalysisToUpdate(AnalysisID ID) {
Pass *Result = getAnalysisOrNullUp(ID);
return Result;
}
virtual unsigned getDepth() const = 0;
virtual void markPassUsed(AnalysisID P, Pass *User) = 0;
void startPass(Pass *P) {}
void endPass(Pass *P) {}
protected:
void setAnalysisResolver(Pass *P, AnalysisResolver *AR);
};
#endif