llvm-6502/include/llvm/IR/LegacyPassManagers.h
Chandler Carruth 69774fa1c4 [LPM] A targeted but somewhat horrible fix to the legacy pass manager's
querying of the pass registry.

The pass manager relies on the static registry of PassInfo objects to
perform all manner of its functionality. I don't understand why it does
much of this. My very vague understanding is that this registry is
touched both during static initialization *and* while each pass is being
constructed. As a consequence it is hard to make accessing it not
require a acquiring some lock. This lock ends up in the hot path of
setting up, tearing down, and invaliditing analyses in the legacy pass
manager.

On most systems you can observe this as a non-trivial % of the time
spent in 'ninja check-llvm'. However, I haven't really seen it be more
than 1% in extreme cases of compiling more real-world software,
including LTO.

Unfortunately, some of the GPU JITs are seeing this taking essentially
all of their time because they have very small IR running through
a small pass pipeline very many times (at least, this is the vague
understanding I have of it).

This patch tries to minimize the cost of looking up PassInfo objects by
leveraging the fact that the objects themselves are immutable and they
are allocated separately on the heap and so don't have their address
change. It also requires a change I made the last time I tried to debug
this problem which removed the ability to de-register a pass from the
registry. This patch creates a single access path to these objects
inside the PMTopLevelManager which memoizes the result of querying the
registry. This is somewhat gross as I don't really know if
PMTopLevelManager is the *right* place to put it, and I dislike using
a mutable member to memoize things, but it seems to work.

For long-lived pass managers this should completely eliminate
the cost of acquiring locks to look into the pass registry once the
memoized cache is warm. For 'ninja check' I measured about 1.5%
reduction in CPU time and in total time on a machine with 32 hardware
threads. For normal compilation, I don't know how much this will help,
sadly. We will still pay the cost while we populate the memoized cache.
I don't think it will hurt though, and for LTO or compiles with many
small functions it should still be a win. However, for tight loops
around a pass manager with many passes and small modules, this will help
tremendously. On the AArch64 backend I saw nearly 50% reductions in time
to complete 2000 cycles of spinning up and tearing down the pipeline.
Measurements from Owen of an actual long-lived pass manager show more
along the lines of 10% improvements.

Differential Revision: http://reviews.llvm.org/D7213

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227299 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-28 09:47:21 +00:00

480 lines
16 KiB
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//===- LegacyPassManagers.h - Legacy Pass Infrastructure --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the LLVM Pass Manager infrastructure.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_LEGACYPASSMANAGERS_H
#define LLVM_IR_LEGACYPASSMANAGERS_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Pass.h"
#include <map>
#include <vector>
//===----------------------------------------------------------------------===//
// Overview:
// The Pass Manager Infrastructure manages passes. It's responsibilities are:
//
// o Manage optimization pass execution order
// o Make required Analysis information available before pass P is run
// o Release memory occupied by dead passes
// o If Analysis information is dirtied by a pass then regenerate Analysis
// information before it is consumed by another pass.
//
// Pass Manager Infrastructure uses multiple pass managers. They are
// PassManager, FunctionPassManager, MPPassManager, FPPassManager, BBPassManager.
// This class hierarchy uses multiple inheritance but pass managers do not
// derive from another pass manager.
//
// PassManager and FunctionPassManager are two top-level pass manager that
// represents the external interface of this entire pass manager infrastucture.
//
// Important classes :
//
// [o] class PMTopLevelManager;
//
// Two top level managers, PassManager and FunctionPassManager, derive from
// PMTopLevelManager. PMTopLevelManager manages information used by top level
// managers such as last user info.
//
// [o] class PMDataManager;
//
// PMDataManager manages information, e.g. list of available analysis info,
// used by a pass manager to manage execution order of passes. It also provides
// a place to implement common pass manager APIs. All pass managers derive from
// PMDataManager.
//
// [o] class BBPassManager : public FunctionPass, public PMDataManager;
//
// BBPassManager manages BasicBlockPasses.
//
// [o] class FunctionPassManager;
//
// This is a external interface used to manage FunctionPasses. This
// interface relies on FunctionPassManagerImpl to do all the tasks.
//
// [o] class FunctionPassManagerImpl : public ModulePass, PMDataManager,
// public PMTopLevelManager;
//
// FunctionPassManagerImpl is a top level manager. It manages FPPassManagers
//
// [o] class FPPassManager : public ModulePass, public PMDataManager;
//
// FPPassManager manages FunctionPasses and BBPassManagers
//
// [o] class MPPassManager : public Pass, public PMDataManager;
//
// MPPassManager manages ModulePasses and FPPassManagers
//
// [o] class PassManager;
//
// This is a external interface used by various tools to manages passes. It
// relies on PassManagerImpl to do all the tasks.
//
// [o] class PassManagerImpl : public Pass, public PMDataManager,
// public PMTopLevelManager
//
// PassManagerImpl is a top level pass manager responsible for managing
// MPPassManagers.
//===----------------------------------------------------------------------===//
#include "llvm/Support/PrettyStackTrace.h"
namespace llvm {
class Module;
class Pass;
class StringRef;
class Value;
class Timer;
class PMDataManager;
// enums for debugging strings
enum PassDebuggingString {
EXECUTION_MSG, // "Executing Pass '" + PassName
MODIFICATION_MSG, // "Made Modification '" + PassName
FREEING_MSG, // " Freeing Pass '" + PassName
ON_BASICBLOCK_MSG, // "' on BasicBlock '" + InstructionName + "'...\n"
ON_FUNCTION_MSG, // "' on Function '" + FunctionName + "'...\n"
ON_MODULE_MSG, // "' on Module '" + ModuleName + "'...\n"
ON_REGION_MSG, // "' on Region '" + Msg + "'...\n'"
ON_LOOP_MSG, // "' on Loop '" + Msg + "'...\n'"
ON_CG_MSG // "' on Call Graph Nodes '" + Msg + "'...\n'"
};
/// PassManagerPrettyStackEntry - This is used to print informative information
/// about what pass is running when/if a stack trace is generated.
class PassManagerPrettyStackEntry : public PrettyStackTraceEntry {
Pass *P;
Value *V;
Module *M;
public:
explicit PassManagerPrettyStackEntry(Pass *p)
: P(p), V(nullptr), M(nullptr) {} // When P is releaseMemory'd.
PassManagerPrettyStackEntry(Pass *p, Value &v)
: P(p), V(&v), M(nullptr) {} // When P is run on V
PassManagerPrettyStackEntry(Pass *p, Module &m)
: P(p), V(nullptr), M(&m) {} // When P is run on M
/// print - Emit information about this stack frame to OS.
void print(raw_ostream &OS) const override;
};
//===----------------------------------------------------------------------===//
// PMStack
//
/// PMStack - This class implements a stack data structure of PMDataManager
/// pointers.
///
/// Top level pass managers (see PassManager.cpp) maintain active Pass Managers
/// using PMStack. Each Pass implements assignPassManager() to connect itself
/// with appropriate manager. assignPassManager() walks PMStack to find
/// suitable manager.
class PMStack {
public:
typedef std::vector<PMDataManager *>::const_reverse_iterator iterator;
iterator begin() const { return S.rbegin(); }
iterator end() const { return S.rend(); }
void pop();
PMDataManager *top() const { return S.back(); }
void push(PMDataManager *PM);
bool empty() const { return S.empty(); }
void dump() const;
private:
std::vector<PMDataManager *> S;
};
//===----------------------------------------------------------------------===//
// PMTopLevelManager
//
/// PMTopLevelManager manages LastUser info and collects common APIs used by
/// top level pass managers.
class PMTopLevelManager {
protected:
explicit PMTopLevelManager(PMDataManager *PMDM);
unsigned getNumContainedManagers() const {
return (unsigned)PassManagers.size();
}
void initializeAllAnalysisInfo();
private:
virtual PMDataManager *getAsPMDataManager() = 0;
virtual PassManagerType getTopLevelPassManagerType() = 0;
public:
/// Schedule pass P for execution. Make sure that passes required by
/// P are run before P is run. Update analysis info maintained by
/// the manager. Remove dead passes. This is a recursive function.
void schedulePass(Pass *P);
/// Set pass P as the last user of the given analysis passes.
void setLastUser(ArrayRef<Pass*> AnalysisPasses, Pass *P);
/// Collect passes whose last user is P
void collectLastUses(SmallVectorImpl<Pass *> &LastUses, Pass *P);
/// Find the pass that implements Analysis AID. Search immutable
/// passes and all pass managers. If desired pass is not found
/// then return NULL.
Pass *findAnalysisPass(AnalysisID AID);
/// Retrieve the PassInfo for an analysis.
const PassInfo *findAnalysisPassInfo(AnalysisID AID) const;
/// Find analysis usage information for the pass P.
AnalysisUsage *findAnalysisUsage(Pass *P);
virtual ~PMTopLevelManager();
/// Add immutable pass and initialize it.
inline void addImmutablePass(ImmutablePass *P) {
P->initializePass();
ImmutablePasses.push_back(P);
}
inline SmallVectorImpl<ImmutablePass *>& getImmutablePasses() {
return ImmutablePasses;
}
void addPassManager(PMDataManager *Manager) {
PassManagers.push_back(Manager);
}
// Add Manager into the list of managers that are not directly
// maintained by this top level pass manager
inline void addIndirectPassManager(PMDataManager *Manager) {
IndirectPassManagers.push_back(Manager);
}
// Print passes managed by this top level manager.
void dumpPasses() const;
void dumpArguments() const;
// Active Pass Managers
PMStack activeStack;
protected:
/// Collection of pass managers
SmallVector<PMDataManager *, 8> PassManagers;
private:
/// Collection of pass managers that are not directly maintained
/// by this pass manager
SmallVector<PMDataManager *, 8> IndirectPassManagers;
// Map to keep track of last user of the analysis pass.
// LastUser->second is the last user of Lastuser->first.
DenseMap<Pass *, Pass *> LastUser;
// Map to keep track of passes that are last used by a pass.
// This inverse map is initialized at PM->run() based on
// LastUser map.
DenseMap<Pass *, SmallPtrSet<Pass *, 8> > InversedLastUser;
/// Immutable passes are managed by top level manager.
SmallVector<ImmutablePass *, 16> ImmutablePasses;
DenseMap<Pass *, AnalysisUsage *> AnUsageMap;
/// Collection of PassInfo objects found via analysis IDs and in this top
/// level manager. This is used to memoize queries to the pass registry.
/// FIXME: This is an egregious hack because querying the pass registry is
/// either slow or racy.
mutable DenseMap<AnalysisID, const PassInfo *> AnalysisPassInfos;
};
//===----------------------------------------------------------------------===//
// PMDataManager
/// PMDataManager provides the common place to manage the analysis data
/// used by pass managers.
class PMDataManager {
public:
explicit PMDataManager() : TPM(nullptr), Depth(0) {
initializeAnalysisInfo();
}
virtual ~PMDataManager();
virtual Pass *getAsPass() = 0;
/// Augment AvailableAnalysis by adding analysis made available by pass P.
void recordAvailableAnalysis(Pass *P);
/// verifyPreservedAnalysis -- Verify analysis presreved by pass P.
void verifyPreservedAnalysis(Pass *P);
/// Remove Analysis that is not preserved by the pass
void removeNotPreservedAnalysis(Pass *P);
/// Remove dead passes used by P.
void removeDeadPasses(Pass *P, StringRef Msg,
enum PassDebuggingString);
/// Remove P.
void freePass(Pass *P, StringRef Msg,
enum PassDebuggingString);
/// Add pass P into the PassVector. Update
/// AvailableAnalysis appropriately if ProcessAnalysis is true.
void add(Pass *P, bool ProcessAnalysis = true);
/// Add RequiredPass into list of lower level passes required by pass P.
/// RequiredPass is run on the fly by Pass Manager when P requests it
/// through getAnalysis interface.
virtual void addLowerLevelRequiredPass(Pass *P, Pass *RequiredPass);
virtual Pass *getOnTheFlyPass(Pass *P, AnalysisID PI, Function &F);
/// Initialize available analysis information.
void initializeAnalysisInfo() {
AvailableAnalysis.clear();
for (unsigned i = 0; i < PMT_Last; ++i)
InheritedAnalysis[i] = nullptr;
}
// Return true if P preserves high level analysis used by other
// passes that are managed by this manager.
bool preserveHigherLevelAnalysis(Pass *P);
/// Populate RequiredPasses with analysis pass that are required by
/// pass P and are available. Populate ReqPassNotAvailable with analysis
/// pass that are required by pass P but are not available.
void collectRequiredAnalysis(SmallVectorImpl<Pass *> &RequiredPasses,
SmallVectorImpl<AnalysisID> &ReqPassNotAvailable,
Pass *P);
/// All Required analyses should be available to the pass as it runs! Here
/// we fill in the AnalysisImpls member of the pass so that it can
/// successfully use the getAnalysis() method to retrieve the
/// implementations it needs.
void initializeAnalysisImpl(Pass *P);
/// Find the pass that implements Analysis AID. If desired pass is not found
/// then return NULL.
Pass *findAnalysisPass(AnalysisID AID, bool Direction);
// Access toplevel manager
PMTopLevelManager *getTopLevelManager() { return TPM; }
void setTopLevelManager(PMTopLevelManager *T) { TPM = T; }
unsigned getDepth() const { return Depth; }
void setDepth(unsigned newDepth) { Depth = newDepth; }
// Print routines used by debug-pass
void dumpLastUses(Pass *P, unsigned Offset) const;
void dumpPassArguments() const;
void dumpPassInfo(Pass *P, enum PassDebuggingString S1,
enum PassDebuggingString S2, StringRef Msg);
void dumpRequiredSet(const Pass *P) const;
void dumpPreservedSet(const Pass *P) const;
unsigned getNumContainedPasses() const {
return (unsigned)PassVector.size();
}
virtual PassManagerType getPassManagerType() const {
assert ( 0 && "Invalid use of getPassManagerType");
return PMT_Unknown;
}
DenseMap<AnalysisID, Pass*> *getAvailableAnalysis() {
return &AvailableAnalysis;
}
// Collect AvailableAnalysis from all the active Pass Managers.
void populateInheritedAnalysis(PMStack &PMS) {
unsigned Index = 0;
for (PMStack::iterator I = PMS.begin(), E = PMS.end();
I != E; ++I)
InheritedAnalysis[Index++] = (*I)->getAvailableAnalysis();
}
protected:
// Top level manager.
PMTopLevelManager *TPM;
// Collection of pass that are managed by this manager
SmallVector<Pass *, 16> PassVector;
// Collection of Analysis provided by Parent pass manager and
// used by current pass manager. At at time there can not be more
// then PMT_Last active pass mangers.
DenseMap<AnalysisID, Pass *> *InheritedAnalysis[PMT_Last];
/// isPassDebuggingExecutionsOrMore - Return true if -debug-pass=Executions
/// or higher is specified.
bool isPassDebuggingExecutionsOrMore() const;
private:
void dumpAnalysisUsage(StringRef Msg, const Pass *P,
const AnalysisUsage::VectorType &Set) const;
// Set of available Analysis. This information is used while scheduling
// pass. If a pass requires an analysis which is not available then
// the required analysis pass is scheduled to run before the pass itself is
// scheduled to run.
DenseMap<AnalysisID, Pass*> AvailableAnalysis;
// Collection of higher level analysis used by the pass managed by
// this manager.
SmallVector<Pass *, 16> HigherLevelAnalysis;
unsigned Depth;
};
//===----------------------------------------------------------------------===//
// FPPassManager
//
/// FPPassManager manages BBPassManagers and FunctionPasses.
/// It batches all function passes and basic block pass managers together and
/// sequence them to process one function at a time before processing next
/// function.
class FPPassManager : public ModulePass, public PMDataManager {
public:
static char ID;
explicit FPPassManager()
: ModulePass(ID), PMDataManager() { }
/// run - Execute all of the passes scheduled for execution. Keep track of
/// whether any of the passes modifies the module, and if so, return true.
bool runOnFunction(Function &F);
bool runOnModule(Module &M) override;
/// cleanup - After running all passes, clean up pass manager cache.
void cleanup();
/// doInitialization - Overrides ModulePass doInitialization for global
/// initialization tasks
///
using ModulePass::doInitialization;
/// doInitialization - Run all of the initializers for the function passes.
///
bool doInitialization(Module &M) override;
/// doFinalization - Overrides ModulePass doFinalization for global
/// finalization tasks
///
using ModulePass::doFinalization;
/// doFinalization - Run all of the finalizers for the function passes.
///
bool doFinalization(Module &M) override;
PMDataManager *getAsPMDataManager() override { return this; }
Pass *getAsPass() override { return this; }
/// Pass Manager itself does not invalidate any analysis info.
void getAnalysisUsage(AnalysisUsage &Info) const override {
Info.setPreservesAll();
}
// Print passes managed by this manager
void dumpPassStructure(unsigned Offset) override;
const char *getPassName() const override {
return "Function Pass Manager";
}
FunctionPass *getContainedPass(unsigned N) {
assert ( N < PassVector.size() && "Pass number out of range!");
FunctionPass *FP = static_cast<FunctionPass *>(PassVector[N]);
return FP;
}
PassManagerType getPassManagerType() const override {
return PMT_FunctionPassManager;
}
};
Timer *getPassTimer(Pass *);
}
#endif