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//===-- Passes.h - Target independent code generation passes ----*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines interfaces to access the target independent code generation
// passes provided by the LLVM backend.
#include "llvm/Pass.h"
#include "llvm/Target/TargetMachine.h"
#include <functional>
#include <string>
namespace llvm {
class MachineFunctionPass;
class PassConfigImpl;
class PassInfo;
class ScheduleDAGInstrs;
class TargetLowering;
class TargetLoweringBase;
class TargetRegisterClass;
class raw_ostream;
struct MachineSchedContext;
// The old pass manager infrastructure is hidden in a legacy namespace now.
namespace legacy {
class PassManagerBase;
using legacy::PassManagerBase;
/// Discriminated union of Pass ID types.
/// The PassConfig API prefers dealing with IDs because they are safer and more
/// efficient. IDs decouple configuration from instantiation. This way, when a
/// pass is overriden, it isn't unnecessarily instantiated. It is also unsafe to
/// refer to a Pass pointer after adding it to a pass manager, which deletes
/// redundant pass instances.
/// However, it is convient to directly instantiate target passes with
/// non-default ctors. These often don't have a registered PassInfo. Rather than
/// force all target passes to implement the pass registry boilerplate, allow
/// the PassConfig API to handle either type.
/// AnalysisID is sadly char*, so PointerIntPair won't work.
class IdentifyingPassPtr {
union {
AnalysisID ID;
Pass *P;
bool IsInstance;
IdentifyingPassPtr() : P(nullptr), IsInstance(false) {}
IdentifyingPassPtr(AnalysisID IDPtr) : ID(IDPtr), IsInstance(false) {}
IdentifyingPassPtr(Pass *InstancePtr) : P(InstancePtr), IsInstance(true) {}
bool isValid() const { return P; }
bool isInstance() const { return IsInstance; }
AnalysisID getID() const {
assert(!IsInstance && "Not a Pass ID");
return ID;
Pass *getInstance() const {
assert(IsInstance && "Not a Pass Instance");
return P;
template <> struct isPodLike<IdentifyingPassPtr> {
static const bool value = true;
/// Target-Independent Code Generator Pass Configuration Options.
/// This is an ImmutablePass solely for the purpose of exposing CodeGen options
/// to the internals of other CodeGen passes.
class TargetPassConfig : public ImmutablePass {
/// Pseudo Pass IDs. These are defined within TargetPassConfig because they
/// are unregistered pass IDs. They are only useful for use with
/// TargetPassConfig APIs to identify multiple occurrences of the same pass.
/// EarlyTailDuplicate - A clone of the TailDuplicate pass that runs early
/// during codegen, on SSA form.
static char EarlyTailDuplicateID;
/// PostRAMachineLICM - A clone of the LICM pass that runs during late machine
/// optimization after regalloc.
static char PostRAMachineLICMID;
PassManagerBase *PM;
AnalysisID StartBefore, StartAfter;
AnalysisID StopAfter;
bool Started;
bool Stopped;
bool AddingMachinePasses;
TargetMachine *TM;
PassConfigImpl *Impl; // Internal data structures
bool Initialized; // Flagged after all passes are configured.
// Target Pass Options
// Targets provide a default setting, user flags override.
bool DisableVerify;
/// Default setting for -enable-tail-merge on this target.
bool EnableTailMerge;
/// Default setting for -enable-shrink-wrap on this target.
bool EnableShrinkWrap;
TargetPassConfig(TargetMachine *tm, PassManagerBase &pm);
// Dummy constructor.
~TargetPassConfig() override;
static char ID;
/// Get the right type of TargetMachine for this target.
template<typename TMC> TMC &getTM() const {
return *static_cast<TMC*>(TM);
void setInitialized() { Initialized = true; }
CodeGenOpt::Level getOptLevel() const { return TM->getOptLevel(); }
/// Set the StartAfter, StartBefore and StopAfter passes to allow running only
/// a portion of the normal code-gen pass sequence.
/// If the StartAfter and StartBefore pass ID is zero, then compilation will
/// begin at the normal point; otherwise, clear the Started flag to indicate
/// that passes should not be added until the starting pass is seen. If the
/// Stop pass ID is zero, then compilation will continue to the end.
/// This function expects that at least one of the StartAfter or the
/// StartBefore pass IDs is null.
void setStartStopPasses(AnalysisID StartBefore, AnalysisID StartAfter,
AnalysisID StopAfter) {
if (StartAfter)
assert(!StartBefore && "Start after and start before passes are given");
this->StartBefore = StartBefore;
this->StartAfter = StartAfter;
this->StopAfter = StopAfter;
Started = (StartAfter == nullptr) && (StartBefore == nullptr);
void setDisableVerify(bool Disable) { setOpt(DisableVerify, Disable); }
bool getEnableTailMerge() const { return EnableTailMerge; }
void setEnableTailMerge(bool Enable) { setOpt(EnableTailMerge, Enable); }
/// Allow the target to override a specific pass without overriding the pass
/// pipeline. When passes are added to the standard pipeline at the
/// point where StandardID is expected, add TargetID in its place.
void substitutePass(AnalysisID StandardID, IdentifyingPassPtr TargetID);
/// Insert InsertedPassID pass after TargetPassID pass.
void insertPass(AnalysisID TargetPassID, IdentifyingPassPtr InsertedPassID);
/// Allow the target to enable a specific standard pass by default.
void enablePass(AnalysisID PassID) { substitutePass(PassID, PassID); }
/// Allow the target to disable a specific standard pass by default.
void disablePass(AnalysisID PassID) {
substitutePass(PassID, IdentifyingPassPtr());
/// Return the pass substituted for StandardID by the target.
/// If no substitution exists, return StandardID.
IdentifyingPassPtr getPassSubstitution(AnalysisID StandardID) const;
/// Return true if the optimized regalloc pipeline is enabled.
bool getOptimizeRegAlloc() const;
/// Return true if shrink wrapping is enabled.
bool getEnableShrinkWrap() const;
/// Return true if the default global register allocator is in use and
/// has not be overriden on the command line with '-regalloc=...'
bool usingDefaultRegAlloc() const;
/// Add common target configurable passes that perform LLVM IR to IR
/// transforms following machine independent optimization.
virtual void addIRPasses();
/// Add passes to lower exception handling for the code generator.
void addPassesToHandleExceptions();
/// Add pass to prepare the LLVM IR for code generation. This should be done
/// before exception handling preparation passes.
virtual void addCodeGenPrepare();
/// Add common passes that perform LLVM IR to IR transforms in preparation for
/// instruction selection.
virtual void addISelPrepare();
/// addInstSelector - This method should install an instruction selector pass,
/// which converts from LLVM code to machine instructions.
virtual bool addInstSelector() {
return true;
/// Add the complete, standard set of LLVM CodeGen passes.
/// Fully developed targets will not generally override this.
virtual void addMachinePasses();
/// Create an instance of ScheduleDAGInstrs to be run within the standard
/// MachineScheduler pass for this function and target at the current
/// optimization level.
/// This can also be used to plug a new MachineSchedStrategy into an instance
/// of the standard ScheduleDAGMI:
/// return new ScheduleDAGMI(C, make_unique<MyStrategy>(C), /* IsPostRA= */false)
/// Return NULL to select the default (generic) machine scheduler.
virtual ScheduleDAGInstrs *
createMachineScheduler(MachineSchedContext *C) const {
return nullptr;
/// Similar to createMachineScheduler but used when postRA machine scheduling
/// is enabled.
virtual ScheduleDAGInstrs *
createPostMachineScheduler(MachineSchedContext *C) const {
return nullptr;
// Helper to verify the analysis is really immutable.
void setOpt(bool &Opt, bool Val);
/// Methods with trivial inline returns are convenient points in the common
/// codegen pass pipeline where targets may insert passes. Methods with
/// out-of-line standard implementations are major CodeGen stages called by
/// addMachinePasses. Some targets may override major stages when inserting
/// passes is insufficient, but maintaining overriden stages is more work.
/// addPreISelPasses - This method should add any "last minute" LLVM->LLVM
/// passes (which are run just before instruction selector).
virtual bool addPreISel() {
return true;
/// addMachineSSAOptimization - Add standard passes that optimize machine
/// instructions in SSA form.
virtual void addMachineSSAOptimization();
/// Add passes that optimize instruction level parallelism for out-of-order
/// targets. These passes are run while the machine code is still in SSA
/// form, so they can use MachineTraceMetrics to control their heuristics.
/// All passes added here should preserve the MachineDominatorTree,
/// MachineLoopInfo, and MachineTraceMetrics analyses.
virtual bool addILPOpts() {
return false;
/// This method may be implemented by targets that want to run passes
/// immediately before register allocation.
virtual void addPreRegAlloc() { }
/// createTargetRegisterAllocator - Create the register allocator pass for
/// this target at the current optimization level.
virtual FunctionPass *createTargetRegisterAllocator(bool Optimized);
/// addFastRegAlloc - Add the minimum set of target-independent passes that
/// are required for fast register allocation.
virtual void addFastRegAlloc(FunctionPass *RegAllocPass);
/// addOptimizedRegAlloc - Add passes related to register allocation.
/// LLVMTargetMachine provides standard regalloc passes for most targets.
virtual void addOptimizedRegAlloc(FunctionPass *RegAllocPass);
/// addPreRewrite - Add passes to the optimized register allocation pipeline
/// after register allocation is complete, but before virtual registers are
/// rewritten to physical registers.
/// These passes must preserve VirtRegMap and LiveIntervals, and when running
/// after RABasic or RAGreedy, they should take advantage of LiveRegMatrix.
/// When these passes run, VirtRegMap contains legal physreg assignments for
/// all virtual registers.
virtual bool addPreRewrite() {
return false;
/// This method may be implemented by targets that want to run passes after
/// register allocation pass pipeline but before prolog-epilog insertion.
virtual void addPostRegAlloc() { }
/// Add passes that optimize machine instructions after register allocation.
virtual void addMachineLateOptimization();
/// This method may be implemented by targets that want to run passes after
/// prolog-epilog insertion and before the second instruction scheduling pass.
virtual void addPreSched2() { }
/// addGCPasses - Add late codegen passes that analyze code for garbage
/// collection. This should return true if GC info should be printed after
/// these passes.
virtual bool addGCPasses();
/// Add standard basic block placement passes.
virtual void addBlockPlacement();
/// This pass may be implemented by targets that want to run passes
/// immediately before machine code is emitted.
virtual void addPreEmitPass() { }
/// Utilities for targets to add passes to the pass manager.
/// Add a CodeGen pass at this point in the pipeline after checking overrides.
/// Return the pass that was added, or zero if no pass was added.
/// @p printAfter if true and adding a machine function pass add an extra
/// machine printer pass afterwards
/// @p verifyAfter if true and adding a machine function pass add an extra
/// machine verification pass afterwards.
AnalysisID addPass(AnalysisID PassID, bool verifyAfter = true,
bool printAfter = true);
/// Add a pass to the PassManager if that pass is supposed to be run, as
/// determined by the StartAfter and StopAfter options. Takes ownership of the
/// pass.
/// @p printAfter if true and adding a machine function pass add an extra
/// machine printer pass afterwards
/// @p verifyAfter if true and adding a machine function pass add an extra
/// machine verification pass afterwards.
void addPass(Pass *P, bool verifyAfter = true, bool printAfter = true);
/// addMachinePasses helper to create the target-selected or overriden
/// regalloc pass.
FunctionPass *createRegAllocPass(bool Optimized);
/// printAndVerify - Add a pass to dump then verify the machine function, if
/// those steps are enabled.
void printAndVerify(const std::string &Banner);
/// Add a pass to print the machine function if printing is enabled.
void addPrintPass(const std::string &Banner);
/// Add a pass to perform basic verification of the machine function if
/// verification is enabled.
void addVerifyPass(const std::string &Banner);
} // namespace llvm
/// List of target independent CodeGen pass IDs.
namespace llvm {
FunctionPass *createAtomicExpandPass(const TargetMachine *TM);
/// createUnreachableBlockEliminationPass - The LLVM code generator does not
/// work well with unreachable basic blocks (what live ranges make sense for a
/// block that cannot be reached?). As such, a code generator should either
/// not instruction select unreachable blocks, or run this pass as its
/// last LLVM modifying pass to clean up blocks that are not reachable from
/// the entry block.
FunctionPass *createUnreachableBlockEliminationPass();
/// MachineFunctionPrinter pass - This pass prints out the machine function to
/// the given stream as a debugging tool.
MachineFunctionPass *
createMachineFunctionPrinterPass(raw_ostream &OS,
const std::string &Banner ="");
/// MIRPrinting pass - this pass prints out the LLVM IR into the given stream
/// using the MIR serialization format.
MachineFunctionPass *createPrintMIRPass(raw_ostream &OS);
/// createCodeGenPreparePass - Transform the code to expose more pattern
/// matching during instruction selection.
FunctionPass *createCodeGenPreparePass(const TargetMachine *TM = nullptr);
/// AtomicExpandID -- Lowers atomic operations in terms of either cmpxchg
/// load-linked/store-conditional loops.
extern char &AtomicExpandID;
/// MachineLoopInfo - This pass is a loop analysis pass.
extern char &MachineLoopInfoID;
/// MachineDominators - This pass is a machine dominators analysis pass.
extern char &MachineDominatorsID;
/// MachineDominanaceFrontier - This pass is a machine dominators analysis pass.
extern char &MachineDominanceFrontierID;
/// EdgeBundles analysis - Bundle machine CFG edges.
extern char &EdgeBundlesID;
/// LiveVariables pass - This pass computes the set of blocks in which each
/// variable is life and sets machine operand kill flags.
extern char &LiveVariablesID;
/// PHIElimination - This pass eliminates machine instruction PHI nodes
/// by inserting copy instructions. This destroys SSA information, but is the
/// desired input for some register allocators. This pass is "required" by
/// these register allocator like this: AU.addRequiredID(PHIEliminationID);
extern char &PHIEliminationID;
/// LiveIntervals - This analysis keeps track of the live ranges of virtual
/// and physical registers.
extern char &LiveIntervalsID;
/// LiveStacks pass. An analysis keeping track of the liveness of stack slots.
extern char &LiveStacksID;
/// TwoAddressInstruction - This pass reduces two-address instructions to
/// use two operands. This destroys SSA information but it is desired by
/// register allocators.
extern char &TwoAddressInstructionPassID;
/// ProcessImpicitDefs pass - This pass removes IMPLICIT_DEFs.
extern char &ProcessImplicitDefsID;
/// RegisterCoalescer - This pass merges live ranges to eliminate copies.
extern char &RegisterCoalescerID;
/// MachineScheduler - This pass schedules machine instructions.
extern char &MachineSchedulerID;
/// PostMachineScheduler - This pass schedules machine instructions postRA.
extern char &PostMachineSchedulerID;
/// SpillPlacement analysis. Suggest optimal placement of spill code between
/// basic blocks.
extern char &SpillPlacementID;
/// ShrinkWrap pass. Look for the best place to insert save and restore
// instruction and update the MachineFunctionInfo with that information.
extern char &ShrinkWrapID;
/// VirtRegRewriter pass. Rewrite virtual registers to physical registers as
/// assigned in VirtRegMap.
extern char &VirtRegRewriterID;
/// UnreachableMachineBlockElimination - This pass removes unreachable
/// machine basic blocks.
extern char &UnreachableMachineBlockElimID;
/// DeadMachineInstructionElim - This pass removes dead machine instructions.
extern char &DeadMachineInstructionElimID;
/// FastRegisterAllocation Pass - This pass register allocates as fast as
/// possible. It is best suited for debug code where live ranges are short.
FunctionPass *createFastRegisterAllocator();
/// BasicRegisterAllocation Pass - This pass implements a degenerate global
/// register allocator using the basic regalloc framework.
FunctionPass *createBasicRegisterAllocator();
/// Greedy register allocation pass - This pass implements a global register
/// allocator for optimized builds.
FunctionPass *createGreedyRegisterAllocator();
/// PBQPRegisterAllocation Pass - This pass implements the Partitioned Boolean
/// Quadratic Prograaming (PBQP) based register allocator.
FunctionPass *createDefaultPBQPRegisterAllocator();
/// PrologEpilogCodeInserter - This pass inserts prolog and epilog code,
/// and eliminates abstract frame references.
extern char &PrologEpilogCodeInserterID;
/// ExpandPostRAPseudos - This pass expands pseudo instructions after
/// register allocation.
extern char &ExpandPostRAPseudosID;
/// createPostRAScheduler - This pass performs post register allocation
/// scheduling.
extern char &PostRASchedulerID;
/// BranchFolding - This pass performs machine code CFG based
/// optimizations to delete branches to branches, eliminate branches to
/// successor blocks (creating fall throughs), and eliminating branches over
/// branches.
extern char &BranchFolderPassID;
/// MachineFunctionPrinterPass - This pass prints out MachineInstr's.
extern char &MachineFunctionPrinterPassID;
/// MIRPrintingPass - this pass prints out the LLVM IR using the MIR
/// serialization format.
extern char &MIRPrintingPassID;
/// TailDuplicate - Duplicate blocks with unconditional branches
/// into tails of their predecessors.
extern char &TailDuplicateID;
/// MachineTraceMetrics - This pass computes critical path and CPU resource
/// usage in an ensemble of traces.
extern char &MachineTraceMetricsID;
/// EarlyIfConverter - This pass performs if-conversion on SSA form by
/// inserting cmov instructions.
extern char &EarlyIfConverterID;
/// This pass performs instruction combining using trace metrics to estimate
/// critical-path and resource depth.
extern char &MachineCombinerID;
/// StackSlotColoring - This pass performs stack coloring and merging.
/// It merges disjoint allocas to reduce the stack size.
extern char &StackColoringID;
/// IfConverter - This pass performs machine code if conversion.
extern char &IfConverterID;
FunctionPass *createIfConverter(std::function<bool(const Function &)> Ftor);
/// MachineBlockPlacement - This pass places basic blocks based on branch
/// probabilities.
extern char &MachineBlockPlacementID;
/// MachineBlockPlacementStats - This pass collects statistics about the
/// basic block placement using branch probabilities and block frequency
/// information.
extern char &MachineBlockPlacementStatsID;
/// GCLowering Pass - Used by gc.root to perform its default lowering
/// operations.
FunctionPass *createGCLoweringPass();
/// ShadowStackGCLowering - Implements the custom lowering mechanism
/// used by the shadow stack GC. Only runs on functions which opt in to
/// the shadow stack collector.
FunctionPass *createShadowStackGCLoweringPass();
/// GCMachineCodeAnalysis - Target-independent pass to mark safe points
/// in machine code. Must be added very late during code generation, just
/// prior to output, and importantly after all CFG transformations (such as
/// branch folding).
extern char &GCMachineCodeAnalysisID;
/// Creates a pass to print GC metadata.
FunctionPass *createGCInfoPrinter(raw_ostream &OS);
/// MachineCSE - This pass performs global CSE on machine instructions.
extern char &MachineCSEID;
/// ImplicitNullChecks - This pass folds null pointer checks into nearby
/// memory operations.
extern char &ImplicitNullChecksID;
/// MachineLICM - This pass performs LICM on machine instructions.
extern char &MachineLICMID;
/// MachineSinking - This pass performs sinking on machine instructions.
extern char &MachineSinkingID;
/// MachineCopyPropagation - This pass performs copy propagation on
/// machine instructions.
extern char &MachineCopyPropagationID;
/// PeepholeOptimizer - This pass performs peephole optimizations -
/// like extension and comparison eliminations.
extern char &PeepholeOptimizerID;
/// OptimizePHIs - This pass optimizes machine instruction PHIs
/// to take advantage of opportunities created during DAG legalization.
extern char &OptimizePHIsID;
/// StackSlotColoring - This pass performs stack slot coloring.
extern char &StackSlotColoringID;
/// createStackProtectorPass - This pass adds stack protectors to functions.
FunctionPass *createStackProtectorPass(const TargetMachine *TM);
/// createMachineVerifierPass - This pass verifies cenerated machine code
/// instructions for correctness.
FunctionPass *createMachineVerifierPass(const std::string& Banner);
/// createDwarfEHPass - This pass mulches exception handling code into a form
/// adapted to code generation. Required if using dwarf exception handling.
FunctionPass *createDwarfEHPass(const TargetMachine *TM);
/// createWinEHPass - Prepares personality functions used by MSVC on Windows,
/// in addition to the Itanium LSDA based personalities.
FunctionPass *createWinEHPass(const TargetMachine *TM);
/// createSjLjEHPreparePass - This pass adapts exception handling code to use
/// the GCC-style builtin setjmp/longjmp (sjlj) to handling EH control flow.
FunctionPass *createSjLjEHPreparePass();
/// LocalStackSlotAllocation - This pass assigns local frame indices to stack
/// slots relative to one another and allocates base registers to access them
/// when it is estimated by the target to be out of range of normal frame
/// pointer or stack pointer index addressing.
extern char &LocalStackSlotAllocationID;
/// ExpandISelPseudos - This pass expands pseudo-instructions.
extern char &ExpandISelPseudosID;
/// createExecutionDependencyFixPass - This pass fixes execution time
/// problems with dependent instructions, such as switching execution
/// domains to match.
/// The pass will examine instructions using and defining registers in RC.
FunctionPass *createExecutionDependencyFixPass(const TargetRegisterClass *RC);
/// UnpackMachineBundles - This pass unpack machine instruction bundles.
extern char &UnpackMachineBundlesID;
FunctionPass *
createUnpackMachineBundles(std::function<bool(const Function &)> Ftor);
/// FinalizeMachineBundles - This pass finalize machine instruction
/// bundles (created earlier, e.g. during pre-RA scheduling).
extern char &FinalizeMachineBundlesID;
/// StackMapLiveness - This pass analyses the register live-out set of
/// stackmap/patchpoint intrinsics and attaches the calculated information to
/// the intrinsic for later emission to the StackMap.
extern char &StackMapLivenessID;
/// createJumpInstrTables - This pass creates jump-instruction tables.
ModulePass *createJumpInstrTablesPass();
/// createForwardControlFlowIntegrityPass - This pass adds control-flow
/// integrity.
ModulePass *createForwardControlFlowIntegrityPass();
/// InterleavedAccess Pass - This pass identifies and matches interleaved
/// memory accesses to target specific intrinsics.
FunctionPass *createInterleavedAccessPass(const TargetMachine *TM);
} // End llvm namespace
/// Target machine pass initializer for passes with dependencies. Use with
/// Target machine pass initializer for passes with dependencies. Use with
#define INITIALIZE_TM_PASS_END(passName, arg, name, cfg, analysis) \
PassInfo *PI = new PassInfo(name, arg, & passName ::ID, \
PassInfo::NormalCtor_t(callDefaultCtor< passName >), cfg, analysis, \
PassInfo::TargetMachineCtor_t(callTargetMachineCtor< passName >)); \
Registry.registerPass(*PI, true); \
return PI; \
} \
void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce) \
/// This initializer registers TargetMachine constructor, so the pass being
/// initialized can use target dependent interfaces. Please do not move this
/// macro to be together with INITIALIZE_PASS, which is a complete target
/// independent initializer, and we don't want to make libScalarOpts depend
/// on libCodeGen.
#define INITIALIZE_TM_PASS(passName, arg, name, cfg, analysis) \
INITIALIZE_TM_PASS_BEGIN(passName, arg, name, cfg, analysis) \
INITIALIZE_TM_PASS_END(passName, arg, name, cfg, analysis)