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      1 //===-- Passes.h - Target independent code generation passes ----*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines interfaces to access the target independent code generation
     11 // passes provided by the LLVM backend.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_CODEGEN_PASSES_H
     16 #define LLVM_CODEGEN_PASSES_H
     17 
     18 #include <functional>
     19 #include <string>
     20 
     21 namespace llvm {
     22 
     23 class Function;
     24 class FunctionPass;
     25 class MachineFunctionPass;
     26 class ModulePass;
     27 class Pass;
     28 class TargetMachine;
     29 class TargetRegisterClass;
     30 class raw_ostream;
     31 
     32 } // End llvm namespace
     33 
     34 /// List of target independent CodeGen pass IDs.
     35 namespace llvm {
     36   FunctionPass *createAtomicExpandPass(const TargetMachine *TM);
     37 
     38   /// createUnreachableBlockEliminationPass - The LLVM code generator does not
     39   /// work well with unreachable basic blocks (what live ranges make sense for a
     40   /// block that cannot be reached?).  As such, a code generator should either
     41   /// not instruction select unreachable blocks, or run this pass as its
     42   /// last LLVM modifying pass to clean up blocks that are not reachable from
     43   /// the entry block.
     44   FunctionPass *createUnreachableBlockEliminationPass();
     45 
     46   /// MachineFunctionPrinter pass - This pass prints out the machine function to
     47   /// the given stream as a debugging tool.
     48   MachineFunctionPass *
     49   createMachineFunctionPrinterPass(raw_ostream &OS,
     50                                    const std::string &Banner ="");
     51 
     52   /// MIRPrinting pass - this pass prints out the LLVM IR into the given stream
     53   /// using the MIR serialization format.
     54   MachineFunctionPass *createPrintMIRPass(raw_ostream &OS);
     55 
     56   /// createCodeGenPreparePass - Transform the code to expose more pattern
     57   /// matching during instruction selection.
     58   FunctionPass *createCodeGenPreparePass(const TargetMachine *TM = nullptr);
     59 
     60   /// AtomicExpandID -- Lowers atomic operations in terms of either cmpxchg
     61   /// load-linked/store-conditional loops.
     62   extern char &AtomicExpandID;
     63 
     64   /// MachineLoopInfo - This pass is a loop analysis pass.
     65   extern char &MachineLoopInfoID;
     66 
     67   /// MachineDominators - This pass is a machine dominators analysis pass.
     68   extern char &MachineDominatorsID;
     69 
     70 /// MachineDominanaceFrontier - This pass is a machine dominators analysis pass.
     71   extern char &MachineDominanceFrontierID;
     72 
     73   /// EdgeBundles analysis - Bundle machine CFG edges.
     74   extern char &EdgeBundlesID;
     75 
     76   /// LiveVariables pass - This pass computes the set of blocks in which each
     77   /// variable is life and sets machine operand kill flags.
     78   extern char &LiveVariablesID;
     79 
     80   /// PHIElimination - This pass eliminates machine instruction PHI nodes
     81   /// by inserting copy instructions.  This destroys SSA information, but is the
     82   /// desired input for some register allocators.  This pass is "required" by
     83   /// these register allocator like this: AU.addRequiredID(PHIEliminationID);
     84   extern char &PHIEliminationID;
     85 
     86   /// LiveIntervals - This analysis keeps track of the live ranges of virtual
     87   /// and physical registers.
     88   extern char &LiveIntervalsID;
     89 
     90   /// LiveStacks pass. An analysis keeping track of the liveness of stack slots.
     91   extern char &LiveStacksID;
     92 
     93   /// TwoAddressInstruction - This pass reduces two-address instructions to
     94   /// use two operands. This destroys SSA information but it is desired by
     95   /// register allocators.
     96   extern char &TwoAddressInstructionPassID;
     97 
     98   /// ProcessImpicitDefs pass - This pass removes IMPLICIT_DEFs.
     99   extern char &ProcessImplicitDefsID;
    100 
    101   /// RegisterCoalescer - This pass merges live ranges to eliminate copies.
    102   extern char &RegisterCoalescerID;
    103 
    104   /// MachineScheduler - This pass schedules machine instructions.
    105   extern char &MachineSchedulerID;
    106 
    107   /// PostMachineScheduler - This pass schedules machine instructions postRA.
    108   extern char &PostMachineSchedulerID;
    109 
    110   /// SpillPlacement analysis. Suggest optimal placement of spill code between
    111   /// basic blocks.
    112   extern char &SpillPlacementID;
    113 
    114   /// ShrinkWrap pass. Look for the best place to insert save and restore
    115   // instruction and update the MachineFunctionInfo with that information.
    116   extern char &ShrinkWrapID;
    117 
    118   /// VirtRegRewriter pass. Rewrite virtual registers to physical registers as
    119   /// assigned in VirtRegMap.
    120   extern char &VirtRegRewriterID;
    121 
    122   /// UnreachableMachineBlockElimination - This pass removes unreachable
    123   /// machine basic blocks.
    124   extern char &UnreachableMachineBlockElimID;
    125 
    126   /// DeadMachineInstructionElim - This pass removes dead machine instructions.
    127   extern char &DeadMachineInstructionElimID;
    128 
    129   /// This pass adds dead/undef flags after analyzing subregister lanes.
    130   extern char &DetectDeadLanesID;
    131 
    132   /// FastRegisterAllocation Pass - This pass register allocates as fast as
    133   /// possible. It is best suited for debug code where live ranges are short.
    134   ///
    135   FunctionPass *createFastRegisterAllocator();
    136 
    137   /// BasicRegisterAllocation Pass - This pass implements a degenerate global
    138   /// register allocator using the basic regalloc framework.
    139   ///
    140   FunctionPass *createBasicRegisterAllocator();
    141 
    142   /// Greedy register allocation pass - This pass implements a global register
    143   /// allocator for optimized builds.
    144   ///
    145   FunctionPass *createGreedyRegisterAllocator();
    146 
    147   /// PBQPRegisterAllocation Pass - This pass implements the Partitioned Boolean
    148   /// Quadratic Prograaming (PBQP) based register allocator.
    149   ///
    150   FunctionPass *createDefaultPBQPRegisterAllocator();
    151 
    152   /// PrologEpilogCodeInserter - This pass inserts prolog and epilog code,
    153   /// and eliminates abstract frame references.
    154   extern char &PrologEpilogCodeInserterID;
    155   MachineFunctionPass *createPrologEpilogInserterPass(const TargetMachine *TM);
    156 
    157   /// ExpandPostRAPseudos - This pass expands pseudo instructions after
    158   /// register allocation.
    159   extern char &ExpandPostRAPseudosID;
    160 
    161   /// createPostRAHazardRecognizer - This pass runs the post-ra hazard
    162   /// recognizer.
    163   extern char &PostRAHazardRecognizerID;
    164 
    165   /// createPostRAScheduler - This pass performs post register allocation
    166   /// scheduling.
    167   extern char &PostRASchedulerID;
    168 
    169   /// BranchFolding - This pass performs machine code CFG based
    170   /// optimizations to delete branches to branches, eliminate branches to
    171   /// successor blocks (creating fall throughs), and eliminating branches over
    172   /// branches.
    173   extern char &BranchFolderPassID;
    174 
    175   /// MachineFunctionPrinterPass - This pass prints out MachineInstr's.
    176   extern char &MachineFunctionPrinterPassID;
    177 
    178   /// MIRPrintingPass - this pass prints out the LLVM IR using the MIR
    179   /// serialization format.
    180   extern char &MIRPrintingPassID;
    181 
    182   /// TailDuplicate - Duplicate blocks with unconditional branches
    183   /// into tails of their predecessors.
    184   extern char &TailDuplicateID;
    185 
    186   /// MachineTraceMetrics - This pass computes critical path and CPU resource
    187   /// usage in an ensemble of traces.
    188   extern char &MachineTraceMetricsID;
    189 
    190   /// EarlyIfConverter - This pass performs if-conversion on SSA form by
    191   /// inserting cmov instructions.
    192   extern char &EarlyIfConverterID;
    193 
    194   /// This pass performs instruction combining using trace metrics to estimate
    195   /// critical-path and resource depth.
    196   extern char &MachineCombinerID;
    197 
    198   /// StackSlotColoring - This pass performs stack coloring and merging.
    199   /// It merges disjoint allocas to reduce the stack size.
    200   extern char &StackColoringID;
    201 
    202   /// IfConverter - This pass performs machine code if conversion.
    203   extern char &IfConverterID;
    204 
    205   FunctionPass *createIfConverter(std::function<bool(const Function &)> Ftor);
    206 
    207   /// MachineBlockPlacement - This pass places basic blocks based on branch
    208   /// probabilities.
    209   extern char &MachineBlockPlacementID;
    210 
    211   /// MachineBlockPlacementStats - This pass collects statistics about the
    212   /// basic block placement using branch probabilities and block frequency
    213   /// information.
    214   extern char &MachineBlockPlacementStatsID;
    215 
    216   /// GCLowering Pass - Used by gc.root to perform its default lowering
    217   /// operations.
    218   FunctionPass *createGCLoweringPass();
    219 
    220   /// ShadowStackGCLowering - Implements the custom lowering mechanism
    221   /// used by the shadow stack GC.  Only runs on functions which opt in to
    222   /// the shadow stack collector.
    223   FunctionPass *createShadowStackGCLoweringPass();
    224 
    225   /// GCMachineCodeAnalysis - Target-independent pass to mark safe points
    226   /// in machine code. Must be added very late during code generation, just
    227   /// prior to output, and importantly after all CFG transformations (such as
    228   /// branch folding).
    229   extern char &GCMachineCodeAnalysisID;
    230 
    231   /// Creates a pass to print GC metadata.
    232   ///
    233   FunctionPass *createGCInfoPrinter(raw_ostream &OS);
    234 
    235   /// MachineCSE - This pass performs global CSE on machine instructions.
    236   extern char &MachineCSEID;
    237 
    238   /// ImplicitNullChecks - This pass folds null pointer checks into nearby
    239   /// memory operations.
    240   extern char &ImplicitNullChecksID;
    241 
    242   /// MachineLICM - This pass performs LICM on machine instructions.
    243   extern char &MachineLICMID;
    244 
    245   /// MachineSinking - This pass performs sinking on machine instructions.
    246   extern char &MachineSinkingID;
    247 
    248   /// MachineCopyPropagation - This pass performs copy propagation on
    249   /// machine instructions.
    250   extern char &MachineCopyPropagationID;
    251 
    252   /// PeepholeOptimizer - This pass performs peephole optimizations -
    253   /// like extension and comparison eliminations.
    254   extern char &PeepholeOptimizerID;
    255 
    256   /// OptimizePHIs - This pass optimizes machine instruction PHIs
    257   /// to take advantage of opportunities created during DAG legalization.
    258   extern char &OptimizePHIsID;
    259 
    260   /// StackSlotColoring - This pass performs stack slot coloring.
    261   extern char &StackSlotColoringID;
    262 
    263   /// \brief This pass lays out funclets contiguously.
    264   extern char &FuncletLayoutID;
    265 
    266   /// This pass inserts the XRay instrumentation sleds if they are supported by
    267   /// the target platform.
    268   extern char &XRayInstrumentationID;
    269 
    270   /// \brief This pass implements the "patchable-function" attribute.
    271   extern char &PatchableFunctionID;
    272 
    273   /// createStackProtectorPass - This pass adds stack protectors to functions.
    274   ///
    275   FunctionPass *createStackProtectorPass(const TargetMachine *TM);
    276 
    277   /// createMachineVerifierPass - This pass verifies cenerated machine code
    278   /// instructions for correctness.
    279   ///
    280   FunctionPass *createMachineVerifierPass(const std::string& Banner);
    281 
    282   /// createDwarfEHPass - This pass mulches exception handling code into a form
    283   /// adapted to code generation.  Required if using dwarf exception handling.
    284   FunctionPass *createDwarfEHPass(const TargetMachine *TM);
    285 
    286   /// createWinEHPass - Prepares personality functions used by MSVC on Windows,
    287   /// in addition to the Itanium LSDA based personalities.
    288   FunctionPass *createWinEHPass(const TargetMachine *TM);
    289 
    290   /// createSjLjEHPreparePass - This pass adapts exception handling code to use
    291   /// the GCC-style builtin setjmp/longjmp (sjlj) to handling EH control flow.
    292   ///
    293   FunctionPass *createSjLjEHPreparePass();
    294 
    295   /// LocalStackSlotAllocation - This pass assigns local frame indices to stack
    296   /// slots relative to one another and allocates base registers to access them
    297   /// when it is estimated by the target to be out of range of normal frame
    298   /// pointer or stack pointer index addressing.
    299   extern char &LocalStackSlotAllocationID;
    300 
    301   /// ExpandISelPseudos - This pass expands pseudo-instructions.
    302   extern char &ExpandISelPseudosID;
    303 
    304   /// createExecutionDependencyFixPass - This pass fixes execution time
    305   /// problems with dependent instructions, such as switching execution
    306   /// domains to match.
    307   ///
    308   /// The pass will examine instructions using and defining registers in RC.
    309   ///
    310   FunctionPass *createExecutionDependencyFixPass(const TargetRegisterClass *RC);
    311 
    312   /// UnpackMachineBundles - This pass unpack machine instruction bundles.
    313   extern char &UnpackMachineBundlesID;
    314 
    315   FunctionPass *
    316   createUnpackMachineBundles(std::function<bool(const Function &)> Ftor);
    317 
    318   /// FinalizeMachineBundles - This pass finalize machine instruction
    319   /// bundles (created earlier, e.g. during pre-RA scheduling).
    320   extern char &FinalizeMachineBundlesID;
    321 
    322   /// StackMapLiveness - This pass analyses the register live-out set of
    323   /// stackmap/patchpoint intrinsics and attaches the calculated information to
    324   /// the intrinsic for later emission to the StackMap.
    325   extern char &StackMapLivenessID;
    326 
    327   /// LiveDebugValues pass
    328   extern char &LiveDebugValuesID;
    329 
    330   /// createJumpInstrTables - This pass creates jump-instruction tables.
    331   ModulePass *createJumpInstrTablesPass();
    332 
    333   /// createForwardControlFlowIntegrityPass - This pass adds control-flow
    334   /// integrity.
    335   ModulePass *createForwardControlFlowIntegrityPass();
    336 
    337   /// InterleavedAccess Pass - This pass identifies and matches interleaved
    338   /// memory accesses to target specific intrinsics.
    339   ///
    340   FunctionPass *createInterleavedAccessPass(const TargetMachine *TM);
    341 
    342   /// LowerEmuTLS - This pass generates __emutls_[vt].xyz variables for all
    343   /// TLS variables for the emulated TLS model.
    344   ///
    345   ModulePass *createLowerEmuTLSPass(const TargetMachine *TM);
    346 
    347   /// This pass lowers the @llvm.load.relative intrinsic to instructions.
    348   /// This is unsafe to do earlier because a pass may combine the constant
    349   /// initializer into the load, which may result in an overflowing evaluation.
    350   ModulePass *createPreISelIntrinsicLoweringPass();
    351 
    352   /// GlobalMerge - This pass merges internal (by default) globals into structs
    353   /// to enable reuse of a base pointer by indexed addressing modes.
    354   /// It can also be configured to focus on size optimizations only.
    355   ///
    356   Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset,
    357                               bool OnlyOptimizeForSize = false,
    358                               bool MergeExternalByDefault = false);
    359 
    360   /// This pass splits the stack into a safe stack and an unsafe stack to
    361   /// protect against stack-based overflow vulnerabilities.
    362   FunctionPass *createSafeStackPass(const TargetMachine *TM = nullptr);
    363 
    364   /// This pass detects subregister lanes in a virtual register that are used
    365   /// independently of other lanes and splits them into separate virtual
    366   /// registers.
    367   extern char &RenameIndependentSubregsID;
    368 
    369   /// This pass is executed POST-RA to collect which physical registers are
    370   /// preserved by given machine function.
    371   FunctionPass *createRegUsageInfoCollector();
    372 
    373   /// Return a MachineFunction pass that identifies call sites
    374   /// and propagates register usage information of callee to caller
    375   /// if available with PysicalRegisterUsageInfo pass.
    376   FunctionPass *createRegUsageInfoPropPass();
    377 
    378   /// This pass performs software pipelining on machine instructions.
    379   extern char &MachinePipelinerID;
    380 } // End llvm namespace
    381 
    382 /// Target machine pass initializer for passes with dependencies. Use with
    383 /// INITIALIZE_TM_PASS_END.
    384 #define INITIALIZE_TM_PASS_BEGIN INITIALIZE_PASS_BEGIN
    385 
    386 /// Target machine pass initializer for passes with dependencies. Use with
    387 /// INITIALIZE_TM_PASS_BEGIN.
    388 #define INITIALIZE_TM_PASS_END(passName, arg, name, cfg, analysis)             \
    389   PassInfo *PI = new PassInfo(                                                 \
    390       name, arg, &passName::ID,                                                \
    391       PassInfo::NormalCtor_t(callDefaultCtor<passName>), cfg, analysis,        \
    392       PassInfo::TargetMachineCtor_t(callTargetMachineCtor<passName>));         \
    393   Registry.registerPass(*PI, true);                                            \
    394   return PI;                                                                   \
    395   }                                                                            \
    396   LLVM_DEFINE_ONCE_FLAG(Initialize##passName##PassFlag);                       \
    397   void llvm::initialize##passName##Pass(PassRegistry &Registry) {              \
    398     llvm::call_once(Initialize##passName##PassFlag,                            \
    399                     initialize##passName##PassOnce, std::ref(Registry));       \
    400   }
    401 
    402 /// This initializer registers TargetMachine constructor, so the pass being
    403 /// initialized can use target dependent interfaces. Please do not move this
    404 /// macro to be together with INITIALIZE_PASS, which is a complete target
    405 /// independent initializer, and we don't want to make libScalarOpts depend
    406 /// on libCodeGen.
    407 #define INITIALIZE_TM_PASS(passName, arg, name, cfg, analysis)                 \
    408   INITIALIZE_TM_PASS_BEGIN(passName, arg, name, cfg, analysis)                 \
    409   INITIALIZE_TM_PASS_END(passName, arg, name, cfg, analysis)
    410 
    411 #endif
    412