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Current view: top level - include/llvm/Transforms/Utils - ValueMapper.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 10 10 100.0 %
Date: 2017-09-14 15:23:50 Functions: 4 4 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- ValueMapper.h - Remapping for constants and metadata -----*- 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 the MapValue interface which is used by various parts of
      11             : // the Transforms/Utils library to implement cloning and linking facilities.
      12             : //
      13             : //===----------------------------------------------------------------------===//
      14             : 
      15             : #ifndef LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H
      16             : #define LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H
      17             : 
      18             : #include "llvm/ADT/ArrayRef.h"
      19             : #include "llvm/IR/ValueHandle.h"
      20             : #include "llvm/IR/ValueMap.h"
      21             : 
      22             : namespace llvm {
      23             : 
      24             : class Value;
      25             : class Instruction;
      26             : typedef ValueMap<const Value *, WeakTrackingVH> ValueToValueMapTy;
      27             : 
      28             : /// This is a class that can be implemented by clients to remap types when
      29             : /// cloning constants and instructions.
      30             : class ValueMapTypeRemapper {
      31             :   virtual void anchor(); // Out of line method.
      32             : 
      33             : public:
      34             :   virtual ~ValueMapTypeRemapper() = default;
      35             : 
      36             :   /// The client should implement this method if they want to remap types while
      37             :   /// mapping values.
      38             :   virtual Type *remapType(Type *SrcTy) = 0;
      39             : };
      40             : 
      41             : /// This is a class that can be implemented by clients to materialize Values on
      42             : /// demand.
      43             : class ValueMaterializer {
      44             :   virtual void anchor(); // Out of line method.
      45             : 
      46             : protected:
      47             :   ~ValueMaterializer() = default;
      48             :   ValueMaterializer() = default;
      49             :   ValueMaterializer(const ValueMaterializer &) = default;
      50             :   ValueMaterializer &operator=(const ValueMaterializer &) = default;
      51             : 
      52             : public:
      53             :   /// This method can be implemented to generate a mapped Value on demand. For
      54             :   /// example, if linking lazily. Returns null if the value is not materialized.
      55             :   virtual Value *materialize(Value *V) = 0;
      56             : };
      57             : 
      58             : /// These are flags that the value mapping APIs allow.
      59             : enum RemapFlags {
      60             :   RF_None = 0,
      61             : 
      62             :   /// If this flag is set, the remapper knows that only local values within a
      63             :   /// function (such as an instruction or argument) are mapped, not global
      64             :   /// values like functions and global metadata.
      65             :   RF_NoModuleLevelChanges = 1,
      66             : 
      67             :   /// If this flag is set, the remapper ignores missing function-local entries
      68             :   /// (Argument, Instruction, BasicBlock) that are not in the value map.  If it
      69             :   /// is unset, it aborts if an operand is asked to be remapped which doesn't
      70             :   /// exist in the mapping.
      71             :   ///
      72             :   /// There are no such assertions in MapValue(), whose results are almost
      73             :   /// unchanged by this flag.  This flag mainly changes the assertion behaviour
      74             :   /// in RemapInstruction().
      75             :   ///
      76             :   /// Since an Instruction's metadata operands (even that point to SSA values)
      77             :   /// aren't guaranteed to be dominated by their definitions, MapMetadata will
      78             :   /// return "!{}" instead of "null" for \a LocalAsMetadata instances whose SSA
      79             :   /// values are unmapped when this flag is set.  Otherwise, \a MapValue()
      80             :   /// completely ignores this flag.
      81             :   ///
      82             :   /// \a MapMetadata() always ignores this flag.
      83             :   RF_IgnoreMissingLocals = 2,
      84             : 
      85             :   /// Instruct the remapper to move distinct metadata instead of duplicating it
      86             :   /// when there are module-level changes.
      87             :   RF_MoveDistinctMDs = 4,
      88             : 
      89             :   /// Any global values not in value map are mapped to null instead of mapping
      90             :   /// to self.  Illegal if RF_IgnoreMissingLocals is also set.
      91             :   RF_NullMapMissingGlobalValues = 8,
      92             : };
      93             : 
      94             : static inline RemapFlags operator|(RemapFlags LHS, RemapFlags RHS) {
      95         970 :   return RemapFlags(unsigned(LHS) | unsigned(RHS));
      96             : }
      97             : 
      98             : /// Context for (re-)mapping values (and metadata).
      99             : ///
     100             : /// A shared context used for mapping and remapping of Value and Metadata
     101             : /// instances using \a ValueToValueMapTy, \a RemapFlags, \a
     102             : /// ValueMapTypeRemapper, and \a ValueMaterializer.
     103             : ///
     104             : /// There are a number of top-level entry points:
     105             : /// - \a mapValue() (and \a mapConstant());
     106             : /// - \a mapMetadata() (and \a mapMDNode());
     107             : /// - \a remapInstruction(); and
     108             : /// - \a remapFunction().
     109             : ///
     110             : /// The \a ValueMaterializer can be used as a callback, but cannot invoke any
     111             : /// of these top-level functions recursively.  Instead, callbacks should use
     112             : /// one of the following to schedule work lazily in the \a ValueMapper
     113             : /// instance:
     114             : /// - \a scheduleMapGlobalInitializer()
     115             : /// - \a scheduleMapAppendingVariable()
     116             : /// - \a scheduleMapGlobalAliasee()
     117             : /// - \a scheduleRemapFunction()
     118             : ///
     119             : /// Sometimes a callback needs a different mapping context.  Such a context can
     120             : /// be registered using \a registerAlternateMappingContext(), which takes an
     121             : /// alternate \a ValueToValueMapTy and \a ValueMaterializer and returns a ID to
     122             : /// pass into the schedule*() functions.
     123             : ///
     124             : /// TODO: lib/Linker really doesn't need the \a ValueHandle in the \a
     125             : /// ValueToValueMapTy.  We should template \a ValueMapper (and its
     126             : /// implementation classes), and explicitly instantiate on two concrete
     127             : /// instances of \a ValueMap (one as \a ValueToValueMap, and one with raw \a
     128             : /// Value pointers).  It may be viable to do away with \a TrackingMDRef in the
     129             : /// \a Metadata side map for the lib/Linker case as well, in which case we'll
     130             : /// need a new template parameter on \a ValueMap.
     131             : ///
     132             : /// TODO: Update callers of \a RemapInstruction() and \a MapValue() (etc.) to
     133             : /// use \a ValueMapper directly.
     134             : class ValueMapper {
     135             :   void *pImpl;
     136             : 
     137             : public:
     138             :   ValueMapper(ValueToValueMapTy &VM, RemapFlags Flags = RF_None,
     139             :               ValueMapTypeRemapper *TypeMapper = nullptr,
     140             :               ValueMaterializer *Materializer = nullptr);
     141             :   ValueMapper(ValueMapper &&) = delete;
     142             :   ValueMapper(const ValueMapper &) = delete;
     143             :   ValueMapper &operator=(ValueMapper &&) = delete;
     144             :   ValueMapper &operator=(const ValueMapper &) = delete;
     145             :   ~ValueMapper();
     146             : 
     147             :   /// Register an alternate mapping context.
     148             :   ///
     149             :   /// Returns a MappingContextID that can be used with the various schedule*()
     150             :   /// API to switch in a different value map on-the-fly.
     151             :   unsigned
     152             :   registerAlternateMappingContext(ValueToValueMapTy &VM,
     153             :                                   ValueMaterializer *Materializer = nullptr);
     154             : 
     155             :   /// Add to the current \a RemapFlags.
     156             :   ///
     157             :   /// \note Like the top-level mapping functions, \a addFlags() must be called
     158             :   /// at the top level, not during a callback in a \a ValueMaterializer.
     159             :   void addFlags(RemapFlags Flags);
     160             : 
     161             :   Metadata *mapMetadata(const Metadata &MD);
     162             :   MDNode *mapMDNode(const MDNode &N);
     163             : 
     164             :   Value *mapValue(const Value &V);
     165             :   Constant *mapConstant(const Constant &C);
     166             : 
     167             :   void remapInstruction(Instruction &I);
     168             :   void remapFunction(Function &F);
     169             : 
     170             :   void scheduleMapGlobalInitializer(GlobalVariable &GV, Constant &Init,
     171             :                                     unsigned MappingContextID = 0);
     172             :   void scheduleMapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
     173             :                                     bool IsOldCtorDtor,
     174             :                                     ArrayRef<Constant *> NewMembers,
     175             :                                     unsigned MappingContextID = 0);
     176             :   void scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
     177             :                                 unsigned MappingContextID = 0);
     178             :   void scheduleRemapFunction(Function &F, unsigned MappingContextID = 0);
     179             : };
     180             : 
     181             : /// Look up or compute a value in the value map.
     182             : ///
     183             : /// Return a mapped value for a function-local value (Argument, Instruction,
     184             : /// BasicBlock), or compute and memoize a value for a Constant.
     185             : ///
     186             : ///  1. If \c V is in VM, return the result.
     187             : ///  2. Else if \c V can be materialized with \c Materializer, do so, memoize
     188             : ///     it in \c VM, and return it.
     189             : ///  3. Else if \c V is a function-local value, return nullptr.
     190             : ///  4. Else if \c V is a \a GlobalValue, return \c nullptr or \c V depending
     191             : ///     on \a RF_NullMapMissingGlobalValues.
     192             : ///  5. Else if \c V is a \a MetadataAsValue wrapping a LocalAsMetadata,
     193             : ///     recurse on the local SSA value, and return nullptr or "metadata !{}" on
     194             : ///     missing depending on RF_IgnoreMissingValues.
     195             : ///  6. Else if \c V is a \a MetadataAsValue, rewrap the return of \a
     196             : ///     MapMetadata().
     197             : ///  7. Else, compute the equivalent constant, and return it.
     198       16281 : inline Value *MapValue(const Value *V, ValueToValueMapTy &VM,
     199             :                        RemapFlags Flags = RF_None,
     200             :                        ValueMapTypeRemapper *TypeMapper = nullptr,
     201             :                        ValueMaterializer *Materializer = nullptr) {
     202       16281 :   return ValueMapper(VM, Flags, TypeMapper, Materializer).mapValue(*V);
     203             : }
     204             : 
     205             : /// Lookup or compute a mapping for a piece of metadata.
     206             : ///
     207             : /// Compute and memoize a mapping for \c MD.
     208             : ///
     209             : ///  1. If \c MD is mapped, return it.
     210             : ///  2. Else if \a RF_NoModuleLevelChanges or \c MD is an \a MDString, return
     211             : ///     \c MD.
     212             : ///  3. Else if \c MD is a \a ConstantAsMetadata, call \a MapValue() and
     213             : ///     re-wrap its return (returning nullptr on nullptr).
     214             : ///  4. Else, \c MD is an \a MDNode.  These are remapped, along with their
     215             : ///     transitive operands.  Distinct nodes are duplicated or moved depending
     216             : ///     on \a RF_MoveDistinctNodes.  Uniqued nodes are remapped like constants.
     217             : ///
     218             : /// \note \a LocalAsMetadata is completely unsupported by \a MapMetadata.
     219             : /// Instead, use \a MapValue() with its wrapping \a MetadataAsValue instance.
     220             : inline Metadata *MapMetadata(const Metadata *MD, ValueToValueMapTy &VM,
     221             :                              RemapFlags Flags = RF_None,
     222             :                              ValueMapTypeRemapper *TypeMapper = nullptr,
     223             :                              ValueMaterializer *Materializer = nullptr) {
     224             :   return ValueMapper(VM, Flags, TypeMapper, Materializer).mapMetadata(*MD);
     225             : }
     226             : 
     227             : /// Version of MapMetadata with type safety for MDNode.
     228         599 : inline MDNode *MapMetadata(const MDNode *MD, ValueToValueMapTy &VM,
     229             :                            RemapFlags Flags = RF_None,
     230             :                            ValueMapTypeRemapper *TypeMapper = nullptr,
     231             :                            ValueMaterializer *Materializer = nullptr) {
     232         599 :   return ValueMapper(VM, Flags, TypeMapper, Materializer).mapMDNode(*MD);
     233             : }
     234             : 
     235             : /// Convert the instruction operands from referencing the current values into
     236             : /// those specified by VM.
     237             : ///
     238             : /// If \a RF_IgnoreMissingLocals is set and an operand can't be found via \a
     239             : /// MapValue(), use the old value.  Otherwise assert that this doesn't happen.
     240             : ///
     241             : /// Note that \a MapValue() only returns \c nullptr for SSA values missing from
     242             : /// \c VM.
     243     1697116 : inline void RemapInstruction(Instruction *I, ValueToValueMapTy &VM,
     244             :                              RemapFlags Flags = RF_None,
     245             :                              ValueMapTypeRemapper *TypeMapper = nullptr,
     246             :                              ValueMaterializer *Materializer = nullptr) {
     247     1697116 :   ValueMapper(VM, Flags, TypeMapper, Materializer).remapInstruction(*I);
     248     1697116 : }
     249             : 
     250             : /// Remap the operands, metadata, arguments, and instructions of a function.
     251             : ///
     252             : /// Calls \a MapValue() on prefix data, prologue data, and personality
     253             : /// function; calls \a MapMetadata() on each attached MDNode; remaps the
     254             : /// argument types using the provided \c TypeMapper; and calls \a
     255             : /// RemapInstruction() on every instruction.
     256             : inline void RemapFunction(Function &F, ValueToValueMapTy &VM,
     257             :                           RemapFlags Flags = RF_None,
     258             :                           ValueMapTypeRemapper *TypeMapper = nullptr,
     259             :                           ValueMaterializer *Materializer = nullptr) {
     260             :   ValueMapper(VM, Flags, TypeMapper, Materializer).remapFunction(F);
     261             : }
     262             : 
     263             : /// Version of MapValue with type safety for Constant.
     264         119 : inline Constant *MapValue(const Constant *V, ValueToValueMapTy &VM,
     265             :                           RemapFlags Flags = RF_None,
     266             :                           ValueMapTypeRemapper *TypeMapper = nullptr,
     267             :                           ValueMaterializer *Materializer = nullptr) {
     268         119 :   return ValueMapper(VM, Flags, TypeMapper, Materializer).mapConstant(*V);
     269             : }
     270             : 
     271             : } // end namespace llvm
     272             : 
     273             : #endif // LLVM_TRANSFORMS_UTILS_VALUEMAPPER_H

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