LLVM API Documentation

Cloning.h

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00001 //===- Cloning.h - Clone various parts of LLVM programs ---------*- C++ -*-===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file defines various functions that are used to clone chunks of LLVM
00011 // code for various purposes.  This varies from copying whole modules into new
00012 // modules, to cloning functions with different arguments, to inlining
00013 // functions, to copying basic blocks to support loop unrolling or superblock
00014 // formation, etc.
00015 //
00016 //===----------------------------------------------------------------------===//
00017 
00018 #ifndef LLVM_TRANSFORMS_UTILS_CLONING_H
00019 #define LLVM_TRANSFORMS_UTILS_CLONING_H
00020 
00021 #include <vector>
00022 #include <map>
00023 
00024 namespace llvm {
00025 
00026 class Module;
00027 class Function;
00028 class BasicBlock;
00029 class Value;
00030 class CallInst;
00031 class InvokeInst;
00032 class ReturnInst;
00033 class CallSite;
00034 class Trace;
00035 class CallGraph;
00036 
00037 /// CloneModule - Return an exact copy of the specified module
00038 ///
00039 Module *CloneModule(const Module *M);
00040 Module *CloneModule(const Module *M, std::map<const Value*, Value*> &ValueMap);
00041 
00042 /// ClonedCodeInfo - This struct can be used to capture information about code
00043 /// being cloned, while it is being cloned.
00044 struct ClonedCodeInfo {
00045   /// ContainsCalls - This is set to true if the cloned code contains a normal
00046   /// call instruction.
00047   bool ContainsCalls;
00048   
00049   /// ContainsUnwinds - This is set to true if the cloned code contains an
00050   /// unwind instruction.
00051   bool ContainsUnwinds;
00052   
00053   /// ContainsDynamicAllocas - This is set to true if the cloned code contains
00054   /// a 'dynamic' alloca.  Dynamic allocas are allocas that are either not in
00055   /// the entry block or they are in the entry block but are not a constant
00056   /// size.
00057   bool ContainsDynamicAllocas;
00058   
00059   ClonedCodeInfo() {
00060     ContainsCalls = false;
00061     ContainsUnwinds = false;
00062     ContainsDynamicAllocas = false;
00063   }
00064 };
00065 
00066 
00067 /// CloneBasicBlock - Return a copy of the specified basic block, but without
00068 /// embedding the block into a particular function.  The block returned is an
00069 /// exact copy of the specified basic block, without any remapping having been
00070 /// performed.  Because of this, this is only suitable for applications where
00071 /// the basic block will be inserted into the same function that it was cloned
00072 /// from (loop unrolling would use this, for example).
00073 ///
00074 /// Also, note that this function makes a direct copy of the basic block, and
00075 /// can thus produce illegal LLVM code.  In particular, it will copy any PHI
00076 /// nodes from the original block, even though there are no predecessors for the
00077 /// newly cloned block (thus, phi nodes will have to be updated).  Also, this
00078 /// block will branch to the old successors of the original block: these
00079 /// successors will have to have any PHI nodes updated to account for the new
00080 /// incoming edges.
00081 ///
00082 /// The correlation between instructions in the source and result basic blocks
00083 /// is recorded in the ValueMap map.
00084 ///
00085 /// If you have a particular suffix you'd like to use to add to any cloned
00086 /// names, specify it as the optional third parameter.
00087 ///
00088 /// If you would like the basic block to be auto-inserted into the end of a
00089 /// function, you can specify it as the optional fourth parameter.
00090 ///
00091 /// If you would like to collect additional information about the cloned
00092 /// function, you can specify a ClonedCodeInfo object with the optional fifth
00093 /// parameter.
00094 ///
00095 BasicBlock *CloneBasicBlock(const BasicBlock *BB,
00096                             std::map<const Value*, Value*> &ValueMap,
00097                             const char *NameSuffix = "", Function *F = 0,
00098                             ClonedCodeInfo *CodeInfo = 0);
00099 
00100 
00101 /// CloneFunction - Return a copy of the specified function, but without
00102 /// embedding the function into another module.  Also, any references specified
00103 /// in the ValueMap are changed to refer to their mapped value instead of the
00104 /// original one.  If any of the arguments to the function are in the ValueMap,
00105 /// the arguments are deleted from the resultant function.  The ValueMap is
00106 /// updated to include mappings from all of the instructions and basicblocks in
00107 /// the function from their old to new values.  The final argument captures
00108 /// information about the cloned code if non-null.
00109 ///
00110 Function *CloneFunction(const Function *F,
00111                         std::map<const Value*, Value*> &ValueMap,
00112                         ClonedCodeInfo *CodeInfo = 0);
00113 
00114 /// CloneFunction - Version of the function that doesn't need the ValueMap.
00115 ///
00116 inline Function *CloneFunction(const Function *F, ClonedCodeInfo *CodeInfo = 0){
00117   std::map<const Value*, Value*> ValueMap;
00118   return CloneFunction(F, ValueMap, CodeInfo);
00119 }
00120 
00121 /// Clone OldFunc into NewFunc, transforming the old arguments into references
00122 /// to ArgMap values.  Note that if NewFunc already has basic blocks, the ones
00123 /// cloned into it will be added to the end of the function.  This function
00124 /// fills in a list of return instructions, and can optionally append the
00125 /// specified suffix to all values cloned.
00126 ///
00127 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
00128                        std::map<const Value*, Value*> &ValueMap,
00129                        std::vector<ReturnInst*> &Returns,
00130                        const char *NameSuffix = "", 
00131                        ClonedCodeInfo *CodeInfo = 0);
00132 
00133 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
00134 /// except that it does some simple constant prop and DCE on the fly.  The
00135 /// effect of this is to copy significantly less code in cases where (for
00136 /// example) a function call with constant arguments is inlined, and those
00137 /// constant arguments cause a significant amount of code in the callee to be
00138 /// dead.  Since this doesn't produce an exactly copy of the input, it can't be
00139 /// used for things like CloneFunction or CloneModule.
00140 void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
00141                                std::map<const Value*, Value*> &ValueMap,
00142                                std::vector<ReturnInst*> &Returns,
00143                                const char *NameSuffix = "", 
00144                                ClonedCodeInfo *CodeInfo = 0);
00145 
00146 
00147 /// CloneTraceInto - Clone T into NewFunc. Original<->clone mapping is
00148 /// saved in ValueMap.
00149 ///
00150 void CloneTraceInto(Function *NewFunc, Trace &T,
00151                     std::map<const Value*, Value*> &ValueMap,
00152                     const char *NameSuffix);
00153 
00154 /// CloneTrace - Returns a copy of the specified trace.
00155 /// It takes a vector of basic blocks clones the basic blocks, removes internal
00156 /// phi nodes, adds it to the same function as the original (although there is
00157 /// no jump to it) and returns the new vector of basic blocks.
00158 std::vector<BasicBlock *> CloneTrace(const std::vector<BasicBlock*> &origTrace);
00159 
00160 /// InlineFunction - This function inlines the called function into the basic
00161 /// block of the caller.  This returns false if it is not possible to inline
00162 /// this call.  The program is still in a well defined state if this occurs
00163 /// though.
00164 ///
00165 /// Note that this only does one level of inlining.  For example, if the
00166 /// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
00167 /// exists in the instruction stream.  Similiarly this will inline a recursive
00168 /// function by one level.
00169 ///
00170 /// If a non-null callgraph pointer is provided, these functions update the
00171 /// CallGraph to represent the program after inlining.
00172 ///
00173 bool InlineFunction(CallInst *C, CallGraph *CG = 0);
00174 bool InlineFunction(InvokeInst *II, CallGraph *CG = 0);
00175 bool InlineFunction(CallSite CS, CallGraph *CG = 0);
00176 
00177 } // End llvm namespace
00178 
00179 #endif