LLVM API Documentation

Scalar.h

Go to the documentation of this file.
00001 //===-- Scalar.h - Scalar Transformations -----------------------*- 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 header file defines prototypes for accessor functions that expose passes
00011 // in the Scalar transformations library.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #ifndef LLVM_TRANSFORMS_SCALAR_H
00016 #define LLVM_TRANSFORMS_SCALAR_H
00017 
00018 #include <cstdlib>
00019 
00020 namespace llvm {
00021 
00022 class ModulePass;
00023 class FunctionPass;
00024 class GetElementPtrInst;
00025 class PassInfo;
00026 class TerminatorInst;
00027 class TargetLowering;
00028 
00029 //===----------------------------------------------------------------------===//
00030 //
00031 // RaisePointerReferences - Try to eliminate as many pointer arithmetic
00032 // expressions as possible, by converting expressions to use getelementptr and
00033 // friends.
00034 //
00035 FunctionPass *createRaisePointerReferencesPass();
00036 
00037 //===----------------------------------------------------------------------===//
00038 //
00039 // Constant Propagation Pass - A worklist driven constant propagation pass
00040 //
00041 FunctionPass *createConstantPropagationPass();
00042 
00043 
00044 //===----------------------------------------------------------------------===//
00045 //
00046 // Sparse Conditional Constant Propagation Pass
00047 //
00048 FunctionPass *createSCCPPass();
00049 
00050 
00051 //===----------------------------------------------------------------------===//
00052 //
00053 // DeadInstElimination - This pass quickly removes trivially dead instructions
00054 // without modifying the CFG of the function.  It is a BasicBlockPass, so it
00055 // runs efficiently when queued next to other BasicBlockPass's.
00056 //
00057 FunctionPass *createDeadInstEliminationPass();
00058 
00059 
00060 //===----------------------------------------------------------------------===//
00061 //
00062 // DeadCodeElimination - This pass is more powerful than DeadInstElimination,
00063 // because it is worklist driven that can potentially revisit instructions when
00064 // their other instructions become dead, to eliminate chains of dead
00065 // computations.
00066 //
00067 FunctionPass *createDeadCodeEliminationPass();
00068 
00069 //===----------------------------------------------------------------------===//
00070 //
00071 // DeadStoreElimination - This pass deletes stores that are post-dominated by
00072 // must-aliased stores and are not loaded used between the stores.
00073 //
00074 FunctionPass *createDeadStoreEliminationPass();
00075 
00076 //===----------------------------------------------------------------------===//
00077 //
00078 // AggressiveDCE - This pass uses the SSA based Aggressive DCE algorithm.  This
00079 // algorithm assumes instructions are dead until proven otherwise, which makes
00080 // it more successful are removing non-obviously dead instructions.
00081 //
00082 FunctionPass *createAggressiveDCEPass();
00083 
00084 
00085 //===----------------------------------------------------------------------===//
00086 //
00087 // Scalar Replacement of Aggregates - Break up alloca's of aggregates into
00088 // multiple allocas if possible.
00089 //
00090 FunctionPass *createScalarReplAggregatesPass();
00091 
00092 
00093 //===----------------------------------------------------------------------===//
00094 //
00095 // GCSE - This pass is designed to be a very quick global transformation that
00096 // eliminates global common subexpressions from a function.  It does this by
00097 // examining the SSA value graph of the function, instead of doing slow
00098 // bit-vector computations.
00099 //
00100 FunctionPass *createGCSEPass();
00101 
00102 
00103 //===----------------------------------------------------------------------===//
00104 //
00105 // InductionVariableSimplify - Transform induction variables in a program to all
00106 // use a single canonical induction variable per loop.
00107 //
00108 FunctionPass *createIndVarSimplifyPass();
00109 
00110 
00111 //===----------------------------------------------------------------------===//
00112 //
00113 // InstructionCombining - Combine instructions to form fewer, simple
00114 //   instructions.  This pass does not modify the CFG, and has a tendency to
00115 //   make instructions dead, so a subsequent DCE pass is useful.
00116 //
00117 // This pass combines things like:
00118 //    %Y = add int 1, %X
00119 //    %Z = add int 1, %Y
00120 // into:
00121 //    %Z = add int 2, %X
00122 //
00123 FunctionPass *createInstructionCombiningPass();
00124 
00125 
00126 //===----------------------------------------------------------------------===//
00127 //
00128 // LICM - This pass is a loop invariant code motion and memory promotion pass.
00129 //
00130 FunctionPass *createLICMPass();
00131 
00132 //===----------------------------------------------------------------------===//
00133 //
00134 // LoopStrengthReduce - This pass is strength reduces GEP instructions that use
00135 // a loop's canonical induction variable as one of their indices.  It takes an
00136 // optional parameter used to consult the target machine whether certain
00137 // transformations are profitable.
00138 //
00139 FunctionPass *createLoopStrengthReducePass(const TargetLowering *TLI = NULL);
00140 
00141 //===----------------------------------------------------------------------===//
00142 //
00143 // LoopUnswitch - This pass is a simple loop unswitching pass.
00144 //
00145 FunctionPass *createLoopUnswitchPass();
00146 
00147 
00148 //===----------------------------------------------------------------------===//
00149 //
00150 // LoopUnroll - This pass is a simple loop unrolling pass.
00151 //
00152 FunctionPass *createLoopUnrollPass();
00153 
00154 //===----------------------------------------------------------------------===//
00155 //
00156 // This pass is used to promote memory references to be register references.  A
00157 // simple example of the transformation performed by this pass is:
00158 //
00159 //        FROM CODE                           TO CODE
00160 //   %X = alloca int, uint 1                 ret int 42
00161 //   store int 42, int *%X
00162 //   %Y = load int* %X
00163 //   ret int %Y
00164 //
00165 FunctionPass *createPromoteMemoryToRegisterPass();
00166 extern const PassInfo *PromoteMemoryToRegisterID;
00167 
00168 //===----------------------------------------------------------------------===//
00169 //
00170 // This pass is used to demote registers to memory references .
00171 // In basically undoes the PromoteMemoryToRegister pass to
00172 // make cfg hacking easier.
00173 FunctionPass *createDemoteRegisterToMemoryPass();
00174 extern const PassInfo *DemoteRegisterToMemoryID;
00175 
00176 //===----------------------------------------------------------------------===//
00177 //
00178 // This pass reassociates commutative expressions in an order that is designed
00179 // to promote better constant propagation, GCSE, LICM, PRE...
00180 //
00181 // For example:  4 + (x + 5)  ->  x + (4 + 5)
00182 //
00183 FunctionPass *createReassociatePass();
00184 
00185 //===----------------------------------------------------------------------===//
00186 //
00187 // This pass eliminates correlated conditions, such as these:
00188 //  if (X == 0)
00189 //    if (X > 2) ;   // Known false
00190 //    else
00191 //      Y = X * Z;   // = 0
00192 //
00193 FunctionPass *createCorrelatedExpressionEliminationPass();
00194 
00195 
00196 // createCondPropagationPass - This pass propagates information about
00197 // conditional expressions through the program, allowing it to eliminate
00198 // conditional branches in some cases.
00199 //
00200 FunctionPass *createCondPropagationPass();
00201 
00202 //===----------------------------------------------------------------------===//
00203 //
00204 // TailDuplication - Eliminate unconditional branches through controlled code
00205 // duplication, creating simpler CFG structures.
00206 //
00207 FunctionPass *createTailDuplicationPass();
00208 
00209 
00210 //===----------------------------------------------------------------------===//
00211 //
00212 // CFG Simplification - Merge basic blocks, eliminate unreachable blocks,
00213 // simplify terminator instructions, etc...
00214 //
00215 FunctionPass *createCFGSimplificationPass();
00216 
00217 
00218 //===----------------------------------------------------------------------===//
00219 //
00220 // BreakCriticalEdges pass - Break all of the critical edges in the CFG by
00221 // inserting a dummy basic block.  This pass may be "required" by passes that
00222 // cannot deal with critical edges.  For this usage, a pass must call:
00223 //
00224 //   AU.addRequiredID(BreakCriticalEdgesID);
00225 //
00226 // This pass obviously invalidates the CFG, but can update forward dominator
00227 // (set, immediate dominators, tree, and frontier) information.
00228 //
00229 FunctionPass *createBreakCriticalEdgesPass();
00230 extern const PassInfo *BreakCriticalEdgesID;
00231 
00232 //===----------------------------------------------------------------------===//
00233 //
00234 // LoopSimplify pass - Insert Pre-header blocks into the CFG for every function
00235 // in the module.  This pass updates dominator information, loop information,
00236 // and does not add critical edges to the CFG.
00237 //
00238 //   AU.addRequiredID(LoopSimplifyID);
00239 //
00240 FunctionPass *createLoopSimplifyPass();
00241 extern const PassInfo *LoopSimplifyID;
00242 
00243 //===----------------------------------------------------------------------===//
00244 // This pass converts SelectInst instructions into conditional branch and PHI
00245 // instructions.  If the OnlyFP flag is set to true, then only floating point
00246 // select instructions are lowered.
00247 //
00248 FunctionPass *createLowerSelectPass(bool OnlyFP = false);
00249 extern const PassInfo *LowerSelectID;
00250 
00251 //===----------------------------------------------------------------------===//
00252 //
00253 // LowerAllocations Pass - Turn malloc and free instructions into %malloc and
00254 // %free calls.
00255 //
00256 //   AU.addRequiredID(LowerAllocationsID);
00257 //
00258 FunctionPass *createLowerAllocationsPass(bool LowerMallocArgToInteger = false);
00259 extern const PassInfo *LowerAllocationsID;
00260 
00261 //===----------------------------------------------------------------------===//
00262 //
00263 // This pass eliminates call instructions to the current function which occur
00264 // immediately before return instructions.
00265 //
00266 FunctionPass *createTailCallEliminationPass();
00267 
00268 //===----------------------------------------------------------------------===//
00269 // This pass converts SwitchInst instructions into a sequence of chained binary
00270 // branch instructions.
00271 //
00272 FunctionPass *createLowerSwitchPass();
00273 extern const PassInfo *LowerSwitchID;
00274 
00275 //===----------------------------------------------------------------------===//
00276 // This pass converts PackedType operations into low-level scalar operations.
00277 //
00278 FunctionPass *createLowerPackedPass();
00279 
00280 //===----------------------------------------------------------------------===//
00281 // This pass converts invoke and unwind instructions to use sjlj exception
00282 // handling mechanisms.  Note that after this pass runs the CFG is not entirely
00283 // accurate (exceptional control flow edges are not correct anymore) so only
00284 // very simple things should be done after the lowerinvoke pass has run (like
00285 // generation of native code).  This should *NOT* be used as a general purpose
00286 // "my LLVM-to-LLVM pass doesn't support the invoke instruction yet" lowering
00287 // pass.
00288 //
00289 FunctionPass *createLowerInvokePass(unsigned JumBufSize = 200, 
00290                                     unsigned JumpBufAlign = 0);
00291 extern const PassInfo *LowerInvokePassID;
00292 
00293 
00294 //===----------------------------------------------------------------------===//
00295 /// createLowerGCPass - This function returns an instance of the "lowergc"
00296 /// pass, which lowers garbage collection intrinsics to normal LLVM code.
00297 ///
00298 FunctionPass *createLowerGCPass();
00299 
00300 //===----------------------------------------------------------------------===//
00301 // This pass reorders basic blocks in order to increase the number of fall-
00302 // through conditional branches.
00303 FunctionPass *createBlockPlacementPass();
00304 
00305 //===----------------------------------------------------------------------===//
00306 // This pass inserts phi nodes at loop boundaries to simplify other loop 
00307 // optimizations.
00308 FunctionPass *createLCSSAPass();
00309 extern const PassInfo *LCSSAID;
00310 
00311 } // End llvm namespace
00312 
00313 #endif