1 //===-- Scalar.h - Scalar Transformations -----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This header file defines prototypes for accessor functions that expose passes
11 // in the Scalar transformations library.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_TRANSFORMS_SCALAR_H
16 #define LLVM_TRANSFORMS_SCALAR_H
22 class GetElementPtrInst;
26 //===----------------------------------------------------------------------===//
28 // RaisePointerReferences - Try to eliminate as many pointer arithmetic
29 // expressions as possible, by converting expressions to use getelementptr and
32 FunctionPass *createRaisePointerReferencesPass();
34 //===----------------------------------------------------------------------===//
36 // Constant Propagation Pass - A worklist driven constant propagation pass
38 FunctionPass *createConstantPropagationPass();
41 //===----------------------------------------------------------------------===//
43 // Sparse Conditional Constant Propagation Pass
45 FunctionPass *createSCCPPass();
48 //===----------------------------------------------------------------------===//
50 // DeadInstElimination - This pass quickly removes trivially dead instructions
51 // without modifying the CFG of the function. It is a BasicBlockPass, so it
52 // runs efficiently when queued next to other BasicBlockPass's.
54 FunctionPass *createDeadInstEliminationPass();
57 //===----------------------------------------------------------------------===//
59 // DeadCodeElimination - This pass is more powerful than DeadInstElimination,
60 // because it is worklist driven that can potentially revisit instructions when
61 // their other instructions become dead, to eliminate chains of dead
64 FunctionPass *createDeadCodeEliminationPass();
66 //===----------------------------------------------------------------------===//
68 // DeadStoreElimination - This pass deletes stores that are post-dominated by
69 // must-aliased stores and are not loaded used between the stores.
71 FunctionPass *createDeadStoreEliminationPass();
73 //===----------------------------------------------------------------------===//
75 // AggressiveDCE - This pass uses the SSA based Aggressive DCE algorithm. This
76 // algorithm assumes instructions are dead until proven otherwise, which makes
77 // it more successful are removing non-obviously dead instructions.
79 FunctionPass *createAggressiveDCEPass();
82 //===----------------------------------------------------------------------===//
84 // Scalar Replacement of Aggregates - Break up alloca's of aggregates into
85 // multiple allocas if possible.
87 FunctionPass *createScalarReplAggregatesPass();
89 //===----------------------------------------------------------------------===//
91 // DecomposeMultiDimRefs - Convert multi-dimensional references consisting of
92 // any combination of 2 or more array and structure indices into a sequence of
93 // instructions (using getelementpr and cast) so that each instruction has at
94 // most one index (except structure references, which need an extra leading
97 // This pass decomposes all multi-dimensional references in a function.
98 FunctionPass *createDecomposeMultiDimRefsPass();
100 // This function decomposes a single instance of such a reference.
101 // Return value: true if the instruction was replaced; false otherwise.
103 bool DecomposeArrayRef(GetElementPtrInst* GEP);
105 //===----------------------------------------------------------------------===//
107 // GCSE - This pass is designed to be a very quick global transformation that
108 // eliminates global common subexpressions from a function. It does this by
109 // examining the SSA value graph of the function, instead of doing slow
110 // bit-vector computations.
112 FunctionPass *createGCSEPass();
115 //===----------------------------------------------------------------------===//
117 // InductionVariableSimplify - Transform induction variables in a program to all
118 // use a single canonical induction variable per loop.
120 FunctionPass *createIndVarSimplifyPass();
123 //===----------------------------------------------------------------------===//
125 // InstructionCombining - Combine instructions to form fewer, simple
126 // instructions. This pass does not modify the CFG, and has a tendency to
127 // make instructions dead, so a subsequent DCE pass is useful.
129 // This pass combines things like:
130 // %Y = add int 1, %X
131 // %Z = add int 1, %Y
133 // %Z = add int 2, %X
135 FunctionPass *createInstructionCombiningPass();
138 //===----------------------------------------------------------------------===//
140 // LICM - This pass is a loop invariant code motion and memory promotion pass.
142 FunctionPass *createLICMPass();
145 //===----------------------------------------------------------------------===//
147 // LoopUnswitch - This pass is a simple loop unswitching pass.
149 FunctionPass *createLoopUnswitchPass();
152 //===----------------------------------------------------------------------===//
154 // LoopUnroll - This pass is a simple loop unrolling pass.
156 FunctionPass *createLoopUnrollPass();
159 //===----------------------------------------------------------------------===//
161 // This pass is used to promote memory references to be register references. A
162 // simple example of the transformation performed by this pass is:
165 // %X = alloca int, uint 1 ret int 42
166 // store int 42, int *%X
170 FunctionPass *createPromoteMemoryToRegister();
173 //===----------------------------------------------------------------------===//
175 // This pass reassociates commutative expressions in an order that is designed
176 // to promote better constant propagation, GCSE, LICM, PRE...
178 // For example: 4 + (x + 5) -> x + (4 + 5)
180 FunctionPass *createReassociatePass();
182 //===----------------------------------------------------------------------===//
184 // This pass eliminates correlated conditions, such as these:
186 // if (X > 2) ; // Known false
190 FunctionPass *createCorrelatedExpressionEliminationPass();
192 //===----------------------------------------------------------------------===//
194 // TailDuplication - Eliminate unconditional branches through controlled code
195 // duplication, creating simpler CFG structures.
197 FunctionPass *createTailDuplicationPass();
200 //===----------------------------------------------------------------------===//
202 // CFG Simplification - Merge basic blocks, eliminate unreachable blocks,
203 // simplify terminator instructions, etc...
205 FunctionPass *createCFGSimplificationPass();
208 //===----------------------------------------------------------------------===//
210 // BreakCriticalEdges pass - Break all of the critical edges in the CFG by
211 // inserting a dummy basic block. This pass may be "required" by passes that
212 // cannot deal with critical edges. For this usage, a pass must call:
214 // AU.addRequiredID(BreakCriticalEdgesID);
216 // This pass obviously invalidates the CFG, but can update forward dominator
217 // (set, immediate dominators, tree, and frontier) information.
219 FunctionPass *createBreakCriticalEdgesPass();
220 extern const PassInfo *BreakCriticalEdgesID;
222 //===----------------------------------------------------------------------===//
224 // LoopSimplify pass - Insert Pre-header blocks into the CFG for every function
225 // in the module. This pass updates dominator information, loop information,
226 // and does not add critical edges to the CFG.
228 // AU.addRequiredID(LoopSimplifyID);
230 FunctionPass *createLoopSimplifyPass();
231 extern const PassInfo *LoopSimplifyID;
233 //===----------------------------------------------------------------------===//
235 // This pass eliminates call instructions to the current function which occur
236 // immediately before return instructions.
238 FunctionPass *createTailCallEliminationPass();
241 //===----------------------------------------------------------------------===//
242 // This pass convert malloc and free instructions to %malloc & %free function
245 FunctionPass *createLowerAllocationsPass();
247 //===----------------------------------------------------------------------===//
248 // This pass converts SwitchInst instructions into a sequence of chained binary
249 // branch instructions.
251 FunctionPass *createLowerSwitchPass();
253 //===----------------------------------------------------------------------===//
254 // This pass converts SelectInst instructions into conditional branch and PHI
255 // instructions. If the OnlyFP flag is set to true, then only floating point
256 // select instructions are lowered.
258 FunctionPass *createLowerSelectPass(bool OnlyFP = false);
260 //===----------------------------------------------------------------------===//
261 // This pass converts invoke and unwind instructions to use sjlj exception
262 // handling mechanisms. Note that after this pass runs the CFG is not entirely
263 // accurate (exceptional control flow edges are not correct anymore) so only
264 // very simple things should be done after the lowerinvoke pass has run (like
265 // generation of native code). This should *NOT* be used as a general purpose
266 // "my LLVM-to-LLVM pass doesn't support the invoke instruction yet" lowering
269 FunctionPass *createLowerInvokePass();
270 extern const PassInfo *LowerInvokePassID;
273 //===----------------------------------------------------------------------===//
274 /// createLowerGCPass - This function returns an instance of the "lowergc"
275 /// pass, which lowers garbage collection intrinsics to normal LLVM code.
277 FunctionPass *createLowerGCPass();
279 //===----------------------------------------------------------------------===//
280 // Returns a pass which converts all instances of ConstantExpression
281 // into regular LLVM instructions.
282 FunctionPass* createLowerConstantExpressionsPass();
285 //===----------------------------------------------------------------------===//
287 // These functions removes symbols from functions and modules.
289 FunctionPass *createSymbolStrippingPass();
290 FunctionPass *createFullSymbolStrippingPass();
292 } // End llvm namespace