1 //===-- Scalar.h - Scalar Transformations ------------------------*- C++ -*-==//
3 // This header file defines prototypes for accessor functions that expose passes
4 // in the Scalar transformations library.
6 //===----------------------------------------------------------------------===//
8 #ifndef LLVM_TRANSFORMS_SCALAR_H
9 #define LLVM_TRANSFORMS_SCALAR_H
14 class GetElementPtrInst;
16 //===----------------------------------------------------------------------===//
18 // Constant Propogation Pass - A worklist driven constant propogation pass
20 Pass *createConstantPropogationPass();
23 //===----------------------------------------------------------------------===//
25 // Sparse Conditional Constant Propogation Pass
27 Pass *createSCCPPass();
30 //===----------------------------------------------------------------------===//
32 // DeadInstElimination - This pass quickly removes trivially dead instructions
33 // without modifying the CFG of the function. It is a BasicBlockPass, so it
34 // runs efficiently when queued next to other BasicBlockPass's.
36 Pass *createDeadInstEliminationPass();
39 //===----------------------------------------------------------------------===//
41 // DeadCodeElimination - This pass is more powerful than DeadInstElimination,
42 // because it is worklist driven that can potentially revisit instructions when
43 // their other instructions become dead, to eliminate chains of dead
46 Pass *createDeadCodeEliminationPass();
49 //===----------------------------------------------------------------------===//
51 // AggressiveDCE - This pass uses the SSA based Aggressive DCE algorithm. This
52 // algorithm assumes instructions are dead until proven otherwise, which makes
53 // it more successful are removing non-obviously dead instructions.
55 Pass *createAggressiveDCEPass();
58 //===----------------------------------------------------------------------===//
60 // DecomposeMultiDimRefs - Convert multi-dimensional references consisting of
61 // any combination of 2 or more array and structure indices into a sequence of
62 // instructions (using getelementpr and cast) so that each instruction has at
63 // most one index (except structure references, which need an extra leading
66 // This pass decomposes all multi-dimensional references in a function.
67 Pass *createDecomposeMultiDimRefsPass();
69 // This function decomposes a single instance of such a reference.
70 // Return value: true if the instruction was replaced; false otherwise.
72 bool DecomposeArrayRef(GetElementPtrInst* GEP);
74 //===----------------------------------------------------------------------===//
76 // GCSE - This pass is designed to be a very quick global transformation that
77 // eliminates global common subexpressions from a function. It does this by
78 // examining the SSA value graph of the function, instead of doing slow
79 // bit-vector computations.
81 Pass *createGCSEPass();
84 //===----------------------------------------------------------------------===//
86 // InductionVariableSimplify - Transform induction variables in a program to all
87 // use a single cannonical induction variable per loop.
89 Pass *createIndVarSimplifyPass();
92 //===----------------------------------------------------------------------===//
94 // InstructionCombining - Combine instructions to form fewer, simple
95 // instructions. This pass does not modify the CFG, and has a tendancy to
96 // make instructions dead, so a subsequent DCE pass is useful.
98 // This pass combines things like:
100 // %Z = add int 1, %Y
102 // %Z = add int 2, %X
104 Pass *createInstructionCombiningPass();
107 //===----------------------------------------------------------------------===//
109 // LICM - This pass is a simple natural loop based loop invariant code motion
112 Pass *createLICMPass();
115 //===----------------------------------------------------------------------===//
117 // PiNodeInsertion - This pass inserts single entry Phi nodes into basic blocks
118 // that are preceeded by a conditional branch, where the branch gives
119 // information about the operands of the condition. For example, this C code:
120 // if (x == 0) { ... = x + 4;
123 // x2 = phi(x); // Node that can hold data flow information about X
126 // Since the direction of the condition branch gives information about X itself
127 // (whether or not it is zero), some passes (like value numbering or ABCD) can
128 // use the inserted Phi/Pi nodes as a place to attach information, in this case
129 // saying that X has a value of 0 in this scope. The power of this analysis
130 // information is that "in the scope" translates to "for all uses of x2".
132 // This special form of Phi node is refered to as a Pi node, following the
133 // terminology defined in the "Array Bounds Checks on Demand" paper.
135 Pass *createPiNodeInsertionPass();
138 //===----------------------------------------------------------------------===//
140 // This pass is used to promote memory references to be register references. A
141 // simple example of the transformation performed by this pass is:
144 // %X = alloca int, uint 1 ret int 42
145 // store int 42, int *%X
149 Pass *createPromoteMemoryToRegister();
152 //===----------------------------------------------------------------------===//
154 // This pass reassociates commutative expressions in an order that is designed
155 // to promote better constant propogation, GCSE, LICM, PRE...
157 // For example: 4 + (x + 5) -> x + (4 + 5)
159 Pass *createReassociatePass();
161 //===----------------------------------------------------------------------===//
163 // This pass eliminates correlated conditions, such as these:
165 // if (X > 2) // Known false
169 Pass *createCorrelatedExpressionEliminationPass();
171 //===----------------------------------------------------------------------===//
173 // CFG Simplification - Merge basic blocks, eliminate unreachable blocks,
174 // simplify terminator instructions, etc...
176 Pass *createCFGSimplificationPass();
178 //===----------------------------------------------------------------------===//
180 // BreakCriticalEdges pass - Break all of the critical edges in the CFG by
181 // inserting a dummy basic block. This pass may be "required" by passes that
182 // cannot deal with critical edges. For this usage, the structure type is
183 // forward declared. This pass obviously invalidates the CFG, but can update
184 // forward dominator (set, immediate dominators, and tree) information.
186 class BreakCriticalEdges;
187 Pass *createBreakCriticalEdgesPass();
189 //===----------------------------------------------------------------------===//
190 // These two passes convert malloc and free instructions to and from %malloc &
191 // %free function calls. The LowerAllocations transformation is a target
192 // dependant tranformation because it depends on the size of data types and
193 // alignment constraints.
195 Pass *createLowerAllocationsPass(const TargetData &TD);
196 Pass *createRaiseAllocationsPass();
199 //===----------------------------------------------------------------------===//
201 // These functions removes symbols from functions and modules.
203 Pass *createSymbolStrippingPass();
204 Pass *createFullSymbolStrippingPass();