1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
//===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This family of functions perform various local transformations to the
// program.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
#define LLVM_TRANSFORMS_UTILS_LOCAL_H
namespace llvm {
class User;
class BasicBlock;
class Function;
class BranchInst;
class Instruction;
class DbgDeclareInst;
class StoreInst;
class Value;
class Pass;
class PHINode;
class AllocaInst;
class ConstantExpr;
class TargetData;
class DIBuilder;
template<typename T> class SmallVectorImpl;
//===----------------------------------------------------------------------===//
// Local constant propagation.
//
/// ConstantFoldTerminator - If a terminator instruction is predicated on a
/// constant value, convert it into an unconditional branch to the constant
/// destination. This is a nontrivial operation because the successors of this
/// basic block must have their PHI nodes updated.
///
bool ConstantFoldTerminator(BasicBlock *BB);
//===----------------------------------------------------------------------===//
// Local dead code elimination.
//
/// isInstructionTriviallyDead - Return true if the result produced by the
/// instruction is not used, and the instruction has no side effects.
///
bool isInstructionTriviallyDead(Instruction *I);
/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
/// trivially dead instruction, delete it. If that makes any of its operands
/// trivially dead, delete them too, recursively. Return true if any
/// instructions were deleted.
bool RecursivelyDeleteTriviallyDeadInstructions(Value *V);
/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
/// dead PHI node, due to being a def-use chain of single-use nodes that
/// either forms a cycle or is terminated by a trivially dead instruction,
/// delete it. If that makes any of its operands trivially dead, delete them
/// too, recursively. Return true if a change was made.
bool RecursivelyDeleteDeadPHINode(PHINode *PN);
/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
/// simplify any instructions in it and recursively delete dead instructions.
///
/// This returns true if it changed the code, note that it can delete
/// instructions in other blocks as well in this block.
///
/// WARNING: Do not use this function on unreachable blocks, as recursive
/// simplification is not able to handle corner-case scenarios that can
/// arise in them.
bool SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD = 0);
//===----------------------------------------------------------------------===//
// Control Flow Graph Restructuring.
//
/// RemovePredecessorAndSimplify - Like BasicBlock::removePredecessor, this
/// method is called when we're about to delete Pred as a predecessor of BB. If
/// BB contains any PHI nodes, this drops the entries in the PHI nodes for Pred.
///
/// Unlike the removePredecessor method, this attempts to simplify uses of PHI
/// nodes that collapse into identity values. For example, if we have:
/// x = phi(1, 0, 0, 0)
/// y = and x, z
///
/// .. and delete the predecessor corresponding to the '1', this will attempt to
/// recursively fold the 'and' to 0.
void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
TargetData *TD = 0);
/// MergeBasicBlockIntoOnlyPred - BB is a block with one predecessor and its
/// predecessor is known to have one successor (BB!). Eliminate the edge
/// between them, moving the instructions in the predecessor into BB. This
/// deletes the predecessor block.
///
void MergeBasicBlockIntoOnlyPred(BasicBlock *BB, Pass *P = 0);
/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
/// unconditional branch, and contains no instructions other than PHI nodes,
/// potential debug intrinsics and the branch. If possible, eliminate BB by
/// rewriting all the predecessors to branch to the successor block and return
/// true. If we can't transform, return false.
bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB);
/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
/// nodes in this block. This doesn't try to be clever about PHI nodes
/// which differ only in the order of the incoming values, but instcombine
/// orders them so it usually won't matter.
///
bool EliminateDuplicatePHINodes(BasicBlock *BB);
/// SimplifyCFG - This function is used to do simplification of a CFG. For
/// example, it adjusts branches to branches to eliminate the extra hop, it
/// eliminates unreachable basic blocks, and does other "peephole" optimization
/// of the CFG. It returns true if a modification was made, possibly deleting
/// the basic block that was pointed to.
///
bool SimplifyCFG(BasicBlock *BB, const TargetData *TD = 0);
/// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
/// and if a predecessor branches to us and one of our successors, fold the
/// setcc into the predecessor and use logical operations to pick the right
/// destination.
bool FoldBranchToCommonDest(BranchInst *BI);
/// DemoteRegToStack - This function takes a virtual register computed by an
/// Instruction and replaces it with a slot in the stack frame, allocated via
/// alloca. This allows the CFG to be changed around without fear of
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for X.
///
AllocaInst *DemoteRegToStack(Instruction &X,
bool VolatileLoads = false,
Instruction *AllocaPoint = 0);
/// DemotePHIToStack - This function takes a virtual register computed by a phi
/// node and replaces it with a slot in the stack frame, allocated via alloca.
/// The phi node is deleted and it returns the pointer to the alloca inserted.
AllocaInst *DemotePHIToStack(PHINode *P, Instruction *AllocaPoint = 0);
/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
/// and it is more than the alignment of the ultimate object, see if we can
/// increase the alignment of the ultimate object, making this check succeed.
unsigned getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
const TargetData *TD = 0);
/// getKnownAlignment - Try to infer an alignment for the specified pointer.
static inline unsigned getKnownAlignment(Value *V, const TargetData *TD = 0) {
return getOrEnforceKnownAlignment(V, 0, TD);
}
///===---------------------------------------------------------------------===//
/// Dbg Intrinsic utilities
///
/// Inserts a llvm.dbg.value instrinsic before the stores to an alloca'd value
/// that has an associated llvm.dbg.decl intrinsic.
bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
StoreInst *SI, DIBuilder &Builder);
/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
/// of llvm.dbg.value intrinsics.
bool LowerDbgDeclare(Function &F);
} // End llvm namespace
#endif
|
