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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
//===-- BBLiveVar.cpp - Live Variable Analysis for a BasicBlock -----------===//
//
// This is a wrapper class for BasicBlock which is used by live var analysis.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LiveVar/BBLiveVar.h"
#include "llvm/Analysis/LiveVar/MethodLiveVarInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/BasicBlock.h"
/// BROKEN: Should not include sparc stuff directly into here
#include "../../Target/Sparc/SparcInternals.h" // Only for PHI defn
using std::cerr;
BBLiveVar::BBLiveVar(const BasicBlock *bb, unsigned id)
: BB(bb), POID(id) {
InSetChanged = OutSetChanged = false;
}
//-----------------------------------------------------------------------------
// calculates def and use sets for each BB
// There are two passes over operands of a machine instruction. This is
// because, we can have instructions like V = V + 1, since we no longer
// assume single definition.
//-----------------------------------------------------------------------------
void BBLiveVar::calcDefUseSets() {
// get the iterator for machine instructions
const MachineCodeForBasicBlock &MIVec = BB->getMachineInstrVec();
// iterate over all the machine instructions in BB
for (MachineCodeForBasicBlock::const_reverse_iterator MII = MIVec.rbegin(),
MIE = MIVec.rend(); MII != MIE; ++MII) {
const MachineInstr *MI = *MII;
if (DEBUG_LV > 1) { // debug msg
cerr << " *Iterating over machine instr ";
MI->dump();
cerr << "\n";
}
// iterate over MI operands to find defs
for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI)
if (OpI.isDef()) // add to Defs only if this operand is a def
addDef(*OpI);
// do for implicit operands as well
for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i)
if (MI->implicitRefIsDefined(i))
addDef(MI->getImplicitRef(i));
bool IsPhi = MI->getOpCode() == PHI;
// iterate over MI operands to find uses
for (MachineInstr::val_const_op_iterator OpI(MI); !OpI.done(); ++OpI) {
const Value *Op = *OpI;
if (Op->getType()->isLabelType())
continue; // don't process labels
if (!OpI.isDef()) { // add to Defs only if this operand is a use
addUse(Op);
if (IsPhi) { // for a phi node
// put args into the PhiArgMap (Val -> BB)
const Value *ArgVal = Op;
const Value *BBVal = *++OpI; // increment to point to BB of value
PhiArgMap[ArgVal] = cast<BasicBlock>(BBVal);
if (DEBUG_LV > 1) {
cerr << " - phi operand ";
printValue(ArgVal);
cerr << " came from BB ";
printValue(PhiArgMap[ArgVal]);
cerr << "\n";
}
} // if( IsPhi )
} // if a use
} // for all operands
// do for implicit operands as well
for (unsigned i = 0; i < MI->getNumImplicitRefs(); ++i) {
assert(!IsPhi && "Phi cannot have implicit opeands");
const Value *Op = MI->getImplicitRef(i);
if (Op->getType()->isLabelType()) // don't process labels
continue;
if (!MI->implicitRefIsDefined(i))
addUse(Op);
}
} // for all machine instructions
}
//-----------------------------------------------------------------------------
// To add an operand which is a def
//-----------------------------------------------------------------------------
void BBLiveVar::addDef(const Value *Op) {
DefSet.insert(Op); // operand is a def - so add to def set
InSet.erase(Op); // this definition kills any uses
InSetChanged = true;
if (DEBUG_LV > 1) {
cerr << " +Def: "; printValue( Op ); cerr << "\n";
}
}
//-----------------------------------------------------------------------------
// To add an operand which is a use
//-----------------------------------------------------------------------------
void BBLiveVar::addUse(const Value *Op) {
InSet.insert(Op); // An operand is a use - so add to use set
OutSet.erase(Op); // remove if there is a def below this use
InSetChanged = true;
if (DEBUG_LV > 1) {
cerr << " Use: "; printValue( Op ); cerr << "\n";
}
}
//-----------------------------------------------------------------------------
// Applies the transfer function to a basic block to produce the InSet using
// the outset.
//-----------------------------------------------------------------------------
bool BBLiveVar::applyTransferFunc() {
// IMPORTANT: caller should check whether the OutSet changed
// (else no point in calling)
LiveVarSet OutMinusDef; // set to hold (Out[B] - Def[B])
OutMinusDef.setDifference(&OutSet, &DefSet);
InSetChanged = InSet.setUnion(&OutMinusDef);
OutSetChanged = false; // no change to OutSet since transf func applied
return InSetChanged;
}
//-----------------------------------------------------------------------------
// calculates Out set using In sets of the predecessors
//-----------------------------------------------------------------------------
bool BBLiveVar::setPropagate(LiveVarSet *OutSet, const LiveVarSet *InSet,
const BasicBlock *PredBB) {
bool Changed = false;
// for all all elements in InSet
for (LiveVarSet::const_iterator InIt = InSet->begin(), InE = InSet->end();
InIt != InE; ++InIt) {
const BasicBlock *PredBBOfPhiArg = PhiArgMap[*InIt];
// if this var is not a phi arg OR
// it's a phi arg and the var went down from this BB
if (!PredBBOfPhiArg || PredBBOfPhiArg == PredBB)
if (OutSet->insert(*InIt).second)
Changed = true;
}
return Changed;
}
//-----------------------------------------------------------------------------
// propogates in set to OutSets of PREDECESSORs
//-----------------------------------------------------------------------------
bool BBLiveVar::applyFlowFunc(std::map<const BasicBlock *, BBLiveVar *> &LVMap){
// IMPORTANT: caller should check whether inset changed
// (else no point in calling)
// If this BB changed any OutSets of preds whose POID is lower, than we need
// another iteration...
//
bool needAnotherIt = false;
for (BasicBlock::pred_const_iterator PI = BB->pred_begin(),
PE = BB->pred_begin(); PI != PE ; ++PI) {
BBLiveVar *PredLVBB = LVMap[*PI];
// do set union
if (setPropagate(&PredLVBB->OutSet, &InSet, *PI)) {
PredLVBB->OutSetChanged = true;
// if the predec POID is lower than mine
if (PredLVBB->getPOId() <= POID)
needAnotherIt = true;
}
} // for
return needAnotherIt;
}
// ----------------- Methods For Debugging (Printing) -----------------
void BBLiveVar::printAllSets() const {
cerr << " Defs: "; DefSet.printSet(); cerr << "\n";
cerr << " In: "; InSet.printSet(); cerr << "\n";
cerr << " Out: "; OutSet.printSet(); cerr << "\n";
}
void BBLiveVar::printInOutSets() const {
cerr << " In: "; InSet.printSet(); cerr << "\n";
cerr << " Out: "; OutSet.printSet(); cerr << "\n";
}
|
