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
|
//===-- TransformInternals.cpp - Implement shared functions for transforms --=//
//
// This file defines shared functions used by the different components of the
// Transforms library.
//
//===----------------------------------------------------------------------===//
#include "TransformInternals.h"
#include "llvm/Type.h"
#include "llvm/Analysis/Expressions.h"
#include "llvm/Function.h"
#include "llvm/iOther.h"
// TargetData Hack: Eventually we will have annotations given to us by the
// backend so that we know stuff about type size and alignments. For now
// though, just use this, because it happens to match the model that GCC uses.
//
const TargetData TD("LevelRaise: Should be GCC though!");
static const Type *getStructOffsetStep(const StructType *STy, unsigned &Offset,
std::vector<Value*> &Indices) {
assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
const StructLayout *SL = TD.getStructLayout(STy);
// This loop terminates always on a 0 <= i < MemberOffsets.size()
unsigned i;
for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
break;
assert(Offset >= SL->MemberOffsets[i] &&
(i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
// Make sure to save the current index...
Indices.push_back(ConstantUInt::get(Type::UByteTy, i));
Offset = SL->MemberOffsets[i];
return STy->getContainedType(i);
}
// getStructOffsetType - Return a vector of offsets that are to be used to index
// into the specified struct type to get as close as possible to index as we
// can. Note that it is possible that we cannot get exactly to Offset, in which
// case we update offset to be the offset we actually obtained. The resultant
// leaf type is returned.
//
// If StopEarly is set to true (the default), the first object with the
// specified type is returned, even if it is a struct type itself. In this
// case, this routine will not drill down to the leaf type. Set StopEarly to
// false if you want a leaf
//
const Type *getStructOffsetType(const Type *Ty, unsigned &Offset,
std::vector<Value*> &Indices,
bool StopEarly = true) {
if (Offset == 0 && StopEarly && !Indices.empty())
return Ty; // Return the leaf type
unsigned ThisOffset;
const Type *NextType;
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
ThisOffset = Offset;
NextType = getStructOffsetStep(STy, ThisOffset, Indices);
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
assert(Offset < TD.getTypeSize(ATy) && "Offset not in composite!");
NextType = ATy->getElementType();
unsigned ChildSize = TD.getTypeSize(NextType);
Indices.push_back(ConstantUInt::get(Type::UIntTy, Offset/ChildSize));
ThisOffset = (Offset/ChildSize)*ChildSize;
} else {
Offset = 0; // Return the offset that we were able to acheive
return Ty; // Return the leaf type
}
unsigned SubOffs = Offset - ThisOffset;
const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
Indices, StopEarly);
Offset = ThisOffset + SubOffs;
return LeafTy;
}
// ConvertableToGEP - This function returns true if the specified value V is
// a valid index into a pointer of type Ty. If it is valid, Idx is filled in
// with the values that would be appropriate to make this a getelementptr
// instruction. The type returned is the root type that the GEP would point to
//
const Type *ConvertableToGEP(const Type *Ty, Value *OffsetVal,
std::vector<Value*> &Indices,
BasicBlock::iterator *BI = 0) {
const CompositeType *CompTy = dyn_cast<CompositeType>(Ty);
if (CompTy == 0) return 0;
// See if the cast is of an integer expression that is either a constant,
// or a value scaled by some amount with a possible offset.
//
analysis::ExprType Expr = analysis::ClassifyExpression(OffsetVal);
// Get the offset and scale values if they exists...
// A scale of zero with Expr.Var != 0 means a scale of 1.
//
int Offset = Expr.Offset ? getConstantValue(Expr.Offset) : 0;
int Scale = Expr.Scale ? getConstantValue(Expr.Scale) : 0;
if (Expr.Var && Scale == 0) Scale = 1; // Scale != 0 if Expr.Var != 0
// Loop over the Scale and Offset values, filling in the Indices vector for
// our final getelementptr instruction.
//
const Type *NextTy = CompTy;
do {
if (!isa<CompositeType>(NextTy))
return 0; // Type must not be ready for processing...
CompTy = cast<CompositeType>(NextTy);
if (const StructType *StructTy = dyn_cast<StructType>(CompTy)) {
// Step into the appropriate element of the structure...
unsigned ActualOffset = (Offset < 0) ? 0 : (unsigned)Offset;
NextTy = getStructOffsetStep(StructTy, ActualOffset, Indices);
Offset -= ActualOffset;
} else {
const Type *ElTy = cast<SequentialType>(CompTy)->getElementType();
if (!ElTy->isSized())
return 0; // Type is unreasonable... escape!
unsigned ElSize = TD.getTypeSize(ElTy);
int ElSizeS = (int)ElSize;
// See if the user is indexing into a different cell of this array...
if (Scale && (Scale >= ElSizeS || -Scale >= ElSizeS)) {
// A scale n*ElSize might occur if we are not stepping through
// array by one. In this case, we will have to insert math to munge
// the index.
//
int ScaleAmt = Scale/ElSizeS;
if (Scale-ScaleAmt*ElSizeS)
return 0; // Didn't scale by a multiple of element size, bail out
Scale = 0; // Scale is consumed
int Index = Offset/ElSize; // is zero unless Offset > ElSize
Offset -= Index*ElSize; // Consume part of the offset
if (BI) { // Generate code?
BasicBlock *BB = (*BI)->getParent();
if (Expr.Var->getType() != Type::UIntTy) {
CastInst *IdxCast = new CastInst(Expr.Var, Type::UIntTy);
if (Expr.Var->hasName())
IdxCast->setName(Expr.Var->getName()+"-idxcast");
*BI = ++BB->getInstList().insert(*BI, IdxCast);
Expr.Var = IdxCast;
}
if (ScaleAmt && ScaleAmt != 1) {
// If we have to scale up our index, do so now
Value *ScaleAmtVal = ConstantUInt::get(Type::UIntTy,
(unsigned)ScaleAmt);
Instruction *Scaler = BinaryOperator::create(Instruction::Mul,
Expr.Var, ScaleAmtVal);
if (Expr.Var->hasName())
Scaler->setName(Expr.Var->getName()+"-scale");
*BI = ++BB->getInstList().insert(*BI, Scaler);
Expr.Var = Scaler;
}
if (Index) { // Add an offset to the index
Value *IndexAmt = ConstantUInt::get(Type::UIntTy, (unsigned)Index);
Instruction *Offseter = BinaryOperator::create(Instruction::Add,
Expr.Var, IndexAmt);
if (Expr.Var->hasName())
Offseter->setName(Expr.Var->getName()+"-offset");
*BI = ++BB->getInstList().insert(*BI, Offseter);
Expr.Var = Offseter;
}
}
Indices.push_back(Expr.Var);
Expr.Var = 0;
} else if (Offset >= (int)ElSize || -Offset >= (int)ElSize) {
// Calculate the index that we are entering into the array cell with
unsigned Index = Offset/ElSize;
Indices.push_back(ConstantUInt::get(Type::UIntTy, Index));
Offset -= (int)(Index*ElSize); // Consume part of the offset
} else if (isa<ArrayType>(CompTy) || Indices.empty()) {
// Must be indexing a small amount into the first cell of the array
// Just index into element zero of the array here.
//
Indices.push_back(ConstantUInt::get(Type::UIntTy, 0));
} else {
return 0; // Hrm. wierd, can't handle this case. Bail
}
NextTy = ElTy;
}
} while (Offset || Scale); // Go until we're done!
return NextTy;
}
|
