1 //===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
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 family of functions determines the possibility of performing constant
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/ConstantFolding.h"
16 #include "llvm/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Instructions.h"
19 #include "llvm/Intrinsics.h"
20 #include "llvm/Support/GetElementPtrTypeIterator.h"
21 #include "llvm/Support/MathExtras.h"
26 //===----------------------------------------------------------------------===//
27 // Constant Folding ...
31 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
32 /// the specified function.
34 llvm::canConstantFoldCallTo(Function *F) {
35 const std::string &Name = F->getName();
37 switch (F->getIntrinsicID()) {
38 case Intrinsic::sqrt_f32:
39 case Intrinsic::sqrt_f64:
40 case Intrinsic::bswap_i16:
41 case Intrinsic::bswap_i32:
42 case Intrinsic::bswap_i64:
43 // FIXME: these should be constant folded as well
44 //case Intrinsic::ctpop_i8:
45 //case Intrinsic::ctpop_i16:
46 //case Intrinsic::ctpop_i32:
47 //case Intrinsic::ctpop_i64:
48 //case Intrinsic::ctlz_i8:
49 //case Intrinsic::ctlz_i16:
50 //case Intrinsic::ctlz_i32:
51 //case Intrinsic::ctlz_i64:
52 //case Intrinsic::cttz_i8:
53 //case Intrinsic::cttz_i16:
54 //case Intrinsic::cttz_i32:
55 //case Intrinsic::cttz_i64:
63 return Name == "acos" || Name == "asin" || Name == "atan" ||
66 return Name == "ceil" || Name == "cos" || Name == "cosf" ||
71 return Name == "fabs" || Name == "fmod" || Name == "floor";
73 return Name == "log" || Name == "log10";
77 return Name == "sin" || Name == "sinh" ||
78 Name == "sqrt" || Name == "sqrtf";
80 return Name == "tan" || Name == "tanh";
87 llvm::ConstantFoldFP(double (*NativeFP)(double), double V, const Type *Ty) {
91 return ConstantFP::get(Ty, V);
95 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
96 /// with the specified arguments, returning null if unsuccessful.
98 llvm::ConstantFoldCall(Function *F, const std::vector<Constant*> &Operands) {
99 const std::string &Name = F->getName();
100 const Type *Ty = F->getReturnType();
102 if (Operands.size() == 1) {
103 if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
104 double V = Op->getValue();
109 return ConstantFoldFP(acos, V, Ty);
110 else if (Name == "asin")
111 return ConstantFoldFP(asin, V, Ty);
112 else if (Name == "atan")
113 return ConstantFP::get(Ty, atan(V));
117 return ConstantFoldFP(ceil, V, Ty);
118 else if (Name == "cos")
119 return ConstantFP::get(Ty, cos(V));
120 else if (Name == "cosh")
121 return ConstantFP::get(Ty, cosh(V));
125 return ConstantFP::get(Ty, exp(V));
129 return ConstantFP::get(Ty, fabs(V));
130 else if (Name == "floor")
131 return ConstantFoldFP(floor, V, Ty);
134 if (Name == "log" && V > 0)
135 return ConstantFP::get(Ty, log(V));
136 else if (Name == "log10" && V > 0)
137 return ConstantFoldFP(log10, V, Ty);
138 else if (Name == "llvm.sqrt.f32" || Name == "llvm.sqrt.f64") {
140 return ConstantFP::get(Ty, sqrt(V));
142 return ConstantFP::get(Ty, 0.0);
147 return ConstantFP::get(Ty, sin(V));
148 else if (Name == "sinh")
149 return ConstantFP::get(Ty, sinh(V));
150 else if (Name == "sqrt" && V >= 0)
151 return ConstantFP::get(Ty, sqrt(V));
152 else if (Name == "sqrtf" && V >= 0)
153 return ConstantFP::get(Ty, sqrt((float)V));
157 return ConstantFP::get(Ty, tan(V));
158 else if (Name == "tanh")
159 return ConstantFP::get(Ty, tanh(V));
164 } else if (ConstantInt *Op = dyn_cast<ConstantInt>(Operands[0])) {
165 uint64_t V = Op->getZExtValue();
166 if (Name == "llvm.bswap.i16")
167 return ConstantInt::get(Ty, ByteSwap_16(V));
168 else if (Name == "llvm.bswap.i32")
169 return ConstantInt::get(Ty, ByteSwap_32(V));
170 else if (Name == "llvm.bswap.i64")
171 return ConstantInt::get(Ty, ByteSwap_64(V));
173 } else if (Operands.size() == 2) {
174 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
175 double Op1V = Op1->getValue();
176 if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
177 double Op2V = Op2->getValue();
181 double V = pow(Op1V, Op2V);
183 return ConstantFP::get(Ty, V);
184 } else if (Name == "fmod") {
186 double V = fmod(Op1V, Op2V);
188 return ConstantFP::get(Ty, V);
189 } else if (Name == "atan2")
190 return ConstantFP::get(Ty, atan2(Op1V,Op2V));