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::isunordered_f32:
39 case Intrinsic::isunordered_f64:
40 case Intrinsic::sqrt_f32:
41 case Intrinsic::sqrt_f64:
42 case Intrinsic::bswap_i16:
43 case Intrinsic::bswap_i32:
44 case Intrinsic::bswap_i64:
45 // FIXME: these should be constant folded as well
46 //case Intrinsic::ctpop_i8:
47 //case Intrinsic::ctpop_i16:
48 //case Intrinsic::ctpop_i32:
49 //case Intrinsic::ctpop_i64:
50 //case Intrinsic::ctlz_i8:
51 //case Intrinsic::ctlz_i16:
52 //case Intrinsic::ctlz_i32:
53 //case Intrinsic::ctlz_i64:
54 //case Intrinsic::cttz_i8:
55 //case Intrinsic::cttz_i16:
56 //case Intrinsic::cttz_i32:
57 //case Intrinsic::cttz_i64:
65 return Name == "acos" || Name == "asin" || Name == "atan" ||
68 return Name == "ceil" || Name == "cos" || Name == "cosf" ||
73 return Name == "fabs" || Name == "fmod" || Name == "floor";
75 return Name == "log" || Name == "log10";
79 return Name == "sin" || Name == "sinh" || Name == "sqrt";
81 return Name == "tan" || Name == "tanh";
88 llvm::ConstantFoldFP(double (*NativeFP)(double), double V, const Type *Ty) {
92 return ConstantFP::get(Ty, V);
96 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
97 /// with the specified arguments, returning null if unsuccessful.
99 llvm::ConstantFoldCall(Function *F, const std::vector<Constant*> &Operands) {
100 const std::string &Name = F->getName();
101 const Type *Ty = F->getReturnType();
103 if (Operands.size() == 1) {
104 if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
105 double V = Op->getValue();
110 return ConstantFoldFP(acos, V, Ty);
111 else if (Name == "asin")
112 return ConstantFoldFP(asin, V, Ty);
113 else if (Name == "atan")
114 return ConstantFP::get(Ty, atan(V));
118 return ConstantFoldFP(ceil, V, Ty);
119 else if (Name == "cos")
120 return ConstantFP::get(Ty, cos(V));
121 else if (Name == "cosh")
122 return ConstantFP::get(Ty, cosh(V));
126 return ConstantFP::get(Ty, exp(V));
130 return ConstantFP::get(Ty, fabs(V));
131 else if (Name == "floor")
132 return ConstantFoldFP(floor, V, Ty);
135 if (Name == "log" && V > 0)
136 return ConstantFP::get(Ty, log(V));
137 else if (Name == "log10" && V > 0)
138 return ConstantFoldFP(log10, V, Ty);
139 else if (Name == "llvm.sqrt.f32" || Name == "llvm.sqrt.f64") {
141 return ConstantFP::get(Ty, sqrt(V));
143 return ConstantFP::get(Ty, 0.0);
148 return ConstantFP::get(Ty, sin(V));
149 else if (Name == "sinh")
150 return ConstantFP::get(Ty, sinh(V));
151 else if (Name == "sqrt" && V >= 0)
152 return ConstantFP::get(Ty, sqrt(V));
156 return ConstantFP::get(Ty, tan(V));
157 else if (Name == "tanh")
158 return ConstantFP::get(Ty, tanh(V));
163 } else if (ConstantUInt *Op = dyn_cast<ConstantUInt>(Operands[0])) {
164 uint64_t V = Op->getValue();
165 if (Name == "llvm.bswap.i16")
166 return ConstantUInt::get(Ty, ByteSwap_16(V));
167 else if (Name == "llvm.bswap.i32")
168 return ConstantUInt::get(Ty, ByteSwap_32(V));
169 else if (Name == "llvm.bswap.i64")
170 return ConstantUInt::get(Ty, ByteSwap_64(V));
172 } else if (Operands.size() == 2) {
173 if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
174 double Op1V = Op1->getValue();
175 if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
176 double Op2V = Op2->getValue();
178 if (Name == "llvm.isunordered.f32" || Name == "llvm.isunordered.f64")
179 return ConstantBool::get(IsNAN(Op1V) || IsNAN(Op2V));
183 double V = pow(Op1V, Op2V);
185 return ConstantFP::get(Ty, V);
186 } else if (Name == "fmod") {
188 double V = fmod(Op1V, Op2V);
190 return ConstantFP::get(Ty, V);
191 } else if (Name == "atan2")
192 return ConstantFP::get(Ty, atan2(Op1V,Op2V));