1 //===------ SimplifyLibCalls.cpp - Library calls simplifier ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This is a utility pass used for testing the InstructionSimplify analysis.
11 // The analysis is applied to every instruction, and if it simplifies then the
12 // instruction is replaced by the simplification. If you are looking for a pass
13 // that performs serious instruction folding, use the instcombine pass instead.
15 //===----------------------------------------------------------------------===//
17 #include "llvm/Transforms/Utils/SimplifyLibCalls.h"
18 #include "llvm/DataLayout.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/Analysis/ValueTracking.h"
21 #include "llvm/Function.h"
22 #include "llvm/IRBuilder.h"
23 #include "llvm/LLVMContext.h"
24 #include "llvm/Target/TargetLibraryInfo.h"
25 #include "llvm/Transforms/Utils/BuildLibCalls.h"
29 /// This class is the abstract base class for the set of optimizations that
30 /// corresponds to one library call.
32 class LibCallOptimization {
36 const TargetLibraryInfo *TLI;
39 LibCallOptimization() { }
40 virtual ~LibCallOptimization() {}
42 /// callOptimizer - This pure virtual method is implemented by base classes to
43 /// do various optimizations. If this returns null then no transformation was
44 /// performed. If it returns CI, then it transformed the call and CI is to be
45 /// deleted. If it returns something else, replace CI with the new value and
47 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B)
50 Value *optimizeCall(CallInst *CI, const DataLayout *TD,
51 const TargetLibraryInfo *TLI, IRBuilder<> &B) {
52 Caller = CI->getParent()->getParent();
55 if (CI->getCalledFunction())
56 Context = &CI->getCalledFunction()->getContext();
58 // We never change the calling convention.
59 if (CI->getCallingConv() != llvm::CallingConv::C)
62 return callOptimizer(CI->getCalledFunction(), CI, B);
66 //===----------------------------------------------------------------------===//
67 // Fortified Library Call Optimizations
68 //===----------------------------------------------------------------------===//
70 struct FortifiedLibCallOptimization : public LibCallOptimization {
72 virtual bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp,
73 bool isString) const = 0;
76 struct InstFortifiedLibCallOptimization : public FortifiedLibCallOptimization {
79 bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp, bool isString) const {
80 if (CI->getArgOperand(SizeCIOp) == CI->getArgOperand(SizeArgOp))
82 if (ConstantInt *SizeCI =
83 dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp))) {
84 if (SizeCI->isAllOnesValue())
87 uint64_t Len = GetStringLength(CI->getArgOperand(SizeArgOp));
88 // If the length is 0 we don't know how long it is and so we can't
90 if (Len == 0) return false;
91 return SizeCI->getZExtValue() >= Len;
93 if (ConstantInt *Arg = dyn_cast<ConstantInt>(
94 CI->getArgOperand(SizeArgOp)))
95 return SizeCI->getZExtValue() >= Arg->getZExtValue();
101 struct MemCpyChkOpt : public InstFortifiedLibCallOptimization {
102 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
104 FunctionType *FT = Callee->getFunctionType();
105 LLVMContext &Context = CI->getParent()->getContext();
107 // Check if this has the right signature.
108 if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
109 !FT->getParamType(0)->isPointerTy() ||
110 !FT->getParamType(1)->isPointerTy() ||
111 FT->getParamType(2) != TD->getIntPtrType(Context) ||
112 FT->getParamType(3) != TD->getIntPtrType(Context))
115 if (isFoldable(3, 2, false)) {
116 B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
117 CI->getArgOperand(2), 1);
118 return CI->getArgOperand(0);
124 struct MemMoveChkOpt : public InstFortifiedLibCallOptimization {
125 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
127 FunctionType *FT = Callee->getFunctionType();
128 LLVMContext &Context = CI->getParent()->getContext();
130 // Check if this has the right signature.
131 if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
132 !FT->getParamType(0)->isPointerTy() ||
133 !FT->getParamType(1)->isPointerTy() ||
134 FT->getParamType(2) != TD->getIntPtrType(Context) ||
135 FT->getParamType(3) != TD->getIntPtrType(Context))
138 if (isFoldable(3, 2, false)) {
139 B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
140 CI->getArgOperand(2), 1);
141 return CI->getArgOperand(0);
147 struct MemSetChkOpt : public InstFortifiedLibCallOptimization {
148 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
150 FunctionType *FT = Callee->getFunctionType();
151 LLVMContext &Context = CI->getParent()->getContext();
153 // Check if this has the right signature.
154 if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
155 !FT->getParamType(0)->isPointerTy() ||
156 !FT->getParamType(1)->isIntegerTy() ||
157 FT->getParamType(2) != TD->getIntPtrType(Context) ||
158 FT->getParamType(3) != TD->getIntPtrType(Context))
161 if (isFoldable(3, 2, false)) {
162 Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(),
164 B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
165 return CI->getArgOperand(0);
171 struct StrCpyChkOpt : public InstFortifiedLibCallOptimization {
172 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
174 StringRef Name = Callee->getName();
175 FunctionType *FT = Callee->getFunctionType();
176 LLVMContext &Context = CI->getParent()->getContext();
178 // Check if this has the right signature.
179 if (FT->getNumParams() != 3 ||
180 FT->getReturnType() != FT->getParamType(0) ||
181 FT->getParamType(0) != FT->getParamType(1) ||
182 FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
183 FT->getParamType(2) != TD->getIntPtrType(Context))
186 // If a) we don't have any length information, or b) we know this will
187 // fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
188 // st[rp]cpy_chk call which may fail at runtime if the size is too long.
189 // TODO: It might be nice to get a maximum length out of the possible
190 // string lengths for varying.
191 if (isFoldable(2, 1, true)) {
192 Value *Ret = EmitStrCpy(CI->getArgOperand(0), CI->getArgOperand(1), B, TD,
193 TLI, Name.substr(2, 6));
200 struct StrNCpyChkOpt : public InstFortifiedLibCallOptimization {
201 virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
203 StringRef Name = Callee->getName();
204 FunctionType *FT = Callee->getFunctionType();
205 LLVMContext &Context = CI->getParent()->getContext();
207 // Check if this has the right signature.
208 if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
209 FT->getParamType(0) != FT->getParamType(1) ||
210 FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
211 !FT->getParamType(2)->isIntegerTy() ||
212 FT->getParamType(3) != TD->getIntPtrType(Context))
215 if (isFoldable(3, 2, false)) {
216 Value *Ret = EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
217 CI->getArgOperand(2), B, TD, TLI,
225 } // End anonymous namespace.
229 class LibCallSimplifierImpl {
230 LibCallSimplifier *Simplifier;
231 const DataLayout *TD;
232 const TargetLibraryInfo *TLI;
233 StringMap<LibCallOptimization*> Optimizations;
235 // Fortified library call optimizations.
236 MemCpyChkOpt MemCpyChk;
237 MemMoveChkOpt MemMoveChk;
238 MemSetChkOpt MemSetChk;
239 StrCpyChkOpt StrCpyChk;
240 StrNCpyChkOpt StrNCpyChk;
242 void initOptimizations();
244 LibCallSimplifierImpl(const DataLayout *TD, const TargetLibraryInfo *TLI) {
249 Value *optimizeCall(CallInst *CI);
252 void LibCallSimplifierImpl::initOptimizations() {
253 // Fortified library call optimizations.
254 Optimizations["__memcpy_chk"] = &MemCpyChk;
255 Optimizations["__memmove_chk"] = &MemMoveChk;
256 Optimizations["__memset_chk"] = &MemSetChk;
257 Optimizations["__strcpy_chk"] = &StrCpyChk;
258 Optimizations["__stpcpy_chk"] = &StrCpyChk;
259 Optimizations["__strncpy_chk"] = &StrNCpyChk;
260 Optimizations["__stpncpy_chk"] = &StrNCpyChk;
263 Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {
264 if (Optimizations.empty())
267 Function *Callee = CI->getCalledFunction();
268 LibCallOptimization *LCO = Optimizations.lookup(Callee->getName());
270 IRBuilder<> Builder(CI);
271 return LCO->optimizeCall(CI, TD, TLI, Builder);
276 LibCallSimplifier::LibCallSimplifier(const DataLayout *TD,
277 const TargetLibraryInfo *TLI) {
278 Impl = new LibCallSimplifierImpl(TD, TLI);
281 LibCallSimplifier::~LibCallSimplifier() {
285 Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
286 return Impl->optimizeCall(CI);