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Fix bugs in strncmp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35708 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -688,82 +688,72 @@ public:
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"Number of 'strncmp' calls simplified") {}
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/// @brief Make sure that the "strncmp" function has the right prototype
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virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){
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if (f->getReturnType() == Type::Int32Ty && f->arg_size() == 3)
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return true;
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virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){
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const FunctionType *FT = F->getFunctionType();
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return FT->getReturnType() == Type::Int32Ty && FT->getNumParams() == 3 &&
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FT->getParamType(0) == FT->getParamType(1) &&
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FT->getParamType(0) == PointerType::get(Type::Int8Ty) &&
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isa<IntegerType>(FT->getParamType(2));
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return false;
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}
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/// @brief Perform the strncpy optimization
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virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) {
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/// @brief Perform the strncmp optimization
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virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) {
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// First, check to see if src and destination are the same. If they are,
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// then the optimization is to replace the CallInst with a constant 0
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// because the call is a no-op.
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Value* s1 = ci->getOperand(1);
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Value* s2 = ci->getOperand(2);
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if (s1 == s2) {
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// strncmp(x,x,l) -> 0
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ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
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ci->eraseFromParent();
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Value *Str1P = CI->getOperand(1);
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Value *Str2P = CI->getOperand(2);
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if (Str1P == Str2P) {
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// strcmp(x,x) -> 0
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CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0));
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CI->eraseFromParent();
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return true;
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}
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// Check the length argument, if it is Constant zero then the strings are
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// considered equal.
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uint64_t len_arg = 0;
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bool len_arg_is_const = false;
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if (ConstantInt* len_CI = dyn_cast<ConstantInt>(ci->getOperand(3))) {
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len_arg_is_const = true;
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len_arg = len_CI->getZExtValue();
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if (len_arg == 0) {
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// strncmp(x,y,0) -> 0
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ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,0));
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ci->eraseFromParent();
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return true;
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}
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ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3));
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if (LengthArg && LengthArg->isZero()) {
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// strncmp(x,y,0) -> 0
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CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0));
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CI->eraseFromParent();
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return true;
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}
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bool isstr_1 = false;
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uint64_t len_1 = 0, StartIdx;
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ConstantArray* A1;
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if (GetConstantStringInfo(s1, A1, len_1, StartIdx)) {
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isstr_1 = true;
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if (len_1 == 0) {
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// strncmp("",x) -> *x
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LoadInst* load = new LoadInst(s1,ci->getName()+".load",ci);
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CastInst* cast =
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CastInst::create(Instruction::SExt, load, Type::Int32Ty,
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ci->getName()+".int", ci);
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ci->replaceAllUsesWith(cast);
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ci->eraseFromParent();
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return true;
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}
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uint64_t Str1Len, Str1StartIdx;
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ConstantArray *A1;
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bool Str1IsCst = GetConstantStringInfo(Str1P, A1, Str1Len, Str1StartIdx);
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if (Str1IsCst && Str1Len == 0) {
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// strcmp("", x) -> *x
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Value *V = new LoadInst(Str2P, CI->getName()+".load", CI);
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V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
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CI->replaceAllUsesWith(V);
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CI->eraseFromParent();
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return true;
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}
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bool isstr_2 = false;
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uint64_t len_2 = 0;
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uint64_t Str2Len, Str2StartIdx;
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ConstantArray* A2;
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if (GetConstantStringInfo(s2, A2, len_2, StartIdx)) {
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isstr_2 = true;
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if (len_2 == 0) {
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// strncmp(x,"") -> *x
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LoadInst* load = new LoadInst(s2,ci->getName()+".val",ci);
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CastInst* cast =
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CastInst::create(Instruction::SExt, load, Type::Int32Ty,
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ci->getName()+".int", ci);
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ci->replaceAllUsesWith(cast);
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ci->eraseFromParent();
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return true;
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}
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bool Str2IsCst = GetConstantStringInfo(Str2P, A2, Str2Len, Str2StartIdx);
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if (Str2IsCst && Str2Len == 0) {
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// strcmp(x,"") -> *x
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Value *V = new LoadInst(Str1P, CI->getName()+".load", CI);
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V = new ZExtInst(V, CI->getType(), CI->getName()+".int", CI);
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CI->replaceAllUsesWith(V);
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CI->eraseFromParent();
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return true;
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}
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if (isstr_1 && isstr_2 && len_arg_is_const) {
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// strncmp(x,y,const) -> constant
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std::string str1 = A1->getAsString();
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std::string str2 = A2->getAsString();
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int result = strncmp(str1.c_str(), str2.c_str(), len_arg);
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ci->replaceAllUsesWith(ConstantInt::get(Type::Int32Ty,result));
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ci->eraseFromParent();
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if (LengthArg && Str1IsCst && Str2IsCst && A1->isCString() &&
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A2->isCString()) {
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// strcmp(x, y) -> cnst (if both x and y are constant strings)
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std::string S1 = A1->getAsString();
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std::string S2 = A2->getAsString();
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int R = strncmp(S1.c_str()+Str1StartIdx, S2.c_str()+Str2StartIdx,
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LengthArg->getZExtValue());
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CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), R));
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CI->eraseFromParent();
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return true;
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}
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return false;
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