1 //===-- WebAssemblyFixFunctionBitcasts.cpp - Fix function bitcasts --------===//
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
23 //===----------------------------------------------------------------------===//
35 #define DEBUG_TYPE "wasm-fix-function-bitcasts"
64 // Recursively descend the def-use lists from V to find non-bitcast users of
68   for (User *U : V->users()) {  in findUses()
69     if (auto *BC = dyn_cast<BitCastOperator>(U))  in findUses()
71     else if (auto *A = dyn_cast<GlobalAlias>(U))  in findUses()
73     else if (auto *CB = dyn_cast<CallBase>(U)) {  in findUses()
74       Value *Callee = CB->getCalledOperand();  in findUses()
78       if (CB->getFunctionType() == F.getValueType())  in findUses()
88 //  - Call with more arguments than needed: arguments are dropped
89 //  - Call with fewer arguments than needed: arguments are filled in with undef
90 //  - Return value is not needed: drop it
91 //  - Return value needed but not present: supply an undef
104 // CMake detects the existence of a function in a toolchain).
110   Module *M = F->getParent();  in createWrapper()
113                                        F->getName() + "_bitcast", M);  in createWrapper()
114   BasicBlock *BB = BasicBlock::Create(M->getContext(), "body", Wrapper);  in createWrapper()
115   const DataLayout &DL = BB->getDataLayout();  in createWrapper()
119   Function::arg_iterator AI = Wrapper->arg_begin();  in createWrapper()
120   Function::arg_iterator AE = Wrapper->arg_end();  in createWrapper()
121   FunctionType::param_iterator PI = F->getFunctionType()->param_begin();  in createWrapper()
122   FunctionType::param_iterator PE = F->getFunctionType()->param_end();  in createWrapper()
126   Type *ExpectedRtnType = F->getFunctionType()->getReturnType();  in createWrapper()
127   Type *RtnType = Ty->getReturnType();  in createWrapper()
129   if ((F->getFunctionType()->getNumParams() != Ty->getNumParams()) ||  in createWrapper()
130       (F->getFunctionType()->isVarArg() != Ty->isVarArg()) ||  in createWrapper()
135     Type *ArgType = AI->getType();  in createWrapper()
144         PtrCast->insertInto(BB, BB->end());  in createWrapper()
146       } else if (ArgType->isStructTy() || ParamType->isStructTy()) {  in createWrapper()
148                           << F->getName() << "\n");  in createWrapper()
152                           << F->getName() << "\n");  in createWrapper()
164     if (F->isVarArg())  in createWrapper()
170     Type *ExpectedRtnType = F->getFunctionType()->getReturnType();  in createWrapper()
171     Type *RtnType = Ty->getReturnType();  in createWrapper()
173     if (RtnType->isVoidTy()) {  in createWrapper()
174       ReturnInst::Create(M->getContext(), BB);  in createWrapper()
175     } else if (ExpectedRtnType->isVoidTy()) {  in createWrapper()
177       ReturnInst::Create(M->getContext(), UndefValue::get(RtnType), BB);  in createWrapper()
179       ReturnInst::Create(M->getContext(), Call, BB);  in createWrapper()
184       Cast->insertInto(BB, BB->end());  in createWrapper()
185       ReturnInst::Create(M->getContext(), Cast, BB);  in createWrapper()
186     } else if (RtnType->isStructTy() || ExpectedRtnType->isStructTy()) {  in createWrapper()
188                         << F->getName() << "\n");  in createWrapper()
192                         << F->getName() << "\n");  in createWrapper()
201     Wrapper->eraseFromParent();  in createWrapper()
203                                F->getName() + "_bitcast_invalid", M);  in createWrapper()
204     BasicBlock *BB = BasicBlock::Create(M->getContext(), "body", Wrapper);  in createWrapper()
205     new UnreachableInst(M->getContext(), BB);  in createWrapper()
206     Wrapper->setName(F->getName() + "_bitcast_invalid");  in createWrapper()
208     LLVM_DEBUG(dbgs() << "createWrapper: no wrapper needed: " << F->getName()  in createWrapper()
210     Wrapper->eraseFromParent();  in createWrapper()
213   LLVM_DEBUG(dbgs() << "createWrapper: " << F->getName() << "\n");  in createWrapper()
220   // Only fix the main function if it's the standard zero-arg form. That way,  in shouldFixMainFunction()
222   // mismatches from the linker for non-standard cases.  in shouldFixMainFunction()
223   return FuncTy->getReturnType() == MainTy->getReturnType() &&  in shouldFixMainFunction()
224          FuncTy->getNumParams() == 0 &&  in shouldFixMainFunction()
225          !FuncTy->isVarArg();  in shouldFixMainFunction()
266   for (auto &UseFunc : Uses) {  in runOnModule()
269     FunctionType *Ty = CB->getFunctionType();  in runOnModule()
271     auto Pair = Wrappers.insert(std::make_pair(std::make_pair(F, Ty), nullptr));  in runOnModule()
273       Pair.first->second = createWrapper(F, Ty);  in runOnModule()
275     Function *Wrapper = Pair.first->second;  in runOnModule()
279     CB->setCalledOperand(Wrapper);  in runOnModule()
285     Main->setName("__original_main");  in runOnModule()
286     auto *MainWrapper =  in runOnModule()
287         cast<Function>(CallMain->getCalledOperand()->stripPointerCasts());  in runOnModule()
289     if (Main->isDeclaration()) {  in runOnModule()
292       MainWrapper->eraseFromParent();  in runOnModule()
296       MainWrapper->setName("main");  in runOnModule()
297       MainWrapper->setLinkage(Main->getLinkage());  in runOnModule()
298       MainWrapper->setVisibility(Main->getVisibility());  in runOnModule()