Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2015, The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
Jean-Luc Brouillet | a2dd52f | 2017-02-16 20:57:26 -0800 | [diff] [blame] | 17 | #include "Assert.h" |
| 18 | #include "Log.h" |
| 19 | #include "RSUtils.h" |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 20 | |
| 21 | #include <algorithm> |
| 22 | #include <vector> |
| 23 | |
| 24 | #include <llvm/IR/CallSite.h> |
| 25 | #include <llvm/IR/Type.h> |
| 26 | #include <llvm/IR/Instructions.h> |
| 27 | #include <llvm/IR/Module.h> |
| 28 | #include <llvm/IR/Function.h> |
| 29 | #include <llvm/Pass.h> |
| 30 | |
| 31 | namespace { // anonymous namespace |
| 32 | |
| 33 | static const bool kDebug = false; |
| 34 | |
| 35 | /* RSX86_64CallConvPass: This pass scans for calls to Renderscript functions in |
| 36 | * the CPU reference driver. For such calls, it identifies the |
| 37 | * pass-by-reference large-object pointer arguments introduced by the frontend |
| 38 | * to conform to the AArch64 calling convention (AAPCS). These pointer |
| 39 | * arguments are converted to pass-by-value to match the calling convention of |
| 40 | * the CPU reference driver. |
| 41 | */ |
| 42 | class RSX86_64CallConvPass: public llvm::ModulePass { |
| 43 | private: |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 44 | bool IsRSFunctionOfInterest(llvm::Function &F) { |
| 45 | // Only Renderscript functions that are not defined locally be considered |
| 46 | if (!F.empty()) // defined locally |
| 47 | return false; |
| 48 | |
| 49 | // llvm intrinsic or internal function |
| 50 | llvm::StringRef FName = F.getName(); |
| 51 | if (FName.startswith("llvm.")) |
| 52 | return false; |
| 53 | |
| 54 | // All other functions need to be checked for large-object parameters. |
| 55 | // Disallowed (non-Renderscript) functions are detected by a different pass. |
| 56 | return true; |
| 57 | } |
| 58 | |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 59 | // Test if this argument needs to be converted to pass-by-value. |
| 60 | bool IsDerefNeeded(llvm::Function *F, llvm::Argument &Arg) { |
| 61 | unsigned ArgNo = Arg.getArgNo(); |
| 62 | llvm::Type *ArgTy = Arg.getType(); |
| 63 | |
| 64 | // Do not consider arguments with 'sret' attribute. Parameters with this |
| 65 | // attribute are actually pointers to structure return values. |
| 66 | if (Arg.hasStructRetAttr()) |
| 67 | return false; |
| 68 | |
| 69 | // Dereference needed only if type is a pointer to a struct |
| 70 | if (!ArgTy->isPointerTy() || !ArgTy->getPointerElementType()->isStructTy()) |
| 71 | return false; |
| 72 | |
| 73 | // Dereference needed only for certain RS struct objects. |
| 74 | llvm::Type *StructTy = ArgTy->getPointerElementType(); |
Stephen Hines | abfa785 | 2015-05-22 19:43:10 -0700 | [diff] [blame] | 75 | if (!isRsObjectType(StructTy)) |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 76 | return false; |
| 77 | |
| 78 | // TODO Find a better way to encode exceptions |
| 79 | llvm::StringRef FName = F->getName(); |
| 80 | // rsSetObject's first parameter is a pointer |
| 81 | if (FName.find("rsSetObject") != std::string::npos && ArgNo == 0) |
| 82 | return false; |
| 83 | // rsClearObject's first parameter is a pointer |
| 84 | if (FName.find("rsClearObject") != std::string::npos && ArgNo == 0) |
| 85 | return false; |
Yang Ni | 02c61f6 | 2015-11-18 16:01:10 -0800 | [diff] [blame] | 86 | // rsForEachInternal's fifth parameter is a pointer |
| 87 | if (FName.find("rsForEachInternal") != std::string::npos && ArgNo == 4) |
| 88 | return false; |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 89 | |
| 90 | return true; |
| 91 | } |
| 92 | |
| 93 | // Compute which arguments to this function need be converted to pass-by-value |
| 94 | bool FillArgsToDeref(llvm::Function *F, std::vector<unsigned> &ArgNums) { |
| 95 | bccAssert(ArgNums.size() == 0); |
| 96 | |
| 97 | for (auto &Arg: F->getArgumentList()) { |
| 98 | if (IsDerefNeeded(F, Arg)) { |
| 99 | ArgNums.push_back(Arg.getArgNo()); |
| 100 | |
| 101 | if (kDebug) { |
| 102 | ALOGV("Lowering argument %u for function %s\n", Arg.getArgNo(), |
| 103 | F->getName().str().c_str()); |
| 104 | } |
| 105 | } |
| 106 | } |
| 107 | return ArgNums.size() > 0; |
| 108 | } |
| 109 | |
| 110 | llvm::Function *RedefineFn(llvm::Function *OrigFn, |
| 111 | std::vector<unsigned> &ArgsToDeref) { |
| 112 | |
| 113 | llvm::FunctionType *FTy = OrigFn->getFunctionType(); |
| 114 | std::vector<llvm::Type *> Params(FTy->param_begin(), FTy->param_end()); |
| 115 | |
| 116 | llvm::FunctionType *NewTy = llvm::FunctionType::get(FTy->getReturnType(), |
| 117 | Params, |
| 118 | FTy->isVarArg()); |
| 119 | llvm::Function *NewFn = llvm::Function::Create(NewTy, |
| 120 | OrigFn->getLinkage(), |
| 121 | OrigFn->getName(), |
| 122 | OrigFn->getParent()); |
| 123 | |
| 124 | // Add the ByVal attribute to the attribute list corresponding to this |
| 125 | // argument. The list at index (i+1) corresponds to the i-th argument. The |
| 126 | // list at index 0 corresponds to the return value's attribute. |
| 127 | for (auto i: ArgsToDeref) { |
| 128 | NewFn->addAttribute(i+1, llvm::Attribute::ByVal); |
| 129 | } |
| 130 | |
| 131 | NewFn->copyAttributesFrom(OrigFn); |
| 132 | NewFn->takeName(OrigFn); |
| 133 | |
| 134 | for (auto AI=OrigFn->arg_begin(), AE=OrigFn->arg_end(), |
| 135 | NAI=NewFn->arg_begin(); |
| 136 | AI != AE; ++ AI, ++NAI) { |
Pirama Arumuga Nainar | f229c40 | 2016-03-06 23:05:45 -0800 | [diff] [blame] | 137 | NAI->takeName(&*AI); |
Pirama Arumuga Nainar | 8c24f8d | 2015-03-17 13:11:25 -0700 | [diff] [blame] | 138 | } |
| 139 | |
| 140 | return NewFn; |
| 141 | } |
| 142 | |
| 143 | void ReplaceCallInsn(llvm::CallSite &CS, |
| 144 | llvm::Function *NewFn, |
| 145 | std::vector<unsigned> &ArgsToDeref) { |
| 146 | |
| 147 | llvm::CallInst *CI = llvm::cast<llvm::CallInst>(CS.getInstruction()); |
| 148 | std::vector<llvm::Value *> Args(CS.arg_begin(), CS.arg_end()); |
| 149 | auto NewCI = llvm::CallInst::Create(NewFn, Args, "", CI); |
| 150 | |
| 151 | // Add the ByVal attribute to the attribute list corresponding to this |
| 152 | // argument. The list at index (i+1) corresponds to the i-th argument. The |
| 153 | // list at index 0 corresponds to the return value's attribute. |
| 154 | for (auto i: ArgsToDeref) { |
| 155 | NewCI->addAttribute(i+1, llvm::Attribute::ByVal); |
| 156 | } |
| 157 | if (CI->isTailCall()) |
| 158 | NewCI->setTailCall(); |
| 159 | |
| 160 | if (!CI->getType()->isVoidTy()) |
| 161 | CI->replaceAllUsesWith(NewCI); |
| 162 | |
| 163 | CI->eraseFromParent(); |
| 164 | } |
| 165 | |
| 166 | public: |
| 167 | static char ID; |
| 168 | |
| 169 | RSX86_64CallConvPass() |
| 170 | : ModulePass (ID) { |
| 171 | } |
| 172 | |
| 173 | virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override { |
| 174 | // This pass does not use any other analysis passes, but it does |
| 175 | // modify the existing functions in the module (thus altering the CFG). |
| 176 | } |
| 177 | |
| 178 | bool runOnModule(llvm::Module &M) override { |
| 179 | // Avoid adding Functions and altering FunctionList while iterating over it |
| 180 | // by collecting functions and processing them later. |
| 181 | std::vector<llvm::Function *> FunctionsToHandle; |
| 182 | |
| 183 | auto &FunctionList = M.getFunctionList(); |
| 184 | for (auto &OrigFn: FunctionList) { |
| 185 | if (!IsRSFunctionOfInterest(OrigFn)) |
| 186 | continue; |
| 187 | FunctionsToHandle.push_back(&OrigFn); |
| 188 | } |
| 189 | |
| 190 | for (auto OrigFn: FunctionsToHandle) { |
| 191 | std::vector<unsigned> ArgsToDeref; |
| 192 | if (!FillArgsToDeref(OrigFn, ArgsToDeref)) |
| 193 | continue; |
| 194 | |
| 195 | // Replace all calls to OrigFn and erase it from parent. |
| 196 | llvm::Function *NewFn = RedefineFn(OrigFn, ArgsToDeref); |
| 197 | while (!OrigFn->use_empty()) { |
| 198 | llvm::CallSite CS(OrigFn->user_back()); |
| 199 | ReplaceCallInsn(CS, NewFn, ArgsToDeref); |
| 200 | } |
| 201 | OrigFn->eraseFromParent(); |
| 202 | } |
| 203 | |
| 204 | return FunctionsToHandle.size() > 0; |
| 205 | } |
| 206 | |
| 207 | }; |
| 208 | |
| 209 | } |
| 210 | |
| 211 | char RSX86_64CallConvPass::ID = 0; |
| 212 | |
| 213 | static llvm::RegisterPass<RSX86_64CallConvPass> X("X86-64-calling-conv", |
| 214 | "remove AArch64 assumptions from calls in X86-64"); |
| 215 | |
| 216 | namespace bcc { |
| 217 | |
| 218 | llvm::ModulePass * |
| 219 | createRSX86_64CallConvPass() { |
| 220 | return new RSX86_64CallConvPass(); |
| 221 | } |
| 222 | |
| 223 | } |