RSInvariant.cpp revision 150eef4097c996e14b50b7f58184265385c44713
11d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross/* 21d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Copyright 2015, The Android Open Source Project 31d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 41d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Licensed under the Apache License, Version 2.0 (the "License"); 51d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * you may not use this file except in compliance with the License. 61d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * You may obtain a copy of the License at 71d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 81d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * http://www.apache.org/licenses/LICENSE-2.0 91d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 101d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Unless required by applicable law or agreed to in writing, software 111d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * distributed under the License is distributed on an "AS IS" BASIS, 121d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 131d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * See the License for the specific language governing permissions and 141d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * limitations under the License. 151d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross */ 161d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 171d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include "bcc/Renderscript/RSTransforms.h" 181d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 191d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/IR/Function.h> 201d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/IR/Instructions.h> 211d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/IR/Metadata.h> 221d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/IR/Module.h> 231d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/IR/Type.h> 241d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross#include <llvm/Pass.h> 251d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 261d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossnamespace { 271d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 281d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross/* 291d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * RSInvariantPass - This pass looks for Loads that access 301d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * RsExpandKernelDriverInfo instances (which should never be written by 311d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * a script, only by the driver) and marks them "invariant.load". 321d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 331d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * There should be only two sources of Loads from such instances: 341d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - An instance can appear as an argument of type 351d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * "RsExpandKernelDriverInfoPfx*" passed to a .expand function by 361d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * the driver. 371d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - An instance can appear as an argument of type 381d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * "rs_kernel_context_t*" passed to an API query function by the 391d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * user. 401d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Only the compiler-generated .expand functions and the API query 411d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * functions can see the fields of RsExpandKernelDriverInfo -- 421d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * rs_kernel_context_t is opaque to user code, so there cannot be any 431d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Loads from it in user code. 441d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 451d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * This pass should be run 461d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - after foreachexp, so that it can see the Loads generated within 471d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * .expand functions 481d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - before inlining, so that it can recognize API query function 491d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * arguments. 501d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * 511d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * WARNINGS: 521d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - If user code or APIs can modify RsExpandKernelDriverInfo 531d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * instances, this pass MAY ALLOW ILLEGAL OPTIMIZATION. 541d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - If this pass runs at a different time, it may be ineffective 551d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * (fail to mark some or all eligible Loads, and thereby cost 561d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * performance). 571d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - If the names of the data types change, this pass may be 581d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * ineffective. 591d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * - If the patterns by which fields are loaded from 601d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * RsExpandKernelDriverInfo instances change, this pass may be 611d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * ineffective. 621d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross */ 631d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossclass RSInvariantPass : public llvm::FunctionPass { 641d93a190e62ec1588b4724ca8759216b2d0b76d7David Grosspublic: 651d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross static char ID; 661d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 671d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross RSInvariantPass() : FunctionPass(ID), EmptyMDNode(nullptr) { } 681d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 691d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross virtual bool doInitialization(llvm::Module &M) { 701d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross EmptyMDNode = llvm::MDNode::get(M.getContext(), llvm::None); 711d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross return true; 721d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 731d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 741d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross virtual bool runOnFunction(llvm::Function &F) { 751d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross bool Changed = false; 761d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 771d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross for (llvm::Value &Arg : F.args()) { 781d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross const llvm::Type *ArgType = Arg.getType(); 791d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross if (ArgType->isPointerTy()) { 801d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross const llvm::Type *ArgPtrDomainType = ArgType->getPointerElementType(); 81e8b9f0607d59e991d984302d790b8b16e3623cc3Pirama Arumuga Nainar if (auto ArgPtrDomainStructType = llvm::dyn_cast<llvm::StructType>(ArgPtrDomainType)) { 82150eef4097c996e14b50b7f58184265385c44713Pirama Arumuga Nainar if (!ArgPtrDomainStructType->isLiteral()) { 83e8b9f0607d59e991d984302d790b8b16e3623cc3Pirama Arumuga Nainar const llvm::StringRef StructName = ArgPtrDomainStructType->getName(); 84e8b9f0607d59e991d984302d790b8b16e3623cc3Pirama Arumuga Nainar if (StructName.equals("struct.rs_kernel_context_t") || StructName.equals("RsExpandKernelDriverInfoPfx")) { 85e8b9f0607d59e991d984302d790b8b16e3623cc3Pirama Arumuga Nainar Changed |= markInvariantUserLoads(&Arg); 86e8b9f0607d59e991d984302d790b8b16e3623cc3Pirama Arumuga Nainar } 871d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 881d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 891d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 901d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 911d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 921d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross return Changed; 931d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 941d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 951d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross virtual const char *getPassName() const { 961d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross return "Renderscript Invariant Load Annotation"; 971d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 981d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 991d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossprivate: 1001d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1011d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross /* 1021d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * Follow def->use chains rooted at Value through calculations 1031d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * "based on" Value (see the "based on" definition at 1041d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * http://llvm.org/docs/LangRef.html#pointer-aliasing-rules). If a 1051d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * chain reaches the pointer operand of a Load, mark that Load as 1061d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * "invariant.load" -- i.e., it accesses memory which does not 1071d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * change. 1081d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross */ 1091d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross bool markInvariantUserLoads(llvm::Value *Value) { 1101d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross bool Changed = false; 1111d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross for (llvm::Use &Use : Value->uses()) { 1121d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross llvm::Instruction *Inst = llvm::cast<llvm::Instruction>(Use.getUser()); 1131d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1141d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross /* 1151d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * We only examine a small set of opcodes here, because these 1161d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * are the opcodes that currently appear in the patterns of 1171d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * interest (foreachexp-generated code, and 1181d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * rsGet*(rs_kernel_context_t*) APIs). Other opcodes could be 1191d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross * added if necessary. 1201d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross */ 1211d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross if (auto BitCast = llvm::dyn_cast<llvm::BitCastInst>(Inst)) { 1221d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross Changed |= markInvariantUserLoads(BitCast); 1231d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } else if (auto GetElementPtr = llvm::dyn_cast<llvm::GetElementPtrInst>(Inst)) { 1241d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross if (Use.get() == GetElementPtr->getPointerOperand()) 1251d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross Changed |= markInvariantUserLoads(GetElementPtr); 1261d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } else if (auto Load = llvm::dyn_cast<llvm::LoadInst>(Inst)) { 1271d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross if (Use.get() == Load->getPointerOperand()) { 1281d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross Load->setMetadata("invariant.load", EmptyMDNode); 1291d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross Changed = true; 1301d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 1311d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 1321d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 1331d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross return Changed; 1341d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross } 1351d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1361d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross // Pointer to empty metadata node used for "invariant.load" marking. 1371d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross llvm::MDNode *EmptyMDNode; 1381d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross}; // end RSInvariantPass 1391d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1401d93a190e62ec1588b4724ca8759216b2d0b76d7David Grosschar RSInvariantPass::ID = 0; 1411d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossllvm::RegisterPass<RSInvariantPass> X("rsinvariant", "RS Invariant Load Pass"); 1421d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1431d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross} // end anonymous namespace 1441d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1451d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossnamespace bcc { 1461d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1471d93a190e62ec1588b4724ca8759216b2d0b76d7David Grossllvm::FunctionPass * 1481d93a190e62ec1588b4724ca8759216b2d0b76d7David GrosscreateRSInvariantPass() { 1491d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross return new RSInvariantPass(); 1501d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross} 1511d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross 1521d93a190e62ec1588b4724ca8759216b2d0b76d7David Gross} // end namespace bcc 153