1 //===-- AllocaHoisting.cpp - Hoist allocas to the entry block --*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Hoist the alloca instructions in the non-entry blocks to the entry blocks. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "NVPTXAllocaHoisting.h" 14 #include "llvm/CodeGen/StackProtector.h" 15 #include "llvm/IR/Constants.h" 16 #include "llvm/IR/Function.h" 17 #include "llvm/IR/Instructions.h" 18 using namespace llvm; 19 20 namespace { 21 // Hoisting the alloca instructions in the non-entry blocks to the entry 22 // block. 23 class NVPTXAllocaHoisting : public FunctionPass { 24 public: 25 static char ID; // Pass ID 26 NVPTXAllocaHoisting() : FunctionPass(ID) {} 27 28 void getAnalysisUsage(AnalysisUsage &AU) const override { 29 AU.addPreserved<StackProtector>(); 30 } 31 32 StringRef getPassName() const override { 33 return "NVPTX specific alloca hoisting"; 34 } 35 36 bool runOnFunction(Function &function) override; 37 }; 38 } // namespace 39 40 bool NVPTXAllocaHoisting::runOnFunction(Function &function) { 41 bool functionModified = false; 42 Function::iterator I = function.begin(); 43 Instruction *firstTerminatorInst = (I++)->getTerminator(); 44 45 for (Function::iterator E = function.end(); I != E; ++I) { 46 for (BasicBlock::iterator BI = I->begin(), BE = I->end(); BI != BE;) { 47 AllocaInst *allocaInst = dyn_cast<AllocaInst>(BI++); 48 if (allocaInst && isa<ConstantInt>(allocaInst->getArraySize())) { 49 allocaInst->moveBefore(firstTerminatorInst); 50 functionModified = true; 51 } 52 } 53 } 54 55 return functionModified; 56 } 57 58 char NVPTXAllocaHoisting::ID = 0; 59 60 namespace llvm { 61 void initializeNVPTXAllocaHoistingPass(PassRegistry &); 62 } 63 64 INITIALIZE_PASS( 65 NVPTXAllocaHoisting, "alloca-hoisting", 66 "Hoisting alloca instructions in non-entry blocks to the entry block", 67 false, false) 68 69 FunctionPass *llvm::createAllocaHoisting() { return new NVPTXAllocaHoisting; } 70