Coverage Report

Created: 2019-04-25 15:07

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/tools/polly/lib/Transform/RewriteByReferenceParameters.cpp
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//===------ RewriteByReferenceParameters.cpp --------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass introduces separate 'alloca' instructions for read-only
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// by-reference function parameters to indicate that these paramters are
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// read-only. After this transformation -mem2reg has more freedom to promote
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// variables to registers, which allows SCEV to work in more cases.
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//
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//===----------------------------------------------------------------------===//
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#include "polly/LinkAllPasses.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/Pass.h"
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#define DEBUG_TYPE "polly-rewrite-byref-params"
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using namespace llvm;
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namespace {
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class RewriteByrefParams : public FunctionPass {
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private:
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  RewriteByrefParams(const RewriteByrefParams &) = delete;
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  const RewriteByrefParams &operator=(const RewriteByrefParams &) = delete;
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public:
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  static char ID;
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  explicit RewriteByrefParams() : FunctionPass(ID) {}
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  virtual void getAnalysisUsage(AnalysisUsage &AU) const override {}
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  void tryRewriteInstruction(Instruction &Inst) {
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    BasicBlock *Entry = &Inst.getParent()->getParent()->getEntryBlock();
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    auto *Call = dyn_cast<CallInst>(&Inst);
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    if (!Call)
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      return;
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    llvm::Function *F = Call->getCalledFunction();
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    if (!F)
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      return;
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    // We currently match for a very specific function. In case this proves
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    // useful, we can make this code dependent on readonly metadata.
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    if (!F->hasName() || F->getName() != "_gfortran_transfer_integer_write")
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      return;
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    auto *BitCast = dyn_cast<BitCastInst>(Call->getOperand(1));
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    if (!BitCast)
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      return;
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    auto *Alloca = dyn_cast<AllocaInst>(BitCast->getOperand(0));
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    if (!Alloca)
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      return;
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    std::string InstName = Alloca->getName();
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    auto NewAlloca =
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        new AllocaInst(Alloca->getType()->getElementType(), 0,
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                       "polly_byref_alloca_" + InstName, &*Entry->begin());
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    auto *LoadedVal =
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        new LoadInst(Alloca, "polly_byref_load_" + InstName, &Inst);
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    new StoreInst(LoadedVal, NewAlloca, &Inst);
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    auto *NewBitCast = new BitCastInst(NewAlloca, BitCast->getType(),
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                                       "polly_byref_cast_" + InstName, &Inst);
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    Call->setOperand(1, NewBitCast);
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  }
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  virtual bool runOnFunction(Function &F) override {
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    for (BasicBlock &BB : F)
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      for (Instruction &Inst : BB)
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        tryRewriteInstruction(Inst);
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    return true;
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  }
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};
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char RewriteByrefParams::ID;
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} // anonymous namespace
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Pass *polly::createRewriteByrefParamsPass() { return new RewriteByrefParams(); }
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INITIALIZE_PASS_BEGIN(RewriteByrefParams, "polly-rewrite-byref-params",
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                      "Polly - Rewrite by reference parameters", false, false)
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INITIALIZE_PASS_END(RewriteByrefParams, "polly-rewrite-byref-params",
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                    "Polly - Rewrite by reference parameters", false, false)