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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
99 lines
3.1 KiB
C++
99 lines
3.1 KiB
C++
//===------ 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/IR/PassManager.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)
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