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//===---- CodePreparation.cpp - Code preparation for Scop Detection -------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// The Polly code preparation pass is executed before SCoP detection. Its
// currently only splits the entry block of the SCoP to make room for alloc
// instructions as they are generated during code generation.
// XXX: In the future, we should remove the need for this pass entirely and
// instead add this spitting to the code generation pass.
#include "polly/CodePreparation.h"
#include "polly/LinkAllPasses.h"
#include "polly/Support/ScopHelper.h"
#include "llvm/Analysis/DominanceFrontier.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
using namespace polly;
namespace {
/// Prepare the IR for the scop detection.
class CodePreparation : public FunctionPass {
CodePreparation(const CodePreparation &) = delete;
const CodePreparation &operator=(const CodePreparation &) = delete;
LoopInfo *LI;
ScalarEvolution *SE;
void clear();
static char ID;
explicit CodePreparation() : FunctionPass(ID) {}
/// @name FunctionPass interface.
void getAnalysisUsage(AnalysisUsage &AU) const override;
void releaseMemory() override;
bool runOnFunction(Function &F) override;
void print(raw_ostream &OS, const Module *) const override;
} // namespace
PreservedAnalyses CodePreparationPass::run(Function &F,
FunctionAnalysisManager &FAM) {
// Find first non-alloca instruction. Every basic block has a non-alloca
// instruction, as every well formed basic block has a terminator.
auto &EntryBlock = F.getEntryBlock();
BasicBlock::iterator I = EntryBlock.begin();
while (isa<AllocaInst>(I))
auto &DT = FAM.getResult<DominatorTreeAnalysis>(F);
auto &LI = FAM.getResult<LoopAnalysis>(F);
// splitBlock updates DT, LI and RI.
splitEntryBlockForAlloca(&EntryBlock, &DT, &LI, nullptr);
PreservedAnalyses PA;
return PA;
void CodePreparation::clear() {}
CodePreparation::~CodePreparation() { clear(); }
void CodePreparation::getAnalysisUsage(AnalysisUsage &AU) const {
bool CodePreparation::runOnFunction(Function &F) {
if (skipFunction(F))
return false;
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
splitEntryBlockForAlloca(&F.getEntryBlock(), this);
return true;
void CodePreparation::releaseMemory() { clear(); }
void CodePreparation::print(raw_ostream &OS, const Module *) const {}
char CodePreparation::ID = 0;
char &polly::CodePreparationID = CodePreparation::ID;
Pass *polly::createCodePreparationPass() { return new CodePreparation(); }
INITIALIZE_PASS_BEGIN(CodePreparation, "polly-prepare",
"Polly - Prepare code for polly", false, false)
INITIALIZE_PASS_END(CodePreparation, "polly-prepare",
"Polly - Prepare code for polly", false, false)