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//===- Codegen/IRBuilder.h - The IR builder used by Polly -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// The Polly IRBuilder file contains Polly specific extensions for the IRBuilder
// that are used e.g. to emit the llvm.loop.parallel metadata.
//
//===----------------------------------------------------------------------===//
#ifndef POLLY_CODEGEN_IRBUILDER_H
#define POLLY_CODEGEN_IRBUILDER_H
#include "llvm/ADT/MapVector.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/ValueMap.h"
namespace llvm {
class ScalarEvolution;
} // namespace llvm
namespace polly {
class Scop;
/// Helper class to annotate newly generated SCoPs with metadata.
///
/// The annotations are twofold:
/// 1) Loops are stored in a stack-like structure in the order they are
/// constructed and the LoopID metadata node is added to the backedge.
/// Contained memory instructions and loop headers are annotated according
/// to all parallel surrounding loops.
/// 2) The new SCoP is assumed alias free (either due to the result of
/// AliasAnalysis queries or runtime alias checks). We annotate therefore
/// all memory instruction with alias scopes to indicate that fact to
/// later optimizations.
/// These alias scopes live in a new alias domain only used in this SCoP.
/// Each base pointer has its own alias scope and is annotated to not
/// alias with any access to different base pointers.
class ScopAnnotator {
public:
ScopAnnotator();
/// Build all alias scopes for the given SCoP.
void buildAliasScopes(Scop &S);
/// Add a new loop @p L which is parallel if @p IsParallel is true.
void pushLoop(llvm::Loop *L, bool IsParallel);
/// Remove the last added loop.
void popLoop(bool isParallel);
/// Annotate the new instruction @p I for all parallel loops.
void annotate(llvm::Instruction *I);
/// Annotate the loop latch @p B wrt. @p L.
void annotateLoopLatch(llvm::BranchInst *B, llvm::Loop *L, bool IsParallel,
bool IsLoopVectorizerDisabled) const;
/// Add alternative alias based pointers
///
/// When annotating instructions with alias scope metadata, the right metadata
/// is identified through the base pointer of the memory access. In some cases
/// (e.g. OpenMP code generation), the base pointer of the memory accesses is
/// not the original base pointer, but was changed when passing the original
/// base pointer over a function boundary. This function allows to provide a
/// map that maps from these new base pointers to the original base pointers
/// to allow the ScopAnnotator to still find the right alias scop annotations.
///
/// @param NewMap A map from new base pointers to original base pointers.
void addAlternativeAliasBases(
llvm::DenseMap<llvm::AssertingVH<llvm::Value>,
llvm::AssertingVH<llvm::Value>> &NewMap) {
AlternativeAliasBases.insert(NewMap.begin(), NewMap.end());
}
/// Delete the set of alternative alias bases
void resetAlternativeAliasBases() { AlternativeAliasBases.clear(); }
/// Add inter iteration alias-free base pointer @p BasePtr.
void addInterIterationAliasFreeBasePtr(llvm::Value *BasePtr);
private:
/// Annotate with the second level alias metadata
///
/// Annotate the instruction @p I with the second level alias metadata
/// to distinguish the individual non-aliasing accesses that have inter
/// iteration alias-free base pointers.
///
/// @param I The instruction to be annotated.
/// @param BasePtr The base pointer of @p I.
void annotateSecondLevel(llvm::Instruction *I, llvm::Value *BasePtr);
/// The ScalarEvolution analysis we use to find base pointers.
llvm::ScalarEvolution *SE;
/// All loops currently under construction.
llvm::SmallVector<llvm::Loop *, 8> ActiveLoops;
/// Metadata pointing to parallel loops currently under construction.
llvm::SmallVector<llvm::MDNode *, 8> ParallelLoops;
/// The alias scope domain for the current SCoP.
llvm::MDNode *AliasScopeDomain;
/// A map from base pointers to its alias scope.
llvm::MapVector<llvm::AssertingVH<llvm::Value>, llvm::MDNode *> AliasScopeMap;
/// A map from base pointers to an alias scope list of other pointers.
llvm::DenseMap<llvm::AssertingVH<llvm::Value>, llvm::MDNode *>
OtherAliasScopeListMap;
/// A map from pointers to second level alias scopes.
llvm::DenseMap<const llvm::SCEV *, llvm::MDNode *> SecondLevelAliasScopeMap;
/// A map from pointers to second level alias scope list of other pointers.
llvm::DenseMap<const llvm::SCEV *, llvm::MDNode *>
SecondLevelOtherAliasScopeListMap;
/// Inter iteration alias-free base pointers.
llvm::SmallPtrSet<llvm::Value *, 4> InterIterationAliasFreeBasePtrs;
llvm::DenseMap<llvm::AssertingVH<llvm::Value>, llvm::AssertingVH<llvm::Value>>
AlternativeAliasBases;
};
/// Add Polly specifics when running IRBuilder.
///
/// This is used to add additional items such as e.g. the llvm.loop.parallel
/// metadata.
class IRInserter : protected llvm::IRBuilderDefaultInserter {
public:
IRInserter() = default;
IRInserter(class ScopAnnotator &A) : Annotator(&A) {}
protected:
void InsertHelper(llvm::Instruction *I, const llvm::Twine &Name,
llvm::BasicBlock *BB,
llvm::BasicBlock::iterator InsertPt) const {
llvm::IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
if (Annotator)
Annotator->annotate(I);
}
private:
class ScopAnnotator *Annotator = nullptr;
};
// TODO: We should not name instructions in NDEBUG builds.
//
// We currently always name instructions, as the polly test suite currently
// matches for certain names.
typedef llvm::IRBuilder<llvm::ConstantFolder, IRInserter> PollyIRBuilder;
/// Return an IR builder pointed before the @p BB terminator.
static inline PollyIRBuilder createPollyIRBuilder(llvm::BasicBlock *BB,
ScopAnnotator &LA) {
PollyIRBuilder Builder(BB->getContext(), llvm::ConstantFolder(),
polly::IRInserter(LA));
Builder.SetInsertPoint(BB->getTerminator());
return Builder;
}
} // namespace polly
#endif
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