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//===- BufferViewFlowAnalysis.h - Buffer dependency analysis ---*- C++ -*-====//
// 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
#include "mlir/IR/Operation.h"
#include "llvm/ADT/SmallPtrSet.h"
namespace mlir {
/// A straight-forward alias analysis which ensures that all dependencies of all
/// values will be determined. This is a requirement for the BufferPlacement
/// class since you need to determine safe positions to place alloc and
/// deallocs. This alias analysis only finds aliases that might have been
/// created on top of the specified view. To find all aliases, resolve the
/// intial alloc/argument value.
class BufferViewFlowAnalysis {
using ValueSetT = SmallPtrSet<Value, 16>;
using ValueMapT = llvm::DenseMap<Value, ValueSetT>;
/// Constructs a new alias analysis using the op provided.
BufferViewFlowAnalysis(Operation *op);
/// Find all immediate dependencies this value could potentially have.
ValueMapT::const_iterator find(Value value) const {
return dependencies.find(value);
/// Returns the begin iterator to iterate over all dependencies.
ValueMapT::const_iterator begin() const { return dependencies.begin(); }
/// Returns the end iterator that can be used in combination with find.
ValueMapT::const_iterator end() const { return dependencies.end(); }
/// Find all immediate and indirect views upon this value. This will find all
/// dependencies on this value that can potentially be later in the execution
/// of the program, but will not return values that this alias might have been
/// created from (such as if the value is created by a subview, this will not
/// return the parent view if there is no cyclic behavior). Note that the
/// resulting set will also contain the value provided as it is an alias of
/// itself.
/// A = *
/// B = subview(A)
/// C = B
/// Results in resolve(B) returning {B, C}
ValueSetT resolve(Value value) const;
/// Removes the given values from all alias sets.
void remove(const SmallPtrSetImpl<Value> &aliasValues);
/// This function constructs a mapping from values to its immediate
/// dependencies.
void build(Operation *op);
/// Maps values to all immediate dependencies this value can have.
ValueMapT dependencies;
} // namespace mlir