CIRBasicAliasAnalysis.h

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//===- CIRBasicAliasAnalysis.h - Basic CIR Alias Analysis -------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines CIRBasicAliasAnalysis, a CIR-specific alias analysis
// implementation based on pointer provenance and distinct allocation sites.
// Register with an mlir::AliasAnalysis aggregate via
// addAnalysisImplementation(), or use registerCIRAliasAnalyses() to add the
// full suite of CIR analyses at once.
//
//===----------------------------------------------------------------------===//
 
#ifndef CLANG_CIR_DIALECT_ANALYSIS_CIRBASICALIASANALYSIS_H
#define CLANG_CIR_DIALECT_ANALYSIS_CIRBASICALIASANALYSIS_H
 
#include "mlir/Analysis/AliasAnalysis.h"
#include "mlir/IR/Operation.h"
#include "mlir/IR/Value.h"
 
namespace cir {
 
/// Basic CIR alias analysis based on pointer provenance and distinct allocation
/// sites. Conservative defaults (MayAlias / ModRef) are returned for cases
/// that are not yet handled.
class CIRBasicAliasAnalysis {
  enum class ObjectRelation {
    /// Provably different underlying allocations.
    Distinct,
    /// Same underlying allocation, no offset.
    Identical,
    /// Cannot determine the relationship.
    Unknown,
  };
 
public:
  CIRBasicAliasAnalysis() = default;
  CIRBasicAliasAnalysis(CIRBasicAliasAnalysis &&) = default;
 
  /// Return the aliasing behavior between two values.
  ///
  /// Returns MayAlias conservatively unless a more precise result can be
  /// determined from CIR-specific information (e.g. distinct alloca ops,
  /// pointer provenance, restrict attributes).
  mlir::AliasResult alias(mlir::Value lhs, mlir::Value rhs);
 
  /// Return the modify-reference behavior of `op` on `location`.
  ///
  /// Returns ModRef conservatively. CIR ops that carry explicit memory-effect
  /// attributes or that are known to be pure/read-only can be handled here.
  mlir::ModRefResult getModRef(mlir::Operation *op, mlir::Value location);
 
private:
  /// Attempt to find the underlying allocation source for `val` by walking
  /// through pointer arithmetic, casts, and other CIR ops. Returns `val` if
  /// no more specific source is found.
  mlir::Value getUnderlyingObject(mlir::Value val);
 
  /// Classify the relationship between \p lhs and \p rhs.  Returns one of:
  ///   Distinct      – provably different allocations
  ///   Identical     – same allocation, no offset
  ///   Unknown       – cannot determine
  ObjectRelation classifyObjects(mlir::Value lhs, mlir::Value rhs);
};
 
} // namespace cir
 
#endif // CLANG_CIR_DIALECT_ANALYSIS_CIRBASICALIASANALYSIS_H