mlir/lib/Analysis/AliasAnalysis.cpp

   1 //===- AliasAnalysis.cpp - Alias Analysis for MLIR ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "mlir/Analysis/AliasAnalysis.h"
  10 #include "mlir/Analysis/AliasAnalysis/LocalAliasAnalysis.h"
  11 #include "mlir/IR/Operation.h"
  12 #include "mlir/IR/Value.h"
  13 #include "mlir/Support/LLVM.h"
  14 #include <memory>
  15
  16 using namespace mlir;
  17
  18 //===----------------------------------------------------------------------===//
  19 // AliasResult
  20 //===----------------------------------------------------------------------===//
  21
  22 /// Merge this alias result with `other` and return a new result that
  23 /// represents the conservative merge of both results.
  24 AliasResult AliasResult::merge(AliasResult other) const {
  25   if (kind == other.kind)
  26     return *this;
  27   // A mix of PartialAlias and MustAlias is PartialAlias.
  28   if ((isPartial() && other.isMust()) || (other.isPartial() && isMust()))
  29     return PartialAlias;
  30   // Otherwise, don't assume anything.
  31   return MayAlias;
  32 }
  33
  34 void AliasResult::print(raw_ostream &os) const {
  35   switch (kind) {
  36   case Kind::NoAlias:
  37     os << "NoAlias";
  38     break;
  39   case Kind::MayAlias:
  40     os << "MayAlias";
  41     break;
  42   case Kind::PartialAlias:
  43     os << "PartialAlias";
  44     break;
  45   case Kind::MustAlias:
  46     os << "MustAlias";
  47     break;
  48   }
  49 }
  50
  51 //===----------------------------------------------------------------------===//
  52 // ModRefResult
  53 //===----------------------------------------------------------------------===//
  54
  55 void ModRefResult::print(raw_ostream &os) const {
  56   switch (kind) {
  57   case Kind::NoModRef:
  58     os << "NoModRef";
  59     break;
  60   case Kind::Ref:
  61     os << "Ref";
  62     break;
  63   case Kind::Mod:
  64     os << "Mod";
  65     break;
  66   case Kind::ModRef:
  67     os << "ModRef";
  68     break;
  69   }
  70 }
  71
  72 //===----------------------------------------------------------------------===//
  73 // AliasAnalysis
  74 //===----------------------------------------------------------------------===//
  75
  76 AliasAnalysis::AliasAnalysis(Operation *op) {
  77   addAnalysisImplementation(LocalAliasAnalysis());
  78 }
  79
  80 AliasResult AliasAnalysis::alias(Value lhs, Value rhs) {
  81   // Check each of the alias analysis implemenations for an alias result.
  82   for (const std::unique_ptr<Concept> &aliasImpl : aliasImpls) {
  83     AliasResult result = aliasImpl->alias(lhs, rhs);
  84     if (!result.isMay())
  85       return result;
  86   }
  87   return AliasResult::MayAlias;
  88 }
  89
  90 ModRefResult AliasAnalysis::getModRef(Operation *op, Value location) {
  91   // Compute the mod-ref behavior by refining a top `ModRef` result with each of
  92   // the alias analysis implementations. We early exit at the point where we
  93   // refine down to a `NoModRef`.
  94   ModRefResult result = ModRefResult::getModAndRef();
  95   for (const std::unique_ptr<Concept> &aliasImpl : aliasImpls) {
  96     result = result.intersect(aliasImpl->getModRef(op, location));
  97     if (result.isNoModRef())
  98       return result;
  99   }
 100   return result;
 101 }