[PM/AA] Extract a minimal interface for CFLAA to its own header file.

[oota-llvm.git] / include / llvm / Analysis / CFLAliasAnalysis.h

diff --git a/include/llvm/Analysis/CFLAliasAnalysis.h b/include/llvm/Analysis/CFLAliasAnalysis.h
new file mode 100644 (file)
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+++ b/include/llvm/Analysis/CFLAliasAnalysis.h
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+//===- CFLAliasAnalysis.h - CFL-Based Alias Analysis Interface ---*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This is the interface for LLVM's primary stateless and local alias analysis.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_CFLALIASANALYSIS_H
+#define LLVM_ANALYSIS_CFLALIASANALYSIS_H
+
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include <forward_list>
+
+namespace llvm {
+
+class CFLAliasAnalysis : public ImmutablePass, public AliasAnalysis {
+  struct FunctionInfo;
+  struct FunctionHandle;
+
+  /// \brief Cached mapping of Functions to their StratifiedSets.
+  /// If a function's sets are currently being built, it is marked
+  /// in the cache as an Optional without a value. This way, if we
+  /// have any kind of recursion, it is discernable from a function
+  /// that simply has empty sets.
+  DenseMap<Function *, Optional<FunctionInfo>> Cache;
+  std::forward_list<FunctionHandle> Handles;
+
+public:
+  static char ID;
+
+  CFLAliasAnalysis();
+  ~CFLAliasAnalysis() override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+  void *getAdjustedAnalysisPointer(const void *ID) override;
+
+  /// \brief Inserts the given Function into the cache.
+  void scan(Function *Fn);
+
+  void evict(Function *Fn);
+
+  /// \brief Ensures that the given function is available in the cache.
+  /// Returns the appropriate entry from the cache.
+  const Optional<FunctionInfo> &ensureCached(Function *Fn);
+
+  AliasResult query(const MemoryLocation &LocA, const MemoryLocation &LocB);
+
+  AliasResult alias(const MemoryLocation &LocA,
+                    const MemoryLocation &LocB) override {
+    if (LocA.Ptr == LocB.Ptr) {
+      if (LocA.Size == LocB.Size) {
+        return MustAlias;
+      } else {
+        return PartialAlias;
+      }
+    }
+
+    // Comparisons between global variables and other constants should be
+    // handled by BasicAA.
+    // TODO: ConstantExpr handling -- CFLAA may report NoAlias when comparing
+    // a GlobalValue and ConstantExpr, but every query needs to have at least
+    // one Value tied to a Function, and neither GlobalValues nor ConstantExprs
+    // are.
+    if (isa<Constant>(LocA.Ptr) && isa<Constant>(LocB.Ptr)) {
+      return AliasAnalysis::alias(LocA, LocB);
+    }
+
+    AliasResult QueryResult = query(LocA, LocB);
+    if (QueryResult == MayAlias)
+      return AliasAnalysis::alias(LocA, LocB);
+
+    return QueryResult;
+  }
+
+  bool doInitialization(Module &M) override;
+
+private:
+  FunctionInfo buildSetsFrom(Function *F);
+};
+
+//===--------------------------------------------------------------------===//
+//
+// createCFLAliasAnalysisPass - This pass implements a set-based approach to
+// alias analysis.
+//
+ImmutablePass *createCFLAliasAnalysisPass();
+
+}
+
+#endif