Merge pull request swiftlang#34126 from atrick/add-accesspath

Add an AccessPath abstraction and formalize memory access

Author: atrick

docs/SILProgrammersManual.md

@@ -13,6 +13,7 @@
 #ifndef SWIFT_SILOPTIMIZER_UTILS_INDEXTREE_H
 #define SWIFT_SILOPTIMIZER_UTILS_INDEXTREE_H
 
+#include "swift/Basic/LLVM.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include <algorithm>
@@ -21,15 +22,18 @@ namespace swift {
 
 // Trie node representing a sequence of unsigned integer indices.
 class IndexTrieNode {
-  static const unsigned RootIdx = ~0U;
-  unsigned Index;
+public:
+  static const int RootIndex = std::numeric_limits<int>::min();
+
+private:
+  int Index;
   llvm::SmallVector<IndexTrieNode*, 8> Children;
   IndexTrieNode *Parent;
 
 public:
-  IndexTrieNode(): Index(RootIdx), Parent(nullptr) {}
+  IndexTrieNode() : Index(RootIndex), Parent(nullptr) {}
 
-  explicit IndexTrieNode(unsigned V, IndexTrieNode *P): Index(V), Parent(P) {}
+  explicit IndexTrieNode(int V, IndexTrieNode *P) : Index(V), Parent(P) {}
 
   IndexTrieNode(IndexTrieNode &) =delete;
   IndexTrieNode &operator=(const IndexTrieNode&) =delete;
@@ -39,19 +43,18 @@ class IndexTrieNode {
       delete N;
   }
 
-  bool isRoot() const { return Index == RootIdx; }
+  bool isRoot() const { return Index == RootIndex; }
 
   bool isLeaf() const { return Children.empty(); }
 
-  unsigned getIndex() const { return Index; }
+  int getIndex() const { return Index; }
 
-  IndexTrieNode *getChild(unsigned Idx) {
-    assert(Idx != RootIdx);
+  IndexTrieNode *getChild(int Idx) {
+    assert(Idx != RootIndex);
 
-    auto I = std::lower_bound(Children.begin(), Children.end(), Idx,
-                              [](IndexTrieNode *a, unsigned i) {
-                                return a->Index < i;
-                              });
+    auto I =
+        std::lower_bound(Children.begin(), Children.end(), Idx,
+                         [](IndexTrieNode *a, int i) { return a->Index < i; });
     if (I != Children.end() && (*I)->Index == Idx)
       return *I;
     auto *N = new IndexTrieNode(Idx, this);

include/swift/SILOptimizer/Utils/IndexTrie.h renamed to include/swift/Basic/IndexTrie.h

@@ -668,6 +668,16 @@ using BuiltinApplyTy = typename Apply_match<BuiltinValueKind, Tys...>::Ty;
 // Define matchers for most of builtin instructions.
 #include "swift/AST/Builtins.def"
 
+#undef BUILTIN_UNARY_OP_MATCH_WITH_ARG_MATCHER
+#undef BUILTIN_BINARY_OP_MATCH_WITH_ARG_MATCHER
+#undef BUILTIN_VARARGS_OP_MATCH_WITH_ARG_MATCHER
+#undef BUILTIN_CAST_OPERATION
+#undef BUILTIN_CAST_OR_BITCAST_OPERATION
+#undef BUILTIN_BINARY_OPERATION_ALL
+#undef BUILTIN_BINARY_PREDICATE
+#undef BUILTIN_MISC_OPERATION
+#undef BUILTIN
+
 //===
 // Convenience compound builtin instructions matchers that succeed
 // if any of the sub-matchers succeed.

include/swift/SIL/MemAccessUtils.h

@@ -67,9 +67,9 @@ inline bool isStrictSubSeqRelation(SubSeqRelation_t Seq) {
 
 /// Extract an integer index from a SILValue.
 ///
-/// Return true if IndexVal is a constant index representable as unsigned
+/// Return true if IndexVal is a constant index representable as an
 /// int. We do not support symbolic projections yet.
-bool getIntegerIndex(SILValue IndexVal, unsigned &IndexConst);
+bool getIntegerIndex(SILValue IndexVal, int &IndexConst);
 
 /// The kind of projection that we are representing.
 ///
@@ -136,11 +136,18 @@ static inline bool isCastProjectionKind(ProjectionKind Kind) {
 /// that immediately contains it.
 ///
 /// This lightweight utility maps a SIL address projection to an index.
+///
+/// project_box does not have a projection index. At the SIL level, the box
+/// storage is considered part of the same object as the. The box projection is
+/// does not affect access path so that box projections can occur on distinct
+/// phi paths in the address def-use chain.
 struct ProjectionIndex {
+  static constexpr int TailIndex = std::numeric_limits<int>::max();
+
   SILValue Aggregate;
-  unsigned Index;
+  int Index = std::numeric_limits<int>::min();
 
-  explicit ProjectionIndex(SILValue V) : Index(~0U) {
+  explicit ProjectionIndex(SILValue V) {
     switch (V->getKind()) {
     default:
       break;
@@ -163,16 +170,9 @@ struct ProjectionIndex {
       break;
     }
     case ValueKind::RefTailAddrInst: {
-      RefTailAddrInst *REA = cast<RefTailAddrInst>(V);
-      Index = 0;
-      Aggregate = REA->getOperand();
-      break;
-    }
-    case ValueKind::ProjectBoxInst: {
-      ProjectBoxInst *PBI = cast<ProjectBoxInst>(V);
-      // A box has only a single payload.
-      Index = 0;
-      Aggregate = PBI->getOperand();
+      RefTailAddrInst *RTA = cast<RefTailAddrInst>(V);
+      Index = TailIndex;
+      Aggregate = RTA->getOperand();
       break;
     }
     case ValueKind::TupleElementAddrInst: {
@@ -233,8 +233,7 @@ class Projection {
       : Projection(dyn_cast<SingleValueInstruction>(I)) {}
   explicit Projection(SingleValueInstruction *I);
 
-  Projection(ProjectionKind Kind, unsigned NewIndex)
-      : Value(Kind, NewIndex) {}
+  Projection(ProjectionKind Kind, int NewIndex) : Value(Kind, NewIndex) {}
 
   Projection(ProjectionKind Kind, TypeBase *Ptr)
       : Value(Kind, Ptr) {}
@@ -252,10 +251,8 @@ class Projection {
 
   /// Convenience method for getting the underlying index. Assumes that this
   /// projection is valid. Otherwise it asserts.
-  unsigned getIndex() const {
-    return Value.getIndex();
-  }
-  
+  int getIndex() const { return Value.getIndex(); }
+
   unsigned getHash() const { return (unsigned)Value.getStorage(); }
 
   /// Determine if I is a value projection instruction whose corresponding
@@ -359,7 +356,7 @@ class Projection {
       return nullptr;
     case ValueKind::IndexAddrInst: {
       auto *i = cast<IndexAddrInst>(v);
-      unsigned scalar;
+      int scalar;
       if (getIntegerIndex(i->getIndex(), scalar))
         return i;
       return nullptr;

include/swift/SIL/PatternMatch.h

@@ -5822,13 +5822,11 @@ class TupleElementAddrInst
 ///                object, including properties declared in a superclass.
 unsigned getFieldIndex(NominalTypeDecl *decl, VarDecl *property);
 
-/// Get the property for a struct or class by its unique index.
+/// Get the property for a struct or class by its unique index, or nullptr if
+/// the index does not match a property declared in this struct or class or
+/// one its superclasses.
 ///
 /// Precondition: \p decl must be a non-resilient struct or class.
-///
-/// Precondition: \p index must be the index of a stored property
-///               (as returned by getFieldIndex()) which is declared
-///               in \p decl, not in a superclass.
 VarDecl *getIndexedField(NominalTypeDecl *decl, unsigned index);
 
 /// A common base for instructions that require a cached field index.

include/swift/SIL/Projection.h

@@ -21,6 +21,7 @@
 #include "swift/AST/Builtins.h"
 #include "swift/AST/SILLayout.h"
 #include "swift/AST/SILOptions.h"
+#include "swift/Basic/IndexTrie.h"
 #include "swift/Basic/LangOptions.h"
 #include "swift/Basic/ProfileCounter.h"
 #include "swift/Basic/Range.h"
@@ -256,6 +257,10 @@ class SILModule {
   /// The indexed profile data to be used for PGO, or nullptr.
   std::unique_ptr<llvm::IndexedInstrProfReader> PGOReader;
 
+  /// A trie of integer indices that gives pointer identity to a path of
+  /// projections, shared between all functions in the module.
+  std::unique_ptr<IndexTrieNode> indexTrieRoot;
+
   /// The options passed into this SILModule.
   const SILOptions &Options;
 
@@ -655,6 +660,8 @@ class SILModule {
     PGOReader = std::move(IPR);
   }
 
+  IndexTrieNode *getIndexTrieRoot() { return indexTrieRoot.get(); }
+
   /// Can value operations (copies and destroys) on the given lowered type
   /// be performed in this module?
   bool isTypeABIAccessible(SILType type,

include/swift/SIL/SILInstruction.h

@@ -19,10 +19,10 @@
 #ifndef SWIFT_SILOPTIMIZER_ANALYSIS_ACCESS_SUMMARY_ANALYSIS_H_
 #define SWIFT_SILOPTIMIZER_ANALYSIS_ACCESS_SUMMARY_ANALYSIS_H_
 
+#include "swift/Basic/IndexTrie.h"
 #include "swift/SIL/SILFunction.h"
 #include "swift/SIL/SILInstruction.h"
 #include "swift/SILOptimizer/Analysis/BottomUpIPAnalysis.h"
-#include "swift/SILOptimizer/Utils/IndexTrie.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 
@@ -173,22 +173,13 @@ class AccessSummaryAnalysis : public BottomUpIPAnalysis {
 
   llvm::SpecificBumpPtrAllocator<FunctionInfo> Allocator;
 
-  /// A trie of integer indices that gives pointer identity to a path of
-  /// projections. This is shared between all functions in the module.
-  std::unique_ptr<IndexTrieNode> SubPathTrie;
-
 public:
-  AccessSummaryAnalysis() : BottomUpIPAnalysis(SILAnalysisKind::AccessSummary) {
-    SubPathTrie.reset(new IndexTrieNode());
-  }
+  AccessSummaryAnalysis()
+      : BottomUpIPAnalysis(SILAnalysisKind::AccessSummary) {}
 
   /// Returns a summary of the accesses performed by the given function.
   const FunctionSummary &getOrCreateSummary(SILFunction *Fn);
 
-  IndexTrieNode *getSubPathTrieRoot() {
-    return SubPathTrie.get();
-  }
-
   /// Returns an IndexTrieNode that represents the single subpath accessed from
   /// BAI or the root if no such node exists.
   const IndexTrieNode *findSubPathAccessed(BeginAccessInst *BAI);

include/swift/SIL/SILModule.h

@@ -39,8 +39,8 @@ bool pointsToLocalObject(SILValue V);
 /// Returns true if \p V is a uniquely identified address or reference. Two
 /// uniquely identified pointers with distinct roots cannot alias. However, a
 /// uniquely identified pointer may alias with unidentified pointers. For
-/// example, the uniquely identified pointer may escape to a call that returns an
-/// alias of that pointer.
+/// example, the uniquely identified pointer may escape to a call that returns
+/// an alias of that pointer.
 ///
 /// It may be any of:
 ///
@@ -53,10 +53,25 @@ bool pointsToLocalObject(SILValue V);
 ///
 /// - an address projection based on an exclusive argument with no levels of
 /// indirection (e.g. ref_element_addr, project_box, etc.).
+///
+/// TODO: Fold this into the AccessedStorage API. pointsToLocalObject should be
+/// performed by AccessedStorage::isUniquelyIdentified.
 inline bool isUniquelyIdentified(SILValue V) {
-  return pointsToLocalObject(V)
-         || (V->getType().isAddress()
-             && isExclusiveArgument(getAccessedAddress(V)));
+  SILValue objectRef = V;
+  if (V->getType().isAddress()) {
+    auto storage = AccessedStorage::compute(V);
+    if (!storage)
+      return false;
+
+    if (storage.isUniquelyIdentified())
+      return true;
+
+    if (!storage.isObjectAccess())
+      return false;
+
+    objectRef = storage.getObject();
+  }
+  return pointsToLocalObject(objectRef);
 }
 
 enum class IsZeroKind {

include/swift/SILOptimizer/Analysis/AccessSummaryAnalysis.h

@@ -70,6 +70,8 @@ PASS(AccessSummaryDumper, "access-summary-dump",
      "Dump Address Parameter Access Summary")
 PASS(AccessedStorageAnalysisDumper, "accessed-storage-analysis-dump",
      "Dump Accessed Storage Analysis Summaries")
+PASS(AccessPathVerification, "access-path-verification",
+     "Verify Access Paths (and Accessed Storage)")
 PASS(AccessedStorageDumper, "accessed-storage-dump",
      "Dump Accessed Storage Information")
 PASS(AccessMarkerElimination, "access-marker-elim",