Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 97 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/Analysis/CaptureTracking.h b/clang-r353983/include/llvm/Analysis/CaptureTracking.h
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+//===----- llvm/Analysis/CaptureTracking.h - Pointer capture ----*- 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 contains routines that help determine which pointers are captured.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_CAPTURETRACKING_H
+#define LLVM_ANALYSIS_CAPTURETRACKING_H
+
+namespace llvm {
+
+  class Value;
+  class Use;
+  class Instruction;
+  class DominatorTree;
+  class OrderedBasicBlock;
+
+  /// The default value for MaxUsesToExplore argument. It's relatively small to
+  /// keep the cost of analysis reasonable for clients like BasicAliasAnalysis,
+  /// where the results can't be cached.
+  /// TODO: we should probably introduce a caching CaptureTracking analysis and
+  /// use it where possible. The caching version can use much higher limit or
+  /// don't have this cap at all.
+  unsigned constexpr DefaultMaxUsesToExplore = 20;
+
+  /// PointerMayBeCaptured - Return true if this pointer value may be captured
+  /// by the enclosing function (which is required to exist).  This routine can
+  /// be expensive, so consider caching the results.  The boolean ReturnCaptures
+  /// specifies whether returning the value (or part of it) from the function
+  /// counts as capturing it or not.  The boolean StoreCaptures specified
+  /// whether storing the value (or part of it) into memory anywhere
+  /// automatically counts as capturing it or not.
+  /// MaxUsesToExplore specifies how many uses should the analysis explore for
+  /// one value before giving up due too "too many uses".
+  bool PointerMayBeCaptured(const Value *V,
+                            bool ReturnCaptures,
+                            bool StoreCaptures,
+                            unsigned MaxUsesToExplore = DefaultMaxUsesToExplore);
+
+  /// PointerMayBeCapturedBefore - Return true if this pointer value may be
+  /// captured by the enclosing function (which is required to exist). If a
+  /// DominatorTree is provided, only captures which happen before the given
+  /// instruction are considered. This routine can be expensive, so consider
+  /// caching the results.  The boolean ReturnCaptures specifies whether
+  /// returning the value (or part of it) from the function counts as capturing
+  /// it or not.  The boolean StoreCaptures specified whether storing the value
+  /// (or part of it) into memory anywhere automatically counts as capturing it
+  /// or not. Captures by the provided instruction are considered if the
+  /// final parameter is true. An ordered basic block in \p OBB could be used
+  /// to speed up capture-tracker queries.
+  /// MaxUsesToExplore specifies how many uses should the analysis explore for
+  /// one value before giving up due too "too many uses".
+  bool PointerMayBeCapturedBefore(const Value *V, bool ReturnCaptures,
+                                  bool StoreCaptures, const Instruction *I,
+                                  const DominatorTree *DT, bool IncludeI = false,
+                                  OrderedBasicBlock *OBB = nullptr,
+                                  unsigned MaxUsesToExplore = DefaultMaxUsesToExplore);
+
+  /// This callback is used in conjunction with PointerMayBeCaptured. In
+  /// addition to the interface here, you'll need to provide your own getters
+  /// to see whether anything was captured.
+  struct CaptureTracker {
+    virtual ~CaptureTracker();
+
+    /// tooManyUses - The depth of traversal has breached a limit. There may be
+    /// capturing instructions that will not be passed into captured().
+    virtual void tooManyUses() = 0;
+
+    /// shouldExplore - This is the use of a value derived from the pointer.
+    /// To prune the search (ie., assume that none of its users could possibly
+    /// capture) return false. To search it, return true.
+    ///
+    /// U->getUser() is always an Instruction.
+    virtual bool shouldExplore(const Use *U);
+
+    /// captured - Information about the pointer was captured by the user of
+    /// use U. Return true to stop the traversal or false to continue looking
+    /// for more capturing instructions.
+    virtual bool captured(const Use *U) = 0;
+  };
+
+  /// PointerMayBeCaptured - Visit the value and the values derived from it and
+  /// find values which appear to be capturing the pointer value. This feeds
+  /// results into and is controlled by the CaptureTracker object.
+  /// MaxUsesToExplore specifies how many uses should the analysis explore for
+  /// one value before giving up due too "too many uses".
+  void PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker,
+                            unsigned MaxUsesToExplore = DefaultMaxUsesToExplore);
+} // end namespace llvm
+
+#endif