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//===----- llvm/Analysis/CaptureTracking.h - Pointer capture ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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;
/// 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.
bool PointerMayBeCaptured(const Value *V,
bool ReturnCaptures,
bool StoreCaptures);
/// 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.
bool PointerMayBeCapturedBefore(const Value *V, bool ReturnCaptures,
bool StoreCaptures, const Instruction *I,
DominatorTree *DT, bool IncludeI = false);
/// 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.
void PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker);
} // end namespace llvm
#endif
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