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9da65a8644
As it turns out, the capture tracker named CaptureBefore used by AA, and now available via the PointerMayBeCapturedBefore function, would have been more-aptly named CapturedBeforeOrAt, because it considers captures at the instruction provided. This is not always what one wants, and it is difficult to get the strictly-before behavior given only the current interface. This adds an additional parameter which controls whether or not you want to include captures at the provided instruction. The default is not to include the instruction provided, so that 'Before' matches its name. No functionality change intended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213582 91177308-0d34-0410-b5e6-96231b3b80d8
79 lines
3.5 KiB
C++
79 lines
3.5 KiB
C++
//===----- llvm/Analysis/CaptureTracking.h - Pointer capture ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains routines that help determine which pointers are captured.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_CAPTURETRACKING_H
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#define LLVM_ANALYSIS_CAPTURETRACKING_H
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namespace llvm {
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class Value;
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class Use;
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class Instruction;
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class DominatorTree;
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/// PointerMayBeCaptured - Return true if this pointer value may be captured
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/// by the enclosing function (which is required to exist). This routine can
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/// be expensive, so consider caching the results. The boolean ReturnCaptures
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/// specifies whether returning the value (or part of it) from the function
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/// counts as capturing it or not. The boolean StoreCaptures specified
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/// whether storing the value (or part of it) into memory anywhere
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/// automatically counts as capturing it or not.
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bool PointerMayBeCaptured(const Value *V,
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bool ReturnCaptures,
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bool StoreCaptures);
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/// PointerMayBeCapturedBefore - Return true if this pointer value may be
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/// captured by the enclosing function (which is required to exist). If a
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/// DominatorTree is provided, only captures which happen before the given
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/// instruction are considered. This routine can be expensive, so consider
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/// caching the results. The boolean ReturnCaptures specifies whether
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/// returning the value (or part of it) from the function counts as capturing
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/// it or not. The boolean StoreCaptures specified whether storing the value
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/// (or part of it) into memory anywhere automatically counts as capturing it
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/// or not. Captures by the provided instruction are considered if the
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/// final parameter is true.
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bool PointerMayBeCapturedBefore(const Value *V, bool ReturnCaptures,
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bool StoreCaptures, const Instruction *I,
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DominatorTree *DT, bool IncludeI = false);
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/// This callback is used in conjunction with PointerMayBeCaptured. In
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/// addition to the interface here, you'll need to provide your own getters
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/// to see whether anything was captured.
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struct CaptureTracker {
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virtual ~CaptureTracker();
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/// tooManyUses - The depth of traversal has breached a limit. There may be
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/// capturing instructions that will not be passed into captured().
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virtual void tooManyUses() = 0;
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/// shouldExplore - This is the use of a value derived from the pointer.
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/// To prune the search (ie., assume that none of its users could possibly
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/// capture) return false. To search it, return true.
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///
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/// U->getUser() is always an Instruction.
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virtual bool shouldExplore(const Use *U);
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/// captured - Information about the pointer was captured by the user of
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/// use U. Return true to stop the traversal or false to continue looking
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/// for more capturing instructions.
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virtual bool captured(const Use *U) = 0;
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};
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/// PointerMayBeCaptured - Visit the value and the values derived from it and
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/// find values which appear to be capturing the pointer value. This feeds
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/// results into and is controlled by the CaptureTracker object.
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void PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker);
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} // end namespace llvm
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#endif
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