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100 lines
3.2 KiB
C
100 lines
3.2 KiB
C
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//===- llvm/IR/MetadataTracking.h - Metadata tracking ---------------------===//
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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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// Low-level functions to enable tracking of metadata that could RAUW.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_METADATATRACKING_H
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#define LLVM_IR_METADATATRACKING_H
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#include "llvm/ADT/PointerUnion.h"
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#include "llvm/Support/Casting.h"
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#include <type_traits>
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namespace llvm {
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class Metadata;
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class MetadataAsValue;
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/// \brief API for tracking metadata references through RAUW and deletion.
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///
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/// Shared API for updating \a Metadata pointers in subclasses that support
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/// RAUW.
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///
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/// This API is not meant to be used directly. See \a TrackingMDRef for a
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/// user-friendly tracking reference.
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class MetadataTracking {
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public:
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/// \brief Track the reference to metadata.
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///
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/// Register \c MD with \c *MD, if the subclass supports tracking. If \c *MD
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/// gets RAUW'ed, \c MD will be updated to the new address. If \c *MD gets
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/// deleted, \c MD will be set to \c nullptr.
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///
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/// If tracking isn't supported, \c *MD will not change.
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///
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/// \return true iff tracking is supported by \c MD.
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static bool track(Metadata *&MD) {
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return track(&MD, *MD, static_cast<Metadata *>(nullptr));
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}
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/// \brief Track the reference to metadata for \a Metadata.
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///
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/// As \a track(Metadata*&), but with support for calling back to \c Owner to
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/// tell it that its operand changed. This could trigger \c Owner being
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/// re-uniqued.
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static bool track(void *Ref, Metadata &MD, Metadata &Owner) {
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return track(Ref, MD, &Owner);
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}
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/// \brief Track the reference to metadata for \a MetadataAsValue.
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///
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/// As \a track(Metadata*&), but with support for calling back to \c Owner to
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/// tell it that its operand changed. This could trigger \c Owner being
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/// re-uniqued.
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static bool track(void *Ref, Metadata &MD, MetadataAsValue &Owner) {
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return track(Ref, MD, &Owner);
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}
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/// \brief Stop tracking a reference to metadata.
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///
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/// Stops \c *MD from tracking \c MD.
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static void untrack(Metadata *&MD) { untrack(&MD, *MD); }
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static void untrack(void *Ref, Metadata &MD);
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/// \brief Move tracking from one reference to another.
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///
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/// Semantically equivalent to \c untrack(MD) followed by \c track(New),
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/// except that ownership callbacks are maintained.
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///
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/// Note: it is an error if \c *MD does not equal \c New.
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///
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/// \return true iff tracking is supported by \c MD.
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static bool retrack(Metadata *&MD, Metadata *&New) {
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return retrack(&MD, *MD, &New);
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}
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static bool retrack(void *Ref, Metadata &MD, void *New);
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/// \brief Check whether metadata is replaceable.
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static bool isReplaceable(const Metadata &MD);
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typedef PointerUnion<MetadataAsValue *, Metadata *> OwnerTy;
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private:
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/// \brief Track a reference to metadata for an owner.
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///
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/// Generalized version of tracking.
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static bool track(void *Ref, Metadata &MD, OwnerTy Owner);
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};
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} // end namespace llvm
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#endif
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