[llvm] r231426 - [objc-arc] Extract out state specific to a ref count from the main objc arc sequence dataflow. This will allow me to separate the actual ARC queries from the meat of the dataflow algorithm.
Michael Gottesman
mgottesman at apple.com
Thu Mar 5 15:29:03 PST 2015
Author: mgottesman
Date: Thu Mar 5 17:29:03 2015
New Revision: 231426
URL: http://llvm.org/viewvc/llvm-project?rev=231426&view=rev
Log:
[objc-arc] Extract out state specific to a ref count from the main objc arc sequence dataflow. This will allow me to separate the actual ARC queries from the meat of the dataflow algorithm.
Added:
llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp
llvm/trunk/lib/Transforms/ObjCARC/PtrState.h
Modified:
llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt
llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
Modified: llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt?rev=231426&r1=231425&r2=231426&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt Thu Mar 5 17:29:03 2015
@@ -9,6 +9,7 @@ add_llvm_library(LLVMObjCARCOpts
DependencyAnalysis.cpp
ProvenanceAnalysis.cpp
ProvenanceAnalysisEvaluator.cpp
+ PtrState.cpp
ADDITIONAL_HEADER_DIRS
${LLVM_MAIN_INCLUDE_DIR}/llvm/Transforms
Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp?rev=231426&r1=231425&r2=231426&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp Thu Mar 5 17:29:03 2015
@@ -30,6 +30,7 @@
#include "ObjCARCAliasAnalysis.h"
#include "ProvenanceAnalysis.h"
#include "BlotMapVector.h"
+#include "PtrState.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
@@ -175,293 +176,6 @@ STATISTIC(NumReleasesAfterOpt,
#endif
namespace {
- /// \enum Sequence
- ///
- /// \brief A sequence of states that a pointer may go through in which an
- /// objc_retain and objc_release are actually needed.
- enum Sequence {
- S_None,
- S_Retain, ///< objc_retain(x).
- S_CanRelease, ///< foo(x) -- x could possibly see a ref count decrement.
- S_Use, ///< any use of x.
- S_Stop, ///< like S_Release, but code motion is stopped.
- S_Release, ///< objc_release(x).
- S_MovableRelease ///< objc_release(x), !clang.imprecise_release.
- };
-
- raw_ostream &operator<<(raw_ostream &OS, const Sequence S)
- LLVM_ATTRIBUTE_UNUSED;
- raw_ostream &operator<<(raw_ostream &OS, const Sequence S) {
- switch (S) {
- case S_None:
- return OS << "S_None";
- case S_Retain:
- return OS << "S_Retain";
- case S_CanRelease:
- return OS << "S_CanRelease";
- case S_Use:
- return OS << "S_Use";
- case S_Release:
- return OS << "S_Release";
- case S_MovableRelease:
- return OS << "S_MovableRelease";
- case S_Stop:
- return OS << "S_Stop";
- }
- llvm_unreachable("Unknown sequence type.");
- }
-}
-
-static Sequence MergeSeqs(Sequence A, Sequence B, bool TopDown) {
- // The easy cases.
- if (A == B)
- return A;
- if (A == S_None || B == S_None)
- return S_None;
-
- if (A > B) std::swap(A, B);
- if (TopDown) {
- // Choose the side which is further along in the sequence.
- if ((A == S_Retain || A == S_CanRelease) &&
- (B == S_CanRelease || B == S_Use))
- return B;
- } else {
- // Choose the side which is further along in the sequence.
- if ((A == S_Use || A == S_CanRelease) &&
- (B == S_Use || B == S_Release || B == S_Stop || B == S_MovableRelease))
- return A;
- // If both sides are releases, choose the more conservative one.
- if (A == S_Stop && (B == S_Release || B == S_MovableRelease))
- return A;
- if (A == S_Release && B == S_MovableRelease)
- return A;
- }
-
- return S_None;
-}
-
-namespace {
- /// \brief Unidirectional information about either a
- /// retain-decrement-use-release sequence or release-use-decrement-retain
- /// reverse sequence.
- struct RRInfo {
- /// After an objc_retain, the reference count of the referenced
- /// object is known to be positive. Similarly, before an objc_release, the
- /// reference count of the referenced object is known to be positive. If
- /// there are retain-release pairs in code regions where the retain count
- /// is known to be positive, they can be eliminated, regardless of any side
- /// effects between them.
- ///
- /// Also, a retain+release pair nested within another retain+release
- /// pair all on the known same pointer value can be eliminated, regardless
- /// of any intervening side effects.
- ///
- /// KnownSafe is true when either of these conditions is satisfied.
- bool KnownSafe;
-
- /// True of the objc_release calls are all marked with the "tail" keyword.
- bool IsTailCallRelease;
-
- /// If the Calls are objc_release calls and they all have a
- /// clang.imprecise_release tag, this is the metadata tag.
- MDNode *ReleaseMetadata;
-
- /// For a top-down sequence, the set of objc_retains or
- /// objc_retainBlocks. For bottom-up, the set of objc_releases.
- SmallPtrSet<Instruction *, 2> Calls;
-
- /// The set of optimal insert positions for moving calls in the opposite
- /// sequence.
- SmallPtrSet<Instruction *, 2> ReverseInsertPts;
-
- /// If this is true, we cannot perform code motion but can still remove
- /// retain/release pairs.
- bool CFGHazardAfflicted;
-
- RRInfo() :
- KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(nullptr),
- CFGHazardAfflicted(false) {}
-
- void clear();
-
- /// Conservatively merge the two RRInfo. Returns true if a partial merge has
- /// occurred, false otherwise.
- bool Merge(const RRInfo &Other);
-
- };
-}
-
-void RRInfo::clear() {
- KnownSafe = false;
- IsTailCallRelease = false;
- ReleaseMetadata = nullptr;
- Calls.clear();
- ReverseInsertPts.clear();
- CFGHazardAfflicted = false;
-}
-
-bool RRInfo::Merge(const RRInfo &Other) {
- // Conservatively merge the ReleaseMetadata information.
- if (ReleaseMetadata != Other.ReleaseMetadata)
- ReleaseMetadata = nullptr;
-
- // Conservatively merge the boolean state.
- KnownSafe &= Other.KnownSafe;
- IsTailCallRelease &= Other.IsTailCallRelease;
- CFGHazardAfflicted |= Other.CFGHazardAfflicted;
-
- // Merge the call sets.
- Calls.insert(Other.Calls.begin(), Other.Calls.end());
-
- // Merge the insert point sets. If there are any differences,
- // that makes this a partial merge.
- bool Partial = ReverseInsertPts.size() != Other.ReverseInsertPts.size();
- for (Instruction *Inst : Other.ReverseInsertPts)
- Partial |= ReverseInsertPts.insert(Inst).second;
- return Partial;
-}
-
-namespace {
- /// \brief This class summarizes several per-pointer runtime properties which
- /// are propogated through the flow graph.
- class PtrState {
- /// True if the reference count is known to be incremented.
- bool KnownPositiveRefCount;
-
- /// True if we've seen an opportunity for partial RR elimination, such as
- /// pushing calls into a CFG triangle or into one side of a CFG diamond.
- bool Partial;
-
- /// The current position in the sequence.
- unsigned char Seq : 8;
-
- /// Unidirectional information about the current sequence.
- RRInfo RRI;
-
- public:
- PtrState() : KnownPositiveRefCount(false), Partial(false),
- Seq(S_None) {}
-
-
- bool IsKnownSafe() const {
- return RRI.KnownSafe;
- }
-
- void SetKnownSafe(const bool NewValue) {
- RRI.KnownSafe = NewValue;
- }
-
- bool IsTailCallRelease() const {
- return RRI.IsTailCallRelease;
- }
-
- void SetTailCallRelease(const bool NewValue) {
- RRI.IsTailCallRelease = NewValue;
- }
-
- bool IsTrackingImpreciseReleases() const {
- return RRI.ReleaseMetadata != nullptr;
- }
-
- const MDNode *GetReleaseMetadata() const {
- return RRI.ReleaseMetadata;
- }
-
- void SetReleaseMetadata(MDNode *NewValue) {
- RRI.ReleaseMetadata = NewValue;
- }
-
- bool IsCFGHazardAfflicted() const {
- return RRI.CFGHazardAfflicted;
- }
-
- void SetCFGHazardAfflicted(const bool NewValue) {
- RRI.CFGHazardAfflicted = NewValue;
- }
-
- void SetKnownPositiveRefCount() {
- DEBUG(dbgs() << "Setting Known Positive.\n");
- KnownPositiveRefCount = true;
- }
-
- void ClearKnownPositiveRefCount() {
- DEBUG(dbgs() << "Clearing Known Positive.\n");
- KnownPositiveRefCount = false;
- }
-
- bool HasKnownPositiveRefCount() const {
- return KnownPositiveRefCount;
- }
-
- void SetSeq(Sequence NewSeq) {
- DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
- Seq = NewSeq;
- }
-
- Sequence GetSeq() const {
- return static_cast<Sequence>(Seq);
- }
-
- void ClearSequenceProgress() {
- ResetSequenceProgress(S_None);
- }
-
- void ResetSequenceProgress(Sequence NewSeq) {
- DEBUG(dbgs() << "Resetting sequence progress.\n");
- SetSeq(NewSeq);
- Partial = false;
- RRI.clear();
- }
-
- void Merge(const PtrState &Other, bool TopDown);
-
- void InsertCall(Instruction *I) {
- RRI.Calls.insert(I);
- }
-
- void InsertReverseInsertPt(Instruction *I) {
- RRI.ReverseInsertPts.insert(I);
- }
-
- void ClearReverseInsertPts() {
- RRI.ReverseInsertPts.clear();
- }
-
- bool HasReverseInsertPts() const {
- return !RRI.ReverseInsertPts.empty();
- }
-
- const RRInfo &GetRRInfo() const {
- return RRI;
- }
- };
-}
-
-void
-PtrState::Merge(const PtrState &Other, bool TopDown) {
- Seq = MergeSeqs(GetSeq(), Other.GetSeq(), TopDown);
- KnownPositiveRefCount &= Other.KnownPositiveRefCount;
-
- // If we're not in a sequence (anymore), drop all associated state.
- if (Seq == S_None) {
- Partial = false;
- RRI.clear();
- } else if (Partial || Other.Partial) {
- // If we're doing a merge on a path that's previously seen a partial
- // merge, conservatively drop the sequence, to avoid doing partial
- // RR elimination. If the branch predicates for the two merge differ,
- // mixing them is unsafe.
- ClearSequenceProgress();
- } else {
- // Otherwise merge the other PtrState's RRInfo into our RRInfo. At this
- // point, we know that currently we are not partial. Stash whether or not
- // the merge operation caused us to undergo a partial merging of reverse
- // insertion points.
- Partial = RRI.Merge(Other.RRI);
- }
-}
-
-namespace {
/// \brief Per-BasicBlock state.
class BBState {
/// The number of unique control paths from the entry which can reach this
Added: llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp?rev=231426&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp (added)
+++ llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp Thu Mar 5 17:29:03 2015
@@ -0,0 +1,115 @@
+//===--- PtrState.cpp -----------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PtrState.h"
+
+using namespace llvm;
+using namespace llvm::objcarc;
+
+raw_ostream &operator<<(raw_ostream &OS, const Sequence S) {
+ switch (S) {
+ case S_None:
+ return OS << "S_None";
+ case S_Retain:
+ return OS << "S_Retain";
+ case S_CanRelease:
+ return OS << "S_CanRelease";
+ case S_Use:
+ return OS << "S_Use";
+ case S_Release:
+ return OS << "S_Release";
+ case S_MovableRelease:
+ return OS << "S_MovableRelease";
+ case S_Stop:
+ return OS << "S_Stop";
+ }
+ llvm_unreachable("Unknown sequence type.");
+}
+
+static Sequence MergeSeqs(Sequence A, Sequence B, bool TopDown) {
+ // The easy cases.
+ if (A == B)
+ return A;
+ if (A == S_None || B == S_None)
+ return S_None;
+
+ if (A > B)
+ std::swap(A, B);
+ if (TopDown) {
+ // Choose the side which is further along in the sequence.
+ if ((A == S_Retain || A == S_CanRelease) &&
+ (B == S_CanRelease || B == S_Use))
+ return B;
+ } else {
+ // Choose the side which is further along in the sequence.
+ if ((A == S_Use || A == S_CanRelease) &&
+ (B == S_Use || B == S_Release || B == S_Stop || B == S_MovableRelease))
+ return A;
+ // If both sides are releases, choose the more conservative one.
+ if (A == S_Stop && (B == S_Release || B == S_MovableRelease))
+ return A;
+ if (A == S_Release && B == S_MovableRelease)
+ return A;
+ }
+
+ return S_None;
+}
+
+void RRInfo::clear() {
+ KnownSafe = false;
+ IsTailCallRelease = false;
+ ReleaseMetadata = nullptr;
+ Calls.clear();
+ ReverseInsertPts.clear();
+ CFGHazardAfflicted = false;
+}
+
+bool RRInfo::Merge(const RRInfo &Other) {
+ // Conservatively merge the ReleaseMetadata information.
+ if (ReleaseMetadata != Other.ReleaseMetadata)
+ ReleaseMetadata = nullptr;
+
+ // Conservatively merge the boolean state.
+ KnownSafe &= Other.KnownSafe;
+ IsTailCallRelease &= Other.IsTailCallRelease;
+ CFGHazardAfflicted |= Other.CFGHazardAfflicted;
+
+ // Merge the call sets.
+ Calls.insert(Other.Calls.begin(), Other.Calls.end());
+
+ // Merge the insert point sets. If there are any differences,
+ // that makes this a partial merge.
+ bool Partial = ReverseInsertPts.size() != Other.ReverseInsertPts.size();
+ for (Instruction *Inst : Other.ReverseInsertPts)
+ Partial |= ReverseInsertPts.insert(Inst).second;
+ return Partial;
+}
+
+void PtrState::Merge(const PtrState &Other, bool TopDown) {
+ Seq = MergeSeqs(GetSeq(), Other.GetSeq(), TopDown);
+ KnownPositiveRefCount &= Other.KnownPositiveRefCount;
+
+ // If we're not in a sequence (anymore), drop all associated state.
+ if (Seq == S_None) {
+ Partial = false;
+ RRI.clear();
+ } else if (Partial || Other.Partial) {
+ // If we're doing a merge on a path that's previously seen a partial
+ // merge, conservatively drop the sequence, to avoid doing partial
+ // RR elimination. If the branch predicates for the two merge differ,
+ // mixing them is unsafe.
+ ClearSequenceProgress();
+ } else {
+ // Otherwise merge the other PtrState's RRInfo into our RRInfo. At this
+ // point, we know that currently we are not partial. Stash whether or not
+ // the merge operation caused us to undergo a partial merging of reverse
+ // insertion points.
+ Partial = RRI.Merge(Other.RRI);
+ }
+}
Added: llvm/trunk/lib/Transforms/ObjCARC/PtrState.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/PtrState.h?rev=231426&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/PtrState.h (added)
+++ llvm/trunk/lib/Transforms/ObjCARC/PtrState.h Thu Mar 5 17:29:03 2015
@@ -0,0 +1,181 @@
+//===--- PtrState.h - ARC State for a Ptr -------------------*- 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 declarations for the ARC state associated with a ptr. It
+// is only used by the ARC Sequence Dataflow computation. By separating this
+// from the actual dataflow, it is easier to consider the mechanics of the ARC
+// optimization separate from the actual predicates being used.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_PTRSTATE_H
+#define LLVM_LIB_TRANSFORMS_OBJCARC_PTRSTATE_H
+
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Debug.h"
+
+namespace llvm {
+namespace objcarc {
+
+/// \enum Sequence
+///
+/// \brief A sequence of states that a pointer may go through in which an
+/// objc_retain and objc_release are actually needed.
+enum Sequence {
+ S_None,
+ S_Retain, ///< objc_retain(x).
+ S_CanRelease, ///< foo(x) -- x could possibly see a ref count decrement.
+ S_Use, ///< any use of x.
+ S_Stop, ///< like S_Release, but code motion is stopped.
+ S_Release, ///< objc_release(x).
+ S_MovableRelease ///< objc_release(x), !clang.imprecise_release.
+};
+
+raw_ostream &operator<<(raw_ostream &OS,
+ const Sequence S) LLVM_ATTRIBUTE_UNUSED;
+
+/// \brief Unidirectional information about either a
+/// retain-decrement-use-release sequence or release-use-decrement-retain
+/// reverse sequence.
+struct RRInfo {
+ /// After an objc_retain, the reference count of the referenced
+ /// object is known to be positive. Similarly, before an objc_release, the
+ /// reference count of the referenced object is known to be positive. If
+ /// there are retain-release pairs in code regions where the retain count
+ /// is known to be positive, they can be eliminated, regardless of any side
+ /// effects between them.
+ ///
+ /// Also, a retain+release pair nested within another retain+release
+ /// pair all on the known same pointer value can be eliminated, regardless
+ /// of any intervening side effects.
+ ///
+ /// KnownSafe is true when either of these conditions is satisfied.
+ bool KnownSafe;
+
+ /// True of the objc_release calls are all marked with the "tail" keyword.
+ bool IsTailCallRelease;
+
+ /// If the Calls are objc_release calls and they all have a
+ /// clang.imprecise_release tag, this is the metadata tag.
+ MDNode *ReleaseMetadata;
+
+ /// For a top-down sequence, the set of objc_retains or
+ /// objc_retainBlocks. For bottom-up, the set of objc_releases.
+ SmallPtrSet<Instruction *, 2> Calls;
+
+ /// The set of optimal insert positions for moving calls in the opposite
+ /// sequence.
+ SmallPtrSet<Instruction *, 2> ReverseInsertPts;
+
+ /// If this is true, we cannot perform code motion but can still remove
+ /// retain/release pairs.
+ bool CFGHazardAfflicted;
+
+ RRInfo()
+ : KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(nullptr),
+ CFGHazardAfflicted(false) {}
+
+ void clear();
+
+ /// Conservatively merge the two RRInfo. Returns true if a partial merge has
+ /// occurred, false otherwise.
+ bool Merge(const RRInfo &Other);
+};
+
+/// \brief This class summarizes several per-pointer runtime properties which
+/// are propogated through the flow graph.
+class PtrState {
+ /// True if the reference count is known to be incremented.
+ bool KnownPositiveRefCount;
+
+ /// True if we've seen an opportunity for partial RR elimination, such as
+ /// pushing calls into a CFG triangle or into one side of a CFG diamond.
+ bool Partial;
+
+ /// The current position in the sequence.
+ unsigned char Seq : 8;
+
+ /// Unidirectional information about the current sequence.
+ RRInfo RRI;
+
+public:
+ PtrState() : KnownPositiveRefCount(false), Partial(false), Seq(S_None) {}
+
+ bool IsKnownSafe() const { return RRI.KnownSafe; }
+
+ void SetKnownSafe(const bool NewValue) { RRI.KnownSafe = NewValue; }
+
+ bool IsTailCallRelease() const { return RRI.IsTailCallRelease; }
+
+ void SetTailCallRelease(const bool NewValue) {
+ RRI.IsTailCallRelease = NewValue;
+ }
+
+ bool IsTrackingImpreciseReleases() const {
+ return RRI.ReleaseMetadata != nullptr;
+ }
+
+ const MDNode *GetReleaseMetadata() const { return RRI.ReleaseMetadata; }
+
+ void SetReleaseMetadata(MDNode *NewValue) { RRI.ReleaseMetadata = NewValue; }
+
+ bool IsCFGHazardAfflicted() const { return RRI.CFGHazardAfflicted; }
+
+ void SetCFGHazardAfflicted(const bool NewValue) {
+ RRI.CFGHazardAfflicted = NewValue;
+ }
+
+ void SetKnownPositiveRefCount() {
+ DEBUG(dbgs() << "Setting Known Positive.\n");
+ KnownPositiveRefCount = true;
+ }
+
+ void ClearKnownPositiveRefCount() {
+ DEBUG(dbgs() << "Clearing Known Positive.\n");
+ KnownPositiveRefCount = false;
+ }
+
+ bool HasKnownPositiveRefCount() const { return KnownPositiveRefCount; }
+
+ void SetSeq(Sequence NewSeq) {
+ DEBUG(dbgs() << "Old: " << Seq << "; New: " << NewSeq << "\n");
+ Seq = NewSeq;
+ }
+
+ Sequence GetSeq() const { return static_cast<Sequence>(Seq); }
+
+ void ClearSequenceProgress() { ResetSequenceProgress(S_None); }
+
+ void ResetSequenceProgress(Sequence NewSeq) {
+ DEBUG(dbgs() << "Resetting sequence progress.\n");
+ SetSeq(NewSeq);
+ Partial = false;
+ RRI.clear();
+ }
+
+ void Merge(const PtrState &Other, bool TopDown);
+
+ void InsertCall(Instruction *I) { RRI.Calls.insert(I); }
+
+ void InsertReverseInsertPt(Instruction *I) { RRI.ReverseInsertPts.insert(I); }
+
+ void ClearReverseInsertPts() { RRI.ReverseInsertPts.clear(); }
+
+ bool HasReverseInsertPts() const { return !RRI.ReverseInsertPts.empty(); }
+
+ const RRInfo &GetRRInfo() const { return RRI; }
+};
+
+} // end namespace objcarc
+} // end namespace llvm
+
+#endif
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