[llvm-commits] [llvm] r173662 - Refactor ObjCARCAliasAnalysis into its own file.
Michael Gottesman
mgottesman at apple.com
Sun Jan 27 21:51:54 PST 2013
Author: mgottesman
Date: Sun Jan 27 23:51:54 2013
New Revision: 173662
URL: http://llvm.org/viewvc/llvm-project?rev=173662&view=rev
Log:
Refactor ObjCARCAliasAnalysis into its own file.
Added:
llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp
llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h
Modified:
llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt
llvm/trunk/lib/Transforms/ObjCARC/ObjCARC.h
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=173662&r1=173661&r2=173662&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/CMakeLists.txt Sun Jan 27 23:51:54 2013
@@ -3,6 +3,7 @@ add_llvm_library(LLVMObjCARCOpts
ObjCARCOpts.cpp
ObjCARCExpand.cpp
ObjCARCAPElim.cpp
+ ObjCARCAliasAnalysis.cpp
)
add_dependencies(LLVMObjCARCOpts intrinsics_gen)
Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARC.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARC.h?rev=173662&r1=173661&r2=173662&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARC.h (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARC.h Sun Jan 27 23:51:54 2013
@@ -26,6 +26,7 @@
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
@@ -145,10 +146,81 @@ static raw_ostream &operator<<(raw_ostre
llvm_unreachable("Unknown instruction class!");
}
+/// \brief Test if the given class is objc_retain or equivalent.
+static inline bool IsRetain(InstructionClass Class) {
+ return Class == IC_Retain ||
+ Class == IC_RetainRV;
+}
+
+/// \brief Test if the given class is objc_autorelease or equivalent.
+static inline bool IsAutorelease(InstructionClass Class) {
+ return Class == IC_Autorelease ||
+ Class == IC_AutoreleaseRV;
+}
+
+/// \brief Test if the given class represents instructions which return their
+/// argument verbatim.
+static inline bool IsForwarding(InstructionClass Class) {
+ // objc_retainBlock technically doesn't always return its argument
+ // verbatim, but it doesn't matter for our purposes here.
+ return Class == IC_Retain ||
+ Class == IC_RetainRV ||
+ Class == IC_Autorelease ||
+ Class == IC_AutoreleaseRV ||
+ Class == IC_RetainBlock ||
+ Class == IC_NoopCast;
+}
+
+/// \brief Test if the given class represents instructions which do nothing if
+/// passed a null pointer.
+static inline bool IsNoopOnNull(InstructionClass Class) {
+ return Class == IC_Retain ||
+ Class == IC_RetainRV ||
+ Class == IC_Release ||
+ Class == IC_Autorelease ||
+ Class == IC_AutoreleaseRV ||
+ Class == IC_RetainBlock;
+}
+
+/// \brief Test if the given class represents instructions which are always safe
+/// to mark with the "tail" keyword.
+static inline bool IsAlwaysTail(InstructionClass Class) {
+ // IC_RetainBlock may be given a stack argument.
+ return Class == IC_Retain ||
+ Class == IC_RetainRV ||
+ Class == IC_AutoreleaseRV;
+}
+
+/// \brief Test if the given class represents instructions which are never safe
+/// to mark with the "tail" keyword.
+static inline bool IsNeverTail(InstructionClass Class) {
+ /// It is never safe to tail call objc_autorelease since by tail calling
+ /// objc_autorelease, we also tail call -[NSObject autorelease] which supports
+ /// fast autoreleasing causing our object to be potentially reclaimed from the
+ /// autorelease pool which violates the semantics of __autoreleasing types in
+ /// ARC.
+ return Class == IC_Autorelease;
+}
+
+/// \brief Test if the given class represents instructions which are always safe
+/// to mark with the nounwind attribute.
+static inline bool IsNoThrow(InstructionClass Class) {
+ // objc_retainBlock is not nounwind because it calls user copy constructors
+ // which could theoretically throw.
+ return Class == IC_Retain ||
+ Class == IC_RetainRV ||
+ Class == IC_Release ||
+ Class == IC_Autorelease ||
+ Class == IC_AutoreleaseRV ||
+ Class == IC_AutoreleasepoolPush ||
+ Class == IC_AutoreleasepoolPop;
+}
/// \brief Determine if F is one of the special known Functions. If it isn't,
/// return IC_CallOrUser.
-static inline InstructionClass GetFunctionClass(const Function *F) {
+static InstructionClass GetFunctionClass(const Function *F)
+ LLVM_ATTRIBUTE_USED;
+static InstructionClass GetFunctionClass(const Function *F) {
Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
// No arguments.
@@ -236,6 +308,48 @@ static inline InstructionClass GetBasicI
return isa<InvokeInst>(V) ? IC_CallOrUser : IC_User;
}
+
+/// \brief This is a wrapper around getUnderlyingObject which also knows how to
+/// look through objc_retain and objc_autorelease calls, which we know to return
+/// their argument verbatim.
+static inline const Value *GetUnderlyingObjCPtr(const Value *V) {
+ for (;;) {
+ V = GetUnderlyingObject(V);
+ if (!IsForwarding(GetBasicInstructionClass(V)))
+ break;
+ V = cast<CallInst>(V)->getArgOperand(0);
+ }
+
+ return V;
+}
+
+/// \brief This is a wrapper around Value::stripPointerCasts which also knows
+/// how to look through objc_retain and objc_autorelease calls, which we know to
+/// return their argument verbatim.
+static inline const Value *StripPointerCastsAndObjCCalls(const Value *V) {
+ for (;;) {
+ V = V->stripPointerCasts();
+ if (!IsForwarding(GetBasicInstructionClass(V)))
+ break;
+ V = cast<CallInst>(V)->getArgOperand(0);
+ }
+ return V;
+}
+
+/// \brief This is a wrapper around Value::stripPointerCasts which also knows
+/// how to look through objc_retain and objc_autorelease calls, which we know to
+/// return their argument verbatim.
+static inline Value *StripPointerCastsAndObjCCalls(Value *V) {
+ for (;;) {
+ V = V->stripPointerCasts();
+ if (!IsForwarding(GetBasicInstructionClass(V)))
+ break;
+ V = cast<CallInst>(V)->getArgOperand(0);
+ }
+ return V;
+}
+
+
} // end namespace objcarc
} // end namespace llvm
Added: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp?rev=173662&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp (added)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp Sun Jan 27 23:51:54 2013
@@ -0,0 +1,164 @@
+//===- ObjCARCAliasAnalysis.cpp - ObjC ARC Optimization -*- mode: c++ -*---===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file defines a simple ARC-aware AliasAnalysis using special knowledge
+/// of Objective C to enhance other optimization passes which rely on the Alias
+/// Analysis infrastructure.
+///
+/// WARNING: This file knows about certain library functions. It recognizes them
+/// by name, and hardwires knowledge of their semantics.
+///
+/// WARNING: This file knows about how certain Objective-C library functions are
+/// used. Naive LLVM IR transformations which would otherwise be
+/// behavior-preserving may break these assumptions.
+///
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "objc-arc-aa"
+#include "ObjCARC.h"
+#include "ObjCARCAliasAnalysis.h"
+
+#include "llvm/IR/Instruction.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/PassAnalysisSupport.h"
+#include "llvm/PassSupport.h"
+
+namespace llvm {
+ class Function;
+ class Value;
+}
+
+using namespace llvm;
+using namespace llvm::objcarc;
+
+// Register this pass...
+char ObjCARCAliasAnalysis::ID = 0;
+INITIALIZE_AG_PASS(ObjCARCAliasAnalysis, AliasAnalysis, "objc-arc-aa",
+ "ObjC-ARC-Based Alias Analysis", false, true, false)
+
+ImmutablePass *llvm::createObjCARCAliasAnalysisPass() {
+ return new ObjCARCAliasAnalysis();
+}
+
+void
+ObjCARCAliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AliasAnalysis::getAnalysisUsage(AU);
+}
+
+AliasAnalysis::AliasResult
+ObjCARCAliasAnalysis::alias(const Location &LocA, const Location &LocB) {
+ if (!EnableARCOpts)
+ return AliasAnalysis::alias(LocA, LocB);
+
+ // First, strip off no-ops, including ObjC-specific no-ops, and try making a
+ // precise alias query.
+ const Value *SA = StripPointerCastsAndObjCCalls(LocA.Ptr);
+ const Value *SB = StripPointerCastsAndObjCCalls(LocB.Ptr);
+ AliasResult Result =
+ AliasAnalysis::alias(Location(SA, LocA.Size, LocA.TBAATag),
+ Location(SB, LocB.Size, LocB.TBAATag));
+ if (Result != MayAlias)
+ return Result;
+
+ // If that failed, climb to the underlying object, including climbing through
+ // ObjC-specific no-ops, and try making an imprecise alias query.
+ const Value *UA = GetUnderlyingObjCPtr(SA);
+ const Value *UB = GetUnderlyingObjCPtr(SB);
+ if (UA != SA || UB != SB) {
+ Result = AliasAnalysis::alias(Location(UA), Location(UB));
+ // We can't use MustAlias or PartialAlias results here because
+ // GetUnderlyingObjCPtr may return an offsetted pointer value.
+ if (Result == NoAlias)
+ return NoAlias;
+ }
+
+ // If that failed, fail. We don't need to chain here, since that's covered
+ // by the earlier precise query.
+ return MayAlias;
+}
+
+bool
+ObjCARCAliasAnalysis::pointsToConstantMemory(const Location &Loc,
+ bool OrLocal) {
+ if (!EnableARCOpts)
+ return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
+
+ // First, strip off no-ops, including ObjC-specific no-ops, and try making
+ // a precise alias query.
+ const Value *S = StripPointerCastsAndObjCCalls(Loc.Ptr);
+ if (AliasAnalysis::pointsToConstantMemory(Location(S, Loc.Size, Loc.TBAATag),
+ OrLocal))
+ return true;
+
+ // If that failed, climb to the underlying object, including climbing through
+ // ObjC-specific no-ops, and try making an imprecise alias query.
+ const Value *U = GetUnderlyingObjCPtr(S);
+ if (U != S)
+ return AliasAnalysis::pointsToConstantMemory(Location(U), OrLocal);
+
+ // If that failed, fail. We don't need to chain here, since that's covered
+ // by the earlier precise query.
+ return false;
+}
+
+AliasAnalysis::ModRefBehavior
+ObjCARCAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
+ // We have nothing to do. Just chain to the next AliasAnalysis.
+ return AliasAnalysis::getModRefBehavior(CS);
+}
+
+AliasAnalysis::ModRefBehavior
+ObjCARCAliasAnalysis::getModRefBehavior(const Function *F) {
+ if (!EnableARCOpts)
+ return AliasAnalysis::getModRefBehavior(F);
+
+ switch (GetFunctionClass(F)) {
+ case IC_NoopCast:
+ return DoesNotAccessMemory;
+ default:
+ break;
+ }
+
+ return AliasAnalysis::getModRefBehavior(F);
+}
+
+AliasAnalysis::ModRefResult
+ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
+ if (!EnableARCOpts)
+ return AliasAnalysis::getModRefInfo(CS, Loc);
+
+ switch (GetBasicInstructionClass(CS.getInstruction())) {
+ case IC_Retain:
+ case IC_RetainRV:
+ case IC_Autorelease:
+ case IC_AutoreleaseRV:
+ case IC_NoopCast:
+ case IC_AutoreleasepoolPush:
+ case IC_FusedRetainAutorelease:
+ case IC_FusedRetainAutoreleaseRV:
+ // These functions don't access any memory visible to the compiler.
+ // Note that this doesn't include objc_retainBlock, because it updates
+ // pointers when it copies block data.
+ return NoModRef;
+ default:
+ break;
+ }
+
+ return AliasAnalysis::getModRefInfo(CS, Loc);
+}
+
+AliasAnalysis::ModRefResult
+ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
+ ImmutableCallSite CS2) {
+ // TODO: Theoretically we could check for dependencies between objc_* calls
+ // and OnlyAccessesArgumentPointees calls or other well-behaved calls.
+ return AliasAnalysis::getModRefInfo(CS1, CS2);
+}
+
Added: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h?rev=173662&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h (added)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.h Sun Jan 27 23:51:54 2013
@@ -0,0 +1,71 @@
+//===- ObjCARCAliasAnalysis.h - ObjC ARC Optimization -*- mode: c++ -*-----===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file declares a simple ARC-aware AliasAnalysis using special knowledge
+/// of Objective C to enhance other optimization passes which rely on the Alias
+/// Analysis infrastructure.
+///
+/// WARNING: This file knows about certain library functions. It recognizes them
+/// by name, and hardwires knowledge of their semantics.
+///
+/// WARNING: This file knows about how certain Objective-C library functions are
+/// used. Naive LLVM IR transformations which would otherwise be
+/// behavior-preserving may break these assumptions.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
+#define LLVM_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
+
+namespace llvm {
+namespace objcarc {
+
+ /// \brief This is a simple alias analysis implementation that uses knowledge
+ /// of ARC constructs to answer queries.
+ ///
+ /// TODO: This class could be generalized to know about other ObjC-specific
+ /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
+ /// even though their offsets are dynamic.
+ class ObjCARCAliasAnalysis : public ImmutablePass,
+ public AliasAnalysis {
+ public:
+ static char ID; // Class identification, replacement for typeinfo
+ ObjCARCAliasAnalysis() : ImmutablePass(ID) {
+ initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
+ }
+
+ private:
+ virtual void initializePass() {
+ InitializeAliasAnalysis(this);
+ }
+
+ /// This method is used when a pass implements an analysis interface through
+ /// multiple inheritance. If needed, it should override this to adjust the
+ /// this pointer as needed for the specified pass info.
+ virtual void *getAdjustedAnalysisPointer(const void *PI) {
+ if (PI == &AliasAnalysis::ID)
+ return static_cast<AliasAnalysis *>(this);
+ return this;
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+ virtual AliasResult alias(const Location &LocA, const Location &LocB);
+ virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
+ virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
+ virtual ModRefBehavior getModRefBehavior(const Function *F);
+ virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
+ const Location &Loc);
+ virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
+ ImmutableCallSite CS2);
+ };
+
+} // namespace objcarc
+} // namespace llvm
+
+#endif // LLVM_TRANSFORMS_OBJCARC_OBJCARCALIASANALYSIS_H
Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp?rev=173662&r1=173661&r2=173662&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp Sun Jan 27 23:51:54 2013
@@ -30,6 +30,7 @@
#define DEBUG_TYPE "objc-arc-opts"
#include "ObjCARC.h"
+#include "ObjCARCAliasAnalysis.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
@@ -131,7 +132,6 @@ namespace {
/// \defgroup ARCUtilities Utility declarations/definitions specific to ARC.
/// @{
-#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/Utils/Local.h"
@@ -260,76 +260,6 @@ static InstructionClass GetInstructionCl
return IC_None;
}
-/// \brief Test if the given class is objc_retain or equivalent.
-static bool IsRetain(InstructionClass Class) {
- return Class == IC_Retain ||
- Class == IC_RetainRV;
-}
-
-/// \brief Test if the given class is objc_autorelease or equivalent.
-static bool IsAutorelease(InstructionClass Class) {
- return Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV;
-}
-
-/// \brief Test if the given class represents instructions which return their
-/// argument verbatim.
-static bool IsForwarding(InstructionClass Class) {
- // objc_retainBlock technically doesn't always return its argument
- // verbatim, but it doesn't matter for our purposes here.
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV ||
- Class == IC_RetainBlock ||
- Class == IC_NoopCast;
-}
-
-/// \brief Test if the given class represents instructions which do nothing if
-/// passed a null pointer.
-static bool IsNoopOnNull(InstructionClass Class) {
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_Release ||
- Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV ||
- Class == IC_RetainBlock;
-}
-
-/// \brief Test if the given class represents instructions which are always safe
-/// to mark with the "tail" keyword.
-static bool IsAlwaysTail(InstructionClass Class) {
- // IC_RetainBlock may be given a stack argument.
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_AutoreleaseRV;
-}
-
-/// \brief Test if the given class represents instructions which are never safe
-/// to mark with the "tail" keyword.
-static bool IsNeverTail(InstructionClass Class) {
- /// It is never safe to tail call objc_autorelease since by tail calling
- /// objc_autorelease, we also tail call -[NSObject autorelease] which supports
- /// fast autoreleasing causing our object to be potentially reclaimed from the
- /// autorelease pool which violates the semantics of __autoreleasing types in
- /// ARC.
- return Class == IC_Autorelease;
-}
-
-/// \brief Test if the given class represents instructions which are always safe
-/// to mark with the nounwind attribute.
-static bool IsNoThrow(InstructionClass Class) {
- // objc_retainBlock is not nounwind because it calls user copy constructors
- // which could theoretically throw.
- return Class == IC_Retain ||
- Class == IC_RetainRV ||
- Class == IC_Release ||
- Class == IC_Autorelease ||
- Class == IC_AutoreleaseRV ||
- Class == IC_AutoreleasepoolPush ||
- Class == IC_AutoreleasepoolPop;
-}
-
/// \brief Erase the given instruction.
///
/// Many ObjC calls return their argument verbatim,
@@ -354,46 +284,6 @@ static void EraseInstruction(Instruction
RecursivelyDeleteTriviallyDeadInstructions(OldArg);
}
-/// \brief This is a wrapper around getUnderlyingObject which also knows how to
-/// look through objc_retain and objc_autorelease calls, which we know to return
-/// their argument verbatim.
-static const Value *GetUnderlyingObjCPtr(const Value *V) {
- for (;;) {
- V = GetUnderlyingObject(V);
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
-
- return V;
-}
-
-/// \brief This is a wrapper around Value::stripPointerCasts which also knows
-/// how to look through objc_retain and objc_autorelease calls, which we know to
-/// return their argument verbatim.
-static const Value *StripPointerCastsAndObjCCalls(const Value *V) {
- for (;;) {
- V = V->stripPointerCasts();
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
- return V;
-}
-
-/// \brief This is a wrapper around Value::stripPointerCasts which also knows
-/// how to look through objc_retain and objc_autorelease calls, which we know to
-/// return their argument verbatim.
-static Value *StripPointerCastsAndObjCCalls(Value *V) {
- for (;;) {
- V = V->stripPointerCasts();
- if (!IsForwarding(GetBasicInstructionClass(V)))
- break;
- V = cast<CallInst>(V)->getArgOperand(0);
- }
- return V;
-}
-
/// \brief Assuming the given instruction is one of the special calls such as
/// objc_retain or objc_release, return the argument value, stripped of no-op
/// casts and forwarding calls.
@@ -553,177 +443,6 @@ static bool DoesObjCBlockEscape(const Va
/// @}
///
-/// \defgroup ARCAA Extends alias analysis using ObjC specific knowledge.
-/// @{
-
-namespace {
- /// \brief This is a simple alias analysis implementation that uses knowledge
- /// of ARC constructs to answer queries.
- ///
- /// TODO: This class could be generalized to know about other ObjC-specific
- /// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
- /// even though their offsets are dynamic.
- class ObjCARCAliasAnalysis : public ImmutablePass,
- public AliasAnalysis {
- public:
- static char ID; // Class identification, replacement for typeinfo
- ObjCARCAliasAnalysis() : ImmutablePass(ID) {
- initializeObjCARCAliasAnalysisPass(*PassRegistry::getPassRegistry());
- }
-
- private:
- virtual void initializePass() {
- InitializeAliasAnalysis(this);
- }
-
- /// This method is used when a pass implements an analysis interface through
- /// multiple inheritance. If needed, it should override this to adjust the
- /// this pointer as needed for the specified pass info.
- virtual void *getAdjustedAnalysisPointer(const void *PI) {
- if (PI == &AliasAnalysis::ID)
- return static_cast<AliasAnalysis *>(this);
- return this;
- }
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual AliasResult alias(const Location &LocA, const Location &LocB);
- virtual bool pointsToConstantMemory(const Location &Loc, bool OrLocal);
- virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
- virtual ModRefBehavior getModRefBehavior(const Function *F);
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
- const Location &Loc);
- virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2);
- };
-} // End of anonymous namespace
-
-// Register this pass...
-char ObjCARCAliasAnalysis::ID = 0;
-INITIALIZE_AG_PASS(ObjCARCAliasAnalysis, AliasAnalysis, "objc-arc-aa",
- "ObjC-ARC-Based Alias Analysis", false, true, false)
-
-ImmutablePass *llvm::createObjCARCAliasAnalysisPass() {
- return new ObjCARCAliasAnalysis();
-}
-
-void
-ObjCARCAliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AliasAnalysis::getAnalysisUsage(AU);
-}
-
-AliasAnalysis::AliasResult
-ObjCARCAliasAnalysis::alias(const Location &LocA, const Location &LocB) {
- if (!EnableARCOpts)
- return AliasAnalysis::alias(LocA, LocB);
-
- // First, strip off no-ops, including ObjC-specific no-ops, and try making a
- // precise alias query.
- const Value *SA = StripPointerCastsAndObjCCalls(LocA.Ptr);
- const Value *SB = StripPointerCastsAndObjCCalls(LocB.Ptr);
- AliasResult Result =
- AliasAnalysis::alias(Location(SA, LocA.Size, LocA.TBAATag),
- Location(SB, LocB.Size, LocB.TBAATag));
- if (Result != MayAlias)
- return Result;
-
- // If that failed, climb to the underlying object, including climbing through
- // ObjC-specific no-ops, and try making an imprecise alias query.
- const Value *UA = GetUnderlyingObjCPtr(SA);
- const Value *UB = GetUnderlyingObjCPtr(SB);
- if (UA != SA || UB != SB) {
- Result = AliasAnalysis::alias(Location(UA), Location(UB));
- // We can't use MustAlias or PartialAlias results here because
- // GetUnderlyingObjCPtr may return an offsetted pointer value.
- if (Result == NoAlias)
- return NoAlias;
- }
-
- // If that failed, fail. We don't need to chain here, since that's covered
- // by the earlier precise query.
- return MayAlias;
-}
-
-bool
-ObjCARCAliasAnalysis::pointsToConstantMemory(const Location &Loc,
- bool OrLocal) {
- if (!EnableARCOpts)
- return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
-
- // First, strip off no-ops, including ObjC-specific no-ops, and try making
- // a precise alias query.
- const Value *S = StripPointerCastsAndObjCCalls(Loc.Ptr);
- if (AliasAnalysis::pointsToConstantMemory(Location(S, Loc.Size, Loc.TBAATag),
- OrLocal))
- return true;
-
- // If that failed, climb to the underlying object, including climbing through
- // ObjC-specific no-ops, and try making an imprecise alias query.
- const Value *U = GetUnderlyingObjCPtr(S);
- if (U != S)
- return AliasAnalysis::pointsToConstantMemory(Location(U), OrLocal);
-
- // If that failed, fail. We don't need to chain here, since that's covered
- // by the earlier precise query.
- return false;
-}
-
-AliasAnalysis::ModRefBehavior
-ObjCARCAliasAnalysis::getModRefBehavior(ImmutableCallSite CS) {
- // We have nothing to do. Just chain to the next AliasAnalysis.
- return AliasAnalysis::getModRefBehavior(CS);
-}
-
-AliasAnalysis::ModRefBehavior
-ObjCARCAliasAnalysis::getModRefBehavior(const Function *F) {
- if (!EnableARCOpts)
- return AliasAnalysis::getModRefBehavior(F);
-
- switch (GetFunctionClass(F)) {
- case IC_NoopCast:
- return DoesNotAccessMemory;
- default:
- break;
- }
-
- return AliasAnalysis::getModRefBehavior(F);
-}
-
-AliasAnalysis::ModRefResult
-ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
- if (!EnableARCOpts)
- return AliasAnalysis::getModRefInfo(CS, Loc);
-
- switch (GetBasicInstructionClass(CS.getInstruction())) {
- case IC_Retain:
- case IC_RetainRV:
- case IC_Autorelease:
- case IC_AutoreleaseRV:
- case IC_NoopCast:
- case IC_AutoreleasepoolPush:
- case IC_FusedRetainAutorelease:
- case IC_FusedRetainAutoreleaseRV:
- // These functions don't access any memory visible to the compiler.
- // Note that this doesn't include objc_retainBlock, because it updates
- // pointers when it copies block data.
- return NoModRef;
- default:
- break;
- }
-
- return AliasAnalysis::getModRefInfo(CS, Loc);
-}
-
-AliasAnalysis::ModRefResult
-ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
- ImmutableCallSite CS2) {
- // TODO: Theoretically we could check for dependencies between objc_* calls
- // and OnlyAccessesArgumentPointees calls or other well-behaved calls.
- return AliasAnalysis::getModRefInfo(CS1, CS2);
-}
-
-/// @}
-///
/// \defgroup ARCOpt ARC Optimization.
/// @{
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