[objc-arc] Introduce the concept of RCIdentity and rename all relevant functions to use that name. NFC.
The RCIdentity root ("Reference Count Identity Root") of a value V is a
dominating value U for which retaining or releasing U is equivalent to
retaining or releasing V. In other words, ARC operations on V are
equivalent to ARC operations on U.
This is a useful property to ascertain since we can use this in the ARC
optimizer to make it easier to match up ARC operations by always mapping
ARC operations to RCIdentityRoots instead of pointers themselves. Then
we perform pairing of retains, releases which are applied to the same
RCIdentityRoot.
In general, the two ways that we see RCIdentical values in ObjC are via:
1. PointerCasts
2. Forwarding Calls that return their argument verbatim.
As such in ObjC, two RCIdentical pointers must always point to the same
memory location.
Previously this concept was implicit in the code and various methods
that dealt with this concept were given functional names that did not
conform to any name in the "ARC" model. This often times resulted in
code that was hard for the non-ARC acquanted to understand resulting in
unhappiness and confusion.
llvm-svn: 229796
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index 76932e6..992cd46 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -144,7 +144,7 @@
/// \defgroup ARCUtilities Utility declarations/definitions specific to ARC.
/// @{
-/// \brief This is similar to StripPointerCastsAndObjCCalls but it stops as soon
+/// \brief This is similar to GetRCIdentityRoot but it stops as soon
/// as it finds a value with multiple uses.
static const Value *FindSingleUseIdentifiedObject(const Value *Arg) {
if (Arg->hasOneUse()) {
@@ -165,7 +165,7 @@
// trivial uses, we can still consider this to be a single-use value.
if (IsObjCIdentifiedObject(Arg)) {
for (const User *U : Arg->users())
- if (!U->use_empty() || StripPointerCastsAndObjCCalls(U) != Arg)
+ if (!U->use_empty() || GetRCIdentityRoot(U) != Arg)
return nullptr;
return Arg;
@@ -1191,7 +1191,7 @@
bool
ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
// Check for the argument being from an immediately preceding call or invoke.
- const Value *Arg = GetObjCArg(RetainRV);
+ const Value *Arg = GetArgRCIdentityRoot(RetainRV);
ImmutableCallSite CS(Arg);
if (const Instruction *Call = CS.getInstruction()) {
if (Call->getParent() == RetainRV->getParent()) {
@@ -1217,7 +1217,7 @@
if (I != Begin) {
do --I; while (I != Begin && IsNoopInstruction(I));
if (GetBasicInstructionClass(I) == IC_AutoreleaseRV &&
- GetObjCArg(I) == Arg) {
+ GetArgRCIdentityRoot(I) == Arg) {
Changed = true;
++NumPeeps;
@@ -1252,7 +1252,7 @@
ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV,
InstructionClass &Class) {
// Check for a return of the pointer value.
- const Value *Ptr = GetObjCArg(AutoreleaseRV);
+ const Value *Ptr = GetArgRCIdentityRoot(AutoreleaseRV);
SmallVector<const Value *, 2> Users;
Users.push_back(Ptr);
do {
@@ -1426,7 +1426,7 @@
continue;
}
- const Value *Arg = GetObjCArg(Inst);
+ const Value *Arg = GetArgRCIdentityRoot(Inst);
// ARC calls with null are no-ops. Delete them.
if (IsNullOrUndef(Arg)) {
@@ -1463,7 +1463,7 @@
bool HasCriticalEdges = false;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
- StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
+ GetRCIdentityRoot(PN->getIncomingValue(i));
if (IsNullOrUndef(Incoming))
HasNull = true;
else if (cast<TerminatorInst>(PN->getIncomingBlock(i)->back())
@@ -1517,7 +1517,7 @@
Type *ParamTy = CInst->getArgOperand(0)->getType();
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming =
- StripPointerCastsAndObjCCalls(PN->getIncomingValue(i));
+ GetRCIdentityRoot(PN->getIncomingValue(i));
if (!IsNullOrUndef(Incoming)) {
CallInst *Clone = cast<CallInst>(CInst->clone());
Value *Op = PN->getIncomingValue(i);
@@ -1718,7 +1718,7 @@
switch (Class) {
case IC_Release: {
- Arg = GetObjCArg(Inst);
+ Arg = GetArgRCIdentityRoot(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
@@ -1752,7 +1752,7 @@
break;
case IC_Retain:
case IC_RetainRV: {
- Arg = GetObjCArg(Inst);
+ Arg = GetArgRCIdentityRoot(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.SetKnownPositiveRefCount();
@@ -1808,7 +1808,7 @@
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
if (AreAnyUnderlyingObjectsAnAlloca(SI->getPointerOperand())) {
BBState::ptr_iterator I = MyStates.findPtrBottomUpState(
- StripPointerCastsAndObjCCalls(SI->getValueOperand()));
+ GetRCIdentityRoot(SI->getValueOperand()));
if (I != MyStates.bottom_up_ptr_end())
MultiOwnersSet.insert(I->first);
}
@@ -1978,7 +1978,7 @@
break;
case IC_Retain:
case IC_RetainRV: {
- Arg = GetObjCArg(Inst);
+ Arg = GetArgRCIdentityRoot(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
@@ -2008,7 +2008,7 @@
break;
}
case IC_Release: {
- Arg = GetObjCArg(Inst);
+ Arg = GetArgRCIdentityRoot(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.ClearKnownPositiveRefCount();
@@ -2372,7 +2372,7 @@
const RRInfo &NewRetainRRI = It->second;
KnownSafeTD &= NewRetainRRI.KnownSafe;
MultipleOwners =
- MultipleOwners || MultiOwnersSet.count(GetObjCArg(NewRetain));
+ MultipleOwners || MultiOwnersSet.count(GetArgRCIdentityRoot(NewRetain));
for (Instruction *NewRetainRelease : NewRetainRRI.Calls) {
DenseMap<Value *, RRInfo>::const_iterator Jt =
Releases.find(NewRetainRelease);
@@ -2581,7 +2581,7 @@
DEBUG(dbgs() << "Visiting: " << *Retain << "\n");
- Value *Arg = GetObjCArg(Retain);
+ Value *Arg = GetArgRCIdentityRoot(Retain);
// If the object being released is in static or stack storage, we know it's
// not being managed by ObjC reference counting, so we can delete pairs
@@ -2593,7 +2593,7 @@
if (const LoadInst *LI = dyn_cast<LoadInst>(Arg))
if (const GlobalVariable *GV =
dyn_cast<GlobalVariable>(
- StripPointerCastsAndObjCCalls(LI->getPointerOperand())))
+ GetRCIdentityRoot(LI->getPointerOperand())))
if (GV->isConstant())
KnownSafe = true;
@@ -2860,7 +2860,7 @@
// Check that we found a retain with the same argument.
if (!Retain ||
!IsRetain(GetBasicInstructionClass(Retain)) ||
- GetObjCArg(Retain) != Arg) {
+ GetArgRCIdentityRoot(Retain) != Arg) {
return nullptr;
}
@@ -2888,7 +2888,7 @@
InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
return nullptr;
- if (GetObjCArg(Autorelease) != Arg)
+ if (GetArgRCIdentityRoot(Autorelease) != Arg)
return nullptr;
return Autorelease;
@@ -2919,7 +2919,7 @@
if (!Ret)
continue;
- const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
+ const Value *Arg = GetRCIdentityRoot(Ret->getOperand(0));
// Look for an ``autorelease'' instruction that is a predecessor of Ret and
// dependent on Arg such that there are no instructions dependent on Arg