Refactor the code for visiting instructions out into helper functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153267 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2012-03-22 18:24:56 +00:00
parent 1508e5e049
commit c7f5c6e0e3

View File

@ -1678,9 +1678,15 @@ namespace {
void CheckForCFGHazards(const BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
BBState &MyStates) const;
bool VisitInstructionBottomUp(Instruction *Inst,
MapVector<Value *, RRInfo> &Retains,
BBState &MyStates);
bool VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
MapVector<Value *, RRInfo> &Retains);
bool VisitInstructionTopDown(Instruction *Inst,
DenseMap<Value *, RRInfo> &Releases,
BBState &MyStates);
bool VisitTopDown(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
DenseMap<Value *, RRInfo> &Releases);
@ -2515,6 +2521,153 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB,
}
}
bool
ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst,
MapVector<Value *, RRInfo> &Retains,
BBState &MyStates) {
bool NestingDetected = false;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
// If we see two releases in a row on the same pointer. If so, make
// a note, and we'll cicle back to revisit it after we've
// hopefully eliminated the second release, which may allow us to
// eliminate the first release too.
// Theoretically we could implement removal of nested retain+release
// pairs by making PtrState hold a stack of states, but this is
// simple and avoids adding overhead for the non-nested case.
if (S.GetSeq() == S_Release || S.GetSeq() == S_MovableRelease)
NestingDetected = true;
S.RRI.clear();
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.SetSeq(ReleaseMetadata ? S_MovableRelease : S_Release);
S.RRI.ReleaseMetadata = ReleaseMetadata;
S.RRI.KnownSafe = S.IsKnownNested() || S.IsKnownIncremented();
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
S.RRI.Calls.insert(Inst);
S.IncrementRefCount();
S.IncrementNestCount();
break;
}
case IC_RetainBlock:
// An objc_retainBlock call with just a use may need to be kept,
// because it may be copying a block from the stack to the heap.
if (!IsRetainBlockOptimizable(Inst))
break;
// FALLTHROUGH
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.DecrementRefCount();
S.SetAtLeastOneRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_CanRelease:
// Don't do retain+release tracking for IC_RetainRV, because it's
// better to let it remain as the first instruction after a call.
if (Class != IC_RetainRV) {
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
Retains[Inst] = S.RRI;
}
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
return NestingDetected;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
MyStates.clearBottomUpPointers();
return NestingDetected;
case IC_AutoreleasepoolPush:
case IC_None:
// These are irrelevant.
return NestingDetected;
default:
break;
}
// Consider any other possible effects of this instruction on each
// pointer being tracked.
for (BBState::ptr_iterator MI = MyStates.bottom_up_ptr_begin(),
ME = MyStates.bottom_up_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; // Handled above.
PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
S.DecrementRefCount();
switch (Seq) {
case S_Use:
S.SetSeq(S_CanRelease);
continue;
case S_CanRelease:
case S_Release:
case S_MovableRelease:
case S_Stop:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
}
// Check for possible direct uses.
switch (Seq) {
case S_Release:
case S_MovableRelease:
if (CanUse(Inst, Ptr, PA, Class)) {
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
S.SetSeq(S_Use);
} else if (Seq == S_Release &&
(Class == IC_User || Class == IC_CallOrUser)) {
// Non-movable releases depend on any possible objc pointer use.
S.SetSeq(S_Stop);
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
}
break;
case S_Stop:
if (CanUse(Inst, Ptr, PA, Class))
S.SetSeq(S_Use);
break;
case S_CanRelease:
case S_Use:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
}
return NestingDetected;
}
bool
ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
DenseMap<const BasicBlock *, BBState> &BBStates,
@ -2560,144 +2713,148 @@ ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
// Visit all the instructions, bottom-up.
for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; --I) {
Instruction *Inst = llvm::prior(I);
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
NestingDetected |= VisitInstructionBottomUp(Inst, Retains, MyStates);
}
switch (Class) {
case IC_Release: {
Arg = GetObjCArg(Inst);
return NestingDetected;
}
PtrState &S = MyStates.getPtrBottomUpState(Arg);
bool
ObjCARCOpt::VisitInstructionTopDown(Instruction *Inst,
DenseMap<Value *, RRInfo> &Releases,
BBState &MyStates) {
bool NestingDetected = false;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
// If we see two releases in a row on the same pointer. If so, make
switch (Class) {
case IC_RetainBlock:
// An objc_retainBlock call with just a use may need to be kept,
// because it may be copying a block from the stack to the heap.
if (!IsRetainBlockOptimizable(Inst))
break;
// FALLTHROUGH
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
// Don't do retain+release tracking for IC_RetainRV, because it's
// better to let it remain as the first instruction after a call.
if (Class != IC_RetainRV) {
// If we see two retains in a row on the same pointer. If so, make
// a note, and we'll cicle back to revisit it after we've
// hopefully eliminated the second release, which may allow us to
// eliminate the first release too.
// hopefully eliminated the second retain, which may allow us to
// eliminate the first retain too.
// Theoretically we could implement removal of nested retain+release
// pairs by making PtrState hold a stack of states, but this is
// simple and avoids adding overhead for the non-nested case.
if (S.GetSeq() == S_Release || S.GetSeq() == S_MovableRelease)
if (S.GetSeq() == S_Retain)
NestingDetected = true;
S.SetSeq(S_Retain);
S.RRI.clear();
MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.SetSeq(ReleaseMetadata ? S_MovableRelease : S_Release);
S.RRI.ReleaseMetadata = ReleaseMetadata;
S.RRI.KnownSafe = S.IsKnownNested() || S.IsKnownIncremented();
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
// Don't check S.IsKnownIncremented() here because it's not
// sufficient.
S.RRI.KnownSafe = S.IsKnownNested();
S.RRI.Calls.insert(Inst);
S.IncrementRefCount();
S.IncrementNestCount();
break;
}
case IC_RetainBlock:
// An objc_retainBlock call with just a use may need to be kept,
// because it may be copying a block from the stack to the heap.
if (!IsRetainBlockOptimizable(Inst))
break;
// FALLTHROUGH
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrBottomUpState(Arg);
S.SetAtLeastOneRefCount();
S.IncrementRefCount();
S.IncrementNestCount();
return NestingDetected;
}
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.DecrementRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Retain:
case S_CanRelease:
S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_Use:
S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
Releases[Inst] = S.RRI;
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
break;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
MyStates.clearTopDownPointers();
return NestingDetected;
case IC_AutoreleasepoolPush:
case IC_None:
// These are irrelevant.
return NestingDetected;
default:
break;
}
// Consider any other possible effects of this instruction on each
// pointer being tracked.
for (BBState::ptr_iterator MI = MyStates.top_down_ptr_begin(),
ME = MyStates.top_down_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; // Handled above.
PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
S.DecrementRefCount();
S.SetAtLeastOneRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Stop:
case S_Release:
case S_MovableRelease:
case S_Use:
S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_CanRelease:
// Don't do retain+release tracking for IC_RetainRV, because it's
// better to let it remain as the first instruction after a call.
if (Class != IC_RetainRV) {
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
Retains[Inst] = S.RRI;
}
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
continue;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
MyStates.clearBottomUpPointers();
continue;
case IC_AutoreleasepoolPush:
case IC_None:
// These are irrelevant.
continue;
default:
break;
}
// Consider any other possible effects of this instruction on each
// pointer being tracked.
for (BBState::ptr_iterator MI = MyStates.bottom_up_ptr_begin(),
ME = MyStates.bottom_up_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; // Handled above.
PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
S.DecrementRefCount();
switch (Seq) {
case S_Use:
S.SetSeq(S_CanRelease);
continue;
case S_CanRelease:
case S_Release:
case S_MovableRelease:
case S_Stop:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
}
}
// Check for possible direct uses.
switch (Seq) {
case S_Release:
case S_MovableRelease:
if (CanUse(Inst, Ptr, PA, Class)) {
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
S.SetSeq(S_Use);
} else if (Seq == S_Release &&
(Class == IC_User || Class == IC_CallOrUser)) {
// Non-movable releases depend on any possible objc pointer use.
S.SetSeq(S_Stop);
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
}
break;
case S_Stop:
if (CanUse(Inst, Ptr, PA, Class))
S.SetSeq(S_Use);
break;
case S_CanRelease:
case S_Retain:
S.SetSeq(S_CanRelease);
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
// One call can't cause a transition from S_Retain to S_CanRelease
// and S_CanRelease to S_Use. If we've made the first transition,
// we're done.
continue;
case S_Use:
case S_CanRelease:
case S_None:
break;
case S_Retain:
llvm_unreachable("bottom-up pointer in retain state!");
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
// Check for possible direct uses.
switch (Seq) {
case S_CanRelease:
if (CanUse(Inst, Ptr, PA, Class))
S.SetSeq(S_Use);
break;
case S_Retain:
case S_Use:
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
return NestingDetected;
@ -2751,138 +2908,7 @@ ObjCARCOpt::VisitTopDown(BasicBlock *BB,
// Visit all the instructions, top-down.
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
Instruction *Inst = I;
InstructionClass Class = GetInstructionClass(Inst);
const Value *Arg = 0;
switch (Class) {
case IC_RetainBlock:
// An objc_retainBlock call with just a use may need to be kept,
// because it may be copying a block from the stack to the heap.
if (!IsRetainBlockOptimizable(Inst))
break;
// FALLTHROUGH
case IC_Retain:
case IC_RetainRV: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
// Don't do retain+release tracking for IC_RetainRV, because it's
// better to let it remain as the first instruction after a call.
if (Class != IC_RetainRV) {
// If we see two retains in a row on the same pointer. If so, make
// a note, and we'll cicle back to revisit it after we've
// hopefully eliminated the second retain, which may allow us to
// eliminate the first retain too.
// Theoretically we could implement removal of nested retain+release
// pairs by making PtrState hold a stack of states, but this is
// simple and avoids adding overhead for the non-nested case.
if (S.GetSeq() == S_Retain)
NestingDetected = true;
S.SetSeq(S_Retain);
S.RRI.clear();
S.RRI.IsRetainBlock = Class == IC_RetainBlock;
// Don't check S.IsKnownIncremented() here because it's not
// sufficient.
S.RRI.KnownSafe = S.IsKnownNested();
S.RRI.Calls.insert(Inst);
}
S.SetAtLeastOneRefCount();
S.IncrementRefCount();
S.IncrementNestCount();
continue;
}
case IC_Release: {
Arg = GetObjCArg(Inst);
PtrState &S = MyStates.getPtrTopDownState(Arg);
S.DecrementRefCount();
S.DecrementNestCount();
switch (S.GetSeq()) {
case S_Retain:
case S_CanRelease:
S.RRI.ReverseInsertPts.clear();
// FALL THROUGH
case S_Use:
S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
Releases[Inst] = S.RRI;
S.ClearSequenceProgress();
break;
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
break;
}
case IC_AutoreleasepoolPop:
// Conservatively, clear MyStates for all known pointers.
MyStates.clearTopDownPointers();
continue;
case IC_AutoreleasepoolPush:
case IC_None:
// These are irrelevant.
continue;
default:
break;
}
// Consider any other possible effects of this instruction on each
// pointer being tracked.
for (BBState::ptr_iterator MI = MyStates.top_down_ptr_begin(),
ME = MyStates.top_down_ptr_end(); MI != ME; ++MI) {
const Value *Ptr = MI->first;
if (Ptr == Arg)
continue; // Handled above.
PtrState &S = MI->second;
Sequence Seq = S.GetSeq();
// Check for possible releases.
if (CanAlterRefCount(Inst, Ptr, PA, Class)) {
S.DecrementRefCount();
switch (Seq) {
case S_Retain:
S.SetSeq(S_CanRelease);
assert(S.RRI.ReverseInsertPts.empty());
S.RRI.ReverseInsertPts.insert(Inst);
// One call can't cause a transition from S_Retain to S_CanRelease
// and S_CanRelease to S_Use. If we've made the first transition,
// we're done.
continue;
case S_Use:
case S_CanRelease:
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
// Check for possible direct uses.
switch (Seq) {
case S_CanRelease:
if (CanUse(Inst, Ptr, PA, Class))
S.SetSeq(S_Use);
break;
case S_Retain:
case S_Use:
case S_None:
break;
case S_Stop:
case S_Release:
case S_MovableRelease:
llvm_unreachable("top-down pointer in release state!");
}
}
NestingDetected |= VisitInstructionTopDown(Inst, Releases, MyStates);
}
CheckForCFGHazards(BB, BBStates, MyStates);