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Diffstat (limited to 'lib/Transforms/ObjCARC/ObjCARCOpts.cpp')
-rw-r--r--lib/Transforms/ObjCARC/ObjCARCOpts.cpp80
1 files changed, 66 insertions, 14 deletions
diff --git a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index 9a02174556fcc..6653ff0bb91a4 100644
--- a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -1,9 +1,8 @@
//===- ObjCARCOpts.cpp - ObjC ARC Optimization ----------------------------===//
//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
@@ -74,6 +73,11 @@ using namespace llvm::objcarc;
#define DEBUG_TYPE "objc-arc-opts"
+static cl::opt<unsigned> MaxPtrStates("arc-opt-max-ptr-states",
+ cl::Hidden,
+ cl::desc("Maximum number of ptr states the optimizer keeps track of"),
+ cl::init(4095));
+
/// \defgroup ARCUtilities Utility declarations/definitions specific to ARC.
/// @{
@@ -220,6 +224,10 @@ namespace {
return !PerPtrTopDown.empty();
}
+ unsigned top_down_ptr_list_size() const {
+ return std::distance(top_down_ptr_begin(), top_down_ptr_end());
+ }
+
using bottom_up_ptr_iterator = decltype(PerPtrBottomUp)::iterator;
using const_bottom_up_ptr_iterator =
decltype(PerPtrBottomUp)::const_iterator;
@@ -238,6 +246,10 @@ namespace {
return !PerPtrBottomUp.empty();
}
+ unsigned bottom_up_ptr_list_size() const {
+ return std::distance(bottom_up_ptr_begin(), bottom_up_ptr_end());
+ }
+
/// Mark this block as being an entry block, which has one path from the
/// entry by definition.
void SetAsEntry() { TopDownPathCount = 1; }
@@ -481,6 +493,10 @@ namespace {
/// A flag indicating whether this optimization pass should run.
bool Run;
+ /// A flag indicating whether the optimization that removes or moves
+ /// retain/release pairs should be performed.
+ bool DisableRetainReleasePairing = false;
+
/// Flags which determine whether each of the interesting runtime functions
/// is in fact used in the current function.
unsigned UsedInThisFunction;
@@ -642,7 +658,7 @@ ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
"Old = "
<< *RetainRV << "\n");
- Constant *NewDecl = EP.get(ARCRuntimeEntryPointKind::Retain);
+ Function *NewDecl = EP.get(ARCRuntimeEntryPointKind::Retain);
cast<CallInst>(RetainRV)->setCalledFunction(NewDecl);
LLVM_DEBUG(dbgs() << "New = " << *RetainRV << "\n");
@@ -691,7 +707,7 @@ void ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F,
<< *AutoreleaseRV << "\n");
CallInst *AutoreleaseRVCI = cast<CallInst>(AutoreleaseRV);
- Constant *NewDecl = EP.get(ARCRuntimeEntryPointKind::Autorelease);
+ Function *NewDecl = EP.get(ARCRuntimeEntryPointKind::Autorelease);
AutoreleaseRVCI->setCalledFunction(NewDecl);
AutoreleaseRVCI->setTailCall(false); // Never tail call objc_autorelease.
Class = ARCInstKind::Autorelease;
@@ -744,6 +760,19 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
LLVM_DEBUG(dbgs() << "Visiting: Class: " << Class << "; " << *Inst << "\n");
+ // Some of the ARC calls can be deleted if their arguments are global
+ // variables that are inert in ARC.
+ if (IsNoopOnGlobal(Class)) {
+ Value *Opnd = Inst->getOperand(0);
+ if (auto *GV = dyn_cast<GlobalVariable>(Opnd->stripPointerCasts()))
+ if (GV->hasAttribute("objc_arc_inert")) {
+ if (!Inst->getType()->isVoidTy())
+ Inst->replaceAllUsesWith(Opnd);
+ Inst->eraseFromParent();
+ continue;
+ }
+ }
+
switch (Class) {
default: break;
@@ -830,7 +859,7 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
// Create the declaration lazily.
LLVMContext &C = Inst->getContext();
- Constant *Decl = EP.get(ARCRuntimeEntryPointKind::Release);
+ Function *Decl = EP.get(ARCRuntimeEntryPointKind::Release);
CallInst *NewCall = CallInst::Create(Decl, Call->getArgOperand(0), "",
Call);
NewCall->setMetadata(MDKindCache.get(ARCMDKindID::ImpreciseRelease),
@@ -849,7 +878,7 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
// For functions which can never be passed stack arguments, add
// a tail keyword.
- if (IsAlwaysTail(Class)) {
+ if (IsAlwaysTail(Class) && !cast<CallInst>(Inst)->isNoTailCall()) {
Changed = true;
LLVM_DEBUG(
dbgs() << "Adding tail keyword to function since it can never be "
@@ -1273,6 +1302,13 @@ bool ObjCARCOpt::VisitBottomUp(BasicBlock *BB,
LLVM_DEBUG(dbgs() << " Visiting " << *Inst << "\n");
NestingDetected |= VisitInstructionBottomUp(Inst, BB, Retains, MyStates);
+
+ // Bail out if the number of pointers being tracked becomes too large so
+ // that this pass can complete in a reasonable amount of time.
+ if (MyStates.bottom_up_ptr_list_size() > MaxPtrStates) {
+ DisableRetainReleasePairing = true;
+ return false;
+ }
}
// If there's a predecessor with an invoke, visit the invoke as if it were
@@ -1395,6 +1431,13 @@ ObjCARCOpt::VisitTopDown(BasicBlock *BB,
LLVM_DEBUG(dbgs() << " Visiting " << Inst << "\n");
NestingDetected |= VisitInstructionTopDown(&Inst, Releases, MyStates);
+
+ // Bail out if the number of pointers being tracked becomes too large so
+ // that this pass can complete in a reasonable amount of time.
+ if (MyStates.top_down_ptr_list_size() > MaxPtrStates) {
+ DisableRetainReleasePairing = true;
+ return false;
+ }
}
LLVM_DEBUG(dbgs() << "\nState Before Checking for CFG Hazards:\n"
@@ -1501,13 +1544,19 @@ bool ObjCARCOpt::Visit(Function &F,
// Use reverse-postorder on the reverse CFG for bottom-up.
bool BottomUpNestingDetected = false;
- for (BasicBlock *BB : llvm::reverse(ReverseCFGPostOrder))
+ for (BasicBlock *BB : llvm::reverse(ReverseCFGPostOrder)) {
BottomUpNestingDetected |= VisitBottomUp(BB, BBStates, Retains);
+ if (DisableRetainReleasePairing)
+ return false;
+ }
// Use reverse-postorder for top-down.
bool TopDownNestingDetected = false;
- for (BasicBlock *BB : llvm::reverse(PostOrder))
+ for (BasicBlock *BB : llvm::reverse(PostOrder)) {
TopDownNestingDetected |= VisitTopDown(BB, BBStates, Releases);
+ if (DisableRetainReleasePairing)
+ return false;
+ }
return TopDownNestingDetected && BottomUpNestingDetected;
}
@@ -1528,7 +1577,7 @@ void ObjCARCOpt::MoveCalls(Value *Arg, RRInfo &RetainsToMove,
for (Instruction *InsertPt : ReleasesToMove.ReverseInsertPts) {
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
- Constant *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
+ Function *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
Call->setDoesNotThrow();
Call->setTailCall();
@@ -1541,7 +1590,7 @@ void ObjCARCOpt::MoveCalls(Value *Arg, RRInfo &RetainsToMove,
for (Instruction *InsertPt : RetainsToMove.ReverseInsertPts) {
Value *MyArg = ArgTy == ParamTy ? Arg :
new BitCastInst(Arg, ParamTy, "", InsertPt);
- Constant *Decl = EP.get(ARCRuntimeEntryPointKind::Release);
+ Function *Decl = EP.get(ARCRuntimeEntryPointKind::Release);
CallInst *Call = CallInst::Create(Decl, MyArg, "", InsertPt);
// Attach a clang.imprecise_release metadata tag, if appropriate.
if (MDNode *M = ReleasesToMove.ReleaseMetadata)
@@ -1877,7 +1926,7 @@ void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
Changed = true;
// If the load has a builtin retain, insert a plain retain for it.
if (Class == ARCInstKind::LoadWeakRetained) {
- Constant *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
+ Function *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
@@ -1906,7 +1955,7 @@ void ObjCARCOpt::OptimizeWeakCalls(Function &F) {
Changed = true;
// If the load has a builtin retain, insert a plain retain for it.
if (Class == ARCInstKind::LoadWeakRetained) {
- Constant *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
+ Function *Decl = EP.get(ARCRuntimeEntryPointKind::Retain);
CallInst *CI = CallInst::Create(Decl, EarlierCall, "", Call);
CI->setTailCall();
}
@@ -2003,6 +2052,9 @@ bool ObjCARCOpt::OptimizeSequences(Function &F) {
// Analyze the CFG of the function, and all instructions.
bool NestingDetected = Visit(F, BBStates, Retains, Releases);
+ if (DisableRetainReleasePairing)
+ return false;
+
// Transform.
bool AnyPairsCompletelyEliminated = PerformCodePlacement(BBStates, Retains,
Releases,
generated by cgit v1.3 (git 2.53.0) at 2026-09-02 20:34:22 +0000