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Refactored out the helper method FindPredecessorAutoreleaseWithSafePath from ObjCARCOpt::OptimizeReturns.

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Now ObjCARCOpt::OptimizeReturns is easy to read and reason about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178715 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2013-04-03 23:39:14 +00:00
parent 681f258ae3
commit 296ffab562
1 changed files with 45 additions and 25 deletions
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70
lib/Transforms/ObjCARC/ObjCARCOpts.cpp
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@ -2834,6 +2834,33 @@ FindPredecessorRetainWithSafePath(const Value *Arg, BasicBlock *BB,
return Retain;
}
/// Look for an ``autorelease'' instruction dependent on Arg such that there are
/// no instructions dependent on Arg that need a positive ref count in between
/// the autorelease and the ret.
static CallInst *
FindPredecessorAutoreleaseWithSafePath(const Value *Arg, BasicBlock *BB,
ReturnInst *Ret,
SmallPtrSet<Instruction *, 4> &DepInsts,
SmallPtrSet<const BasicBlock *, 4> &V,
ProvenanceAnalysis &PA) {
FindDependencies(NeedsPositiveRetainCount, Arg,
BB, Ret, DepInsts, V, PA);
if (DepInsts.size() != 1)
return 0;
CallInst *Autorelease =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
if (!Autorelease)
return 0;
InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
return 0;
if (GetObjCArg(Autorelease) != Arg)
return 0;
return Autorelease;
}
/// Look for this pattern:
/// \code
/// %call = call i8* @something(...)
@ -2854,32 +2881,26 @@ void ObjCARCOpt::OptimizeReturns(Function &F) {
DEBUG(dbgs() << "ObjCARCOpt::OptimizeReturns: Visiting: " << *Ret << "\n");
if (!Ret) continue;
if (!Ret)
continue;
const Value *Arg = StripPointerCastsAndObjCCalls(Ret->getOperand(0));
FindDependencies(NeedsPositiveRetainCount, Arg,
BB, Ret, DependingInstructions, Visited, PA);
if (DependingInstructions.size() != 1)
goto next_block;
{
CallInst *Autorelease =
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
if (!Autorelease)
goto next_block;
InstructionClass AutoreleaseClass = GetBasicInstructionClass(Autorelease);
if (!IsAutorelease(AutoreleaseClass))
goto next_block;
if (GetObjCArg(Autorelease) != Arg)
goto next_block;
// Look for an ``autorelease'' instruction that is a predecssor of Ret and
// dependent on Arg such that there are no instructions dependent on Arg
// that need a positive ref count in between the autorelease and Ret.
CallInst *Autorelease =
FindPredecessorAutoreleaseWithSafePath(Arg, BB, Ret,
DependingInstructions, Visited,
PA);
if (Autorelease) {
DependingInstructions.clear();
Visited.clear();
CallInst *Retain = 0;
if ((Retain = FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
DependingInstructions,
Visited, PA))) {
CallInst *Retain =
FindPredecessorRetainWithSafePath(Arg, BB, Autorelease,
DependingInstructions, Visited, PA);
if (Retain) {
DependingInstructions.clear();
Visited.clear();
@ -2898,8 +2919,7 @@ void ObjCARCOpt::OptimizeReturns(Function &F) {
}
}
}
next_block:
DependingInstructions.clear();
Visited.clear();
}