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Refactored out a part of ObjCARCOpt::OptimizeReturns into its own method HasSafePathToPredecessorCall.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178710 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2013-04-03 23:04:28 +00:00
parent 60d1c0bca3
commit ca4cb5b6df
1 changed files with 33 additions and 22 deletions
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55
lib/Transforms/ObjCARC/ObjCARCOpts.cpp
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@ -2779,6 +2779,34 @@ bool ObjCARCOpt::OptimizeSequences(Function &F) {
NestingDetected;
}
// Check if there is a dependent call earlier that does not have anything in
// between the Retain and the call that can affect the reference count of their
// shared pointer argument. Note that Retain need not be in BB.
static bool
HasSafePathToPredecessorCall(const Value *Arg, Instruction *Retain,
SmallPtrSet<Instruction *, 4> &DepInsts,
SmallPtrSet<const BasicBlock *, 4> &Visited,
ProvenanceAnalysis &PA) {
FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
DepInsts, Visited, PA);
if (DepInsts.size() != 1)
return false;
CallInst *Call =
dyn_cast_or_null<CallInst>(*DepInsts.begin());
// Check that the pointer is the return value of the call.
if (!Call || Arg != Call)
return false;
// Check that the call is a regular call.
InstructionClass Class = GetBasicInstructionClass(Call);
if (Class != IC_CallOrUser && Class != IC_Call)
return false;
return true;
}
/// Look for this pattern:
/// \code
/// %call = call i8* @something(...)
@ -2840,28 +2868,11 @@ void ObjCARCOpt::OptimizeReturns(Function &F) {
DependingInstructions.clear();
Visited.clear();
// Check that there is nothing that can affect the reference
// count between the retain and the call.
// Note that Retain need not be in BB.
FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
DependingInstructions, Visited, PA);
if (DependingInstructions.size() != 1)
goto next_block;
{
CallInst *Call =
dyn_cast_or_null<CallInst>(*DependingInstructions.begin());
// Check that the pointer is the return value of the call.
if (!Call || Arg != Call)
goto next_block;
// Check that the call is a regular call.
InstructionClass Class = GetBasicInstructionClass(Call);
if (Class != IC_CallOrUser && Class != IC_Call)
goto next_block;
// Check that there is nothing that can affect the reference count
// between the retain and the call. Note that Retain need not be in BB.
if (HasSafePathToPredecessorCall(Arg, Retain, DependingInstructions,
Visited, PA)) {
// If so, we can zap the retain and autorelease.
Changed = true;
++NumRets;