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[objc-arc] Ensure that the cfg path count does not overflow when we multiply TopDownPathCount/BottomUpPathCount.

Browse Source 
rdar://12480535

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183489 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman
2013-06-07 06:16:49 +00:00
parent 57148c166a
commit 9eb856bc29
2 changed files with 569 additions and 13 deletions
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48
lib/Transforms/ObjCARC/ObjCARCOpts.cpp
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@@ -670,13 +670,20 @@ namespace {
void MergePred(const BBState &Other);
void MergeSucc(const BBState &Other);
/// Return the number of possible unique paths from an entry to an exit
/// Compute the number of possible unique paths from an entry to an exit
/// which pass through this block. This is only valid after both the
/// top-down and bottom-up traversals are complete.
unsigned GetAllPathCount() const {
///
/// Returns true if overflow occured. Returns false if overflow did not
/// occur.
bool GetAllPathCountWithOverflow(unsigned &PathCount) const {
assert(TopDownPathCount != 0);
assert(BottomUpPathCount != 0);
return TopDownPathCount * BottomUpPathCount;
unsigned long long Product =
(unsigned long long)TopDownPathCount*BottomUpPathCount;
PathCount = Product;
// Overflow occured if any of the upper bits of Product are set.
return Product >> 32;
}
// Specialized CFG utilities.
@@ -2543,8 +2550,14 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
const RRInfo &NewRetainReleaseRRI = Jt->second;
assert(NewRetainReleaseRRI.Calls.count(NewRetain));
if (ReleasesToMove.Calls.insert(NewRetainRelease)) {
OldDelta -=
BBStates[NewRetainRelease->getParent()].GetAllPathCount();
// If we overflow when we compute the path count, don't remove/move
// anything.
const BBState &NRRBBState = BBStates[NewRetainRelease->getParent()];
unsigned PathCount;
if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
return false;
OldDelta -= PathCount;
// Merge the ReleaseMetadata and IsTailCallRelease values.
if (FirstRelease) {
@@ -2569,8 +2582,14 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
RE = NewRetainReleaseRRI.ReverseInsertPts.end();
RI != RE; ++RI) {
Instruction *RIP = *RI;
if (ReleasesToMove.ReverseInsertPts.insert(RIP))
NewDelta -= BBStates[RIP->getParent()].GetAllPathCount();
if (ReleasesToMove.ReverseInsertPts.insert(RIP)) {
// If we overflow when we compute the path count, don't
// remove/move anything.
const BBState &RIPBBState = BBStates[RIP->getParent()];
if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
return false;
NewDelta -= PathCount;
}
}
NewReleases.push_back(NewRetainRelease);
}
@@ -2600,8 +2619,13 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
const RRInfo &NewReleaseRetainRRI = Jt->second;
assert(NewReleaseRetainRRI.Calls.count(NewRelease));
if (RetainsToMove.Calls.insert(NewReleaseRetain)) {
unsigned PathCount =
BBStates[NewReleaseRetain->getParent()].GetAllPathCount();
// If we overflow when we compute the path count, don't remove/move
// anything.
const BBState &NRRBBState = BBStates[NewReleaseRetain->getParent()];
unsigned PathCount;
if (NRRBBState.GetAllPathCountWithOverflow(PathCount))
return false;
OldDelta += PathCount;
OldCount += PathCount;
@@ -2613,7 +2637,11 @@ ObjCARCOpt::ConnectTDBUTraversals(DenseMap<const BasicBlock *, BBState>
RI != RE; ++RI) {
Instruction *RIP = *RI;
if (RetainsToMove.ReverseInsertPts.insert(RIP)) {
PathCount = BBStates[RIP->getParent()].GetAllPathCount();
// If we overflow when we compute the path count, don't
// remove/move anything.
const BBState &RIPBBState = BBStates[RIP->getParent()];
if (RIPBBState.GetAllPathCountWithOverflow(PathCount))
return false;
NewDelta += PathCount;
NewCount += PathCount;
}