Thread-safety analysis: better handling of unreachable blocks. Fixes a bug
where a call to function marked 'noreturn' is followed by unreachable
implicit destructor calls.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164394 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ThreadSafety.cpp b/lib/Analysis/ThreadSafety.cpp
index d9ab61e..bc8a3c0 100644
--- a/lib/Analysis/ThreadSafety.cpp
+++ b/lib/Analysis/ThreadSafety.cpp
@@ -892,6 +892,7 @@
SourceLocation EntryLoc; // Location of first statement in block
SourceLocation ExitLoc; // Location of last statement in block.
unsigned EntryIndex; // Used to replay contexts later
+ bool Reachable; // Is this block reachable?
const FactSet &getSet(CFGBlockSide Side) const {
return Side == CBS_Entry ? EntrySet : ExitSet;
@@ -902,7 +903,7 @@
private:
CFGBlockInfo(LocalVarContext EmptyCtx)
- : EntryContext(EmptyCtx), ExitContext(EmptyCtx)
+ : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
{ }
public:
@@ -2183,6 +2184,9 @@
PostOrderCFGView *SortedGraph = AC.getAnalysis<PostOrderCFGView>();
PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
+ // Mark entry block as reachable
+ BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
+
// Compute SSA names for local variables
LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
@@ -2270,10 +2274,16 @@
if (*PI == 0 || !VisitedBlocks.alreadySet(*PI))
continue;
+ int PrevBlockID = (*PI)->getBlockID();
+ CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
+
// Ignore edges from blocks that can't return.
- if ((*PI)->hasNoReturnElement())
+ if ((*PI)->hasNoReturnElement() || !PrevBlockInfo->Reachable)
continue;
+ // Okay, we can reach this block from the entry.
+ CurrBlockInfo->Reachable = true;
+
// If the previous block ended in a 'continue' or 'break' statement, then
// a difference in locksets is probably due to a bug in that block, rather
// than in some other predecessor. In that case, keep the other
@@ -2285,8 +2295,7 @@
}
}
- int PrevBlockID = (*PI)->getBlockID();
- CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
+
FactSet PrevLockset;
getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
@@ -2300,6 +2309,10 @@
}
}
+ // Skip rest of block if it's not reachable.
+ if (!CurrBlockInfo->Reachable)
+ continue;
+
// Process continue and break blocks. Assume that the lockset for the
// resulting block is unaffected by any discrepancies in them.
for (unsigned SpecialI = 0, SpecialN = SpecialBlocks.size();
@@ -2386,23 +2399,13 @@
}
}
-
- // Check to make sure that the exit block is reachable
- bool ExitUnreachable = true;
- for (CFGBlock::const_pred_iterator PI = CFGraph->getExit().pred_begin(),
- PE = CFGraph->getExit().pred_end(); PI != PE; ++PI) {
- if (!(*PI)->hasNoReturnElement()) {
- ExitUnreachable = false;
- break;
- }
- }
- // Skip the final check if the exit block is unreachable.
- if (ExitUnreachable)
- return;
-
CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
+ // Skip the final check if the exit block is unreachable.
+ if (!Final->Reachable)
+ return;
+
// FIXME: Should we call this function for all blocks which exit the function?
intersectAndWarn(Initial->EntrySet, Final->ExitSet,
Final->ExitLoc,
diff --git a/test/SemaCXX/warn-thread-safety-analysis.cpp b/test/SemaCXX/warn-thread-safety-analysis.cpp
index fa8786a..fd3577c 100644
--- a/test/SemaCXX/warn-thread-safety-analysis.cpp
+++ b/test/SemaCXX/warn-thread-safety-analysis.cpp
@@ -64,6 +64,7 @@
void endNoWarnOnWrites() UNLOCK_FUNCTION("*");
+// For testing handling of smart pointers.
template<class T>
class SmartPtr {
public:
@@ -80,6 +81,15 @@
};
+// For testing destructor calls and cleanup.
+class MyString {
+public:
+ MyString(const char* s);
+ ~MyString();
+};
+
+
+
Mutex sls_mu;
Mutex sls_mu2 __attribute__((acquired_after(sls_mu)));
@@ -3250,12 +3260,6 @@
namespace TrylockWithCleanups {
-class MyString {
-public:
- MyString(const char* s);
- ~MyString();
-};
-
struct Foo {
Mutex mu_;
int a GUARDED_BY(mu_);
@@ -3460,6 +3464,7 @@
};
void exitNow() __attribute__((noreturn));
+void exitDestruct(const MyString& ms) __attribute__((noreturn));
Mutex fatalmu_;
@@ -3482,6 +3487,10 @@
}
}
+void test4() EXCLUSIVE_LOCKS_REQUIRED(fatalmu_) {
+ exitDestruct("foo");
+}
+
} // end namespace UnreachableExitTest