[cfe-commits] r60523 - /cfe/trunk/lib/Analysis/RegionStore.cpp
Ted Kremenek
kremenek at apple.com
Wed Dec 3 18:08:27 PST 2008
Author: kremenek
Date: Wed Dec 3 20:08:27 2008
New Revision: 60523
URL: http://llvm.org/viewvc/llvm-project?rev=60523&view=rev
Log:
Revamp RegionStoreManager::RemoveDeadBindings. This method now does a complete mark-and-sweep of the store, removing dead regions and recording the set of live and dead symbols appropriately.
Modified:
cfe/trunk/lib/Analysis/RegionStore.cpp
Modified: cfe/trunk/lib/Analysis/RegionStore.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/RegionStore.cpp?rev=60523&r1=60522&r2=60523&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/RegionStore.cpp (original)
+++ cfe/trunk/lib/Analysis/RegionStore.cpp Wed Dec 3 20:08:27 2008
@@ -52,6 +52,17 @@
};
}
+// KillSet GDM stuff.
+typedef llvm::ImmutableSet<const MemRegion*> RegionKillSetTy;
+static int RegionKillSetTyIndex = 0;
+namespace clang {
+ template<> struct GRStateTrait<RegionKillSetTy>
+ : public GRStatePartialTrait<RegionKillSetTy> {
+ static void* GDMIndex() { return &RegionKillSetTyIndex; }
+ };
+}
+
+
namespace {
class VISIBILITY_HIDDEN RegionStoreManager : public StoreManager {
@@ -116,10 +127,15 @@
assert (false && "Not implemented.");
return 0;
}
-
+
+ /// RemoveDeadBindings - Scans a RegionStore for dead values. It returns
+ /// a new Store with these values removed, and populates LSymbols and
+ /// DSymbols with the known set of live and dead symbols respectively.
Store RemoveDeadBindings(Store store, Stmt* Loc, const LiveVariables& Live,
llvm::SmallVectorImpl<const MemRegion*>& RegionRoots,
LiveSymbolsTy& LSymbols, DeadSymbolsTy& DSymbols);
+
+ void UpdateLiveSymbols(SVal X, LiveSymbolsTy& LSymbols);
Store BindDecl(Store store, const VarDecl* VD, SVal* InitVal, unsigned Count);
@@ -605,22 +621,130 @@
}
+void RegionStoreManager::UpdateLiveSymbols(SVal X, LiveSymbolsTy& LSymbols) {
+ for (SVal::symbol_iterator SI=X.symbol_begin(),SE=X.symbol_end();SI!=SE;++SI)
+ LSymbols.insert(*SI);
+}
+
Store RegionStoreManager::RemoveDeadBindings(Store store, Stmt* Loc,
const LiveVariables& Live,
llvm::SmallVectorImpl<const MemRegion*>& RegionRoots,
LiveSymbolsTy& LSymbols, DeadSymbolsTy& DSymbols) {
RegionBindingsTy B = GetRegionBindings(store);
- typedef SVal::symbol_iterator symbol_iterator;
-
- // FIXME: Mark all region binding value's symbol as live. We also omit symbols
- // in SymbolicRegions.
+
+ // Lazily constructed backmap from MemRegions to SubRegions.
+ typedef llvm::ImmutableSet<const MemRegion*> SubRegionsTy;
+ typedef llvm::ImmutableMap<const MemRegion*, SubRegionsTy> SubRegionsMapTy;
+
+ // FIXME: As a future optimization we can modifiy BumpPtrAllocator to have
+ // the ability to reuse memory. This way we can keep TmpAlloc around as
+ // an instance variable of RegionStoreManager (avoiding repeated malloc
+ // overhead).
+ llvm::BumpPtrAllocator TmpAlloc;
+
+ // Factory objects.
+ SubRegionsMapTy::Factory SubRegMapF(TmpAlloc);
+ SubRegionsTy::Factory SubRegF(TmpAlloc);
+
+ // The backmap from regions to subregions.
+ SubRegionsMapTy SubRegMap = SubRegMapF.GetEmptyMap();
+
+ // Do a pass over the regions in the store. For VarRegions we check if
+ // the variable is still live and if so add it to the list of live roots.
+ // For other regions we populate our region backmap.
for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
- SVal X = I.getData();
- for (symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end(); SI!=SE; ++SI)
- LSymbols.insert(*SI);
+ const MemRegion* R = I.getKey();
+ if (const VarRegion* VR = dyn_cast<VarRegion>(R)) {
+ if (Live.isLive(Loc, VR->getDecl()))
+ RegionRoots.push_back(VR); // This is a live "root".
+ }
+ else {
+ // Get the super region for R.
+ const MemRegion* SuperR = cast<SubRegion>(R)->getSuperRegion();
+ // Get the current set of subregions for SuperR.
+ const SubRegionsTy* SRptr = SubRegMap.lookup(SuperR);
+ SubRegionsTy SR = SRptr ? *SRptr : SubRegF.GetEmptySet();
+ // Add R to the subregions of SuperR.
+ SubRegMap = SubRegMapF.Add(SubRegMap, SuperR, SubRegF.Add(SR, R));
+
+ // Finally, check if SuperR is a VarRegion. We need to do this
+ // to also mark SuperR as a root (as it may not have a value directly
+ // bound to it in the store).
+ if (const VarRegion* VR = dyn_cast<VarRegion>(SuperR)) {
+ if (Live.isLive(Loc, VR->getDecl()))
+ RegionRoots.push_back(VR); // This is a live "root".
+ }
+ }
}
+
+ // Process the worklist of RegionRoots. This performs a "mark-and-sweep"
+ // of the store. We want to find all live symbols and dead regions.
+ llvm::SmallPtrSet<const MemRegion*, 10> Marked;
+
+ while (!RegionRoots.empty()) {
+ // Dequeue the next region on the worklist.
+ const MemRegion* R = RegionRoots.back();
+ RegionRoots.pop_back();
+
+ // Check if we have already processed this region.
+ if (Marked.count(R)) continue;
+
+ // Mark this region as processed. This is needed for termination in case
+ // a region is referenced more than once.
+ Marked.insert(R);
+
+ // Mark the symbol for any live SymbolicRegion as "live". This means we
+ // should continue to track that symbol.
+ if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R))
+ LSymbols.insert(SymR->getSymbol());
+
+ // Get the data binding for R (if any).
+ RegionBindingsTy::data_type* Xptr = B.lookup(R);
+ if (Xptr) {
+ SVal X = *Xptr;
+ UpdateLiveSymbols(X, LSymbols); // Update the set of live symbols.
+
+ // If X is a region, then add it the RegionRoots.
+ if (loc::MemRegionVal* RegionX = dyn_cast<loc::MemRegionVal>(&X))
+ RegionRoots.push_back(RegionX->getRegion());
+ }
+
+ // Get the subregions of R. These are RegionRoots as well since they
+ // represent values that are also bound to R.
+ const SubRegionsTy* SRptr = SubRegMap.lookup(R);
+ if (!SRptr) continue;
+ SubRegionsTy SR = *SRptr;
+
+ for (SubRegionsTy::iterator I=SR.begin(), E=SR.end(); I!=E; ++I)
+ RegionRoots.push_back(*I);
+ }
+
+ // We have now scanned the store, marking reachable regions and symbols
+ // as live. We now remove all the regions that are dead from the store
+ // as well as update DSymbols with the set symbols that are now dead.
+
+ for (RegionBindingsTy::iterator I = B.begin(), E = B.end(); I != E; ++I) {
+ const MemRegion* R = I.getKey();
+
+ // If this region live? Is so, none of its symbols are dead.
+ if (Marked.count(R))
+ continue;
+
+ // Remove this dead region from the store.
+ store = Remove(store, loc::MemRegionVal(R));
+ // Mark all non-live symbols that this region references as dead.
+ if (const SymbolicRegion* SymR = dyn_cast<SymbolicRegion>(R)) {
+ SymbolID Sym = SymR->getSymbol();
+ if (!LSymbols.count(Sym)) DSymbols.insert(Sym);
+ }
+
+ SVal X = I.getData();
+ SVal::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
+ for (; SI != SE; ++SI) { if (!LSymbols.count(*SI)) DSymbols.insert(*SI); }
+ }
+
return store;
}
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