CaptureTracking: Plug a loophole in the "too many uses" heuristic.

[oota-llvm.git] / lib / Analysis / MemoryDependenceAnalysis.cpp

diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 57bce84e8331f2fe758b769f24690817e69cc122..fe1c8743a44f559d78500bd16254da18f737f224 100644 (file)
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -1,4 +1,4 @@
-//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation  --*- C++ -*-===//
+//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -47,9 +47,7 @@ STATISTIC(NumCacheCompleteNonLocalPtr,
           "Number of block queries that were completely cached");
 
 // Limit for the number of instructions to scan in a block.
-// FIXME: Figure out what a sane value is for this.
-//        (500 is relatively insane.)
-static const int BlockScanLimit = 500;
+static const int BlockScanLimit = 100;
 
 char MemoryDependenceAnalysis::ID = 0;
 
@@ -91,7 +89,7 @@ bool MemoryDependenceAnalysis::runOnFunction(Function &) {
   AA = &getAnalysis<AliasAnalysis>();
   TD = getAnalysisIfAvailable<DataLayout>();
   DT = getAnalysisIfAvailable<DominatorTree>();
-  if (PredCache == 0)
+  if (!PredCache)
     PredCache.reset(new PredIteratorCache());
   return false;
 }
@@ -913,7 +911,6 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
                             SmallVectorImpl<NonLocalDepResult> &Result,
                             DenseMap<BasicBlock*, Value*> &Visited,
                             bool SkipFirstBlock) {
-
   // Look up the cached info for Pointer.
   ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
 
@@ -1001,8 +998,17 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
     for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
          I != E; ++I) {
       Visited.insert(std::make_pair(I->getBB(), Addr));
-      if (!I->getResult().isNonLocal() && DT->isReachableFromEntry(I->getBB()))
+      if (I->getResult().isNonLocal()) {
+        continue;
+      }
+
+      if (!DT) {
+        Result.push_back(NonLocalDepResult(I->getBB(),
+                                           MemDepResult::getUnknown(),
+                                           Addr));
+      } else if (DT->isReachableFromEntry(I->getBB())) {
         Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
+      }
     }
     ++NumCacheCompleteNonLocalPtr;
     return false;
@@ -1047,9 +1053,16 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
                                                  NumSortedEntries);
 
       // If we got a Def or Clobber, add this to the list of results.
-      if (!Dep.isNonLocal() && DT->isReachableFromEntry(BB)) {
-        Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
-        continue;
+      if (!Dep.isNonLocal()) {
+        if (!DT) {
+          Result.push_back(NonLocalDepResult(BB,
+                                             MemDepResult::getUnknown(),
+                                             Pointer.getAddr()));
+          continue;
+        } else if (DT->isReachableFromEntry(BB)) {
+          Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
+          continue;
+        }
       }
     }
 
@@ -1136,7 +1149,7 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
 
         // Make sure to clean up the Visited map before continuing on to
         // PredTranslationFailure.
-        for (unsigned i = 0; i < PredList.size(); i++)
+        for (unsigned i = 0, n = PredList.size(); i < n; ++i)
           Visited.erase(PredList[i].first);
 
         goto PredTranslationFailure;
@@ -1148,7 +1161,7 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
     // any results for.  (getNonLocalPointerDepFromBB will modify our
     // datastructures in ways the code after the PredTranslationFailure label
     // doesn't expect.)
-    for (unsigned i = 0; i < PredList.size(); i++) {
+    for (unsigned i = 0, n = PredList.size(); i < n; ++i) {
       BasicBlock *Pred = PredList[i].first;
       PHITransAddr &PredPointer = PredList[i].second;
       Value *PredPtrVal = PredPointer.getAddr();