Fix batch of converting RegisterPass<> to INTIALIZE_PASS().

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

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index d541b5535d3c65faea3adf6eb88d8b1e14351560..3c67a348fe84f735f705b93845411732f197e699 100644 (file)
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -103,8 +103,8 @@ MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
                                  "derived loop"),
                         cl::init(100));
 
-static RegisterPass<ScalarEvolution>
-R("scalar-evolution", "Scalar Evolution Analysis", false, true);
+INITIALIZE_PASS(ScalarEvolution, "scalar-evolution",
+                "Scalar Evolution Analysis", false, true);
 char ScalarEvolution::ID = 0;
 
 //===----------------------------------------------------------------------===//
@@ -845,6 +845,13 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
     return getAddRecExpr(Operands, AddRec->getLoop());
   }
 
+  // As a special case, fold trunc(undef) to undef. We don't want to
+  // know too much about SCEVUnknowns, but this special case is handy
+  // and harmless.
+  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
+    if (isa<UndefValue>(U->getValue()))
+      return getSCEV(UndefValue::get(Ty));
+
   // The cast wasn't folded; create an explicit cast node. We can reuse
   // the existing insert position since if we get here, we won't have
   // made any changes which would invalidate it.
@@ -1163,6 +1170,13 @@ const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
     return getAddRecExpr(Ops, AR->getLoop());
   }
 
+  // As a special case, fold anyext(undef) to undef. We don't want to
+  // know too much about SCEVUnknowns, but this special case is handy
+  // and harmless.
+  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
+    if (isa<UndefValue>(U->getValue()))
+      return getSCEV(UndefValue::get(Ty));
+
   // If the expression is obviously signed, use the sext cast value.
   if (isa<SCEVSMaxExpr>(Op))
     return SExt;
@@ -2428,6 +2442,10 @@ const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
 ///
 const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS,
                                           const SCEV *RHS) {
+  // Fast path: X - X --> 0.
+  if (LHS == RHS)
+    return getConstant(LHS->getType(), 0);
+
   // X - Y --> X + -Y
   return getAddExpr(LHS, getNegativeSCEV(RHS));
 }
@@ -3657,6 +3675,26 @@ void ScalarEvolution::forgetValue(Value *V) {
         ConstantEvolutionLoopExitValue.erase(PN);
     }
 
+    // If there's a SCEVUnknown tying this value into the SCEV
+    // space, remove it from the folding set map. The SCEVUnknown
+    // object and any other SCEV objects which reference it
+    // (transitively) remain allocated, effectively leaked until
+    // the underlying BumpPtrAllocator is freed.
+    //
+    // This permits SCEV pointers to be used as keys in maps
+    // such as the ValuesAtScopes map.
+    FoldingSetNodeID ID;
+    ID.AddInteger(scUnknown);
+    ID.AddPointer(I);
+    void *IP;
+    if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
+      UniqueSCEVs.RemoveNode(S);
+
+      // This isn't necessary, but we might as well remove the
+      // value from the ValuesAtScopes map too.
+      ValuesAtScopes.erase(S);
+    }
+
     PushDefUseChildren(I, Worklist);
   }
 }