[analyzer] Cache the "concrete offset base" for regions with symbolic offsets.

This makes it faster to access and invalidate bindings with symbolic offsets
by only computing this information once.

No intended functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161635 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 37 insertions, 10 deletions

diff --git a/lib/StaticAnalyzer/Core/MemRegion.cpp b/lib/StaticAnalyzer/Core/MemRegion.cpp
index b2e7055c31..58abc9a280 100644
--- a/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1038,12 +1038,14 @@ RegionRawOffset ElementRegion::getAsArrayOffset() const {
 
 RegionOffset MemRegion::getAsOffset() const {
   const MemRegion *R = this;
+  const MemRegion *SymbolicOffsetBase = 0;
   int64_t Offset = 0;
 
   while (1) {
     switch (R->getKind()) {
     default:
-      return RegionOffset();
+      return RegionOffset(R, RegionOffset::Symbolic);
+
     case SymbolicRegionKind:
     case AllocaRegionKind:
     case CompoundLiteralRegionKind:
@@ -1053,6 +1055,7 @@ RegionOffset MemRegion::getAsOffset() const {
     case ObjCIvarRegionKind:
     case CXXTempObjectRegionKind:
       goto Finish;
+
     case CXXBaseObjectRegionKind: {
       const CXXBaseObjectRegion *BOR = cast<CXXBaseObjectRegion>(R);
       R = BOR->getSuperRegion();
@@ -1070,8 +1073,14 @@ RegionOffset MemRegion::getAsOffset() const {
       const CXXRecordDecl *Child = Ty->getAsCXXRecordDecl();
       if (!Child) {
         // We cannot compute the offset of the base class.
-        return RegionOffset();
+        SymbolicOffsetBase = R;
       }
+
+      // Don't bother calculating precise offsets if we already have a
+      // symbolic offset somewhere in the chain.
+      if (SymbolicOffsetBase)
+        continue;
+
       const ASTRecordLayout &Layout = getContext().getASTRecordLayout(Child);
 
       CharUnits BaseOffset;
@@ -1087,29 +1096,46 @@ RegionOffset MemRegion::getAsOffset() const {
     }
     case ElementRegionKind: {
       const ElementRegion *ER = cast<ElementRegion>(R);
-      QualType EleTy = ER->getValueType();
+      R = ER->getSuperRegion();
 
-      if (!IsCompleteType(getContext(), EleTy))
-        return RegionOffset();
+      QualType EleTy = ER->getValueType();
+      if (!IsCompleteType(getContext(), EleTy)) {
+        // We cannot compute the offset of the base class.
+        SymbolicOffsetBase = R;
+        continue;
+      }
 
       SVal Index = ER->getIndex();
       if (const nonloc::ConcreteInt *CI=dyn_cast<nonloc::ConcreteInt>(&Index)) {
+        // Don't bother calculating precise offsets if we already have a
+        // symbolic offset somewhere in the chain. 
+        if (SymbolicOffsetBase)
+          continue;
+
         int64_t i = CI->getValue().getSExtValue();
         // This type size is in bits.
         Offset += i * getContext().getTypeSize(EleTy);
       } else {
         // We cannot compute offset for non-concrete index.
-        return RegionOffset();
+        SymbolicOffsetBase = R;
       }
-      R = ER->getSuperRegion();
       break;
     }
     case FieldRegionKind: {
       const FieldRegion *FR = cast<FieldRegion>(R);
+      R = FR->getSuperRegion();
+
       const RecordDecl *RD = FR->getDecl()->getParent();
-      if (!RD->isCompleteDefinition())
+      if (!RD->isCompleteDefinition()) {
         // We cannot compute offset for incomplete type.
-        return RegionOffset();
+        SymbolicOffsetBase = R;
+      }
+
+      // Don't bother calculating precise offsets if we already have a
+      // symbolic offset somewhere in the chain.
+      if (SymbolicOffsetBase)
+        continue;
+
       // Get the field number.
       unsigned idx = 0;
       for (RecordDecl::field_iterator FI = RD->field_begin(), 
@@ -1120,13 +1146,14 @@ RegionOffset MemRegion::getAsOffset() const {
       const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
       // This is offset in bits.
       Offset += Layout.getFieldOffset(idx);
-      R = FR->getSuperRegion();
       break;
     }
     }
   }
 
  Finish:
+  if (SymbolicOffsetBase)
+    return RegionOffset(SymbolicOffsetBase, RegionOffset::Symbolic);
   return RegionOffset(R, Offset);
 }