Don't allow pwrite to resize a stream.

[oota-llvm.git] / lib / Support / FoldingSet.cpp

diff --git a/lib/Support/FoldingSet.cpp b/lib/Support/FoldingSet.cpp
index 145f12dc1e5d2e6d92586f59e1654d8a72097f6b..b8538ffe1f9fe08ba493a9a55401c282f8e4c3c5 100644 (file)
--- a/lib/Support/FoldingSet.cpp
+++ b/lib/Support/FoldingSet.cpp
@@ -51,8 +51,8 @@ bool FoldingSetNodeIDRef::operator<(FoldingSetNodeIDRef RHS) const {
 ///
 void FoldingSetNodeID::AddPointer(const void *Ptr) {
   // Note: this adds pointers to the hash using sizes and endianness that
-  // depend on the host.  It doesn't matter however, because hashing on
-  // pointer values in inherently unstable.  Nothing  should depend on the 
+  // depend on the host. It doesn't matter, however, because hashing on
+  // pointer values is inherently unstable. Nothing should depend on the
   // ordering of nodes in the folding set.
   Bits.append(reinterpret_cast<unsigned *>(&Ptr),
               reinterpret_cast<unsigned *>(&Ptr+1));
@@ -101,6 +101,8 @@ void FoldingSetNodeID::AddString(StringRef String) {
     // Otherwise do it the hard way.
     // To be compatible with above bulk transfer, we need to take endianness
     // into account.
+    static_assert(sys::IsBigEndianHost || sys::IsLittleEndianHost,
+                  "Unexpected host endianness");
     if (sys::IsBigEndianHost) {
       for (Pos += 4; Pos <= Size; Pos += 4) {
         unsigned V = ((unsigned char)String[Pos - 4] << 24) |
@@ -109,8 +111,7 @@ void FoldingSetNodeID::AddString(StringRef String) {
                       (unsigned char)String[Pos - 1];
         Bits.push_back(V);
       }
-    } else {
-      assert(sys::IsLittleEndianHost && "Unexpected host endianness");
+    } else {  // Little-endian host
       for (Pos += 4; Pos <= Size; Pos += 4) {
         unsigned V = ((unsigned char)String[Pos - 1] << 24) |
                      ((unsigned char)String[Pos - 2] << 16) |
@@ -190,7 +191,7 @@ FoldingSetNodeID::Intern(BumpPtrAllocator &Allocator) const {
 static FoldingSetImpl::Node *GetNextPtr(void *NextInBucketPtr) {
   // The low bit is set if this is the pointer back to the bucket.
   if (reinterpret_cast<intptr_t>(NextInBucketPtr) & 1)
-    return 0;
+    return nullptr;
   
   return static_cast<FoldingSetImpl::Node*>(NextInBucketPtr);
 }
@@ -222,6 +223,8 @@ static void **AllocateBuckets(unsigned NumBuckets) {
 //===----------------------------------------------------------------------===//
 // FoldingSetImpl Implementation
 
+void FoldingSetImpl::anchor() {}
+
 FoldingSetImpl::FoldingSetImpl(unsigned Log2InitSize) {
   assert(5 < Log2InitSize && Log2InitSize < 32 &&
          "Initial hash table size out of range");
@@ -262,7 +265,7 @@ void FoldingSetImpl::GrowHashTable() {
     while (Node *NodeInBucket = GetNextPtr(Probe)) {
       // Figure out the next link, remove NodeInBucket from the old link.
       Probe = NodeInBucket->getNextInBucket();
-      NodeInBucket->SetNextInBucket(0);
+      NodeInBucket->SetNextInBucket(nullptr);
 
       // Insert the node into the new bucket, after recomputing the hash.
       InsertNode(NodeInBucket,
@@ -285,7 +288,7 @@ FoldingSetImpl::Node
   void **Bucket = GetBucketFor(IDHash, Buckets, NumBuckets);
   void *Probe = *Bucket;
   
-  InsertPos = 0;
+  InsertPos = nullptr;
   
   FoldingSetNodeID TempID;
   while (Node *NodeInBucket = GetNextPtr(Probe)) {
@@ -298,14 +301,14 @@ FoldingSetImpl::Node
   
   // Didn't find the node, return null with the bucket as the InsertPos.
   InsertPos = Bucket;
-  return 0;
+  return nullptr;
 }
 
 /// InsertNode - Insert the specified node into the folding set, knowing that it
 /// is not already in the map.  InsertPos must be obtained from 
 /// FindNodeOrInsertPos.
 void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
-  assert(N->getNextInBucket() == 0);
+  assert(!N->getNextInBucket());
   // Do we need to grow the hashtable?
   if (NumNodes+1 > NumBuckets*2) {
     GrowHashTable();
@@ -323,7 +326,7 @@ void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
   // If this is the first insertion into this bucket, its next pointer will be
   // null.  Pretend as if it pointed to itself, setting the low bit to indicate
   // that it is a pointer to the bucket.
-  if (Next == 0)
+  if (!Next)
     Next = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(Bucket)|1);
 
   // Set the node's next pointer, and make the bucket point to the node.
@@ -337,10 +340,10 @@ bool FoldingSetImpl::RemoveNode(Node *N) {
   // Because each bucket is a circular list, we don't need to compute N's hash
   // to remove it.
   void *Ptr = N->getNextInBucket();
-  if (Ptr == 0) return false;  // Not in folding set.
+  if (!Ptr) return false;  // Not in folding set.
 
   --NumNodes;
-  N->SetNextInBucket(0);
+  N->SetNextInBucket(nullptr);
 
   // Remember what N originally pointed to, either a bucket or another node.
   void *NodeNextPtr = Ptr;
@@ -390,7 +393,7 @@ FoldingSetImpl::Node *FoldingSetImpl::GetOrInsertNode(FoldingSetImpl::Node *N) {
 FoldingSetIteratorImpl::FoldingSetIteratorImpl(void **Bucket) {
   // Skip to the first non-null non-self-cycle bucket.
   while (*Bucket != reinterpret_cast<void*>(-1) &&
-         (*Bucket == 0 || GetNextPtr(*Bucket) == 0))
+         (!*Bucket || !GetNextPtr(*Bucket)))
     ++Bucket;
   
   NodePtr = static_cast<FoldingSetNode*>(*Bucket);
@@ -410,7 +413,7 @@ void FoldingSetIteratorImpl::advance() {
     do {
       ++Bucket;
     } while (*Bucket != reinterpret_cast<void*>(-1) &&
-             (*Bucket == 0 || GetNextPtr(*Bucket) == 0));
+             (!*Bucket || !GetNextPtr(*Bucket)));
     
     NodePtr = static_cast<FoldingSetNode*>(*Bucket);
   }
@@ -420,5 +423,5 @@ void FoldingSetIteratorImpl::advance() {
 // FoldingSetBucketIteratorImpl Implementation
 
 FoldingSetBucketIteratorImpl::FoldingSetBucketIteratorImpl(void **Bucket) {
-  Ptr = (*Bucket == 0 || GetNextPtr(*Bucket) == 0) ? (void*) Bucket : *Bucket;
+  Ptr = (!*Bucket || !GetNextPtr(*Bucket)) ? (void*) Bucket : *Bucket;
 }