[PATCH] D28183: [SmallPtrSet] Introduce a find primitive and rewrite count/erase in terms of it
Philip Reames via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 30 12:14:45 PST 2016
reames created this revision.
reames added reviewers: sanjoy, chandlerc.
reames added a subscriber: llvm-commits.
Herald added a subscriber: mcrosier.
This was originally motivated by a compile time problem I've since figured out how to solve differently, but the cleanup seemed useful. We had the same logic - which essentially implemented find - in several places. By commoning them out, I can implement find and allow erase to be inlined at the call sites if profitable.
https://reviews.llvm.org/D28183
Files:
include/llvm/ADT/SmallPtrSet.h
lib/Support/SmallPtrSet.cpp
Index: include/llvm/ADT/SmallPtrSet.h
===================================================================
--- include/llvm/ADT/SmallPtrSet.h
+++ include/llvm/ADT/SmallPtrSet.h
@@ -162,22 +162,40 @@
/// return true, otherwise return false. This is hidden from the client so
/// that the derived class can check that the right type of pointer is passed
/// in.
- bool erase_imp(const void * Ptr);
+ bool erase_imp(const void * Ptr) {
+ const void *const *P = find_imp(Ptr);
+ if (P != EndPointer()) {
+ const void ** Loc = const_cast<const void **>(P);
+ *Loc = getTombstoneMarker();
+ NumTombstones++;
+ return true;
+ }
+ return false;
+ }
- bool count_imp(const void * Ptr) const {
+
+ /// Returns the raw pointer needed to construct an iterator. If element not
+ /// found, this will be EndPointer. Otherwise, it will be a pointer to the
+ /// slot which stores Ptr;
+ const void *const * find_imp(const void * Ptr) const {
if (isSmall()) {
// Linear search for the item.
for (const void *const *APtr = SmallArray,
*const *E = SmallArray + NumNonEmpty; APtr != E; ++APtr)
if (*APtr == Ptr)
- return true;
- return false;
+ return APtr;
+ return EndPointer();
}
// Big set case.
- return *FindBucketFor(Ptr) == Ptr;
+ auto *Bucket = FindBucketFor(Ptr);
+ if (*Bucket == Ptr)
+ return Bucket;
+ return EndPointer();
}
+
+
private:
bool isSmall() const { return CurArray == SmallArray; }
@@ -368,7 +386,11 @@
/// count - Return 1 if the specified pointer is in the set, 0 otherwise.
size_type count(PtrType Ptr) const {
- return count_imp(PtrTraits::getAsVoidPointer(Ptr)) ? 1 : 0;
+ return find(Ptr) != endPtr() ? 1 : 0;
+ }
+ iterator find(PtrType Ptr) const {
+ auto *P = find_imp(PtrTraits::getAsVoidPointer(Ptr));
+ return iterator(P, EndPointer());
}
template <typename IterT>
Index: lib/Support/SmallPtrSet.cpp
===================================================================
--- lib/Support/SmallPtrSet.cpp
+++ lib/Support/SmallPtrSet.cpp
@@ -61,31 +61,6 @@
return std::make_pair(Bucket, true);
}
-bool SmallPtrSetImplBase::erase_imp(const void * Ptr) {
- if (isSmall()) {
- // Check to see if it is in the set.
- for (const void **APtr = CurArray, **E = CurArray + NumNonEmpty; APtr != E;
- ++APtr)
- if (*APtr == Ptr) {
- // If it is in the set, replace this element.
- *APtr = getTombstoneMarker();
- ++NumTombstones;
- return true;
- }
-
- return false;
- }
-
- // Okay, we know we have space. Find a hash bucket.
- void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
- if (*Bucket != Ptr) return false; // Not in the set?
-
- // Set this as a tombstone.
- *Bucket = getTombstoneMarker();
- ++NumTombstones;
- return true;
-}
-
const void * const *SmallPtrSetImplBase::FindBucketFor(const void *Ptr) const {
unsigned Bucket = DenseMapInfo<void *>::getHashValue(Ptr) & (CurArraySize-1);
unsigned ArraySize = CurArraySize;
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