[llvm] r214135 - IR: Optimize size of use-list order shuffle vectors
Duncan P. N. Exon Smith
dexonsmith at apple.com
Mon Jul 28 15:41:50 PDT 2014
Author: dexonsmith
Date: Mon Jul 28 17:41:50 2014
New Revision: 214135
URL: http://llvm.org/viewvc/llvm-project?rev=214135&view=rev
Log:
IR: Optimize size of use-list order shuffle vectors
Since we're storing lots of these, save two-pointers per vector with a
custom type rather than using the relatively heavy `SmallVector`.
Part of PR5680.
Modified:
llvm/trunk/include/llvm/IR/UseListOrder.h
llvm/trunk/lib/Bitcode/Writer/ValueEnumerator.cpp
Modified: llvm/trunk/include/llvm/IR/UseListOrder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/UseListOrder.h?rev=214135&r1=214134&r2=214135&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/UseListOrder.h (original)
+++ llvm/trunk/include/llvm/IR/UseListOrder.h Mon Jul 28 17:41:50 2014
@@ -25,11 +25,58 @@ class Module;
class Function;
class Value;
+/// \brief Structure to hold a use-list shuffle vector.
+///
+/// Stores most use-lists locally, but large use-lists use an extra heap entry.
+/// Costs two fewer pointers than the equivalent \a SmallVector.
+class UseListShuffleVector {
+ unsigned Size;
+ union {
+ unsigned *Ptr;
+ unsigned Array[6];
+ } Storage;
+
+ bool isSmall() const { return Size <= 6; }
+ unsigned *data() { return isSmall() ? Storage.Array : Storage.Ptr; }
+ const unsigned *data() const {
+ return isSmall() ? Storage.Array : Storage.Ptr;
+ }
+
+public:
+ UseListShuffleVector() : Size(0) {}
+ UseListShuffleVector(UseListShuffleVector &&X) {
+ std::memcpy(this, &X, sizeof(UseListShuffleVector));
+ X.Size = 0;
+ }
+ explicit UseListShuffleVector(size_t Size) : Size(Size) {
+ if (!isSmall())
+ Storage.Ptr = new unsigned[Size];
+ }
+ ~UseListShuffleVector() {
+ if (!isSmall())
+ delete Storage.Ptr;
+ }
+
+ typedef unsigned *iterator;
+ typedef const unsigned *const_iterator;
+
+ size_t size() const { return Size; }
+ iterator begin() { return data(); }
+ iterator end() { return begin() + size(); }
+ const_iterator begin() const { return data(); }
+ const_iterator end() const { return begin() + size(); }
+ unsigned &operator[](size_t I) { return data()[I]; }
+ unsigned operator[](size_t I) const { return data()[I]; }
+};
+
/// \brief Structure to hold a use-list order.
struct UseListOrder {
- const Function *F;
const Value *V;
- SmallVector<unsigned, 8> Shuffle;
+ const Function *F;
+ UseListShuffleVector Shuffle;
+
+ UseListOrder(const Value *V, const Function *F, size_t ShuffleSize)
+ : V(V), F(F), Shuffle(ShuffleSize) {}
};
typedef std::vector<UseListOrder> UseListOrderStack;
Modified: llvm/trunk/lib/Bitcode/Writer/ValueEnumerator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Bitcode/Writer/ValueEnumerator.cpp?rev=214135&r1=214134&r2=214135&view=diff
==============================================================================
--- llvm/trunk/lib/Bitcode/Writer/ValueEnumerator.cpp (original)
+++ llvm/trunk/lib/Bitcode/Writer/ValueEnumerator.cpp Mon Jul 28 17:41:50 2014
@@ -133,12 +133,11 @@ static void predictValueUseListOrderImpl
return;
// Store the shuffle.
- UseListOrder O;
- O.V = V;
- O.F = F;
- for (auto &I : List)
- O.Shuffle.push_back(I.second);
- Stack.push_back(O);
+ UseListOrder O(V, F, List.size());
+ assert(List.size() == O.Shuffle.size() && "Wrong size");
+ for (size_t I = 0, E = List.size(); I != E; ++I)
+ O.Shuffle[I] = List[I].second;
+ Stack.emplace_back(std::move(O));
}
static void predictValueUseListOrder(const Value *V, const Function *F,
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