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-rw-r--r--llvm/lib/Support/Allocator.cpp235
1 files changed, 131 insertions, 104 deletions
diff --git a/llvm/lib/Support/Allocator.cpp b/llvm/lib/Support/Allocator.cpp
index db0d8f31e55..f5a207844b8 100644
--- a/llvm/lib/Support/Allocator.cpp
+++ b/llvm/lib/Support/Allocator.cpp
@@ -15,127 +15,154 @@
#include "llvm/Support/Recycler.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Streams.h"
-#include <ostream>
-using namespace llvm;
-//===----------------------------------------------------------------------===//
-// MemRegion class implementation
-//===----------------------------------------------------------------------===//
+namespace llvm {
-namespace {
-/// MemRegion - This is one chunk of the BumpPtrAllocator.
-class MemRegion {
- unsigned RegionSize;
- MemRegion *Next;
- char *NextPtr;
-public:
- void Init(unsigned size, unsigned Alignment, MemRegion *next) {
- RegionSize = size;
- Next = next;
- NextPtr = (char*)(this+1);
-
- // Align NextPtr.
- NextPtr = (char*)((intptr_t)(NextPtr+Alignment-1) &
- ~(intptr_t)(Alignment-1));
- }
-
- const MemRegion *getNext() const { return Next; }
- unsigned getNumBytesAllocated() const {
- return NextPtr-(const char*)this;
- }
-
- /// Allocate - Allocate and return at least the specified number of bytes.
- ///
- void *Allocate(size_t AllocSize, size_t Alignment, MemRegion **RegPtr) {
-
- char* Result = (char*) (((uintptr_t) (NextPtr+Alignment-1))
- & ~((uintptr_t) Alignment-1));
-
- // Speculate the new value of NextPtr.
- char* NextPtrTmp = Result + AllocSize;
-
- // If we are still within the current region, return Result.
- if (unsigned (NextPtrTmp - (char*) this) <= RegionSize) {
- NextPtr = NextPtrTmp;
- return Result;
- }
-
- // Otherwise, we have to allocate a new chunk. Create one twice as big as
- // this one.
- MemRegion *NewRegion = (MemRegion *)malloc(RegionSize*2);
- NewRegion->Init(RegionSize*2, Alignment, this);
-
- // Update the current "first region" pointer to point to the new region.
- *RegPtr = NewRegion;
-
- // Try allocating from it now.
- return NewRegion->Allocate(AllocSize, Alignment, RegPtr);
- }
-
- /// Deallocate - Recursively release all memory for this and its next regions
- /// to the system.
- void Deallocate() {
- MemRegion *next = Next;
- free(this);
- if (next)
- next->Deallocate();
- }
+BumpPtrAllocator::BumpPtrAllocator(size_t size, size_t threshold,
+ SlabAllocator &allocator)
+ : SlabSize(size), SizeThreshold(threshold), Allocator(allocator),
+ CurSlab(0), BytesAllocated(0) {
+ StartNewSlab();
+}
- /// DeallocateAllButLast - Recursively release all memory for this and its
- /// next regions to the system stopping at the last region in the list.
- /// Returns the pointer to the last region.
- MemRegion *DeallocateAllButLast() {
- MemRegion *next = Next;
- if (!next)
- return this;
- free(this);
- return next->DeallocateAllButLast();
- }
-};
+BumpPtrAllocator::~BumpPtrAllocator() {
+ DeallocateSlabs(CurSlab);
}
-//===----------------------------------------------------------------------===//
-// BumpPtrAllocator class implementation
-//===----------------------------------------------------------------------===//
+/// AlignPtr - Align Ptr to Alignment bytes, rounding up. Alignment should
+/// be a power of two. This method rounds up, so AlignPtr(7, 4) == 8 and
+/// AlignPtr(8, 4) == 8.
+char *BumpPtrAllocator::AlignPtr(char *Ptr, size_t Alignment) {
+ assert(Alignment && (Alignment & (Alignment - 1)) == 0 &&
+ "Alignment is not a power of two!");
-BumpPtrAllocator::BumpPtrAllocator() {
- TheMemory = malloc(4096);
- ((MemRegion*)TheMemory)->Init(4096, 1, 0);
+ // Do the alignment.
+ return (char*)(((uintptr_t)Ptr + Alignment - 1) &
+ ~(uintptr_t)(Alignment - 1));
}
-BumpPtrAllocator::~BumpPtrAllocator() {
- ((MemRegion*)TheMemory)->Deallocate();
+/// StartNewSlab - Allocate a new slab and move the bump pointers over into
+/// the new slab. Modifies CurPtr and End.
+void BumpPtrAllocator::StartNewSlab() {
+ MemSlab *NewSlab = Allocator.Allocate(SlabSize);
+ NewSlab->NextPtr = CurSlab;
+ CurSlab = NewSlab;
+ CurPtr = (char*)(CurSlab + 1);
+ End = CurPtr + CurSlab->Size;
+}
+
+/// DeallocateSlabs - Deallocate all memory slabs after and including this
+/// one.
+void BumpPtrAllocator::DeallocateSlabs(MemSlab *Slab) {
+ while (Slab) {
+ MemSlab *NextSlab = Slab->NextPtr;
+#ifndef NDEBUG
+ // Poison the memory so stale pointers crash sooner. Note we must
+ // preserve the Size and NextPtr fields at the beginning.
+ memset(Slab + 1, 0xCD, Slab->Size - sizeof(MemSlab));
+#endif
+ Allocator.Deallocate(Slab);
+ Slab = NextSlab;
+ }
}
+/// Reset - Deallocate all but the current slab and reset the current pointer
+/// to the beginning of it, freeing all memory allocated so far.
void BumpPtrAllocator::Reset() {
- MemRegion *MRP = (MemRegion*)TheMemory;
- MRP = MRP->DeallocateAllButLast();
- MRP->Init(4096, 1, 0);
- TheMemory = MRP;
+ DeallocateSlabs(CurSlab->NextPtr);
+ CurSlab->NextPtr = 0;
+ CurPtr = (char*)(CurSlab + 1);
+ End = CurPtr + CurSlab->Size;
}
-void *BumpPtrAllocator::Allocate(size_t Size, size_t Align) {
- MemRegion *MRP = (MemRegion*)TheMemory;
- void *Ptr = MRP->Allocate(Size, Align, &MRP);
- TheMemory = MRP;
+/// Allocate - Allocate space at the specified alignment.
+///
+void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
+ // Keep track of how many bytes we've allocated.
+ BytesAllocated += Size;
+
+ // 0-byte alignment means 1-byte alignment.
+ if (Alignment == 0) Alignment = 1;
+
+ // Allocate the aligned space, going forwards from CurPtr.
+ char *Ptr = AlignPtr(CurPtr, Alignment);
+
+ // Check if we can hold it.
+ if (Ptr + Size < End) {
+ CurPtr = Ptr + Size;
+ return Ptr;
+ }
+
+ // If Size is really big, allocate a separate slab for it.
+ if (Size > SizeThreshold) {
+ size_t PaddedSize = Size + sizeof(MemSlab) + Alignment - 1;
+ MemSlab *NewSlab = Allocator.Allocate(PaddedSize);
+
+ // Put the new slab after the current slab, since we are not allocating
+ // into it.
+ NewSlab->NextPtr = CurSlab->NextPtr;
+ CurSlab->NextPtr = NewSlab;
+
+ Ptr = AlignPtr((char*)(NewSlab + 1), Alignment);
+ assert((uintptr_t)Ptr + Size < (uintptr_t)NewSlab + NewSlab->Size);
+ return Ptr;
+ }
+
+ // Otherwise, start a new slab and try again.
+ StartNewSlab();
+ Ptr = AlignPtr(CurPtr, Alignment);
+ CurPtr = Ptr + Size;
+ assert(CurPtr < End && "Unable to allocate memory!");
return Ptr;
}
+unsigned BumpPtrAllocator::GetNumSlabs() const {
+ unsigned NumSlabs = 0;
+ for (MemSlab *Slab = CurSlab; Slab != 0; Slab = Slab->NextPtr) {
+ ++NumSlabs;
+ }
+ return NumSlabs;
+}
+
void BumpPtrAllocator::PrintStats() const {
- unsigned BytesUsed = 0;
- unsigned NumRegions = 0;
- const MemRegion *R = (MemRegion*)TheMemory;
- for (; R; R = R->getNext(), ++NumRegions)
- BytesUsed += R->getNumBytesAllocated();
-
- cerr << "\nNumber of memory regions: " << NumRegions << "\n";
- cerr << "Bytes allocated: " << BytesUsed << "\n";
+ unsigned NumSlabs = 0;
+ size_t TotalMemory = 0;
+ for (MemSlab *Slab = CurSlab; Slab != 0; Slab = Slab->NextPtr) {
+ TotalMemory += Slab->Size;
+ ++NumSlabs;
+ }
+
+ cerr << "\nNumber of memory regions: " << NumSlabs << '\n'
+ << "Bytes used: " << BytesAllocated << '\n'
+ << "Bytes allocated: " << TotalMemory << '\n'
+ << "Bytes wasted: " << (TotalMemory - BytesAllocated)
+ << " (includes alignment, etc)\n";
+}
+
+MallocSlabAllocator BumpPtrAllocator::DefaultSlabAllocator =
+ MallocSlabAllocator();
+
+SlabAllocator::~SlabAllocator() { }
+
+MallocSlabAllocator::~MallocSlabAllocator() { }
+
+MemSlab *MallocSlabAllocator::Allocate(size_t Size) {
+ MemSlab *Slab = (MemSlab*)Allocator.Allocate(Size, 0);
+ Slab->Size = Size;
+ Slab->NextPtr = 0;
+ return Slab;
+}
+
+void MallocSlabAllocator::Deallocate(MemSlab *Slab) {
+ Allocator.Deallocate(Slab);
+}
+
+void PrintRecyclerStats(size_t Size,
+ size_t Align,
+ size_t FreeListSize) {
+ cerr << "Recycler element size: " << Size << '\n'
+ << "Recycler element alignment: " << Align << '\n'
+ << "Number of elements free for recycling: " << FreeListSize << '\n';
}
-void llvm::PrintRecyclerStats(size_t Size,
- size_t Align,
- size_t FreeListSize) {
- cerr << "Recycler element size: " << Size << '\n';
- cerr << "Recycler element alignment: " << Align << '\n';
- cerr << "Number of elements free for recycling: " << FreeListSize << '\n';
}
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