DataExtractor: Fix integer truncation issues in LEB128 extraction.

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

diff --git a/lib/Support/Allocator.cpp b/lib/Support/Allocator.cpp
index 230c421f1fe17bc681e0dbdfe3b891cbaeac46ba..b8978302e7460bf54e99143ade7441d7378e8696 100644 (file)
--- a/lib/Support/Allocator.cpp
+++ b/lib/Support/Allocator.cpp
@@ -15,16 +15,15 @@
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Recycler.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Memory.h"
 #include <cstring>
 
 namespace llvm {
 
 BumpPtrAllocator::BumpPtrAllocator(size_t size, size_t threshold,
                                    SlabAllocator &allocator)
-    : SlabSize(size), SizeThreshold(threshold), Allocator(allocator),
-      CurSlab(0), BytesAllocated(0) {
-  StartNewSlab();
-}
+    : SlabSize(size), SizeThreshold(std::min(size, threshold)),
+      Allocator(allocator), CurSlab(0), BytesAllocated(0) { }
 
 BumpPtrAllocator::~BumpPtrAllocator() {
   DeallocateSlabs(CurSlab);
@@ -45,6 +44,12 @@ char *BumpPtrAllocator::AlignPtr(char *Ptr, size_t Alignment) {
 /// StartNewSlab - Allocate a new slab and move the bump pointers over into
 /// the new slab.  Modifies CurPtr and End.
 void BumpPtrAllocator::StartNewSlab() {
+  // If we allocated a big number of slabs already it's likely that we're going
+  // to allocate more. Increase slab size to reduce mallocs and possibly memory
+  // overhead. The factors are chosen conservatively to avoid overallocation.
+  if (BytesAllocated >= SlabSize * 128)
+    SlabSize *= 2;
+
   MemSlab *NewSlab = Allocator.Allocate(SlabSize);
   NewSlab->NextPtr = CurSlab;
   CurSlab = NewSlab;
@@ -60,6 +65,7 @@ void BumpPtrAllocator::DeallocateSlabs(MemSlab *Slab) {
 #ifndef NDEBUG
     // Poison the memory so stale pointers crash sooner.  Note we must
     // preserve the Size and NextPtr fields at the beginning.
+    sys::Memory::setRangeWritable(Slab + 1, Slab->Size - sizeof(MemSlab));
     memset(Slab + 1, 0xCD, Slab->Size - sizeof(MemSlab));
 #endif
     Allocator.Deallocate(Slab);
@@ -70,6 +76,8 @@ void BumpPtrAllocator::DeallocateSlabs(MemSlab *Slab) {
 /// 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() {
+  if (!CurSlab)
+    return;
   DeallocateSlabs(CurSlab->NextPtr);
   CurSlab->NextPtr = 0;
   CurPtr = (char*)(CurSlab + 1);
@@ -79,6 +87,9 @@ void BumpPtrAllocator::Reset() {
 /// Allocate - Allocate space at the specified alignment.
 ///
 void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
+  if (!CurSlab) // Start a new slab if we haven't allocated one already.
+    StartNewSlab();
+
   // Keep track of how many bytes we've allocated.
   BytesAllocated += Size;
 
@@ -95,8 +106,8 @@ void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
   }
 
   // If Size is really big, allocate a separate slab for it.
-  if (Size > SizeThreshold) {
-    size_t PaddedSize = Size + sizeof(MemSlab) + Alignment - 1;
+  size_t PaddedSize = Size + sizeof(MemSlab) + Alignment - 1;
+  if (PaddedSize > SizeThreshold) {
     MemSlab *NewSlab = Allocator.Allocate(PaddedSize);
 
     // Put the new slab after the current slab, since we are not allocating
@@ -125,6 +136,14 @@ unsigned BumpPtrAllocator::GetNumSlabs() const {
   return NumSlabs;
 }
 
+size_t BumpPtrAllocator::getTotalMemory() const {
+  size_t TotalMemory = 0;
+  for (MemSlab *Slab = CurSlab; Slab != 0; Slab = Slab->NextPtr) {
+    TotalMemory += Slab->Size;
+  }
+  return TotalMemory;
+}
+  
 void BumpPtrAllocator::PrintStats() const {
   unsigned NumSlabs = 0;
   size_t TotalMemory = 0;