Initial checkin of pool allocator library

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5429 91177308-0d34-0410-b5e6-96231b3b80d8

runtime/GCCLibraries/libpoolalloc/Makefile

@@ -0,0 +1,4 @@
+LEVEL = ../../..
+LIBNAME = poolalloc
+include ../Makefile.libs
+

runtime/GCCLibraries/libpoolalloc/PoolAllocatorChained.c

@@ -0,0 +1,166 @@
+#include <assert.h>
+#include <stdlib.h>
+
+#undef assert
+#define assert(X)
+
+
+#define NODES_PER_SLAB 512
+
+typedef struct PoolTy {
+  void    *Data;
+  unsigned NodeSize;
+} PoolTy;
+
+/* PoolSlab Structure - Hold NODES_PER_SLAB objects of the current node type.
+ *   Invariants: FirstUnused <= LastUsed+1
+ */
+typedef struct PoolSlab {
+  unsigned FirstUnused;     /* First empty node in slab    */
+  int LastUsed;             /* Last allocated node in slab */
+  struct PoolSlab *Next;
+  unsigned char AllocatedBitVector[NODES_PER_SLAB/8];
+  char Data[1];   /* Buffer to hold data in this slab... variable sized */
+} PoolSlab;
+
+#define NODE_ALLOCATED(POOLSLAB, NODENUM) \
+   ((POOLSLAB)->AllocatedBitVector[(NODENUM) >> 3] & (1 << ((NODENUM) & 7)))
+#define MARK_NODE_ALLOCATED(POOLSLAB, NODENUM) \
+   (POOLSLAB)->AllocatedBitVector[(NODENUM) >> 3] |= 1 << ((NODENUM) & 7)
+#define MARK_NODE_FREE(POOLSLAB, NODENUM) \
+   (POOLSLAB)->AllocatedBitVector[(NODENUM) >> 3] &= ~(1 << ((NODENUM) & 7))
+
+
+/* poolinit - Initialize a pool descriptor to empty
+ */
+void poolinit(PoolTy *Pool, unsigned Size) {
+  assert(Pool && "Null pool pointer passed in!");
+
+  Pool->NodeSize = Size;
+  Pool->Data = 0;
+}
+
+/* pooldestroy - Release all memory allocated for a pool
+ */
+void pooldestroy(PoolTy *Pool) {
+  PoolSlab *PS = (PoolSlab*)Pool->Data;
+  while (PS) {
+    PoolSlab *Next = PS->Next;
+    free(PS);
+    PS = Next;
+  }
+}
+
+static void *FindSlabEntry(PoolSlab *PS, unsigned NodeSize) {
+  /* Loop through all of the slabs looking for one with an opening */
+  for (; PS; PS = PS->Next) {
+    /* Check to see if there are empty entries at the end of the slab... */
+    if (PS->LastUsed < NODES_PER_SLAB-1) {
+      /* Mark the returned entry used */
+      MARK_NODE_ALLOCATED(PS, PS->LastUsed+1);
+
+      /* If we are allocating out the first unused field, bump its index also */
+      if (PS->FirstUnused == PS->LastUsed+1)
+        PS->FirstUnused++;
+
+      /* Return the entry, increment LastUsed field. */
+      return &PS->Data[0] + ++PS->LastUsed * NodeSize;
+    }
+
+    /* If not, check to see if this node has a declared "FirstUnused" value that
+     * is less than the number of nodes allocated...
+     */
+    if (PS->FirstUnused < NODES_PER_SLAB) {
+      /* Successfully allocate out the first unused node */
+      unsigned Idx = PS->FirstUnused;
+      
+      /* Increment FirstUnused to point to the new first unused value... */
+      do {
+        ++PS->FirstUnused;
+      } while (PS->FirstUnused < NODES_PER_SLAB &&
+               NODE_ALLOCATED(PS, PS->FirstUnused));
+
+      return &PS->Data[0] + Idx*NodeSize;
+    }
+  }
+
+  /* No empty nodes available, must grow # slabs! */
+  return 0;
+}
+
+char *poolalloc(PoolTy *Pool) {
+  unsigned NodeSize = Pool->NodeSize;
+  PoolSlab *PS = (PoolSlab*)Pool->Data;
+  void *Result;
+
+  if ((Result = FindSlabEntry(PS, NodeSize)))
+    return Result;
+
+  /* Otherwise we must allocate a new slab and add it to the list */
+  PS = (PoolSlab*)malloc(sizeof(PoolSlab)+NodeSize*NODES_PER_SLAB-1);
+
+  /* Initialize the slab to indicate that the first element is allocated */
+  PS->FirstUnused = 1;
+  PS->LastUsed = 0;
+  PS->AllocatedBitVector[0] = 1;
+
+  /* Add the slab to the list... */
+  PS->Next = (PoolSlab*)Pool->Data;
+  Pool->Data = PS;
+  return &PS->Data[0];
+}
+
+void poolfree(PoolTy *Pool, char *Node) {
+  unsigned NodeSize = Pool->NodeSize, Idx;
+  PoolSlab *PS = (PoolSlab*)Pool->Data;
+  PoolSlab **PPS = (PoolSlab**)&Pool->Data;
+
+  /* Seach for the slab that contains this node... */
+  while (&PS->Data[0] > Node || &PS->Data[NodeSize*NODES_PER_SLAB] < Node) {
+    assert(PS && "free'd node not found in allocation pool specified!");
+    PPS = &PS->Next;
+    PS = PS->Next;
+  }
+
+  Idx = (Node-&PS->Data[0])/NodeSize;
+  assert(Idx < NODES_PER_SLAB && "Pool slab searching loop broken!");
+
+  /* Update the first free field if this node is below the free node line */
+  if (Idx < PS->FirstUnused) PS->FirstUnused = Idx;
+  
+  /* If we are not freeing the last element in a slab... */
+  if (Idx != PS->LastUsed) {
+    MARK_NODE_FREE(PS, Idx);
+    return;
+  } 
+
+  /* Otherwise we are freeing the last element in a slab... shrink the
+   * LastUsed marker down to last used node.
+   */
+  do {
+    --PS->LastUsed;
+    /* Fixme, this should scan the allocated array an entire byte at a time for
+     * performance!
+     */
+  } while (PS->LastUsed >= 0 && (!NODE_ALLOCATED(PS, PS->LastUsed)));
+  
+  assert(PS->FirstUnused <= PS->LastUsed+1 &&
+         "FirstUnused field was out of date!");
+    
+  /* Ok, if this slab is empty, we unlink it from the of slabs and either move
+   * it to the head of the list, or free it, depending on whether or not there
+   * is already an empty slab at the head of the list.
+   */
+  if (PS->LastUsed == -1) {   /* Empty slab? */
+    PoolSlab *HeadSlab;
+    *PPS = PS->Next;   /* Unlink from the list of slabs... */
+
+    HeadSlab = (PoolSlab*)Pool->Data;
+    if (HeadSlab && HeadSlab->LastUsed == -1){/* List already has empty slab? */
+      free(PS);                               /* Free memory for slab */
+    } else {
+      PS->Next = HeadSlab;                    /* No empty slab yet, add this */
+      Pool->Data = PS;                        /* one to the head of the list */
+    }
+  }
+}