1 files changed, 122 insertions, 0 deletions
diff --git a/runtime/GC/SemiSpace/semispace.c b/runtime/GC/SemiSpace/semispace.c
new file mode 100644
index 0000000000..cb5864b0bd
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+++ b/runtime/GC/SemiSpace/semispace.c
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+/*===-- semispace.c - Simple semi-space copying garbage collector ---------===*\
+|*
+|*                     The LLVM Compiler Infrastructure
+|*
+|* This file was developed by the LLVM research group and is distributed under
+|* the University of Illinois Open Source License. See LICENSE.TXT for details.
+|* 
+|*===----------------------------------------------------------------------===*|
+|* 
+|* This garbage collector is an extremely simple copying collector.  It splits
+|* the managed region of memory into two pieces: the current space to allocate
+|* from, and the copying space.  When the portion being allocated from fills up,
+|* a garbage collection cycle happens, which copies all live blocks to the other
+|* half of the managed space.
+|*
+\*===----------------------------------------------------------------------===*/
+
+#include "../GCInterface.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* AllocPtr - This points to the next byte that is available for allocation.
+ */
+static char *AllocPtr;
+
+/* AllocEnd - This points to the first byte not available for allocation.  When
+ * AllocPtr passes this, we have run out of space.
+ */
+static char *AllocEnd;
+
+/* CurSpace/OtherSpace - These pointers point to the two regions of memory that
+ * we switch between.  The unallocated portion of the CurSpace is known to be
+ * zero'd out, but the OtherSpace contains junk.
+ */
+static void *CurSpace, *OtherSpace;
+
+/* SpaceSize - The size of each space. */
+static unsigned SpaceSize;
+
+/* llvm_gc_initialize - Allocate the two spaces that we plan to switch between.
+ */
+void llvm_gc_initialize(unsigned InitialHeapSize) {
+  SpaceSize = InitialHeapSize/2;
+  CurSpace = AllocPtr = calloc(1, SpaceSize);
+  OtherSpace = malloc(SpaceSize);
+  AllocEnd = AllocPtr + SpaceSize;
+}
+
+/* We always want to inline the fast path, but never want to inline the slow
+ * path.
+ */
+void *llvm_gc_allocate(unsigned Size) __attribute__((always_inline));
+static void* llvm_gc_alloc_slow(unsigned Size) __attribute__((noinline));
+
+void *llvm_gc_allocate(unsigned Size) {
+  char *OldAP = AllocPtr;
+  char *NewEnd = OldAP+Size;
+  if (NewEnd > AllocEnd)
+    return llvm_gc_alloc_slow(Size);
+  AllocPtr = NewEnd;
+  return OldAP;
+}
+
+static void* llvm_gc_alloc_slow(unsigned Size) {
+  llvm_gc_collect();
+  if (AllocPtr+Size > AllocEnd) {
+    fprintf(stderr, "Garbage collector ran out of memory "
+            "allocating object of size: %d\n", Size);
+    exit(1);
+  }
+
+  return llvm_gc_allocate(Size);
+}
+
+
+static void process_pointer(void **Root, void *Meta) {
+  printf("process_root[0x%p] = 0x%p\n", (void*) Root, (void*) *Root);
+}
+
+void llvm_gc_collect() {
+  // Clear out the space we will be copying into.
+  // FIXME: This should do the copy, then clear out whatever space is left.
+  memset(OtherSpace, 0, SpaceSize);
+
+  printf("Garbage collecting!!\n");
+  llvm_cg_walk_gcroots(process_pointer);
+  abort();
+}
+
+/* We use no read/write barriers */
+void *llvm_gc_read(void *ObjPtr, void **FieldPtr) { return *FieldPtr; }
+void llvm_gc_write(void *V, void *ObjPtr, void **FieldPtr) { *FieldPtr = V; }
+
+
+/*===----------------------------------------------------------------------===**
+ * FIXME: This should be in a code-generator specific library, but for now this
+ * will work for all code generators.
+ */
+typedef struct GCRoot {
+  void **RootPtr;
+  void *Meta;
+} GCRoot;
+
+typedef struct GCRoots {
+  struct GCRoots *Next;
+  unsigned NumRoots;
+  GCRoot RootRecords[];
+} GCRoots;
+GCRoots *llvm_gc_root_chain;
+
+void llvm_cg_walk_gcroots(void (*FP)(void **Root, void *Meta)) {
+  GCRoots *R = llvm_gc_root_chain;
+  for (; R; R = R->Next) {
+    unsigned i, e;
+    for (i = 0, e = R->NumRoots; i != e; ++i)
+      FP(R->RootRecords[i].RootPtr, R->RootRecords[i].Meta);
+  }
+}
+/* END FIXME! */
+
+