Check in an EARLY START on a simple copying collector
llvm-svn: 13698
diff --git a/llvm/runtime/GC/SemiSpace/semispace.c b/llvm/runtime/GC/SemiSpace/semispace.c
new file mode 100644
index 0000000..3792f86
--- /dev/null
+++ b/llvm/runtime/GC/SemiSpace/semispace.c
@@ -0,0 +1,98 @@
+/*===-- 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>
+
+/* FIXME: This should be in a code-generator specific library!
+ */
+typedef struct GCRoot {
+ void **RootPtr;
+ void *Meta;
+} GCRoot;
+
+typedef struct GCRoots {
+ struct GCRoots *Next;
+ unsigned NumRoots;
+ GCRoot RootRecords[];
+} GCRoots;
+GCRoots *llvm_gc_root_chain;
+
+static 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! */
+
+
+
+/* We use no read/write barriers */
+void *llvm_gc_read(void **P) { return *P; }
+void llvm_gc_write(void *V, void **P) { *P = V; }
+
+
+/* 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;
+
+void llvm_gc_initialize() {
+ AllocPtr = calloc(1, 1000);
+ AllocEnd = AllocPtr + 1000;
+}
+
+/* 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();
+ return llvm_gc_allocate(Size);
+}
+
+
+static void process_root(void **Root, void *Meta) {
+ printf("process_root[0x%X] = 0x%X\n", Root, *Root);
+}
+
+void llvm_gc_collect() {
+ printf("Garbage collecting!!\n");
+ llvm_cg_walk_gcroots(process_root);
+ abort();
+
+ /* TODO: Iterate through roots. */
+}