From 9772629794cc28bc93b3c610386f1af50594e38c Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Thu, 27 May 2004 05:51:31 +0000
Subject: [PATCH] Continue the implementation

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13818 91177308-0d34-0410-b5e6-96231b3b80d8
---
 runtime/GC/SemiSpace/semispace.c | 102 +++++++++++++++++++------------
 1 file changed, 63 insertions(+), 39 deletions(-)

diff --git a/runtime/GC/SemiSpace/semispace.c b/runtime/GC/SemiSpace/semispace.c
index 93327edc88a..a005a48c888 100644
--- a/runtime/GC/SemiSpace/semispace.c
+++ b/runtime/GC/SemiSpace/semispace.c
@@ -18,37 +18,7 @@
 #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; }
-
+#include <string.h>
 
 /* AllocPtr - This points to the next byte that is available for allocation.
  */
@@ -59,9 +29,22 @@ static char *AllocPtr;
  */
 static char *AllocEnd;
 
-void llvm_gc_initialize() {
-  AllocPtr = calloc(1, 1000);
-  AllocEnd = AllocPtr + 1000;
+/* 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
@@ -81,18 +64,59 @@ void *llvm_gc_allocate(unsigned Size) {
 
 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_root(void **Root, void *Meta) {
+static void process_pointer(void **Root, void *Meta) {
   printf("process_root[0x%X] = 0x%X\n", (unsigned) Root, (unsigned) *Root);
 }
 
 void llvm_gc_collect() {
-  printf("Garbage collecting!!\n");
-  llvm_cg_walk_gcroots(process_root);
-  abort();
+  // 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);
 
-  /* TODO: Iterate through roots. */
+  printf("Garbage collecting!!\n");
+  llvm_cg_walk_gcroots(process_pointer);
+  abort();
 }
+
+/* We use no read/write barriers */
+void *llvm_gc_read(void **P) { return *P; }
+void llvm_gc_write(void *V, void **P) { *P = 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! */
+
+