Initial revision

1 files changed, 351 insertions, 0 deletions

diff --git a/gc/headers.c b/gc/headers.c
new file mode 100644
index 0000000..9564a6a
--- /dev/null
+++ b/gc/headers.c
@@ -0,0 +1,351 @@
+/* 
+ * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
+ * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose,  provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ */
+ 
+/*
+ * This implements:
+ * 1. allocation of heap block headers
+ * 2. A map from addresses to heap block addresses to heap block headers
+ *
+ * Access speed is crucial.  We implement an index structure based on a 2
+ * level tree.
+ */
+ 
+# include "gc_priv.h"
+
+bottom_index * GC_all_bottom_indices = 0;
+				/* Pointer to first (lowest addr) */
+				/* bottom_index.		  */
+
+bottom_index * GC_all_bottom_indices_end = 0;
+				/* Pointer to last (highest addr) */
+				/* bottom_index.		  */
+ 
+/* Non-macro version of header location routine */
+hdr * GC_find_header(h)
+ptr_t h;
+{
+#   ifdef HASH_TL
+	register hdr * result;
+	GET_HDR(h, result);
+	return(result);
+#   else
+	return(HDR_INNER(h));
+#   endif
+}
+ 
+/* Routines to dynamically allocate collector data structures that will */
+/* never be freed.							 */
+ 
+static ptr_t scratch_free_ptr = 0;
+ 
+ptr_t GC_scratch_end_ptr = 0;
+
+ptr_t GC_scratch_last_end_ptr = 0;
+		/* End point of last obtained scratch area */
+ 
+ptr_t GC_scratch_alloc(bytes)
+register word bytes;
+{
+    register ptr_t result = scratch_free_ptr;
+
+#   ifdef ALIGN_DOUBLE
+#	define GRANULARITY (2 * sizeof(word))
+#   else
+#	define GRANULARITY sizeof(word)
+#   endif
+    bytes += GRANULARITY-1;
+    bytes &= ~(GRANULARITY-1);
+    scratch_free_ptr += bytes;
+    if (scratch_free_ptr <= GC_scratch_end_ptr) {
+        return(result);
+    }
+    {
+        word bytes_to_get = MINHINCR * HBLKSIZE;
+         
+        if (bytes_to_get <= bytes) {
+          /* Undo the damage, and get memory directly */
+	    bytes_to_get = bytes;
+#	    ifdef USE_MMAP
+		bytes_to_get += GC_page_size - 1;
+		bytes_to_get &= ~(GC_page_size - 1);
+#	    endif
+   	    result = (ptr_t)GET_MEM(bytes_to_get);
+            scratch_free_ptr -= bytes;
+	    GC_scratch_last_end_ptr = result + bytes;
+            return(result);
+        }
+        result = (ptr_t)GET_MEM(bytes_to_get);
+        if (result == 0) {
+#	    ifdef PRINTSTATS
+                GC_printf0("Out of memory - trying to allocate less\n");
+#	    endif
+            scratch_free_ptr -= bytes;
+	    bytes_to_get = bytes;
+#	    ifdef USE_MMAP
+		bytes_to_get += GC_page_size - 1;
+		bytes_to_get &= ~(GC_page_size - 1);
+#	    endif
+            return((ptr_t)GET_MEM(bytes_to_get));
+        }
+        scratch_free_ptr = result;
+        GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
+        GC_scratch_last_end_ptr = GC_scratch_end_ptr;
+        return(GC_scratch_alloc(bytes));
+    }
+}
+
+static hdr * hdr_free_list = 0;
+
+/* Return an uninitialized header */
+static hdr * alloc_hdr()
+{
+    register hdr * result;
+    
+    if (hdr_free_list == 0) {
+        result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
+    } else {
+        result = hdr_free_list;
+        hdr_free_list = (hdr *) (result -> hb_next);
+    }
+    return(result);
+}
+
+static void free_hdr(hhdr)
+hdr * hhdr;
+{
+    hhdr -> hb_next = (struct hblk *) hdr_free_list;
+    hdr_free_list = hhdr;
+}
+ 
+void GC_init_headers()
+{
+    register unsigned i;
+    
+    GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
+    BZERO(GC_all_nils, sizeof(bottom_index));
+    for (i = 0; i < TOP_SZ; i++) {
+        GC_top_index[i] = GC_all_nils;
+    }
+}
+
+/* Make sure that there is a bottom level index block for address addr  */
+/* Return FALSE on failure.						*/
+static GC_bool get_index(addr)
+word addr;
+{
+    word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
+    bottom_index * r;
+    bottom_index * p;
+    bottom_index ** prev;
+    bottom_index *pi;
+    
+#   ifdef HASH_TL
+      unsigned i = TL_HASH(hi);
+      bottom_index * old;
+      
+      old = p = GC_top_index[i];
+      while(p != GC_all_nils) {
+          if (p -> key == hi) return(TRUE);
+          p = p -> hash_link;
+      }
+      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
+      if (r == 0) return(FALSE);
+      BZERO(r, sizeof (bottom_index));
+      r -> hash_link = old;
+      GC_top_index[i] = r;
+#   else
+      if (GC_top_index[hi] != GC_all_nils) return(TRUE);
+      r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
+      if (r == 0) return(FALSE);
+      GC_top_index[hi] = r;
+      BZERO(r, sizeof (bottom_index));
+#   endif
+    r -> key = hi;
+    /* Add it to the list of bottom indices */
+      prev = &GC_all_bottom_indices;  	/* pointer to p */
+      pi = 0;				/* bottom_index preceding p */
+      while ((p = *prev) != 0 && p -> key < hi) {
+	pi = p;
+	prev = &(p -> asc_link);
+      }
+      r -> desc_link = pi;
+      if (0 == p) {
+	GC_all_bottom_indices_end = r;
+      } else {
+	p -> desc_link = r;
+      }
+      r -> asc_link = p;
+      *prev = r;
+    return(TRUE);
+}
+
+/* Install a header for block h.  */
+/* The header is uninitialized.	  */
+/* Returns FALSE on failure.	  */
+GC_bool GC_install_header(h)
+register struct hblk * h;
+{
+    hdr * result;
+    
+    if (!get_index((word) h)) return(FALSE);
+    result = alloc_hdr();
+    SET_HDR(h, result);
+#   ifdef USE_MUNMAP
+	result -> hb_last_reclaimed = GC_gc_no;
+#   endif
+    return(result != 0);
+}
+
+/* Set up forwarding counts for block h of size sz */
+GC_bool GC_install_counts(h, sz)
+register struct hblk * h;
+register word sz; /* bytes */
+{
+    register struct hblk * hbp;
+    register int i;
+    
+    for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
+        if (!get_index((word) hbp)) return(FALSE);
+    }
+    if (!get_index((word)h + sz - 1)) return(FALSE);
+    for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
+        i = HBLK_PTR_DIFF(hbp, h);
+        SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
+    }
+    return(TRUE);
+}
+
+/* Remove the header for block h */
+void GC_remove_header(h)
+register struct hblk * h;
+{
+    hdr ** ha;
+    
+    GET_HDR_ADDR(h, ha);
+    free_hdr(*ha);
+    *ha = 0;
+}
+
+/* Remove forwarding counts for h */
+void GC_remove_counts(h, sz)
+register struct hblk * h;
+register word sz; /* bytes */
+{
+    register struct hblk * hbp;
+    
+    for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
+        SET_HDR(hbp, 0);
+    }
+}
+
+/* Apply fn to all allocated blocks */
+/*VARARGS1*/
+void GC_apply_to_all_blocks(fn, client_data)
+void (*fn)(/* struct hblk *h, word client_data */);
+word client_data;
+{
+    register int j;
+    register bottom_index * index_p;
+    
+    for (index_p = GC_all_bottom_indices; index_p != 0;
+         index_p = index_p -> asc_link) {
+        for (j = BOTTOM_SZ-1; j >= 0;) {
+            if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
+                if (index_p->index[j]->hb_map != GC_invalid_map) {
+                    (*fn)(((struct hblk *)
+                  	      (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
+                  	       << LOG_HBLKSIZE)),
+                          client_data);
+                }
+                j--;
+             } else if (index_p->index[j] == 0) {
+                j--;
+             } else {
+                j -= (word)(index_p->index[j]);
+             }
+         }
+     }
+}
+
+/* Get the next valid block whose address is at least h	*/
+/* Return 0 if there is none.				*/
+struct hblk * GC_next_used_block(h)
+struct hblk * h;
+{
+    register bottom_index * bi;
+    register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
+    
+    GET_BI(h, bi);
+    if (bi == GC_all_nils) {
+        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
+        bi = GC_all_bottom_indices;
+        while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
+        j = 0;
+    }
+    while(bi != 0) {
+        while (j < BOTTOM_SZ) {
+	    hdr * hhdr = bi -> index[j];
+            if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+                j++;
+            } else {
+                if (hhdr->hb_map != GC_invalid_map) {
+                    return((struct hblk *)
+                  	      (((bi -> key << LOG_BOTTOM_SZ) + j)
+                  	       << LOG_HBLKSIZE));
+                } else {
+                    j += divHBLKSZ(hhdr -> hb_sz);
+                }
+            }
+        }
+        j = 0;
+        bi = bi -> asc_link;
+    }
+    return(0);
+}
+
+/* Get the last (highest address) block whose address is 	*/
+/* at most h.  Return 0 if there is none.			*/
+/* Unlike the above, this may return a free block.		*/
+struct hblk * GC_prev_block(h)
+struct hblk * h;
+{
+    register bottom_index * bi;
+    register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
+    
+    GET_BI(h, bi);
+    if (bi == GC_all_nils) {
+        register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
+        bi = GC_all_bottom_indices_end;
+        while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
+        j = BOTTOM_SZ - 1;
+    }
+    while(bi != 0) {
+        while (j >= 0) {
+	    hdr * hhdr = bi -> index[j];
+	    if (0 == hhdr) {
+		--j;
+            } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+                j -= (signed_word)hhdr;
+            } else {
+                return((struct hblk *)
+                          (((bi -> key << LOG_BOTTOM_SZ) + j)
+                  	       << LOG_HBLKSIZE));
+            }
+        }
+        j = BOTTOM_SZ - 1;
+        bi = bi -> desc_link;
+    }
+    return(0);
+}