[gawk-diffs] [SCM] gawk branch, master, updated. gawk-4.1.0-2414-g6b12d4f

[Andrew J. Schorr]

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- Log -----------------------------------------------------------------
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=6b12d4f726b9578d5c878fa765d5c167c9d71618

commit 6b12d4f726b9578d5c878fa765d5c167c9d71618
Author: Andrew J. Schorr <address@hidden>
Date:   Wed Jan 25 14:58:35 2017 -0500

    Minor rewrite of block allocator to improve clarity.

diff --git a/ChangeLog b/ChangeLog
index 944b26e..eb60152 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,22 @@
+2017-01-25         Andrew J. Schorr     <address@hidden>
+
+       * awk.h (BLOCK): Remove typedef. BLOCK was used for 2 different
+       purposes: to contain a block allocation list header, and to hold
+       each individual allocated item. This was confusing, because the "size"
+       field was set only in the header, but not in each element.
+       (struct block_header): The block header contains a pointer to the first
+       element and the element size.
+       (struct block_item): Represent a single allocated item. This contains
+       only a pointer to the next element. This reduces the minimum allocated
+       item size from 2 pointers to 1 (16 bytes to 8 bytes on x86_64).
+       (nextfree): Change array item type from BLOCK to struct block_header.
+       (getblock, freeblock): Change cast from 'BLOCK' to 'struct block_item'.
+       * node.c (nextfree): Now an array of 'struct block_header' instead of
+       BLOCK. Switch the ordering to put the next pointer before the size.
+       (more_blocks): Replace 'BLOCK' with 'struct block_item', and add
+       an assert to ensure that the allocation size is at least as large
+       as 'struct block_item', i.e. 1 pointer.
+
 2017-01-22         Andrew J. Schorr     <address@hidden>
 
        * awk.h (numtype_choose): New backend macro used to implement
diff --git a/awk.h b/awk.h
index 34c0e07..6616351 100644
--- a/awk.h
+++ b/awk.h
@@ -1050,10 +1050,14 @@ struct flagtab {
 };
 
 
-typedef struct block_item {
-       size_t size;
+struct block_item {
+       struct block_item *freep;
+};
+
+struct block_header {
        struct block_item *freep;
-} BLOCK;
+       size_t size;
+};
 
 enum block_id {
        BLOCK_INVALID = 0,      /* not legal */
@@ -1118,7 +1122,7 @@ extern afunc_t int_array_func[];
 /* special node used to indicate success in array routines (not NULL) */
 extern NODE *success_node;
 
-extern BLOCK nextfree[];
+extern struct block_header nextfree[];
 extern bool field0_valid;
 
 extern int do_flags;
@@ -1305,10 +1309,10 @@ DEREF(NODE *r)
                                &((n)->var_value) : r_get_lhs((n), (r))
 
 #define getblock(p, id, ty)  (void) ((p = (ty) nextfree[id].freep) ? \
-                       (ty) (nextfree[id].freep = ((BLOCK *) p)->freep) \
+                       (ty) (nextfree[id].freep = ((struct block_item *) 
p)->freep) \
                        : (p = (ty) more_blocks(id)))
-#define freeblock(p, id)        (void) (((BLOCK *) p)->freep = 
nextfree[id].freep, \
-                                       nextfree[id].freep = (BLOCK *) p)
+#define freeblock(p, id)        (void) (((struct block_item *) p)->freep = 
nextfree[id].freep, \
+                                       nextfree[id].freep = (struct block_item 
*) p)
 
 #define getnode(n)     getblock(n, BLOCK_NODE, NODE *)
 #define freenode(n)    freeblock(n, BLOCK_NODE)
diff --git a/node.c b/node.c
index 97f65fa..f1f8017 100644
--- a/node.c
+++ b/node.c
@@ -1001,32 +1001,33 @@ void init_btowc_cache()
 
 #define BLOCKCHUNK 100
 
-BLOCK nextfree[BLOCK_MAX] = {
-       { 0, NULL},     /* invalid */
-       { sizeof(NODE), NULL },
-       { sizeof(BUCKET), NULL },
+struct block_header nextfree[BLOCK_MAX] = {
+       { NULL, 0},     /* invalid */
+       { NULL, sizeof(NODE) },
+       { NULL, sizeof(BUCKET) },
 };
 
 
 /* more_blocks --- get more blocks of memory and add to the free list;
-       size of a block must be >= sizeof(BLOCK)
+       size of a block must be >= sizeof(struct block_item)
  */
 
 void *
 more_blocks(int id)
 {
-       BLOCK *freep, *np, *next;
+       struct block_item *freep, *np, *next;
        char *p, *endp;
        size_t size;
 
        size = nextfree[id].size;
 
-       emalloc(freep, BLOCK *, BLOCKCHUNK * size, "more_blocks");
+       assert(size >= sizeof(struct block_item));
+       emalloc(freep, struct block_item *, BLOCKCHUNK * size, "more_blocks");
        p = (char *) freep;
        endp = p + BLOCKCHUNK * size;
 
        for (np = freep; ; np = next) {
-               next = (BLOCK *) (p += size);
+               next = (struct block_item *) (p += size);
                if (p >= endp) {
                        np->freep = NULL;
                        break;

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog |   19 +++++++++++++++++++
 awk.h     |   18 +++++++++++-------
 node.c    |   17 +++++++++--------
 3 files changed, 39 insertions(+), 15 deletions(-)


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