From 3dbb260e5f277a350da7251e01dd3284f973f36f Mon Sep 17 00:00:00 2001
From: Ivan Maidanski <ivmai@mail.ru>
Date: Fri, 20 Jan 2023 09:37:48 +0300
Subject: Simplify code of GC_allochblk_nth (refactoring)

Issue #510 (bdwgc).

* allchblk.c (GC_hblk_fl_from_blocks): Change type of blocks argument
from word to size_t.
* allchblk.c (setup_header): Reformat comment.
* allchblk.c (GC_get_first_part): Change type of total_size local
variable from word to size_t; add assertion that bytes argument is
multiple of HBLKSIZE.
* allchblk.c (GC_get_first_part): Specify that result of
GC_install_header() is unlikely to be NULL.
* alloc.c (GC_add_to_heap): Likewise.
* allchblk.c (AVOID_SPLIT_REMAPPED): Define only if USE_MUNMAP.
* allchblk.c (GC_allochblk): Remove comment; change blocks*HBLKSIZE<0
to blocks>=GC_SIZE_MAX/(2*HBLKSIZE) and expect its result unlikely to
be true.
* allchblk.c (GC_allochblk): Vhange type of blocks local variable from
word to size_t.
* malloc.c (GC_alloc_large): Likewise.
* allchblk.c (GC_drop_blacklisted_count): New STATIC varible (replaces\
count static one in GC_allochblk_nth).
* allchblk.c (next_hblk_fits_better, find_nonbl_hblk,
drop_hblk_in_chunks): New static function (move code GC_allochblk_nth).
* allchblk.c (GC_allochblk_nth): Refine comment; add assertion that
sz is non-zero; change type of size_needed and size_avail from
signed_word to word; add and refine comments; call find_nonbl_hblk,
next_hblk_fits_better and drop_hblk_in_chunks; simplify code in the
loop; rename lasthbp to last_hbp local variable; rename thishdr to
last_hdr local variable; remove thishbp local variable; add assertion
that hhdr->hb_sz>=size_needed.
* include/private/gc_priv.h (GC_allochblk): Move comment from
allchblk.c.
* include/private/gc_priv.h (GC_alloc_large) Move comment from
malloc.c.
* malloc.c (GC_alloc_large): Remove total_bytes local variable.
* malloc.c (GC_alloc_large, GC_alloc_large_and_clear,
GC_generic_malloc): Specify that result (or h) is unlikely to be NULL.
---
 malloc.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

(limited to 'malloc.c')

diff --git a/malloc.c b/malloc.c
index dc72a62d..e0643790 100644
--- a/malloc.c
+++ b/malloc.c
@@ -33,14 +33,11 @@ STATIC GC_bool GC_alloc_reclaim_list(struct obj_kind *kind)
     return TRUE;
 }
 
-/* Allocate a large block of size lb bytes.  The block is not cleared.  */
-/* flags argument should be 0 or IGNORE_OFF_PAGE.  EXTRA_BYTES value    */
-/* was already added to lb.                                             */
 GC_INNER ptr_t GC_alloc_large(size_t lb, int k, unsigned flags)
 {
     struct hblk * h;
-    word n_blocks;
-    ptr_t result;
+    size_t n_blocks;
+    ptr_t result = NULL;
     GC_bool retry = FALSE;
 
     GC_ASSERT(I_HOLD_LOCK());
@@ -52,15 +49,16 @@ GC_INNER ptr_t GC_alloc_large(size_t lb, int k, unsigned flags)
       GC_init();
       LOCK();
     }
-    /* Do our share of marking work */
-        if (GC_incremental && !GC_dont_gc) {
+    /* Do our share of marking work.    */
+    if (GC_incremental && !GC_dont_gc) {
             ENTER_GC();
             GC_collect_a_little_inner((int)n_blocks);
             EXIT_GC();
-        }
+    }
+
     h = GC_allochblk(lb, k, flags);
 #   ifdef USE_MUNMAP
-        if (0 == h) {
+        if (NULL == h) {
             GC_merge_unmapped();
             h = GC_allochblk(lb, k, flags);
         }
@@ -69,12 +67,9 @@ GC_INNER ptr_t GC_alloc_large(size_t lb, int k, unsigned flags)
         h = GC_allochblk(lb, k, flags);
         retry = TRUE;
     }
-    if (h == 0) {
-        result = 0;
-    } else {
-        size_t total_bytes = n_blocks * HBLKSIZE;
+    if (EXPECT(h != NULL, TRUE)) {
         if (n_blocks > 1) {
-            GC_large_allocd_bytes += total_bytes;
+            GC_large_allocd_bytes += HBLKSIZE * n_blocks;
             if (GC_large_allocd_bytes > GC_max_large_allocd_bytes)
                 GC_max_large_allocd_bytes = GC_large_allocd_bytes;
         }
@@ -92,7 +87,7 @@ STATIC ptr_t GC_alloc_large_and_clear(size_t lb, int k, unsigned flags)
 
     GC_ASSERT(I_HOLD_LOCK());
     result = GC_alloc_large(lb, k, flags);
-    if (result != NULL
+    if (EXPECT(result != NULL, TRUE)
           && (GC_debugging_started || GC_obj_kinds[k].ok_init)) {
         /* Clear the whole block, in case of GC_realloc call. */
         BZERO(result, HBLKSIZE * OBJ_SZ_TO_BLOCKS(lb));
@@ -263,7 +258,7 @@ GC_API GC_ATTR_MALLOC void * GC_CALL GC_generic_malloc(size_t lb, int k)
         init = GC_obj_kinds[k].ok_init;
         LOCK();
         result = (ptr_t)GC_alloc_large(lb_rounded, k, 0);
-        if (0 != result) {
+        if (EXPECT(result != NULL, TRUE)) {
           if (GC_debugging_started) {
             BZERO(result, HBLKSIZE * OBJ_SZ_TO_BLOCKS(lb_rounded));
           } else {
-- 
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