This gets away with the top caller of sbitmap_alloc in a tramp3d
compile which is pre_and_rev_post_order_compute_fn (yeah, we're
invoking that way too often). I've introduced those auto_*_flag
things for region based VN but I think it makes sense to use
those also for the non-region case.
Code-size of pre_and_rev_post_order_compute_fn increases with the
patch though, likely for allocation/deallocation code of the
flag which is inlined and due to the extra tail loop. Memory
locality should improve here though (->flags is in the same
cache line as ->index which we access anyway) - but that's
maybe wishful thinking, micro-benchmarking this seems hard and
large vs. small CFGs might tell different stories as well.
Bootstrapped and tested on x86_64-unknown-linux-gnu, OK?
Thanks,
Richard.
2019-11-21 Richard Biener <rguent...@suse.de>
* cfganal.c (pre_and_rev_post_order_compute_fn): Use an
auto_bb_flag instead of an sbitmap for visited handling.
Index: gcc/cfganal.c
===================================================================
--- gcc/cfganal.c (revision 278496)
+++ gcc/cfganal.c (working copy)
@@ -967,11 +967,8 @@ pre_and_rev_post_order_compute_fn (struc
else
rev_post_order_num -= NUM_FIXED_BLOCKS;
- /* Allocate bitmap to track nodes that have been visited. */
- auto_sbitmap visited (last_basic_block_for_fn (fn));
-
- /* None of the nodes in the CFG have been visited yet. */
- bitmap_clear (visited);
+ /* BB flag to track nodes that have been visited. */
+ auto_bb_flag visited (fn);
/* Push the first edge on to the stack. */
stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (fn)->succs));
@@ -988,10 +985,10 @@ pre_and_rev_post_order_compute_fn (struc
/* Check if the edge destination has been visited yet. */
if (dest != EXIT_BLOCK_PTR_FOR_FN (fn)
- && ! bitmap_bit_p (visited, dest->index))
+ && ! (dest->flags & visited))
{
/* Mark that we have visited the destination. */
- bitmap_set_bit (visited, dest->index);
+ dest->flags |= visited;
if (pre_order)
pre_order[pre_order_num] = dest->index;
@@ -1032,6 +1029,10 @@ pre_and_rev_post_order_compute_fn (struc
rev_post_order[rev_post_order_num--] = ENTRY_BLOCK;
}
+ /* Clear the temporarily allocated flag. */
+ for (int i = 0; i < pre_order_num; ++i)
+ BASIC_BLOCK_FOR_FN (fn, rev_post_order[i])->flags &= ~visited;
+
return pre_order_num;
}
