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Fix possible sanopt compile-time hog

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While working on bitmap operations I figured sanopt.cc uses
a sbitmap worklist, iterating using bitmap_first_set_bit on it.
That's quadratic since bitmap_first_set_bit for sbitmap is O(n).

The fix is to use regular bitmaps for the worklist and the bitmap
feeding it and to avoid a useless copy.

	* sanopt.cc (sanitize_asan_mark_unpoison): Use bitmap
	for with_poison and alias worklist to it.
	(sanitize_asan_mark_poison): Likewise.
This commit is contained in:
Richard Biener 2023-02-14 16:14:51 +01:00
parent e1dfac7e71
commit 86bc090961
1 changed files with 6 additions and 11 deletions
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17
gcc/sanopt.cc
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@ -987,15 +987,11 @@ static void
sanitize_asan_mark_unpoison (void)
{
/* 1) Find all BBs that contain an ASAN_MARK poison call. */
auto_sbitmap with_poison (last_basic_block_for_fn (cfun) + 1);
bitmap_clear (with_poison);
auto_bitmap with_poison;
basic_block bb;
FOR_EACH_BB_FN (bb, cfun)
{
if (bitmap_bit_p (with_poison, bb->index))
continue;
gimple_stmt_iterator gsi;
for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
{
@ -1010,8 +1006,8 @@ sanitize_asan_mark_unpoison (void)
auto_sbitmap poisoned (last_basic_block_for_fn (cfun) + 1);
bitmap_clear (poisoned);
auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1);
bitmap_copy (worklist, with_poison);
/* We now treat with_poison as worklist. */
bitmap worklist = with_poison;
/* 2) Propagate the information to all reachable blocks. */
while (!bitmap_empty_p (worklist))
@ -1088,8 +1084,7 @@ static void
sanitize_asan_mark_poison (void)
{
/* 1) Find all BBs that possibly contain an ASAN_CHECK. */
auto_sbitmap with_check (last_basic_block_for_fn (cfun) + 1);
bitmap_clear (with_check);
auto_bitmap with_check;
basic_block bb;
FOR_EACH_BB_FN (bb, cfun)
@ -1108,8 +1103,8 @@ sanitize_asan_mark_poison (void)
auto_sbitmap can_reach_check (last_basic_block_for_fn (cfun) + 1);
bitmap_clear (can_reach_check);
auto_sbitmap worklist (last_basic_block_for_fn (cfun) + 1);
bitmap_copy (worklist, with_check);
/* We now treat with_check as worklist. */
bitmap worklist = with_check;
/* 2) Propagate the information to all definitions blocks. */
while (!bitmap_empty_p (worklist))