diff options
Diffstat (limited to 'gcc/cfganal.c')
-rw-r--r-- | gcc/cfganal.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/gcc/cfganal.c b/gcc/cfganal.c index 56853b9..762eea4 100644 --- a/gcc/cfganal.c +++ b/gcc/cfganal.c @@ -1465,3 +1465,56 @@ bitmap_union_of_preds (sbitmap dst, sbitmap *src, basic_block b) *r++ |= *p++; } } + +/* Returns the list of basic blocks in the function in an order that guarantees + that if a block X has just a single predecessor Y, then Y is after X in the + ordering. */ + +basic_block * +single_pred_before_succ_order (void) +{ + basic_block x, y; + basic_block *order = XNEWVEC (basic_block, n_basic_blocks); + unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS; + unsigned np, i; + sbitmap visited = sbitmap_alloc (last_basic_block); + +#define MARK_VISITED(BB) (bitmap_set_bit (visited, (BB)->index)) +#define VISITED_P(BB) (bitmap_bit_p (visited, (BB)->index)) + + bitmap_clear (visited); + + MARK_VISITED (ENTRY_BLOCK_PTR); + FOR_EACH_BB (x) + { + if (VISITED_P (x)) + continue; + + /* Walk the predecessors of x as long as they have precisely one + predecessor and add them to the list, so that they get stored + after x. */ + for (y = x, np = 1; + single_pred_p (y) && !VISITED_P (single_pred (y)); + y = single_pred (y)) + np++; + for (y = x, i = n - np; + single_pred_p (y) && !VISITED_P (single_pred (y)); + y = single_pred (y), i++) + { + order[i] = y; + MARK_VISITED (y); + } + order[i] = y; + MARK_VISITED (y); + + gcc_assert (i == n - 1); + n -= np; + } + + sbitmap_free (visited); + gcc_assert (n == 0); + return order; + +#undef MARK_VISITED +#undef VISITED_P +} |