On Mon, 24 Jul 2017, Jeff Law wrote:
> As Uli noted, we should be using std::swap.
>
> Can you please repost ?
* domwalk.c (cmp_bb_postorder): Simplify.
(sort_bbs_postorder): New function. Use it...
(dom_walker::walk): ...here to optimize common cases.
---
gcc/domwalk.c | 53 ++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 36 insertions(+), 17 deletions(-)
diff --git a/gcc/domwalk.c b/gcc/domwalk.c
index a0daae6b2d8..df51b8c4451 100644
--- a/gcc/domwalk.c
+++ b/gcc/domwalk.c
@@ -128,19 +128,46 @@ along with GCC; see the file COPYING3. If not see
which is currently an abstraction over walking tree statements. Thus
the dominator walker is currently only useful for trees. */
+/* Reverse postorder index of each basic block. */
static int *bb_postorder;
static int
cmp_bb_postorder (const void *a, const void *b)
{
- basic_block bb1 = *(basic_block *)const_cast<void *>(a);
- basic_block bb2 = *(basic_block *)const_cast<void *>(b);
- if (bb1->index == bb2->index)
- return 0;
+ basic_block bb1 = *(const basic_block *)(a);
+ basic_block bb2 = *(const basic_block *)(b);
+ int n1 = bb_postorder[bb1->index], n2 = bb_postorder[bb2->index];
/* Place higher completion number first (pop off lower number first). */
- if (bb_postorder[bb1->index] > bb_postorder[bb2->index])
- return -1;
- return 1;
+ return (n1 < n2) - (n1 > n2);
+}
+
+/* Permute array BBS of N basic blocks in postorder,
+ i.e. by descending number in BB_POSTORDER array. */
+
+static void
+sort_bbs_postorder (basic_block *bbs, int n)
+{
+ if (__builtin_expect (n == 2, true))
+ {
+ basic_block bb0 = bbs[0], bb1 = bbs[1];
+ if (bb_postorder[bb0->index] < bb_postorder[bb1->index])
+ bbs[0] = bb1, bbs[1] = bb0;
+ }
+ else if (__builtin_expect (n == 3, true))
+ {
+ basic_block bb0 = bbs[0], bb1 = bbs[1], bb2 = bbs[2];
+ if (bb_postorder[bb0->index] < bb_postorder[bb1->index])
+ std::swap (bb0, bb1);
+ if (bb_postorder[bb1->index] < bb_postorder[bb2->index])
+ {
+ std::swap (bb1, bb2);
+ if (bb_postorder[bb0->index] < bb_postorder[bb1->index])
+ std::swap (bb0, bb1);
+ }
+ bbs[0] = bb0, bbs[1] = bb1, bbs[2] = bb2;
+ }
+ else
+ qsort (bbs, n, sizeof *bbs, cmp_bb_postorder);
}
/* Constructor for a dom walker.
@@ -284,16 +311,8 @@ dom_walker::walk (basic_block bb)
for (dest = first_dom_son (m_dom_direction, bb);
dest; dest = next_dom_son (m_dom_direction, dest))
worklist[sp++] = dest;
- if (m_dom_direction == CDI_DOMINATORS)
- switch (sp - saved_sp)
- {
- case 0:
- case 1:
- break;
- default:
- qsort (&worklist[saved_sp], sp - saved_sp,
- sizeof (basic_block), cmp_bb_postorder);
- }
+ if (sp - saved_sp > 1 && m_dom_direction == CDI_DOMINATORS)
+ sort_bbs_postorder (&worklist[saved_sp], sp - saved_sp);
}
/* NULL is used to mark pop operations in the recursion stack. */
while (sp > 0 && !worklist[sp - 1])
--
2.13.3
