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Re: [patch] Fix a couple of VEC_reserve uses, speed up update_ssa a bit
On Fri, Aug 10, 2012 at 12:15 AM, Richard Henderson <rth@redhat.com> wrote:
> On 08/09/2012 03:06 PM, Steven Bosscher wrote:
>> + unsigned old_len = name_to_id ? VEC_length (unsigned, name_to_id) : 0;
>> + VEC_reserve (unsigned, heap, name_to_id, num_ssa_names - old_len);
>
> VEC_length already handles NULL input.
I didn't know that. Consider that hunk changed to this:
Index: tree-ssa-pre.c
===================================================================
--- tree-ssa-pre.c (revision 190267)
+++ tree-ssa-pre.c (working copy)
@@ -249,7 +249,8 @@ alloc_expression_id (pre_expr expr)
/* VEC_safe_grow_cleared allocates no headroom. Avoid frequent
re-allocations by using VEC_reserve upfront. There is no
VEC_quick_grow_cleared unfortunately. */
- VEC_reserve (unsigned, heap, name_to_id, num_ssa_names);
+ unsigned old_len = VEC_length (unsigned, name_to_id);
+ VEC_reserve (unsigned, heap, name_to_id, num_ssa_names - old_len);
VEC_safe_grow_cleared (unsigned, heap, name_to_id, num_ssa_names);
gcc_assert (VEC_index (unsigned, name_to_id, version) == 0);
VEC_replace (unsigned, name_to_id, version, expr->id);