Re: [patch] Fix a couple of VEC_reserve uses, speed up update_ssa a bit
On Fri, Aug 10, 2012 at 12:20 AM, Steven Bosscher stevenb@gmail.com wrote: On Fri, Aug 10, 2012 at 12:15 AM, Richard Henderson r...@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); Ok with that change. Thanks, Richard.
[patch] Fix a couple of VEC_reserve uses, speed up update_ssa a bit
Hello, VEC_reserve allocates an *extra* number of slots. There is unfortunately no VEC_resize op (one of the first things to add after the merge of the cxx branch, I suppose...), so to grow a VEC without increasing the used slots count (the VEC_length) it's necessary to compute the number of extra slots needed and reserve only that number of slots. So something like: VEC_reserve (ssa_name_info_p, heap, info_for_ssa_name, num_ssa_names); on an existing VEC with non-null length is wrong. In the worst case, the VEC_length is already num_ssa_names and the VEC ends up twice as large as necessary. Another thing I noticed, is that in update_ssa() we're sbitmap_zero'ing new_ssa_names and old_ssa_names even after we've already done so in init_update_ssa. This might seem like a micro-optimization, but it cuts the time spent in the timevar tree SSA incremental in half for the test case of PR54146... Bootstrappedtested on powerpc64-unknown-linux-gnu. OK for trunk? Ciao! Steven vec_reserve.diff Description: Binary data
Re: [patch] Fix a couple of VEC_reserve uses, speed up update_ssa a bit
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. r~
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 r...@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);
