On Mon, Mar 11, 2019 at 12:39 PM Richard Biener <rguent...@suse.de> wrote:
>
>
> The following fixes a missed vectorization of std::min() when
> only one argument is a temporary. The following patch is the least
> intrusive and safest one - PRE already performs the necessary
> work to make this vectorizable, it's just that we end up with
> a dead store and clobber of a stack-local that the vectorizer is
> not happy about. The easiest fix is to schedule an update-address-taken
> phase at the right spot which rewrites it into SSA and then DCE
> can get rid of it. DSE would also do the job but is more expensive.
> Since PRE/VN have the chance to expose things that can be written
> into SSA doing so before loop opts sounds like a good idea in any case.
>
> Bootstrap & regtest running on x86_64-unknown-linux-gnu.
>
> Queued for GCC 10 for which I also have a fix for phiprop which
> usually deals with std::min/max if-conversion. The one below
> is quite safe but it's not a regression unfortunately.
Applied as r270800.
Richard.
> Richard.
>
> 2019-03-11 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/89653
> * tree-ssa-loop.c (pass_data_tree_loop_init): Execute
> update-address-taken before the pass.
> * passes.def (pass_tree_loop_init): Put comment before it.
>
> * g++.dg/vect/pr89653.cc: New testcase.
>
> Index: gcc/tree-ssa-loop.c
> ===================================================================
> --- gcc/tree-ssa-loop.c (revision 269569)
> +++ gcc/tree-ssa-loop.c (working copy)
> @@ -330,7 +330,7 @@ const pass_data pass_data_tree_loop_init
> PROP_cfg, /* properties_required */
> 0, /* properties_provided */
> 0, /* properties_destroyed */
> - 0, /* todo_flags_start */
> + TODO_update_address_taken, /* todo_flags_start */
> 0, /* todo_flags_finish */
> };
>
> Index: gcc/passes.def
> ===================================================================
> --- gcc/passes.def (revision 269569)
> +++ gcc/passes.def (working copy)
> @@ -261,6 +261,8 @@ along with GCC; see the file COPYING3.
> NEXT_PASS (pass_fix_loops);
> NEXT_PASS (pass_tree_loop);
> PUSH_INSERT_PASSES_WITHIN (pass_tree_loop)
> + /* Before loop_init we rewrite no longer addressed locals into SSA
> + form if possible. */
> NEXT_PASS (pass_tree_loop_init);
> NEXT_PASS (pass_tree_unswitch);
> NEXT_PASS (pass_scev_cprop);
> Index: gcc/testsuite/g++.dg/vect/pr89653.cc
> ===================================================================
> --- gcc/testsuite/g++.dg/vect/pr89653.cc (nonexistent)
> +++ gcc/testsuite/g++.dg/vect/pr89653.cc (working copy)
> @@ -0,0 +1,12 @@
> +// { dg-do compile }
> +// { dg-require-effective-target vect_double }
> +
> +#include <algorithm>
> +
> +void loop1(double * const __restrict__ vec, double x, int end)
> +{
> + for (int i = 0; i < end; ++i)
> + vec[i] = std::min(vec[i], vec[i]/x);
> +}
> +
> +// { dg-final { scan-tree-dump "vectorized 1 loops" "vect" } }
