On Tue, May 31, 2016 at 10:22 AM, Eric Botcazou <ebotca...@adacore.com> wrote:
> Hi,
>
> it's a regression present on the mainline and 6 branch: for the attached Ada
> testcase, optab_for_tree_code segfaults because the function is invoked on a
> NULL_TREE vectype_out from the vectorizer (vectorizable_reduction):
>
> if (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info) == TREE_CODE_REDUCTION
> || STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info)
> == INTEGER_INDUC_COND_REDUCTION)
> {
> if (reduction_code_for_scalar_code (orig_code, &epilog_reduc_code))
> {
> reduc_optab = optab_for_tree_code (epilog_reduc_code, vectype_out,
> optab_default);
>
> Naive attempts at working around the NULL_TREE result in bogus vectorization
> and GIMPLE verification failure so it seems clear that vectype_out ought not
> to be NULL_TREE here.
>
> The problems stems from vect_determine_vectorization_factor, namely:
>
> /* Bool ops don't participate in vectorization factor
> computation. For comparison use compared types to
> compute a factor. */
> if (TREE_CODE (scalar_type) == BOOLEAN_TYPE
> && is_gimple_assign (stmt)
> && gimple_assign_rhs_code (stmt) != COND_EXPR)
> {
> if (STMT_VINFO_RELEVANT_P (stmt_info))
> mask_producers.safe_push (stmt_info);
> bool_result = true;
>
> if (gimple_code (stmt) == GIMPLE_ASSIGN
> && TREE_CODE_CLASS (gimple_assign_rhs_code (stmt))
> == tcc_comparison
> && TREE_CODE (TREE_TYPE (gimple_assign_rhs1 (stmt)))
> != BOOLEAN_TYPE)
> scalar_type = TREE_TYPE (gimple_assign_rhs1 (stmt));
> else
> {
> if (!analyze_pattern_stmt && gsi_end_p (pattern_def_si))
> {
> pattern_def_seq = NULL;
> gsi_next (&si);
> }
> continue;
> }
> }
>
> which leaves STMT_VINFO_VECTYPE set to NULL_TREE. It would have been nice to
> say in the comment why boolean operations don't participate in vectorization
> factor computation; one can only assume that it's because they are somehow
> treated specially, so the proposed fix does the same in vectorizable_reduction
> (and is probably a no-op except for Ada because of the precision test).
Note that vect_determine_vectorization_factor is supposed to set the
vector type on all
stmts. That it doesn't is a bug. Do you run into the else branch? I
think that should
only trigger with STMT_VINFO_RELEVANT_P and thus the stmt in mask_producers
which should later get post-processed and have the VECTYPE set.
But maybe Ilya can shed some more light on this (awkward) code.
Richard.
> Tested on x86_64-suse-linux, OK for mainline and 6 branch?
>
>
> 2016-05-31 Eric Botcazou <ebotca...@adacore.com>
>
> * tree-vect-loop.c (vectorizable_reduction): Also return false if the
> scalar type is a boolean type.
>
>
> 2016-05-31 Eric Botcazou <ebotca...@adacore.com>
>
> * gnat.dg/opt56.ad[sb]: New test.
>
> --
> Eric Botcazou
