On Tue, Jun 30, 2020 at 11:44 AM Martin Liška <mli...@suse.cz> wrote:
>
> Hi.
>
> The patch is about blocking of vector expansion of comparisons
> that are only feeding a VEC_COND_EXPR statements.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> The problematic mips64 test-case looks good now.
>
> Ready to be installed?
So why does
static tree
expand_vector_comparison (gimple_stmt_iterator *gsi, tree type, tree op0,
tree op1, enum tree_code code)
{
tree t;
if (!expand_vec_cmp_expr_p (TREE_TYPE (op0), type, code)
&& !expand_vec_cond_expr_p (type, TREE_TYPE (op0), code))
^^^^
not return true
{
but
/* Expand a vector condition to scalars, by using many conditions
on the vector's elements. */
static void
expand_vector_condition (gimple_stmt_iterator *gsi, auto_bitmap *dce_ssa_names)
{
...
if (expand_vec_cond_expr_p (type, TREE_TYPE (a1), code))
{
gcc_assert (TREE_CODE (a) == SSA_NAME || TREE_CODE (a) == VECTOR_CST);
return;
does? What's special about the problematical mips testcase? Can't you produce
the same "bad" result when the comparison is used in a non-VEC_COND?
There's a PR reference missing in the ChangeLog.
Richard.
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> * tree-vect-generic.c (expand_vector_comparison): Do not expand
> comparison that only feed first argument of a VEC_COND_EXPR statement.
> ---
> gcc/tree-vect-generic.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
> index a4b56195903..4606decd0f2 100644
> --- a/gcc/tree-vect-generic.c
> +++ b/gcc/tree-vect-generic.c
> @@ -379,6 +379,30 @@ static tree
> expand_vector_comparison (gimple_stmt_iterator *gsi, tree type, tree op0,
> tree op1, enum tree_code code)
> {
> + tree lhs = gimple_assign_lhs (gsi_stmt (*gsi));
> + use_operand_p use_p;
> + imm_use_iterator iterator;
> + bool vec_cond_expr_only = true;
> + bool has_use = false;
> +
> + /* As seen in PR95830, we should not expand comparisons that are only
> + feeding a VEC_COND_EXPR statement. */
> + FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
> + {
> + has_use = true;
> + gassign *use = dyn_cast<gassign *> (USE_STMT (use_p));
> + if (use == NULL
> + || gimple_assign_rhs_code (use) != VEC_COND_EXPR
> + || gimple_assign_rhs1 (use) != lhs)
> + {
> + vec_cond_expr_only = false;
> + break;
> + }
> + }
> +
> + if (has_use && vec_cond_expr_only)
> + return NULL_TREE;
> +
> tree t;
> if (!expand_vec_cmp_expr_p (TREE_TYPE (op0), type, code)
> && !expand_vec_cond_expr_p (type, TREE_TYPE (op0), code))
> --
> 2.27.0
>
