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Reduce vector comparison of uniform vectors to a scalar comparison

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gcc/
	* tree-ssa-dom.c (reduce_vector_comparison_to_scalar_comparison): New
	function.
	(dom_opt_dom_walker::optimize_stmt): Use it.
This commit is contained in:
Jeff Law 2021-08-27 15:27:38 -04:00
parent 94a047359f
commit ac6d5c9112
1 changed files with 65 additions and 0 deletions
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65
gcc/tree-ssa-dom.c
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@ -1891,6 +1891,66 @@ dom_opt_dom_walker::test_for_singularity (gimple *stmt,
}
}
/* If STMT is a comparison of two uniform vectors reduce it to a comparison
of scalar objects, otherwise leave STMT unchanged. */
static void
reduce_vector_comparison_to_scalar_comparison (gimple *stmt)
{
if (gimple_code (stmt) == GIMPLE_COND)
{
tree lhs = gimple_cond_lhs (stmt);
tree rhs = gimple_cond_rhs (stmt);
/* We may have a vector comparison where both arms are uniform
vectors. If so, we can simplify the vector comparison down
to a scalar comparison. */
if (TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE
&& TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE)
{
/* If either operand is an SSA_NAME, then look back to its
defining statement to try and get at a suitable source. */
if (TREE_CODE (rhs) == SSA_NAME)
{
gimple *def_stmt = SSA_NAME_DEF_STMT (rhs);
if (gimple_assign_single_p (def_stmt))
rhs = gimple_assign_rhs1 (def_stmt);
}
if (TREE_CODE (lhs) == SSA_NAME)
{
gimple *def_stmt = SSA_NAME_DEF_STMT (lhs);
if (gimple_assign_single_p (def_stmt))
lhs = gimple_assign_rhs1 (def_stmt);
}
/* Now see if they are both uniform vectors and if so replace
the vector comparison with a scalar comparison. */
tree rhs_elem = rhs ? uniform_vector_p (rhs) : NULL_TREE;
tree lhs_elem = lhs ? uniform_vector_p (lhs) : NULL_TREE;
if (rhs_elem && lhs_elem)
{
if (dump_file && dump_flags & TDF_DETAILS)
{
fprintf (dump_file, "Reducing vector comparison: ");
print_gimple_stmt (dump_file, stmt, 0);
}
gimple_cond_set_rhs (as_a <gcond *>(stmt), rhs_elem);
gimple_cond_set_lhs (as_a <gcond *>(stmt), lhs_elem);
gimple_set_modified (stmt, true);
if (dump_file && dump_flags & TDF_DETAILS)
{
fprintf (dump_file, "To scalar equivalent: ");
print_gimple_stmt (dump_file, stmt, 0);
fprintf (dump_file, "\n");
}
}
}
}
}
/* Optimize the statement in block BB pointed to by iterator SI.
We try to perform some simplistic global redundancy elimination and
@ -1933,6 +1993,11 @@ dom_opt_dom_walker::optimize_stmt (basic_block bb, gimple_stmt_iterator *si,
update_stmt_if_modified (stmt);
opt_stats.num_stmts++;
/* STMT may be a comparison of uniform vectors that we can simplify
down to a comparison of scalars. Do that transformation first
so that all the scalar optimizations from here onward apply. */
reduce_vector_comparison_to_scalar_comparison (stmt);
/* Const/copy propagate into USES, VUSES and the RHS of VDEFs. */
cprop_into_stmt (stmt, m_evrp_range_analyzer);