The following fixes the SLP miscompile in PR68861 which happens because
we didn't think of stmts appering multiple times in a SLP node when
doing the operand swapping support.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2015-12-16 Richard Biener <rguent...@suse.de>
PR tree-optimization/68861
* tree-vect-slp.c (vect_build_slp_tree): Properly handle
duplicate stmts when applying swapping to stmts.
Index: gcc/tree-vect-slp.c
===================================================================
*** gcc/tree-vect-slp.c (revision 231675)
--- gcc/tree-vect-slp.c (working copy)
*************** vect_build_slp_tree (vec_info *vinfo,
*** 1049,1059 ****
if we end up building the operand from scalars as
we'll continue to process swapped operand two. */
for (j = 0; j < group_size; ++j)
! if (!matches[j])
{
gimple *stmt = SLP_TREE_SCALAR_STMTS (*node)[j];
! swap_ssa_operands (stmt, gimple_assign_rhs1_ptr (stmt),
! gimple_assign_rhs2_ptr (stmt));
}
/* If we have all children of child built up from scalars then
--- 1049,1077 ----
if we end up building the operand from scalars as
we'll continue to process swapped operand two. */
for (j = 0; j < group_size; ++j)
! {
! gimple *stmt = SLP_TREE_SCALAR_STMTS (*node)[j];
! gimple_set_plf (stmt, GF_PLF_1, false);
! }
! for (j = 0; j < group_size; ++j)
! {
! gimple *stmt = SLP_TREE_SCALAR_STMTS (*node)[j];
! if (!matches[j])
! {
! /* Avoid swapping operands twice. */
! if (gimple_plf (stmt, GF_PLF_1))
! continue;
! swap_ssa_operands (stmt, gimple_assign_rhs1_ptr (stmt),
! gimple_assign_rhs2_ptr (stmt));
! gimple_set_plf (stmt, GF_PLF_1, true);
! }
! }
! /* Verify we swap all duplicates or none. */
! if (flag_checking)
! for (j = 0; j < group_size; ++j)
{
gimple *stmt = SLP_TREE_SCALAR_STMTS (*node)[j];
! gcc_assert (gimple_plf (stmt, GF_PLF_1) == ! matches[j]);
}
/* If we have all children of child built up from scalars then
