Hi, the attached testcase exhibits a corruption of the SSA form:
t.c: In function 'foo': t.c:9:10: error: definition in block 2 follows the use for SSA_NAME: vect_p.7_12 in statement: # VUSE <.MEM_6(D)> vect_var_.8_13 = MEM[(struct R *)vect_p.7_12]; t.c:9:10: internal compiler error: verify_ssa failed Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. introduced by SLP on x86-64 at -O2 -ftree-vectorize -fno-vect-cost-model. This is a wrong statement rewriting in vectorizable_load. Before SLP we have: D.2687_1 = arg.d2; D.2688_2 = arg.d1; D.2689_3 = 0.0 - D.2688_2; D.2690_4 = D.2687_1 * D.2689_3; D.2692.d1 = D.2690_4; vect_check_interleaving computes that field d1 is accessed before field d2 because the structure is defined as struct R { double d1; double d2; }; but it's the opposite in the code. So, in vectorizable_load, first_stmt is the load of d1 and new statements are wrongly inserted _after_ the load of d2. Note that, on release branches (4.5 and 4.6 at least), you get wrong code. Proposed fix attached. It adds a GSI parameter to vect_create_data_ref_ptr. Tested on {i586,x86_64}-suse-linux, OK for the mainline? And the branches? 2011-03-27 Eric Botcazou <ebotca...@adacore.com> * tree-vectorizer.h (vect_create_data_ref_ptr): Adjust prototype. * tree-vect-data-refs.c (vect_create_data_ref_ptr): Add GSI parameter. Insert new statements at it in lieu of STMT. (vect_setup_realignment): Adjust call to vect_create_data_ref_ptr. * tree-vect-stmts.c (vectorizable_store): Likewise. (vectorizable_load): Likewise. 2011-03-27 Eric Botcazou <ebotca...@adacore.com> * gcc.dg/slp-1.c: New test. -- Eric Botcazou
Index: tree-vectorizer.h =================================================================== --- tree-vectorizer.h (revision 171572) +++ tree-vectorizer.h (working copy) @@ -824,7 +824,8 @@ extern bool vect_analyze_data_ref_access extern bool vect_prune_runtime_alias_test_list (loop_vec_info); extern bool vect_analyze_data_refs (loop_vec_info, bb_vec_info, int *); extern tree vect_create_data_ref_ptr (gimple, struct loop *, tree, tree *, - gimple *, bool, bool *); + gimple_stmt_iterator *, gimple *, + bool, bool *); extern tree bump_vector_ptr (tree, gimple, gimple_stmt_iterator *, gimple, tree); extern tree vect_create_destination_var (tree, tree); extern bool vect_strided_store_supported (tree); Index: tree-vect-data-refs.c =================================================================== --- tree-vect-data-refs.c (revision 171572) +++ tree-vect-data-refs.c (working copy) @@ -2922,9 +2922,10 @@ vect_create_addr_base_for_vector_ref (gi 2. AT_LOOP: the loop where the vector memref is to be created. 3. OFFSET (optional): an offset to be added to the initial address accessed by the data-ref in STMT. - 4. ONLY_INIT: indicate if vp is to be updated in the loop, or remain + 4. BSI: location where the new stmts are to be placed if there is no loop + 5. ONLY_INIT: indicate if vp is to be updated in the loop, or remain pointing to the initial address. - 5. TYPE: if not NULL indicates the required type of the data-ref. + 6. TYPE: if not NULL indicates the required type of the data-ref. Output: 1. Declare a new ptr to vector_type, and have it point to the base of the @@ -2952,9 +2953,9 @@ vect_create_addr_base_for_vector_ref (gi 4. Return the pointer. */ tree -vect_create_data_ref_ptr (gimple stmt, struct loop *at_loop, - tree offset, tree *initial_address, gimple *ptr_incr, - bool only_init, bool *inv_p) +vect_create_data_ref_ptr (gimple stmt, struct loop *at_loop, tree offset, + tree *initial_address, gimple_stmt_iterator *gsi, + gimple *ptr_incr, bool only_init, bool *inv_p) { tree base_name; stmt_vec_info stmt_info = vinfo_for_stmt (stmt); @@ -2980,7 +2981,6 @@ vect_create_data_ref_ptr (gimple stmt, s gimple incr; tree step; bb_vec_info bb_vinfo = STMT_VINFO_BB_VINFO (stmt_info); - gimple_stmt_iterator gsi = gsi_for_stmt (stmt); tree base; if (loop_vinfo) @@ -3125,7 +3125,7 @@ vect_create_data_ref_ptr (gimple stmt, s gcc_assert (!new_bb); } else - gsi_insert_seq_before (&gsi, new_stmt_list, GSI_SAME_STMT); + gsi_insert_seq_before (gsi, new_stmt_list, GSI_SAME_STMT); } *initial_address = new_temp; @@ -3147,7 +3147,7 @@ vect_create_data_ref_ptr (gimple stmt, s gcc_assert (!new_bb); } else - gsi_insert_before (&gsi, vec_stmt, GSI_SAME_STMT); + gsi_insert_before (gsi, vec_stmt, GSI_SAME_STMT); } else vect_ptr_init = new_temp; @@ -3672,7 +3672,7 @@ vect_setup_realignment (gimple stmt, gim gcc_assert (!compute_in_loop); vec_dest = vect_create_destination_var (scalar_dest, vectype); ptr = vect_create_data_ref_ptr (stmt, loop_for_initial_load, NULL_TREE, - &init_addr, &inc, true, &inv_p); + &init_addr, NULL, &inc, true, &inv_p); new_stmt = gimple_build_assign_with_ops (BIT_AND_EXPR, NULL_TREE, ptr, build_int_cst (TREE_TYPE (ptr), Index: tree-vect-stmts.c =================================================================== --- tree-vect-stmts.c (revision 171572) +++ tree-vect-stmts.c (working copy) @@ -3582,7 +3582,7 @@ vectorizable_store (gimple stmt, gimple_ gcc_assert (useless_type_conversion_p (vectype, TREE_TYPE (vec_oprnd))); dataref_ptr = vect_create_data_ref_ptr (first_stmt, NULL, NULL_TREE, - &dummy, &ptr_incr, false, + &dummy, gsi, &ptr_incr, false, &inv_p); gcc_assert (bb_vinfo || !inv_p); } @@ -4109,9 +4109,8 @@ vectorizable_load (gimple stmt, gimple_s { /* 1. Create the vector pointer update chain. */ if (j == 0) - dataref_ptr = vect_create_data_ref_ptr (first_stmt, - at_loop, offset, - &dummy, &ptr_incr, false, + dataref_ptr = vect_create_data_ref_ptr (first_stmt, at_loop, offset, + &dummy, gsi, &ptr_incr, false, &inv_p); else dataref_ptr =
/* { dg-do compile } */ /* { dg-options "-O2 -ftree-vectorize -fno-vect-cost-model" } */ struct R { double d1; double d2; }; struct R foo (struct R arg) { struct R ret; ret.d1 = arg.d2 * (0.0 - arg.d1); ret.d2 = ret.d1; return ret; }