This fixes PR53774, a case where reassoc produced non-canonical statements like a = 4 + b. The reason it did so was that it assigned a rank of zero to things that are not constant. Fixed by pre-computing a rank for all SSA default defs.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied. Richard. 2012-06-27 Richard Guenther <rguent...@suse.de> PR tree-optimization/53774 * tree-ssa-reassoc.c (get_rank): All default defs have precomputed rank. (init_reassoc): Precompute rank for all SSA default defs. Index: gcc/tree-ssa-reassoc.c =================================================================== --- gcc/tree-ssa-reassoc.c (revision 188987) +++ gcc/tree-ssa-reassoc.c (working copy) @@ -383,14 +383,10 @@ get_rank (tree e) int i, n; tree op; - if (TREE_CODE (SSA_NAME_VAR (e)) == PARM_DECL - && SSA_NAME_IS_DEFAULT_DEF (e)) + if (SSA_NAME_IS_DEFAULT_DEF (e)) return find_operand_rank (e); stmt = SSA_NAME_DEF_STMT (e); - if (gimple_bb (stmt) == NULL) - return 0; - if (gimple_code (stmt) == GIMPLE_PHI) return phi_rank (stmt); @@ -484,7 +480,7 @@ sort_by_operand_rank (const void *pa, co /* It's nicer for optimize_expression if constants that are likely to fold when added/multiplied//whatever are put next to each other. Since all constants have rank 0, order them by type. */ - if (oeb->rank == 0 && oea->rank == 0) + if (oeb->rank == 0 && oea->rank == 0) { if (constant_type (oeb->op) != constant_type (oea->op)) return constant_type (oeb->op) - constant_type (oea->op); @@ -3441,7 +3437,7 @@ transform_stmt_to_multiply (gimple_stmt_ print_gimple_stmt (dump_file, stmt, 0, 0); } - gimple_assign_set_rhs_with_ops_1 (gsi, MULT_EXPR, rhs1, rhs2, NULL_TREE); + gimple_assign_set_rhs_with_ops (gsi, MULT_EXPR, rhs1, rhs2); update_stmt (gsi_stmt (*gsi)); remove_visited_stmt_chain (rhs1); @@ -3647,7 +3643,6 @@ init_reassoc (void) { int i; long rank = 2; - tree param; int *bbs = XNEWVEC (int, last_basic_block + 1); /* Find the loops, so that we can prevent moving calculations in @@ -3666,24 +3661,15 @@ init_reassoc (void) bb_rank = XCNEWVEC (long, last_basic_block + 1); operand_rank = pointer_map_create (); - /* Give each argument a distinct rank. */ - for (param = DECL_ARGUMENTS (current_function_decl); - param; - param = DECL_CHAIN (param)) - { - if (gimple_default_def (cfun, param) != NULL) - { - tree def = gimple_default_def (cfun, param); - insert_operand_rank (def, ++rank); - } - } - - /* Give the chain decl a distinct rank. */ - if (cfun->static_chain_decl != NULL) - { - tree def = gimple_default_def (cfun, cfun->static_chain_decl); - if (def != NULL) - insert_operand_rank (def, ++rank); + /* Give each default definition a distinct rank. This includes + parameters and the static chain. Walk backwards over all + SSA names so that we get proper rank ordering according + to tree_swap_operands_p. */ + for (i = num_ssa_names - 1; i > 0; --i) + { + tree name = ssa_name (i); + if (name && SSA_NAME_IS_DEFAULT_DEF (name)) + insert_operand_rank (name, ++rank); } /* Set up rank for each BB */