1 /* Data structures and function declarations for the SSA value propagation 2 engine. 3 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 4 Contributed by Diego Novillo <dnovillo@redhat.com> 5 6 This file is part of GCC. 7 8 GCC is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 2, or (at your option) 11 any later version. 12 13 GCC is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with GCC; see the file COPYING. If not, write to 20 the Free Software Foundation, 51 Franklin Street, Fifth Floor, 21 Boston, MA 02110-1301, USA. */ 22 23 #ifndef _TREE_SSA_PROPAGATE_H 24 #define _TREE_SSA_PROPAGATE_H 1 25 26 /* Use the TREE_VISITED bitflag to mark statements and PHI nodes that 27 have been deemed varying and should not be simulated again. */ 28 #define DONT_SIMULATE_AGAIN(T) TREE_VISITED (T) 29 30 /* Lattice values used for propagation purposes. Specific instances 31 of a propagation engine must return these values from the statement 32 and PHI visit functions to direct the engine. */ 33 enum ssa_prop_result { 34 /* The statement produces nothing of interest. No edges will be 35 added to the work lists. */ 36 SSA_PROP_NOT_INTERESTING, 37 38 /* The statement produces an interesting value. The set SSA_NAMEs 39 returned by SSA_PROP_VISIT_STMT should be added to 40 INTERESTING_SSA_EDGES. If the statement being visited is a 41 conditional jump, SSA_PROP_VISIT_STMT should indicate which edge 42 out of the basic block should be marked executable. */ 43 SSA_PROP_INTERESTING, 44 45 /* The statement produces a varying (i.e., useless) value and 46 should not be simulated again. If the statement being visited 47 is a conditional jump, all the edges coming out of the block 48 will be considered executable. */ 49 SSA_PROP_VARYING 50 }; 51 52 53 struct prop_value_d { 54 /* Lattice value. Each propagator is free to define its own 55 lattice and this field is only meaningful while propagating. 56 It will not be used by substitute_and_fold. */ 57 unsigned lattice_val; 58 59 /* Propagated value. */ 60 tree value; 61 62 /* If this value is held in an SSA name for a non-register 63 variable, this field holds the actual memory reference 64 associated with this value. This field is taken from 65 the LHS of the assignment that generated the associated SSA 66 name. However, in the case of PHI nodes, this field is copied 67 from the PHI arguments (assuming that all the arguments have 68 the same memory reference). See replace_vuses_in for a more 69 detailed description. */ 70 tree mem_ref; 71 }; 72 73 typedef struct prop_value_d prop_value_t; 74 75 76 /* Type of value ranges. See value_range_d for a description of these 77 types. */ 78 enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING }; 79 80 /* Range of values that can be associated with an SSA_NAME after VRP 81 has executed. */ 82 struct value_range_d 83 { 84 /* Lattice value represented by this range. */ 85 enum value_range_type type; 86 87 /* Minimum and maximum values represented by this range. These 88 values should be interpreted as follows: 89 90 - If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must 91 be NULL. 92 93 - If TYPE == VR_RANGE then MIN holds the minimum value and 94 MAX holds the maximum value of the range [MIN, MAX]. 95 96 - If TYPE == ANTI_RANGE the variable is known to NOT 97 take any values in the range [MIN, MAX]. */ 98 tree min; 99 tree max; 100 101 /* Set of SSA names whose value ranges are equivalent to this one. 102 This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE. */ 103 bitmap equiv; 104 }; 105 106 typedef struct value_range_d value_range_t; 107 108 109 /* Call-back functions used by the value propagation engine. */ 110 typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (tree, edge *, tree *); 111 typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (tree); 112 113 114 /* In tree-ssa-propagate.c */ 115 void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn); 116 tree get_rhs (tree); 117 bool set_rhs (tree *, tree); 118 tree first_vdef (tree); 119 bool stmt_makes_single_load (tree); 120 bool stmt_makes_single_store (tree); 121 prop_value_t *get_value_loaded_by (tree, prop_value_t *); 122 bool replace_uses_in (tree, bool *, prop_value_t *); 123 void substitute_and_fold (prop_value_t *, bool); 124 125 #endif /* _TREE_SSA_PROPAGATE_H */ 126