X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=blobdiff_plain;f=gcc%2Ftree-ssa-ccp.c;h=c530eded8c69680bd6b2e2022af4bdceb37d4057;hp=7f28a9f9e93b5ff1b28e871aca271fe85deca845;hb=67f3526e422c69b4b0b0fc6fc72345e243433e5f;hpb=db97ad4157917ee22e26683eac93acea1f2b8cea diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 7f28a9f9e93..c530eded8c6 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -37,26 +37,23 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "system.h" #include "coretypes.h" #include "tm.h" -#include "errors.h" -#include "ggc.h" #include "tree.h" -#include "langhooks.h" - -/* These RTL headers are needed for basic-block.h. */ +#include "flags.h" #include "rtl.h" #include "tm_p.h" -#include "hard-reg-set.h" +#include "ggc.h" #include "basic-block.h" - +#include "output.h" +#include "errors.h" +#include "expr.h" +#include "function.h" #include "diagnostic.h" -#include "tree-inline.h" -#include "tree-flow.h" -#include "tree-gimple.h" +#include "timevar.h" #include "tree-dump.h" +#include "tree-flow.h" #include "tree-pass.h" -#include "timevar.h" -#include "expr.h" -#include "flags.h" +#include "tree-ssa-propagate.h" +#include "langhooks.h" /* Possible lattice values. */ @@ -64,14 +61,11 @@ typedef enum { UNINITIALIZED = 0, UNDEFINED, + UNKNOWN_VAL, CONSTANT, VARYING } latticevalue; -/* Use the TREE_VISITED bitflag to mark statements and PHI nodes that have - been deemed VARYING and shouldn't be simulated again. */ -#define DONT_SIMULATE_AGAIN(T) TREE_VISITED (T) - /* Main structure for CCP. Contains the lattice value and, if it's a constant, the constant value. */ typedef struct @@ -80,178 +74,116 @@ typedef struct tree const_val; } value; -/* A bitmap to keep track of executable blocks in the CFG. */ -static sbitmap executable_blocks; - -/* Array of control flow edges on the worklist. */ -static GTY(()) varray_type cfg_blocks = NULL; - -static unsigned int cfg_blocks_num = 0; -static int cfg_blocks_tail; -static int cfg_blocks_head; - -static sbitmap bb_in_list; - /* This is used to track the current value of each variable. */ static value *value_vector; -/* Worklist of SSA edges which will need reexamination as their definition - has changed. SSA edges are def-use edges in the SSA web. For each - edge, we store the definition statement or PHI node D. The destination - nodes that need to be visited are accessed using immediate_uses - (D). */ -static GTY(()) varray_type ssa_edges; - -/* Identical to SSA_EDGES. For performance reasons, the list of SSA - edges is split into two. One contains all SSA edges who need to be - reexamined because their lattice value changed to varying (this - worklist), and the other contains all other SSA edges to be - reexamined (ssa_edges). - - Since most values in the program are varying, the ideal situation - is to move them to that lattice value as quickly as possible. - Thus, it doesn't make sense to process any other type of lattice - value until all varying values are propagated fully, which is one - thing using the varying worklist achieves. In addition, if you - don't use a separate worklist for varying edges, you end up with - situations where lattice values move from - undefined->constant->varying instead of undefined->varying. -*/ -static GTY(()) varray_type varying_ssa_edges; - - -static void initialize (void); -static void finalize (void); -static void visit_phi_node (tree); -static tree ccp_fold (tree); -static value cp_lattice_meet (value, value); -static void visit_stmt (tree); -static void visit_cond_stmt (tree); -static void visit_assignment (tree); -static void add_var_to_ssa_edges_worklist (tree, value); -static void add_outgoing_control_edges (basic_block); -static void add_control_edge (edge); -static void def_to_varying (tree); -static void set_lattice_value (tree, value); -static void simulate_block (basic_block); -static void simulate_stmt (tree); -static void substitute_and_fold (void); -static value evaluate_stmt (tree); -static void dump_lattice_value (FILE *, const char *, value); -static bool replace_uses_in (tree, bool *); -static latticevalue likely_value (tree); -static tree get_rhs (tree); -static bool set_rhs (tree *, tree); -static value *get_value (tree); -static value get_default_value (tree); -static tree ccp_fold_builtin (tree, tree); -static bool get_strlen (tree, tree *, bitmap); -static inline bool cfg_blocks_empty_p (void); -static void cfg_blocks_add (basic_block); -static basic_block cfg_blocks_get (void); -static bool need_imm_uses_for (tree var); - -/* Process an SSA edge worklist. WORKLIST is the SSA edge worklist to - drain. This pops statements off the given WORKLIST and processes - them until there are no more statements on WORKLIST. */ + +/* Dump lattice value VAL to file OUTF prefixed by PREFIX. */ static void -process_ssa_edge_worklist (varray_type *worklist) +dump_lattice_value (FILE *outf, const char *prefix, value val) { - /* Drain the entire worklist. */ - while (VARRAY_ACTIVE_SIZE (*worklist) > 0) + switch (val.lattice_val) { - /* Pull the statement to simulate off the worklist. */ - tree stmt = VARRAY_TOP_TREE (*worklist); - stmt_ann_t ann = stmt_ann (stmt); - VARRAY_POP (*worklist); - - /* visit_stmt can "cancel" reevaluation of some statements. - If it does, then in_ccp_worklist will be zero. */ - if (ann->in_ccp_worklist) - { - ann->in_ccp_worklist = 0; - simulate_stmt (stmt); - } - } + case UNDEFINED: + fprintf (outf, "%sUNDEFINED", prefix); + break; + case VARYING: + fprintf (outf, "%sVARYING", prefix); + break; + case UNKNOWN_VAL: + fprintf (outf, "%sUNKNOWN_VAL", prefix); + break; + case CONSTANT: + fprintf (outf, "%sCONSTANT ", prefix); + print_generic_expr (outf, val.const_val, dump_flags); + break; + default: + gcc_unreachable (); + } } - -/* Main entry point for SSA Conditional Constant Propagation. FNDECL is - the declaration for the function to optimize. - - On exit, VARS_TO_RENAME will contain the symbols that have been exposed by - the propagation of ADDR_EXPR expressions into pointer dereferences and need - to be renamed into SSA. - PHASE indicates which dump file from the DUMP_FILES array to use when - dumping debugging information. */ -static void -tree_ssa_ccp (void) -{ - initialize (); +/* Return a default value for variable VAR using the following rules: - /* Iterate until the worklists are empty. */ - while (!cfg_blocks_empty_p () - || VARRAY_ACTIVE_SIZE (ssa_edges) > 0 - || VARRAY_ACTIVE_SIZE (varying_ssa_edges) > 0) - { - if (!cfg_blocks_empty_p ()) - { - /* Pull the next block to simulate off the worklist. */ - basic_block dest_block = cfg_blocks_get (); - simulate_block (dest_block); - } + 1- Function arguments are considered VARYING. + + 2- Global and static variables that are declared constant are + considered CONSTANT. - /* In order to move things to varying as quickly as - possible,process the VARYING_SSA_EDGES worklist first. */ - process_ssa_edge_worklist (&varying_ssa_edges); + 3- Any other virtually defined variable is considered UNKNOWN_VAL. - /* Now process the SSA_EDGES worklist. */ - process_ssa_edge_worklist (&ssa_edges); - } + 4- Any other value is considered UNDEFINED. This is useful when + considering PHI nodes. PHI arguments that are undefined do not + change the constant value of the PHI node, which allows for more + constants to be propagated. */ - /* Now perform substitutions based on the known constant values. */ - substitute_and_fold (); +static value +get_default_value (tree var) +{ + value val; + tree sym; - /* Now cleanup any unreachable code. */ - cleanup_tree_cfg (); + if (TREE_CODE (var) == SSA_NAME) + sym = SSA_NAME_VAR (var); + else + { + gcc_assert (DECL_P (var)); + sym = var; + } - /* Free allocated memory. */ - finalize (); + val.lattice_val = UNDEFINED; + val.const_val = NULL_TREE; - /* Debugging dumps. */ - if (dump_file && (dump_flags & TDF_DETAILS)) + if (TREE_CODE (var) == SSA_NAME + && SSA_NAME_VALUE (var) + && is_gimple_min_invariant (SSA_NAME_VALUE (var))) { - dump_referenced_vars (dump_file); - fprintf (dump_file, "\n\n"); + val.lattice_val = CONSTANT; + val.const_val = SSA_NAME_VALUE (var); } -} - -static bool -gate_ccp (void) -{ - return flag_tree_ccp != 0; -} + else if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym)) + { + /* Function arguments and volatile variables are considered VARYING. */ + val.lattice_val = VARYING; + } + else if (TREE_STATIC (sym)) + { + /* Globals and static variables are considered UNKNOWN_VAL, + unless they are declared 'const'. */ + if (TREE_READONLY (sym) + && DECL_INITIAL (sym) + && is_gimple_min_invariant (DECL_INITIAL (sym))) + { + val.lattice_val = CONSTANT; + val.const_val = DECL_INITIAL (sym); + } + else + { + val.const_val = NULL_TREE; + val.lattice_val = UNKNOWN_VAL; + } + } + else if (!is_gimple_reg (sym)) + { + val.const_val = NULL_TREE; + val.lattice_val = UNKNOWN_VAL; + } + else + { + enum tree_code code; + tree stmt = SSA_NAME_DEF_STMT (var); -struct tree_opt_pass pass_ccp = -{ - "ccp", /* name */ - gate_ccp, /* gate */ - tree_ssa_ccp, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - TV_TREE_CCP, /* tv_id */ - PROP_cfg | PROP_ssa, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_dump_func | TODO_rename_vars - | TODO_ggc_collect | TODO_verify_ssa - | TODO_verify_stmts /* todo_flags_finish */ -}; + if (!IS_EMPTY_STMT (stmt)) + { + code = TREE_CODE (stmt); + if (code != MODIFY_EXPR && code != PHI_NODE) + val.lattice_val = VARYING; + } + } + return val; +} /* Get the constant value associated with variable VAR. */ @@ -260,10 +192,7 @@ get_value (tree var) { value *val; -#if defined ENABLE_CHECKING - if (TREE_CODE (var) != SSA_NAME) - abort (); -#endif + gcc_assert (TREE_CODE (var) == SSA_NAME); val = &value_vector[SSA_NAME_VERSION (var)]; if (val->lattice_val == UNINITIALIZED) @@ -273,94 +202,318 @@ get_value (tree var) } -/* Simulate the execution of BLOCK. Evaluate the statement associated - with each variable reference inside the block. */ +/* Set the lattice value for variable VAR to VAL. Return true if VAL + is different from VAR's previous value. */ + +static bool +set_lattice_value (tree var, value val) +{ + value *old = get_value (var); + + if (val.lattice_val == UNDEFINED) + { + /* CONSTANT->UNDEFINED is never a valid state transition. */ + gcc_assert (old->lattice_val != CONSTANT); + + /* UNKNOWN_VAL->UNDEFINED is never a valid state transition. */ + gcc_assert (old->lattice_val != UNKNOWN_VAL); + + /* VARYING->UNDEFINED is generally not a valid state transition, + except for values which are initialized to VARYING. */ + gcc_assert (old->lattice_val != VARYING + || get_default_value (var).lattice_val == VARYING); + } + else if (val.lattice_val == CONSTANT) + /* VARYING -> CONSTANT is an invalid state transition, except + for objects which start off in a VARYING state. */ + gcc_assert (old->lattice_val != VARYING + || get_default_value (var).lattice_val == VARYING); + + /* If the constant for VAR has changed, then this VAR is really varying. */ + if (old->lattice_val == CONSTANT + && val.lattice_val == CONSTANT + && !simple_cst_equal (old->const_val, val.const_val)) + { + val.lattice_val = VARYING; + val.const_val = NULL_TREE; + } + + if (old->lattice_val != val.lattice_val) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + dump_lattice_value (dump_file, "Lattice value changed to ", val); + fprintf (dump_file, ". Adding definition to SSA edges.\n"); + } + + *old = val; + return true; + } + + return false; +} + + +/* Set the lattice value for the variable VAR to VARYING. */ static void -simulate_block (basic_block block) +def_to_varying (tree var) { - tree phi; + value val; + val.lattice_val = VARYING; + val.const_val = NULL_TREE; + set_lattice_value (var, val); +} - /* There is nothing to do for the exit block. */ - if (block == EXIT_BLOCK_PTR) - return; - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, "\nSimulating block %d\n", block->index); +/* Return the likely latticevalue for STMT. + + If STMT has no operands, then return CONSTANT. + + Else if any operands of STMT are undefined, then return UNDEFINED. + + Else if any operands of STMT are constants, then return CONSTANT. + + Else return VARYING. */ + +static latticevalue +likely_value (tree stmt) +{ + vuse_optype vuses; + int found_constant = 0; + stmt_ann_t ann; + tree use; + ssa_op_iter iter; + + /* If the statement makes aliased loads or has volatile operands, it + won't fold to a constant value. */ + ann = stmt_ann (stmt); + if (ann->makes_aliased_loads || ann->has_volatile_ops) + return VARYING; - /* Always simulate PHI nodes, even if we have simulated this block - before. */ - for (phi = phi_nodes (block); phi; phi = PHI_CHAIN (phi)) - visit_phi_node (phi); + /* A CALL_EXPR is assumed to be varying. This may be overly conservative, + in the presence of const and pure calls. */ + if (get_call_expr_in (stmt) != NULL_TREE) + return VARYING; + + get_stmt_operands (stmt); + + FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) + { + value *val = get_value (use); + + if (val->lattice_val == UNDEFINED) + return UNDEFINED; - /* If this is the first time we've simulated this block, then we - must simulate each of its statements. */ - if (!TEST_BIT (executable_blocks, block->index)) + if (val->lattice_val == CONSTANT) + found_constant = 1; + } + + vuses = VUSE_OPS (ann); + + if (NUM_VUSES (vuses)) { - block_stmt_iterator j; - unsigned int normal_edge_count; - edge e, normal_edge; - - /* Note that we have simulated this block. */ - SET_BIT (executable_blocks, block->index); - - for (j = bsi_start (block); !bsi_end_p (j); bsi_next (&j)) - visit_stmt (bsi_stmt (j)); - - /* We can not predict when abnormal edges will be executed, so - once a block is considered executable, we consider any - outgoing abnormal edges as executable. - - At the same time, if this block has only one successor that is - reached by non-abnormal edges, then add that successor to the - worklist. */ - normal_edge_count = 0; - normal_edge = NULL; - for (e = block->succ; e; e = e->succ_next) + tree vuse = VUSE_OP (vuses, 0); + value *val = get_value (vuse); + + if (val->lattice_val == UNKNOWN_VAL) + return UNKNOWN_VAL; + + /* There should be no VUSE operands that are UNDEFINED. */ + gcc_assert (val->lattice_val != UNDEFINED); + + if (val->lattice_val == CONSTANT) + found_constant = 1; + } + + return ((found_constant || (!USE_OPS (ann) && !vuses)) ? CONSTANT : VARYING); +} + + +/* Function indicating whether we ought to include information for VAR + when calculating immediate uses. */ + +static bool +need_imm_uses_for (tree var) +{ + return get_value (var)->lattice_val != VARYING; +} + + +/* Initialize local data structures for CCP. */ + +static void +ccp_initialize (void) +{ + basic_block bb; + sbitmap is_may_def; + + value_vector = (value *) xmalloc (num_ssa_names * sizeof (value)); + memset (value_vector, 0, num_ssa_names * sizeof (value)); + + /* Set of SSA_NAMEs that are defined by a V_MAY_DEF. */ + is_may_def = sbitmap_alloc (num_ssa_names); + sbitmap_zero (is_may_def); + + /* Initialize simulation flags for PHI nodes and statements. */ + FOR_EACH_BB (bb) + { + block_stmt_iterator i; + + /* Mark all V_MAY_DEF operands VARYING. */ + for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) { - if (e->flags & EDGE_ABNORMAL) + bool is_varying = false; + tree stmt = bsi_stmt (i); + ssa_op_iter iter; + tree def; + + get_stmt_operands (stmt); + + /* Get the default value for each DEF and V_MUST_DEF. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, + (SSA_OP_DEF | SSA_OP_VMUSTDEF)) { - add_control_edge (e); + if (get_value (def)->lattice_val == VARYING) + is_varying = true; } - else + + /* Mark all V_MAY_DEF operands VARYING. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_VMAYDEF) + { + get_value (def)->lattice_val = VARYING; + SET_BIT (is_may_def, SSA_NAME_VERSION (def)); + } + + /* Statements other than MODIFY_EXPR, COND_EXPR and + SWITCH_EXPR are not interesting for constant propagation. + Mark them VARYING. */ + if (TREE_CODE (stmt) != MODIFY_EXPR + && TREE_CODE (stmt) != COND_EXPR + && TREE_CODE (stmt) != SWITCH_EXPR) + is_varying = true; + + DONT_SIMULATE_AGAIN (stmt) = is_varying; + } + } + + /* Now process PHI nodes. */ + FOR_EACH_BB (bb) + { + tree phi, var; + int x; + + for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) + { + value *val = get_value (PHI_RESULT (phi)); + + for (x = 0; x < PHI_NUM_ARGS (phi); x++) { - normal_edge_count++; - normal_edge = e; + var = PHI_ARG_DEF (phi, x); + + /* If one argument has a V_MAY_DEF, the result is + VARYING. */ + if (TREE_CODE (var) == SSA_NAME) + { + if (TEST_BIT (is_may_def, SSA_NAME_VERSION (var))) + { + val->lattice_val = VARYING; + SET_BIT (is_may_def, SSA_NAME_VERSION (PHI_RESULT (phi))); + break; + } + } } - } - if (normal_edge_count == 1) - add_control_edge (normal_edge); + DONT_SIMULATE_AGAIN (phi) = (val->lattice_val == VARYING); + } } + + sbitmap_free (is_may_def); + + /* Compute immediate uses for variables we care about. */ + compute_immediate_uses (TDFA_USE_OPS | TDFA_USE_VOPS, need_imm_uses_for); } -/* Follow the def-use edges for statement DEF_STMT and simulate all the - statements reached by it. */ +/* Replace USE references in statement STMT with their immediate reaching + definition. Return true if at least one reference was replaced. If + REPLACED_ADDRESSES_P is given, it will be set to true if an address + constant was replaced. */ -static void -simulate_stmt (tree use_stmt) +static bool +replace_uses_in (tree stmt, bool *replaced_addresses_p) { - basic_block use_bb = bb_for_stmt (use_stmt); + bool replaced = false; + use_operand_p use; + ssa_op_iter iter; - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nSimulating statement (from ssa_edges): "); - print_generic_stmt (dump_file, use_stmt, dump_flags); - } + if (replaced_addresses_p) + *replaced_addresses_p = false; + + get_stmt_operands (stmt); - if (TREE_CODE (use_stmt) == PHI_NODE) + FOR_EACH_SSA_USE_OPERAND (use, stmt, iter, SSA_OP_USE) { - /* PHI nodes are always visited, regardless of whether or not the - destination block is executable. */ - visit_phi_node (use_stmt); + tree tuse = USE_FROM_PTR (use); + value *val = get_value (tuse); + + if (val->lattice_val != CONSTANT) + continue; + + if (TREE_CODE (stmt) == ASM_EXPR + && !may_propagate_copy_into_asm (tuse)) + continue; + + SET_USE (use, val->const_val); + + replaced = true; + if (POINTER_TYPE_P (TREE_TYPE (tuse)) && replaced_addresses_p) + *replaced_addresses_p = true; } - else if (TEST_BIT (executable_blocks, use_bb->index)) + + return replaced; +} + + +/* Replace the VUSE references in statement STMT with its immediate reaching + definition. Return true if the reference was replaced. If + REPLACED_ADDRESSES_P is given, it will be set to true if an address + constant was replaced. */ + +static bool +replace_vuse_in (tree stmt, bool *replaced_addresses_p) +{ + bool replaced = false; + vuse_optype vuses; + use_operand_p vuse; + value *val; + + if (replaced_addresses_p) + *replaced_addresses_p = false; + + get_stmt_operands (stmt); + + vuses = STMT_VUSE_OPS (stmt); + + if (NUM_VUSES (vuses) != 1) + return false; + + vuse = VUSE_OP_PTR (vuses, 0); + val = get_value (USE_FROM_PTR (vuse)); + + if (val->lattice_val == CONSTANT + && TREE_CODE (stmt) == MODIFY_EXPR + && DECL_P (TREE_OPERAND (stmt, 1)) + && TREE_OPERAND (stmt, 1) == SSA_NAME_VAR (USE_FROM_PTR (vuse))) { - /* Otherwise, visit the statement containing the use reached by - DEF, only if the destination block is marked executable. */ - visit_stmt (use_stmt); + TREE_OPERAND (stmt, 1) = val->const_val; + replaced = true; + if (POINTER_TYPE_P (TREE_TYPE (USE_FROM_PTR (vuse))) + && replaced_addresses_p) + *replaced_addresses_p = true; } + + return replaced; } @@ -371,6 +524,7 @@ static void substitute_and_fold (void) { basic_block bb; + unsigned int i; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, @@ -420,19 +574,23 @@ substitute_and_fold (void) print_generic_stmt (dump_file, stmt, TDF_SLIM); } - if (replace_uses_in (stmt, &replaced_address)) + if (replace_uses_in (stmt, &replaced_address) + || replace_vuse_in (stmt, &replaced_address)) { bool changed = fold_stmt (bsi_stmt_ptr (i)); stmt = bsi_stmt(i); - modify_stmt (stmt); + /* If we folded a builtin function, we'll likely need to rename VDEFs. */ if (replaced_address || changed) - { - mark_new_vars_to_rename (stmt, vars_to_rename); - if (maybe_clean_eh_stmt (stmt)) - tree_purge_dead_eh_edges (bb); - } + mark_new_vars_to_rename (stmt, vars_to_rename); + + /* If we cleaned up EH information from the statement, + remove EH edges. */ + if (maybe_clean_eh_stmt (stmt)) + tree_purge_dead_eh_edges (bb); + + modify_stmt (stmt); } if (dump_file && (dump_flags & TDF_DETAILS)) @@ -443,127 +601,50 @@ substitute_and_fold (void) } } } -} - - -/* Loop through the PHI_NODE's parameters for BLOCK and compare their - lattice values to determine PHI_NODE's lattice value. The value of a - PHI node is determined calling cp_lattice_meet() with all the arguments - of the PHI node that are incoming via executable edges. */ - -static void -visit_phi_node (tree phi) -{ - bool short_circuit = 0; - value phi_val, *curr_val; - int i; - - /* If the PHI node has already been deemed to be VARYING, don't simulate - it again. */ - if (DONT_SIMULATE_AGAIN (phi)) - return; - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nVisiting PHI node: "); - print_generic_expr (dump_file, phi, dump_flags); - } - curr_val = get_value (PHI_RESULT (phi)); - switch (curr_val->lattice_val) + /* And transfer what we learned from VALUE_VECTOR into the + SSA_NAMEs themselves. This probably isn't terribly important + since we probably constant propagated the values to their + use sites above. */ + for (i = 0; i < num_ssa_names; i++) { - case VARYING: - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, "\n Shortcircuit. Default of VARYING."); - short_circuit = 1; - break; + tree name = ssa_name (i); + value *value; - case CONSTANT: - phi_val = *curr_val; - break; - - case UNDEFINED: - case UNINITIALIZED: - phi_val.lattice_val = UNDEFINED; - phi_val.const_val = NULL_TREE; - break; - - default: - abort (); - } + if (!name) + continue; - /* If the variable is volatile or the variable is never referenced in a - real operand, then consider the PHI node VARYING. */ - if (short_circuit || TREE_THIS_VOLATILE (SSA_NAME_VAR (PHI_RESULT (phi)))) - { - phi_val.lattice_val = VARYING; - phi_val.const_val = NULL; + value = get_value (name); + if (value->lattice_val == CONSTANT + && is_gimple_reg (name) + && is_gimple_min_invariant (value->const_val)) + SSA_NAME_VALUE (name) = value->const_val; } - else - for (i = 0; i < PHI_NUM_ARGS (phi); i++) - { - /* Compute the meet operator over all the PHI arguments. */ - edge e = PHI_ARG_EDGE (phi, i); - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, - "\n Argument #%d (%d -> %d %sexecutable)\n", - i, e->src->index, e->dest->index, - (e->flags & EDGE_EXECUTABLE) ? "" : "not "); - } - - /* If the incoming edge is executable, Compute the meet operator for - the existing value of the PHI node and the current PHI argument. */ - if (e->flags & EDGE_EXECUTABLE) - { - tree rdef = PHI_ARG_DEF (phi, i); - value *rdef_val, val; - - if (is_gimple_min_invariant (rdef)) - { - val.lattice_val = CONSTANT; - val.const_val = rdef; - rdef_val = &val; - } - else - rdef_val = get_value (rdef); - - phi_val = cp_lattice_meet (phi_val, *rdef_val); +} - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\t"); - print_generic_expr (dump_file, rdef, dump_flags); - dump_lattice_value (dump_file, "\tValue: ", *rdef_val); - fprintf (dump_file, "\n"); - } - if (phi_val.lattice_val == VARYING) - break; - } - } +/* Free allocated storage. */ - if (dump_file && (dump_flags & TDF_DETAILS)) - { - dump_lattice_value (dump_file, "\n PHI node value: ", phi_val); - fprintf (dump_file, "\n\n"); - } +static void +ccp_finalize (void) +{ + /* Perform substitutions based on the known constant values. */ + substitute_and_fold (); - set_lattice_value (PHI_RESULT (phi), phi_val); - if (phi_val.lattice_val == VARYING) - DONT_SIMULATE_AGAIN (phi) = 1; + free (value_vector); } + /* Compute the meet operator between VAL1 and VAL2: - any M UNDEFINED = any - any M VARYING = VARYING - Ci M Cj = Ci if (i == j) - Ci M Cj = VARYING if (i != j) */ + any M UNDEFINED = any + any M VARYING = VARYING + any M UNKNOWN_VAL = UNKNOWN_VAL + Ci M Cj = Ci if (i == j) + Ci M Cj = VARYING if (i != j) */ static value -cp_lattice_meet (value val1, value val2) +ccp_lattice_meet (value val1, value val2) { value result; @@ -581,6 +662,15 @@ cp_lattice_meet (value val1, value val2) return result; } + /* any M UNKNOWN_VAL = UNKNOWN_VAL. */ + if (val1.lattice_val == UNKNOWN_VAL + || val2.lattice_val == UNKNOWN_VAL) + { + result.lattice_val = UNKNOWN_VAL; + result.const_val = NULL_TREE; + return result; + } + /* Ci M Cj = Ci if (i == j) Ci M Cj = VARYING if (i != j) */ if (simple_cst_equal (val1.const_val, val2.const_val) == 1) @@ -598,221 +688,124 @@ cp_lattice_meet (value val1, value val2) } -/* Evaluate statement STMT. If the statement produces an output value and - its evaluation changes the lattice value of its output, do the following: - - - If the statement is an assignment, add all the SSA edges starting at - this definition. - - - If the statement is a conditional branch: - . If the statement evaluates to non-constant, add all edges to - worklist. - . If the statement is constant, add the edge executed as the - result of the branch. */ +/* Loop through the PHI_NODE's parameters for BLOCK and compare their + lattice values to determine PHI_NODE's lattice value. The value of a + PHI node is determined calling ccp_lattice_meet() with all the arguments + of the PHI node that are incoming via executable edges. */ -static void -visit_stmt (tree stmt) +static enum ssa_prop_result +ccp_visit_phi_node (tree phi) { - size_t i; - stmt_ann_t ann; - def_optype defs; - v_may_def_optype v_may_defs; - v_must_def_optype v_must_defs; - - /* If the statement has already been deemed to be VARYING, don't simulate - it again. */ - if (DONT_SIMULATE_AGAIN (stmt)) - return; + value new_val, *old_val; + int i; if (dump_file && (dump_flags & TDF_DETAILS)) { - fprintf (dump_file, "\nVisiting statement: "); - print_generic_stmt (dump_file, stmt, TDF_SLIM); - fprintf (dump_file, "\n"); - } - - ann = stmt_ann (stmt); - - /* If this statement is already in the worklist then "cancel" it. The - reevaluation implied by the worklist entry will produce the same - value we generate here and thus reevaluating it again from the - worklist is pointless. */ - if (ann->in_ccp_worklist) - ann->in_ccp_worklist = 0; - - /* Now examine the statement. If the statement is an assignment that - produces a single output value, evaluate its RHS to see if the lattice - value of its output has changed. */ - if (TREE_CODE (stmt) == MODIFY_EXPR - && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME) - visit_assignment (stmt); - - /* Definitions made by statements other than assignments to SSA_NAMEs - represent unknown modifications to their outputs. Mark them VARYING. */ - else if (NUM_DEFS (defs = DEF_OPS (ann)) != 0) - { - DONT_SIMULATE_AGAIN (stmt) = 1; - for (i = 0; i < NUM_DEFS (defs); i++) - { - tree def = DEF_OP (defs, i); - def_to_varying (def); - } + fprintf (dump_file, "\nVisiting PHI node: "); + print_generic_expr (dump_file, phi, dump_flags); } - /* If STMT is a conditional branch, see if we can determine which branch - will be taken. */ - else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) - visit_cond_stmt (stmt); - - /* Any other kind of statement is not interesting for constant - propagation and, therefore, not worth simulating. */ - else + old_val = get_value (PHI_RESULT (phi)); + switch (old_val->lattice_val) { - DONT_SIMULATE_AGAIN (stmt) = 1; - - /* If STMT is a computed goto, then mark all the output edges - executable. */ - if (computed_goto_p (stmt)) - add_outgoing_control_edges (bb_for_stmt (stmt)); - } - - /* Mark all V_MAY_DEF operands VARYING. */ - v_may_defs = V_MAY_DEF_OPS (ann); - for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++) - def_to_varying (V_MAY_DEF_RESULT (v_may_defs, i)); - - /* Mark all V_MUST_DEF operands VARYING. */ - v_must_defs = V_MUST_DEF_OPS (ann); - for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++) - def_to_varying (V_MUST_DEF_OP (v_must_defs, i)); -} - + case VARYING: + return SSA_PROP_NOT_INTERESTING; -/* Visit the assignment statement STMT. Set the value of its LHS to the - value computed by the RHS. */ + case CONSTANT: + new_val = *old_val; + break; -static void -visit_assignment (tree stmt) -{ - value val; - tree lhs, rhs; + case UNKNOWN_VAL: + /* To avoid the default value of UNKNOWN_VAL overriding + that of its possible constant arguments, temporarily + set the PHI node's default lattice value to be + UNDEFINED. If the PHI node's old value was UNKNOWN_VAL and + the new value is UNDEFINED, then we prevent the invalid + transition by not calling set_lattice_value. */ + new_val.lattice_val = UNDEFINED; + new_val.const_val = NULL_TREE; + break; - lhs = TREE_OPERAND (stmt, 0); - rhs = TREE_OPERAND (stmt, 1); + case UNDEFINED: + case UNINITIALIZED: + new_val.lattice_val = UNDEFINED; + new_val.const_val = NULL_TREE; + break; - if (TREE_THIS_VOLATILE (SSA_NAME_VAR (lhs))) - { - /* Volatile variables are always VARYING. */ - val.lattice_val = VARYING; - val.const_val = NULL_TREE; - } - else if (TREE_CODE (rhs) == SSA_NAME) - { - /* For a simple copy operation, we copy the lattice values. */ - value *nval = get_value (rhs); - val = *nval; - } - else - { - /* Evaluate the statement. */ - val = evaluate_stmt (stmt); + default: + gcc_unreachable (); } - /* FIXME: Hack. If this was a definition of a bitfield, we need to widen - the constant value into the type of the destination variable. This - should not be necessary if GCC represented bitfields properly. */ - { - tree lhs = TREE_OPERAND (stmt, 0); - if (val.lattice_val == CONSTANT - && TREE_CODE (lhs) == COMPONENT_REF - && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1))) - { - tree w = widen_bitfield (val.const_val, TREE_OPERAND (lhs, 1), lhs); - - if (w && is_gimple_min_invariant (w)) - val.const_val = w; - else - { - val.lattice_val = VARYING; - val.const_val = NULL; - } - } - } - - /* Set the lattice value of the statement's output. */ - set_lattice_value (lhs, val); - if (val.lattice_val == VARYING) - DONT_SIMULATE_AGAIN (stmt) = 1; -} - - -/* Visit the conditional statement STMT. If it evaluates to a constant value, - mark outgoing edges appropriately. */ - -static void -visit_cond_stmt (tree stmt) -{ - edge e; - value val; - basic_block block; - - block = bb_for_stmt (stmt); - val = evaluate_stmt (stmt); - - /* Find which edge out of the conditional block will be taken and add it - to the worklist. If no single edge can be determined statically, add - all outgoing edges from BLOCK. */ - e = find_taken_edge (block, val.const_val); - if (e) - add_control_edge (e); - else + for (i = 0; i < PHI_NUM_ARGS (phi); i++) { - DONT_SIMULATE_AGAIN (stmt) = 1; - add_outgoing_control_edges (block); - } -} - + /* Compute the meet operator over all the PHI arguments. */ + edge e = PHI_ARG_EDGE (phi, i); -/* Add all the edges coming out of BB to the control flow worklist. */ - -static void -add_outgoing_control_edges (basic_block bb) -{ - edge e; - - for (e = bb->succ; e; e = e->succ_next) - add_control_edge (e); -} + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, + "\n Argument #%d (%d -> %d %sexecutable)\n", + i, e->src->index, e->dest->index, + (e->flags & EDGE_EXECUTABLE) ? "" : "not "); + } + /* If the incoming edge is executable, Compute the meet operator for + the existing value of the PHI node and the current PHI argument. */ + if (e->flags & EDGE_EXECUTABLE) + { + tree rdef = PHI_ARG_DEF (phi, i); + value *rdef_val, val; -/* Add edge E to the control flow worklist. */ + if (is_gimple_min_invariant (rdef)) + { + val.lattice_val = CONSTANT; + val.const_val = rdef; + rdef_val = &val; + } + else + rdef_val = get_value (rdef); -static void -add_control_edge (edge e) -{ - basic_block bb = e->dest; - if (bb == EXIT_BLOCK_PTR) - return; + new_val = ccp_lattice_meet (new_val, *rdef_val); - /* If the edge had already been executed, skip it. */ - if (e->flags & EDGE_EXECUTABLE) - return; + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "\t"); + print_generic_expr (dump_file, rdef, dump_flags); + dump_lattice_value (dump_file, "\tValue: ", *rdef_val); + fprintf (dump_file, "\n"); + } - e->flags |= EDGE_EXECUTABLE; + if (new_val.lattice_val == VARYING) + break; + } + } - /* If the block is already in the list, we're done. */ - if (TEST_BIT (bb_in_list, bb->index)) - return; + if (dump_file && (dump_flags & TDF_DETAILS)) + { + dump_lattice_value (dump_file, "\n PHI node value: ", new_val); + fprintf (dump_file, "\n\n"); + } - cfg_blocks_add (bb); + /* Check for an invalid change from UNKNOWN_VAL to UNDEFINED. */ + if (old_val->lattice_val == UNKNOWN_VAL + && new_val.lattice_val == UNDEFINED) + return SSA_PROP_NOT_INTERESTING; - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, "Adding Destination of edge (%d -> %d) to worklist\n\n", - e->src->index, e->dest->index); + /* Otherwise, make the transition to the new value. */ + if (set_lattice_value (PHI_RESULT (phi), new_val)) + { + if (new_val.lattice_val == VARYING) + return SSA_PROP_VARYING; + else + return SSA_PROP_INTERESTING; + } + else + return SSA_PROP_NOT_INTERESTING; } -/* CCP specific front-end to the non-destructive constant folding routines. +/* CCP specific front-end to the non-destructive constant folding + routines. Attempt to simplify the RHS of STMT knowing that one or more operands are constants. @@ -825,18 +818,25 @@ ccp_fold (tree stmt) { tree rhs = get_rhs (stmt); enum tree_code code = TREE_CODE (rhs); - int kind = TREE_CODE_CLASS (code); + enum tree_code_class kind = TREE_CODE_CLASS (code); tree retval = NULL_TREE; + vuse_optype vuses; + + vuses = STMT_VUSE_OPS (stmt); /* If the RHS is just a variable, then that variable must now have a constant value that we can return directly. */ if (TREE_CODE (rhs) == SSA_NAME) return get_value (rhs)->const_val; + else if (DECL_P (rhs) + && NUM_VUSES (vuses) == 1 + && rhs == SSA_NAME_VAR (VUSE_OP (vuses, 0))) + return get_value (VUSE_OP (vuses, 0))->const_val; /* Unary operators. Note that we know the single operand must be a constant. So this should almost always return a simplified RHS. */ - if (kind == '1') + if (kind == tcc_unary) { /* Handle unary operators which can appear in GIMPLE form. */ tree op0 = TREE_OPERAND (rhs, 0); @@ -849,9 +849,7 @@ ccp_fold (tree stmt) op0 = get_value (op0)->const_val; } - retval = nondestructive_fold_unary_to_constant (code, - TREE_TYPE (rhs), - op0); + retval = fold_unary_to_constant (code, TREE_TYPE (rhs), op0); /* If we folded, but did not create an invariant, then we can not use this expression. */ @@ -876,8 +874,8 @@ ccp_fold (tree stmt) /* Binary and comparison operators. We know one or both of the operands are constants. */ - else if (kind == '2' - || kind == '<' + else if (kind == tcc_binary + || kind == tcc_comparison || code == TRUTH_AND_EXPR || code == TRUTH_OR_EXPR || code == TRUTH_XOR_EXPR) @@ -902,9 +900,7 @@ ccp_fold (tree stmt) op1 = val->const_val; } - retval = nondestructive_fold_binary_to_constant (code, - TREE_TYPE (rhs), - op0, op1); + retval = fold_binary_to_constant (code, TREE_TYPE (rhs), op0, op1); /* If we folded, but did not create an invariant, then we can not use this expression. */ @@ -1001,9 +997,12 @@ evaluate_stmt (tree stmt) else { /* The statement produced a nonconstant value. If the statement - had undefined operands, then the result of the statement should - be undefined. Else the result of the statement is VARYING. */ + had undefined or virtual operands, then the result of the + statement should be undefined or virtual respectively. + Else the result of the statement is VARYING. */ val.lattice_val = (likelyvalue == UNDEFINED ? UNDEFINED : VARYING); + val.lattice_val = (likelyvalue == UNKNOWN_VAL + ? UNKNOWN_VAL : val.lattice_val); val.const_val = NULL_TREE; } @@ -1011,483 +1010,301 @@ evaluate_stmt (tree stmt) } -/* Debugging dumps. */ - -static void -dump_lattice_value (FILE *outf, const char *prefix, value val) -{ - switch (val.lattice_val) - { - case UNDEFINED: - fprintf (outf, "%sUNDEFINED", prefix); - break; - case VARYING: - fprintf (outf, "%sVARYING", prefix); - break; - case CONSTANT: - fprintf (outf, "%sCONSTANT ", prefix); - print_generic_expr (outf, val.const_val, dump_flags); - break; - default: - abort (); - } -} - -/* Given a constant value VAL for bitfield FIELD, and a destination - variable VAR, return VAL appropriately widened to fit into VAR. If - FIELD is wider than HOST_WIDE_INT, NULL is returned. */ - -tree -widen_bitfield (tree val, tree field, tree var) -{ - unsigned HOST_WIDE_INT var_size, field_size; - tree wide_val; - unsigned HOST_WIDE_INT mask; - unsigned int i; - - /* We can only do this if the size of the type and field and VAL are - all constants representable in HOST_WIDE_INT. */ - if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1) - || !host_integerp (DECL_SIZE (field), 1) - || !host_integerp (val, 0)) - return NULL_TREE; - - var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1); - field_size = tree_low_cst (DECL_SIZE (field), 1); - - /* Give up if either the bitfield or the variable are too wide. */ - if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT) - return NULL_TREE; - -#if defined ENABLE_CHECKING - if (var_size < field_size) - abort (); -#endif - - /* If the sign bit of the value is not set or the field's type is unsigned, - just mask off the high order bits of the value. */ - if (DECL_UNSIGNED (field) - || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1)))) - { - /* Zero extension. Build a mask with the lower 'field_size' bits - set and a BIT_AND_EXPR node to clear the high order bits of - the value. */ - for (i = 0, mask = 0; i < field_size; i++) - mask |= ((HOST_WIDE_INT) 1) << i; - - wide_val = build (BIT_AND_EXPR, TREE_TYPE (var), val, - fold_convert (TREE_TYPE (var), build_int_2 (mask, 0))); - } - else - { - /* Sign extension. Create a mask with the upper 'field_size' - bits set and a BIT_IOR_EXPR to set the high order bits of the - value. */ - for (i = 0, mask = 0; i < (var_size - field_size); i++) - mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1); - - wide_val = build (BIT_IOR_EXPR, TREE_TYPE (var), val, - fold_convert (TREE_TYPE (var), build_int_2 (mask, 0))); - } - - return fold (wide_val); -} - - -/* Function indicating whether we ought to include information for 'var' - when calculating immediate uses. */ - -static bool -need_imm_uses_for (tree var) -{ - return get_value (var)->lattice_val != VARYING; -} - - -/* Initialize local data structures and worklists for CCP. */ +/* Visit the assignment statement STMT. Set the value of its LHS to the + value computed by the RHS and store LHS in *OUTPUT_P. */ -static void -initialize (void) +static enum ssa_prop_result +visit_assignment (tree stmt, tree *output_p) { - edge e; - basic_block bb; - sbitmap virtual_var; - - /* Worklists of SSA edges. */ - VARRAY_TREE_INIT (ssa_edges, 20, "ssa_edges"); - VARRAY_TREE_INIT (varying_ssa_edges, 20, "varying_ssa_edges"); - - executable_blocks = sbitmap_alloc (last_basic_block); - sbitmap_zero (executable_blocks); - - bb_in_list = sbitmap_alloc (last_basic_block); - sbitmap_zero (bb_in_list); + value val; + tree lhs, rhs; + vuse_optype vuses; + v_must_def_optype v_must_defs; - value_vector = (value *) xmalloc (num_ssa_names * sizeof (value)); - memset (value_vector, 0, num_ssa_names * sizeof (value)); + lhs = TREE_OPERAND (stmt, 0); + rhs = TREE_OPERAND (stmt, 1); + vuses = STMT_VUSE_OPS (stmt); + v_must_defs = STMT_V_MUST_DEF_OPS (stmt); - /* 1 if ssa variable is used in a virtual variable context. */ - virtual_var = sbitmap_alloc (num_ssa_names); - sbitmap_zero (virtual_var); + gcc_assert (NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt)) == 0); + gcc_assert (NUM_V_MUST_DEFS (v_must_defs) == 1 + || TREE_CODE (lhs) == SSA_NAME); - /* Initialize default values and simulation flags for PHI nodes, statements - and edges. */ - FOR_EACH_BB (bb) + /* We require the SSA version number of the lhs for the value_vector. + Make sure we have it. */ + if (TREE_CODE (lhs) != SSA_NAME) { - block_stmt_iterator i; - tree stmt; - stmt_ann_t ann; - def_optype defs; - v_may_def_optype v_may_defs; - v_must_def_optype v_must_defs; - size_t x; - int vary; - - /* Get the default value for each definition. */ - for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) - { - vary = 0; - stmt = bsi_stmt (i); - get_stmt_operands (stmt); - ann = stmt_ann (stmt); - defs = DEF_OPS (ann); - for (x = 0; x < NUM_DEFS (defs); x++) - { - tree def = DEF_OP (defs, x); - if (get_value (def)->lattice_val == VARYING) - vary = 1; - } - DONT_SIMULATE_AGAIN (stmt) = vary; - - /* Mark all V_MAY_DEF operands VARYING. */ - v_may_defs = V_MAY_DEF_OPS (ann); - for (x = 0; x < NUM_V_MAY_DEFS (v_may_defs); x++) - { - tree res = V_MAY_DEF_RESULT (v_may_defs, x); - get_value (res)->lattice_val = VARYING; - SET_BIT (virtual_var, SSA_NAME_VERSION (res)); - } - - /* Mark all V_MUST_DEF operands VARYING. */ - v_must_defs = V_MUST_DEF_OPS (ann); - for (x = 0; x < NUM_V_MUST_DEFS (v_must_defs); x++) - { - tree v_must_def = V_MUST_DEF_OP (v_must_defs, x); - get_value (v_must_def)->lattice_val = VARYING; - SET_BIT (virtual_var, SSA_NAME_VERSION (v_must_def)); - } - } - - for (e = bb->succ; e; e = e->succ_next) - e->flags &= ~EDGE_EXECUTABLE; + /* If we make it here, then stmt only has one definition: + a V_MUST_DEF. */ + lhs = V_MUST_DEF_RESULT (v_must_defs, 0); } - /* Now process PHI nodes. */ - FOR_EACH_BB (bb) + if (TREE_CODE (rhs) == SSA_NAME) { - tree phi, var; - int x; - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - { - value *val; - val = get_value (PHI_RESULT (phi)); - if (val->lattice_val != VARYING) - { - for (x = 0; x < PHI_NUM_ARGS (phi); x++) - { - var = PHI_ARG_DEF (phi, x); - /* If one argument is virtual, the result is virtual, and - therefore varying. */ - if (TREE_CODE (var) == SSA_NAME) - { - if (TEST_BIT (virtual_var, SSA_NAME_VERSION (var))) - { - val->lattice_val = VARYING; - SET_BIT (virtual_var, - SSA_NAME_VERSION (PHI_RESULT (phi))); - break; - } - } - } - } - DONT_SIMULATE_AGAIN (phi) = ((val->lattice_val == VARYING) ? 1 : 0); - } + /* For a simple copy operation, we copy the lattice values. */ + value *nval = get_value (rhs); + val = *nval; } - - sbitmap_free (virtual_var); - /* Compute immediate uses for variables we care about. */ - compute_immediate_uses (TDFA_USE_OPS, need_imm_uses_for); - - if (dump_file && (dump_flags & TDF_DETAILS)) - dump_immediate_uses (dump_file); - - VARRAY_BB_INIT (cfg_blocks, 20, "cfg_blocks"); - - /* Seed the algorithm by adding the successors of the entry block to the - edge worklist. */ - for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) + else if (DECL_P (rhs) + && NUM_VUSES (vuses) == 1 + && rhs == SSA_NAME_VAR (VUSE_OP (vuses, 0))) { - if (e->dest != EXIT_BLOCK_PTR) - { - e->flags |= EDGE_EXECUTABLE; - cfg_blocks_add (e->dest); - } + /* Same as above, but the rhs is not a gimple register and yet + has a known VUSE. */ + value *nval = get_value (VUSE_OP (vuses, 0)); + val = *nval; } -} - - -/* Free allocated storage. */ - -static void -finalize (void) -{ - ssa_edges = NULL; - varying_ssa_edges = NULL; - cfg_blocks = NULL; - free (value_vector); - sbitmap_free (bb_in_list); - sbitmap_free (executable_blocks); - free_df (); -} - -/* Is the block worklist empty. */ - -static inline bool -cfg_blocks_empty_p (void) -{ - return (cfg_blocks_num == 0); -} - -/* Add a basic block to the worklist. */ + else + /* Evaluate the statement. */ + val = evaluate_stmt (stmt); -static void -cfg_blocks_add (basic_block bb) -{ - if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR) - return; + /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant + value to be a VIEW_CONVERT_EXPR of the old constant value. This is + valid because a VIEW_CONVERT_EXPR is valid everywhere an operand of + aggregate type is valid. - if (TEST_BIT (bb_in_list, bb->index)) - return; + ??? Also, if this was a definition of a bitfield, we need to widen + the constant value into the type of the destination variable. This + should not be necessary if GCC represented bitfields properly. */ + { + tree orig_lhs = TREE_OPERAND (stmt, 0); - if (cfg_blocks_empty_p ()) + if (TREE_CODE (orig_lhs) == VIEW_CONVERT_EXPR + && val.lattice_val == CONSTANT) { - cfg_blocks_tail = cfg_blocks_head = 0; - cfg_blocks_num = 1; + val.const_val = build1 (VIEW_CONVERT_EXPR, + TREE_TYPE (TREE_OPERAND (orig_lhs, 0)), + val.const_val); + orig_lhs = TREE_OPERAND (orig_lhs, 1); } - else + + if (val.lattice_val == CONSTANT + && TREE_CODE (orig_lhs) == COMPONENT_REF + && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs, 1))) { - cfg_blocks_num++; - if (cfg_blocks_num > VARRAY_SIZE (cfg_blocks)) + tree w = widen_bitfield (val.const_val, TREE_OPERAND (orig_lhs, 1), + orig_lhs); + + if (w && is_gimple_min_invariant (w)) + val.const_val = w; + else { - /* We have to grow the array now. Adjust to queue to occupy the - full space of the original array. */ - cfg_blocks_tail = VARRAY_SIZE (cfg_blocks); - cfg_blocks_head = 0; - VARRAY_GROW (cfg_blocks, 2 * VARRAY_SIZE (cfg_blocks)); + val.lattice_val = VARYING; + val.const_val = NULL; } - else - cfg_blocks_tail = (cfg_blocks_tail + 1) % VARRAY_SIZE (cfg_blocks); } - VARRAY_BB (cfg_blocks, cfg_blocks_tail) = bb; - SET_BIT (bb_in_list, bb->index); -} - -/* Remove a block from the worklist. */ - -static basic_block -cfg_blocks_get (void) -{ - basic_block bb; - - bb = VARRAY_BB (cfg_blocks, cfg_blocks_head); - -#ifdef ENABLE_CHECKING - if (cfg_blocks_empty_p () || !bb) - abort (); -#endif - - cfg_blocks_head = (cfg_blocks_head + 1) % VARRAY_SIZE (cfg_blocks); - --cfg_blocks_num; - RESET_BIT (bb_in_list, bb->index); - - return bb; -} + } -/* We have just defined a new value for VAR. Add all immediate uses - of VAR to the ssa_edges or varying_ssa_edges worklist. */ -static void -add_var_to_ssa_edges_worklist (tree var, value val) -{ - tree stmt = SSA_NAME_DEF_STMT (var); - dataflow_t df = get_immediate_uses (stmt); - int num_uses = num_immediate_uses (df); - int i; + /* If LHS is not a gimple register, then it cannot take on an + UNDEFINED value. */ + if (!is_gimple_reg (SSA_NAME_VAR (lhs)) + && val.lattice_val == UNDEFINED) + val.lattice_val = UNKNOWN_VAL; - for (i = 0; i < num_uses; i++) + /* Set the lattice value of the statement's output. */ + if (set_lattice_value (lhs, val)) { - tree use = immediate_use (df, i); - - if (!DONT_SIMULATE_AGAIN (use)) - { - stmt_ann_t ann = stmt_ann (use); - if (ann->in_ccp_worklist == 0) - { - ann->in_ccp_worklist = 1; - if (val.lattice_val == VARYING) - VARRAY_PUSH_TREE (varying_ssa_edges, use); - else - VARRAY_PUSH_TREE (ssa_edges, use); - } - } + *output_p = lhs; + if (val.lattice_val == VARYING) + return SSA_PROP_VARYING; + else + return SSA_PROP_INTERESTING; } + else + return SSA_PROP_NOT_INTERESTING; } -/* Set the lattice value for the variable VAR to VARYING. */ -static void -def_to_varying (tree var) +/* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING + if it can determine which edge will be taken. Otherwise, return + SSA_PROP_VARYING. */ + +static enum ssa_prop_result +visit_cond_stmt (tree stmt, edge *taken_edge_p) { value val; - val.lattice_val = VARYING; - val.const_val = NULL_TREE; - set_lattice_value (var, val); -} + basic_block block; -/* Set the lattice value for variable VAR to VAL. */ + block = bb_for_stmt (stmt); + val = evaluate_stmt (stmt); -static void -set_lattice_value (tree var, value val) -{ - value *old = get_value (var); + /* Find which edge out of the conditional block will be taken and add it + to the worklist. If no single edge can be determined statically, + return SSA_PROP_VARYING to feed all the outgoing edges to the + propagation engine. */ + *taken_edge_p = val.const_val ? find_taken_edge (block, val.const_val) : 0; + if (*taken_edge_p) + return SSA_PROP_INTERESTING; + else + return SSA_PROP_VARYING; +} -#ifdef ENABLE_CHECKING - if (val.lattice_val == UNDEFINED) - { - /* CONSTANT->UNDEFINED is never a valid state transition. */ - if (old->lattice_val == CONSTANT) - abort (); - /* VARYING->UNDEFINED is generally not a valid state transition, - except for values which are initialized to VARYING. */ - if (old->lattice_val == VARYING - && get_default_value (var).lattice_val != VARYING) - abort (); - } - else if (val.lattice_val == CONSTANT) - { - /* VARYING -> CONSTANT is an invalid state transition, except - for objects which start off in a VARYING state. */ - if (old->lattice_val == VARYING - && get_default_value (var).lattice_val != VARYING) - abort (); - } -#endif +/* Evaluate statement STMT. If the statement produces an output value and + its evaluation changes the lattice value of its output, return + SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the + output value. + + If STMT is a conditional branch and we can determine its truth + value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying + value, return SSA_PROP_VARYING. */ - /* If the constant for VAR has changed, then this VAR is really varying. */ - if (old->lattice_val == CONSTANT && val.lattice_val == CONSTANT - && !simple_cst_equal (old->const_val, val.const_val)) +static enum ssa_prop_result +ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) +{ + stmt_ann_t ann; + v_may_def_optype v_may_defs; + v_must_def_optype v_must_defs; + tree def; + ssa_op_iter iter; + + if (dump_file && (dump_flags & TDF_DETAILS)) { - val.lattice_val = VARYING; - val.const_val = NULL_TREE; + fprintf (dump_file, "\nVisiting statement: "); + print_generic_stmt (dump_file, stmt, TDF_SLIM); + fprintf (dump_file, "\n"); } - if (old->lattice_val != val.lattice_val) - { - if (dump_file && (dump_flags & TDF_DETAILS)) - { - dump_lattice_value (dump_file, - "Lattice value changed to ", val); - fprintf (dump_file, ". Adding definition to SSA edges.\n"); - } + ann = stmt_ann (stmt); - add_var_to_ssa_edges_worklist (var, val); - *old = val; + v_must_defs = V_MUST_DEF_OPS (ann); + v_may_defs = V_MAY_DEF_OPS (ann); + if (TREE_CODE (stmt) == MODIFY_EXPR + && NUM_V_MAY_DEFS (v_may_defs) == 0 + && (NUM_V_MUST_DEFS (v_must_defs) == 1 + || TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME)) + { + /* If the statement is an assignment that produces a single + output value, evaluate its RHS to see if the lattice value of + its output has changed. */ + return visit_assignment (stmt, output_p); + } + else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) + { + /* If STMT is a conditional branch, see if we can determine + which branch will be taken. */ + return visit_cond_stmt (stmt, taken_edge_p); } -} -/* Replace USE references in statement STMT with their immediate reaching - definition. Return true if at least one reference was replaced. If - REPLACED_ADDRESSES_P is given, it will be set to true if an address - constant was replaced. */ + /* Any other kind of statement is not interesting for constant + propagation and, therefore, not worth simulating. */ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); -static bool -replace_uses_in (tree stmt, bool *replaced_addresses_p) -{ - bool replaced = false; - use_optype uses; - size_t i; + /* Definitions made by statements other than assignments to + SSA_NAMEs represent unknown modifications to their outputs. + Mark them VARYING. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) + def_to_varying (def); - if (replaced_addresses_p) - *replaced_addresses_p = false; + /* Mark all V_MAY_DEF operands VARYING. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_VMAYDEF) + def_to_varying (def); - get_stmt_operands (stmt); + return SSA_PROP_VARYING; +} - uses = STMT_USE_OPS (stmt); - for (i = 0; i < NUM_USES (uses); i++) - { - use_operand_p use = USE_OP_PTR (uses, i); - value *val = get_value (USE_FROM_PTR (use)); - if (val->lattice_val == CONSTANT) - { - SET_USE (use, val->const_val); - replaced = true; - if (POINTER_TYPE_P (TREE_TYPE (USE_FROM_PTR (use))) - && replaced_addresses_p) - *replaced_addresses_p = true; - } - } +/* Main entry point for SSA Conditional Constant Propagation. - return replaced; + [ DESCRIBE MAIN ALGORITHM HERE ] */ + +static void +execute_ssa_ccp (void) +{ + ccp_initialize (); + ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); + ccp_finalize (); } -/* Return the likely latticevalue for STMT. - If STMT has no operands, then return CONSTANT. +static bool +gate_ccp (void) +{ + return flag_tree_ccp != 0; +} - Else if any operands of STMT are undefined, then return UNDEFINED. - Else if any operands of STMT are constants, then return CONSTANT. +struct tree_opt_pass pass_ccp = +{ + "ccp", /* name */ + gate_ccp, /* gate */ + execute_ssa_ccp, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_TREE_CCP, /* tv_id */ + PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_cleanup_cfg | TODO_dump_func | TODO_rename_vars + | TODO_ggc_collect | TODO_verify_ssa + | TODO_verify_stmts, /* todo_flags_finish */ + 0 /* letter */ +}; - Else return VARYING. */ -static latticevalue -likely_value (tree stmt) +/* Given a constant value VAL for bitfield FIELD, and a destination + variable VAR, return VAL appropriately widened to fit into VAR. If + FIELD is wider than HOST_WIDE_INT, NULL is returned. */ + +tree +widen_bitfield (tree val, tree field, tree var) { - use_optype uses; - size_t i; - int found_constant = 0; - stmt_ann_t ann; + unsigned HOST_WIDE_INT var_size, field_size; + tree wide_val; + unsigned HOST_WIDE_INT mask; + unsigned int i; - /* If the statement makes aliased loads or has volatile operands, it - won't fold to a constant value. */ - ann = stmt_ann (stmt); - if (ann->makes_aliased_loads || ann->has_volatile_ops) - return VARYING; + /* We can only do this if the size of the type and field and VAL are + all constants representable in HOST_WIDE_INT. */ + if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1) + || !host_integerp (DECL_SIZE (field), 1) + || !host_integerp (val, 0)) + return NULL_TREE; - /* A CALL_EXPR is assumed to be varying. This may be overly conservative, - in the presence of const and pure calls. */ - if (get_call_expr_in (stmt) != NULL_TREE) - return VARYING; + var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1); + field_size = tree_low_cst (DECL_SIZE (field), 1); - get_stmt_operands (stmt); + /* Give up if either the bitfield or the variable are too wide. */ + if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT) + return NULL_TREE; + + gcc_assert (var_size >= field_size); - uses = USE_OPS (ann); - for (i = 0; i < NUM_USES (uses); i++) + /* If the sign bit of the value is not set or the field's type is unsigned, + just mask off the high order bits of the value. */ + if (DECL_UNSIGNED (field) + || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1)))) { - tree use = USE_OP (uses, i); - value *val = get_value (use); + /* Zero extension. Build a mask with the lower 'field_size' bits + set and a BIT_AND_EXPR node to clear the high order bits of + the value. */ + for (i = 0, mask = 0; i < field_size; i++) + mask |= ((HOST_WIDE_INT) 1) << i; - if (val->lattice_val == UNDEFINED) - return UNDEFINED; + wide_val = build (BIT_AND_EXPR, TREE_TYPE (var), val, + fold_convert (TREE_TYPE (var), + build_int_cst (NULL_TREE, mask))); + } + else + { + /* Sign extension. Create a mask with the upper 'field_size' + bits set and a BIT_IOR_EXPR to set the high order bits of the + value. */ + for (i = 0, mask = 0; i < (var_size - field_size); i++) + mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1); - if (val->lattice_val == CONSTANT) - found_constant = 1; + wide_val = build (BIT_IOR_EXPR, TREE_TYPE (var), val, + fold_convert (TREE_TYPE (var), + build_int_cst (NULL_TREE, mask))); } - return ((found_constant || !uses) ? CONSTANT : VARYING); + return fold (wide_val); } + /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X]. BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE is the desired result type. */ @@ -1551,7 +1368,7 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) || lrem || hrem) return NULL_TREE; - idx = build_int_2_wide (lquo, hquo); + idx = build_int_cst_wide (NULL_TREE, lquo, hquo); } /* Assume the low bound is zero. If there is a domain type, get the @@ -1579,9 +1396,10 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) return build (ARRAY_REF, orig_type, base, idx, min_idx, size_int (tree_low_cst (elt_size, 1) - / (TYPE_ALIGN (elt_type) / BITS_PER_UNIT))); + / (TYPE_ALIGN_UNIT (elt_type)))); } + /* A subroutine of fold_stmt_r. Attempts to fold *(S+O) to S.X. BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE is the desired result type. */ @@ -1591,7 +1409,7 @@ static tree maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, tree orig_type, bool base_is_ptr) { - tree f, t, field_type, tail_array_field; + tree f, t, field_type, tail_array_field, field_offset; if (TREE_CODE (record_type) != RECORD_TYPE && TREE_CODE (record_type) != UNION_TYPE @@ -1611,7 +1429,9 @@ maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, continue; if (DECL_BIT_FIELD (f)) continue; - if (TREE_CODE (DECL_FIELD_OFFSET (f)) != INTEGER_CST) + + field_offset = byte_position (f); + if (TREE_CODE (field_offset) != INTEGER_CST) continue; /* ??? Java creates "interesting" fields for representing base classes. @@ -1624,7 +1444,7 @@ maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, tail_array_field = NULL_TREE; /* Check to see if this offset overlaps with the field. */ - cmp = tree_int_cst_compare (DECL_FIELD_OFFSET (f), offset); + cmp = tree_int_cst_compare (field_offset, offset); if (cmp > 0) continue; @@ -1691,6 +1511,7 @@ maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, orig_type, false); } + /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET). Return the simplified expression, or NULL if nothing could be done. */ @@ -1729,6 +1550,11 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) /* Strip the ADDR_EXPR. */ base = TREE_OPERAND (base, 0); + /* Fold away CONST_DECL to its value, if the type is scalar. */ + if (TREE_CODE (base) == CONST_DECL + && is_gimple_min_invariant (DECL_INITIAL (base))) + return DECL_INITIAL (base); + /* Try folding *(&B+O) to B[X]. */ t = maybe_fold_offset_to_array_ref (base, offset, TREE_TYPE (expr)); if (t) @@ -1787,6 +1613,7 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) return NULL_TREE; } + /* A subroutine of fold_stmt_r. EXPR is a PLUS_EXPR. A quaint feature extant in our address arithmetic is that there @@ -1904,6 +1731,7 @@ maybe_fold_stmt_addition (tree expr) return t; } + /* Subroutine of fold_stmt called via walk_tree. We perform several simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ @@ -1990,288 +1818,98 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) return NULL_TREE; } -/* Fold the statement pointed by STMT_P. In some cases, this function may - replace the whole statement with a new one. Returns true iff folding - makes any changes. */ - -bool -fold_stmt (tree *stmt_p) -{ - tree rhs, result, stmt; - bool changed = false; - - stmt = *stmt_p; - - /* If we replaced constants and the statement makes pointer dereferences, - then we may need to fold instances of *&VAR into VAR, etc. */ - if (walk_tree (stmt_p, fold_stmt_r, &changed, NULL)) - { - *stmt_p - = build_function_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], - NULL); - return true; - } - - rhs = get_rhs (stmt); - if (!rhs) - return changed; - result = NULL_TREE; - - if (TREE_CODE (rhs) == CALL_EXPR) - { - tree callee; - - /* Check for builtins that CCP can handle using information not - available in the generic fold routines. */ - callee = get_callee_fndecl (rhs); - if (callee && DECL_BUILT_IN (callee)) - result = ccp_fold_builtin (stmt, rhs); - else - { - /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve - here are when we've propagated the address of a decl into the - object slot. */ - /* ??? Should perhaps do this in fold proper. However, doing it - there requires that we create a new CALL_EXPR, and that requires - copying EH region info to the new node. Easier to just do it - here where we can just smash the call operand. */ - callee = TREE_OPERAND (rhs, 0); - if (TREE_CODE (callee) == OBJ_TYPE_REF - && lang_hooks.fold_obj_type_ref - && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR - && DECL_P (TREE_OPERAND (OBJ_TYPE_REF_OBJECT (callee), 0))) - { - tree t; - - /* ??? Caution: Broken ADDR_EXPR semantics means that - looking at the type of the operand of the addr_expr - can yield an array type. See silly exception in - check_pointer_types_r. */ - - t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); - t = lang_hooks.fold_obj_type_ref (callee, t); - if (t) - { - TREE_OPERAND (rhs, 0) = t; - changed = true; - } - } - } - } - - /* If we couldn't fold the RHS, hand over to the generic fold routines. */ - if (result == NULL_TREE) - result = fold (rhs); - - /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that - may have been added by fold, and "useless" type conversions that might - now be apparent due to propagation. */ - STRIP_USELESS_TYPE_CONVERSION (result); - - if (result != rhs) - changed |= set_rhs (stmt_p, result); - - return changed; -} - -/* Get the main expression from statement STMT. */ - -static tree -get_rhs (tree stmt) -{ - enum tree_code code = TREE_CODE (stmt); - - switch (code) - { - case RETURN_EXPR: - stmt = TREE_OPERAND (stmt, 0); - if (stmt) - return get_rhs (stmt); - else - return NULL; - - case MODIFY_EXPR: - return TREE_OPERAND (stmt, 1); - - case COND_EXPR: - return COND_EXPR_COND (stmt); - case SWITCH_EXPR: - return SWITCH_COND (stmt); - case GOTO_EXPR: - return GOTO_DESTINATION (stmt); - case LABEL_EXPR: - return LABEL_EXPR_LABEL (stmt); - - default: - return stmt; - } -} - -/* Set the main expression of *STMT_P to EXPR. */ +/* Return the string length of ARG in LENGTH. If ARG is an SSA name variable, + follow its use-def chains. If LENGTH is not NULL and its value is not + equal to the length we determine, or if we are unable to determine the + length, return false. VISITED is a bitmap of visited variables. */ static bool -set_rhs (tree *stmt_p, tree expr) +get_strlen (tree arg, tree *length, bitmap visited) { - tree stmt = *stmt_p, op; - enum tree_code code = TREE_CODE (expr); - stmt_ann_t ann; - - /* Verify the constant folded result is valid gimple. */ - if (TREE_CODE_CLASS (code) == '2') - { - if (!is_gimple_val (TREE_OPERAND (expr, 0)) - || !is_gimple_val (TREE_OPERAND (expr, 1))) - return false; - } - else if (TREE_CODE_CLASS (code) == '1') + tree var, def_stmt, val; + + if (TREE_CODE (arg) != SSA_NAME) { - if (!is_gimple_val (TREE_OPERAND (expr, 0))) + val = c_strlen (arg, 1); + if (!val) return false; - } - - switch (TREE_CODE (stmt)) - { - case RETURN_EXPR: - op = TREE_OPERAND (stmt, 0); - if (TREE_CODE (op) != MODIFY_EXPR) - { - TREE_OPERAND (stmt, 0) = expr; - break; - } - stmt = op; - /* FALLTHRU */ - - case MODIFY_EXPR: - TREE_OPERAND (stmt, 1) = expr; - break; - - case COND_EXPR: - COND_EXPR_COND (stmt) = expr; - break; - case SWITCH_EXPR: - SWITCH_COND (stmt) = expr; - break; - case GOTO_EXPR: - GOTO_DESTINATION (stmt) = expr; - break; - case LABEL_EXPR: - LABEL_EXPR_LABEL (stmt) = expr; - break; - - default: - /* Replace the whole statement with EXPR. If EXPR has no side - effects, then replace *STMT_P with an empty statement. */ - ann = stmt_ann (stmt); - *stmt_p = TREE_SIDE_EFFECTS (expr) ? expr : build_empty_stmt (); - (*stmt_p)->common.ann = (tree_ann_t) ann; - - if (TREE_SIDE_EFFECTS (expr)) - { - def_optype defs; - v_may_def_optype v_may_defs; - v_must_def_optype v_must_defs; - size_t i; - - /* Fix all the SSA_NAMEs created by *STMT_P to point to its new - replacement. */ - defs = DEF_OPS (ann); - for (i = 0; i < NUM_DEFS (defs); i++) - { - tree var = DEF_OP (defs, i); - if (TREE_CODE (var) == SSA_NAME) - SSA_NAME_DEF_STMT (var) = *stmt_p; - } - v_may_defs = V_MAY_DEF_OPS (ann); - for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++) - { - tree var = V_MAY_DEF_RESULT (v_may_defs, i); - if (TREE_CODE (var) == SSA_NAME) - SSA_NAME_DEF_STMT (var) = *stmt_p; - } - - v_must_defs = V_MUST_DEF_OPS (ann); - for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++) - { - tree var = V_MUST_DEF_OP (v_must_defs, i); - if (TREE_CODE (var) == SSA_NAME) - SSA_NAME_DEF_STMT (var) = *stmt_p; - } - } - break; + if (*length && simple_cst_equal (val, *length) != 1) + return false; + + *length = val; + return true; } - return true; -} + /* If we were already here, break the infinite cycle. */ + if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) + return true; + bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); + var = arg; + def_stmt = SSA_NAME_DEF_STMT (var); -/* Return a default value for variable VAR using the following rules: + switch (TREE_CODE (def_stmt)) + { + case MODIFY_EXPR: + { + tree len, rhs; + + /* The RHS of the statement defining VAR must either have a + constant length or come from another SSA_NAME with a constant + length. */ + rhs = TREE_OPERAND (def_stmt, 1); + STRIP_NOPS (rhs); + if (TREE_CODE (rhs) == SSA_NAME) + return get_strlen (rhs, length, visited); - 1- Global and static variables are considered VARYING, unless they are - declared const. + /* See if the RHS is a constant length. */ + len = c_strlen (rhs, 1); + if (len) + { + if (*length && simple_cst_equal (len, *length) != 1) + return false; - 2- Function arguments are considered VARYING. + *length = len; + return true; + } - 3- Any other value is considered UNDEFINED. This is useful when - considering PHI nodes. PHI arguments that are undefined do not - change the constant value of the PHI node, which allows for more - constants to be propagated. */ + break; + } -static value -get_default_value (tree var) -{ - value val; - tree sym; + case PHI_NODE: + { + /* All the arguments of the PHI node must have the same constant + length. */ + int i; - if (TREE_CODE (var) == SSA_NAME) - sym = SSA_NAME_VAR (var); - else - { -#ifdef ENABLE_CHECKING - if (!DECL_P (var)) - abort (); -#endif - sym = var; - } + for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++) + { + tree arg = PHI_ARG_DEF (def_stmt, i); - val.lattice_val = UNDEFINED; - val.const_val = NULL_TREE; + /* If this PHI has itself as an argument, we cannot + determine the string length of this argument. However, + if we can find a constant string length for the other + PHI args then we can still be sure that this is a + constant string length. So be optimistic and just + continue with the next argument. */ + if (arg == PHI_RESULT (def_stmt)) + continue; - if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym)) - { - /* Function arguments and volatile variables are considered VARYING. */ - val.lattice_val = VARYING; - } - else if (decl_function_context (sym) != current_function_decl - || TREE_STATIC (sym)) - { - /* Globals and static variables are considered VARYING, unless they - are declared 'const'. */ - val.lattice_val = VARYING; + if (!get_strlen (arg, length, visited)) + return false; + } - if (TREE_READONLY (sym) - && DECL_INITIAL (sym) - && is_gimple_min_invariant (DECL_INITIAL (sym))) - { - val.lattice_val = CONSTANT; - val.const_val = DECL_INITIAL (sym); + return true; } - } - else - { - enum tree_code code; - tree stmt = SSA_NAME_DEF_STMT (var); - if (!IS_EMPTY_STMT (stmt)) - { - code = TREE_CODE (stmt); - if (code != MODIFY_EXPR && code != PHI_NODE) - val.lattice_val = VARYING; - } + default: + break; } - return val; + + return false; } @@ -2382,7 +2020,7 @@ ccp_fold_builtin (tree stmt, tree fn) break; default: - abort (); + gcc_unreachable (); } if (result && ignore) @@ -2391,106 +2029,130 @@ ccp_fold_builtin (tree stmt, tree fn) } -/* Return the string length of ARG in LENGTH. If ARG is an SSA name variable, - follow its use-def chains. If LENGTH is not NULL and its value is not - equal to the length we determine, or if we are unable to determine the - length, return false. VISITED is a bitmap of visited variables. */ +/* Fold the statement pointed by STMT_P. In some cases, this function may + replace the whole statement with a new one. Returns true iff folding + makes any changes. */ -static bool -get_strlen (tree arg, tree *length, bitmap visited) +bool +fold_stmt (tree *stmt_p) { - tree var, def_stmt, val; - - if (TREE_CODE (arg) != SSA_NAME) - { - val = c_strlen (arg, 1); - if (!val) - return false; + tree rhs, result, stmt; + bool changed = false; - if (*length && simple_cst_equal (val, *length) != 1) - return false; + stmt = *stmt_p; - *length = val; + /* If we replaced constants and the statement makes pointer dereferences, + then we may need to fold instances of *&VAR into VAR, etc. */ + if (walk_tree (stmt_p, fold_stmt_r, &changed, NULL)) + { + *stmt_p + = build_function_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], + NULL); return true; } - /* If we were already here, break the infinite cycle. */ - if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) - return true; - bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); - - var = arg; - def_stmt = SSA_NAME_DEF_STMT (var); + rhs = get_rhs (stmt); + if (!rhs) + return changed; + result = NULL_TREE; - switch (TREE_CODE (def_stmt)) + if (TREE_CODE (rhs) == CALL_EXPR) { - case MODIFY_EXPR: - { - tree len, rhs; - - /* The RHS of the statement defining VAR must either have a - constant length or come from another SSA_NAME with a constant - length. */ - rhs = TREE_OPERAND (def_stmt, 1); - STRIP_NOPS (rhs); - if (TREE_CODE (rhs) == SSA_NAME) - return get_strlen (rhs, length, visited); + tree callee; - /* See if the RHS is a constant length. */ - len = c_strlen (rhs, 1); - if (len) + /* Check for builtins that CCP can handle using information not + available in the generic fold routines. */ + callee = get_callee_fndecl (rhs); + if (callee && DECL_BUILT_IN (callee)) + result = ccp_fold_builtin (stmt, rhs); + else + { + /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve + here are when we've propagated the address of a decl into the + object slot. */ + /* ??? Should perhaps do this in fold proper. However, doing it + there requires that we create a new CALL_EXPR, and that requires + copying EH region info to the new node. Easier to just do it + here where we can just smash the call operand. */ + callee = TREE_OPERAND (rhs, 0); + if (TREE_CODE (callee) == OBJ_TYPE_REF + && lang_hooks.fold_obj_type_ref + && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR + && DECL_P (TREE_OPERAND + (OBJ_TYPE_REF_OBJECT (callee), 0))) { - if (*length && simple_cst_equal (len, *length) != 1) - return false; + tree t; - *length = len; - return true; - } + /* ??? Caution: Broken ADDR_EXPR semantics means that + looking at the type of the operand of the addr_expr + can yield an array type. See silly exception in + check_pointer_types_r. */ - break; + t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); + t = lang_hooks.fold_obj_type_ref (callee, t); + if (t) + { + TREE_OPERAND (rhs, 0) = t; + changed = true; + } + } } + } - case PHI_NODE: - { - /* All the arguments of the PHI node must have the same constant - length. */ - int i; + /* If we couldn't fold the RHS, hand over to the generic fold routines. */ + if (result == NULL_TREE) + result = fold (rhs); - for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++) - { - tree arg = PHI_ARG_DEF (def_stmt, i); + /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that + may have been added by fold, and "useless" type conversions that might + now be apparent due to propagation. */ + STRIP_USELESS_TYPE_CONVERSION (result); - /* If this PHI has itself as an argument, we cannot - determine the string length of this argument. However, - if we can find a constant string length for the other - PHI args then we can still be sure that this is a - constant string length. So be optimistic and just - continue with the next argument. */ - if (arg == PHI_RESULT (def_stmt)) - continue; + if (result != rhs) + changed |= set_rhs (stmt_p, result); - if (!get_strlen (arg, length, visited)) - return false; - } + return changed; +} - return true; - } + +/* Convert EXPR into a GIMPLE value suitable for substitution on the + RHS of an assignment. Insert the necessary statements before + iterator *SI_P. */ - default: - break; +static tree +convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr) +{ + tree_stmt_iterator ti; + tree stmt = bsi_stmt (*si_p); + tree tmp, stmts = NULL; + + push_gimplify_context (); + tmp = get_initialized_tmp_var (expr, &stmts, NULL); + pop_gimplify_context (NULL); + + /* The replacement can expose previously unreferenced variables. */ + for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti)) + { + find_new_referenced_vars (tsi_stmt_ptr (ti)); + mark_new_vars_to_rename (tsi_stmt (ti), vars_to_rename); } + if (EXPR_HAS_LOCATION (stmt)) + annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt)); - return false; + bsi_insert_before (si_p, stmts, BSI_SAME_STMT); + + return tmp; } - + /* A simple pass that attempts to fold all builtin functions. This pass is run after we've propagated as many constants as we can. */ static void execute_fold_all_builtins (void) { + bool cfg_changed = false; basic_block bb; FOR_EACH_BB (bb) { @@ -2528,8 +2190,16 @@ execute_fold_all_builtins (void) print_generic_stmt (dump_file, *stmtp, dump_flags); } - if (set_rhs (stmtp, result)) - modify_stmt (*stmtp); + if (!set_rhs (stmtp, result)) + { + result = convert_to_gimple_builtin (&i, result); + if (result && !set_rhs (stmtp, result)) + abort (); + } + modify_stmt (*stmtp); + if (maybe_clean_eh_stmt (*stmtp) + && tree_purge_dead_eh_edges (bb)) + cfg_changed = true; if (dump_file && (dump_flags & TDF_DETAILS)) { @@ -2539,8 +2209,13 @@ execute_fold_all_builtins (void) } } } + + /* Delete unreachable blocks. */ + if (cfg_changed) + cleanup_tree_cfg (); } + struct tree_opt_pass pass_fold_builtins = { "fab", /* name */ @@ -2550,12 +2225,12 @@ struct tree_opt_pass pass_fold_builtins = NULL, /* next */ 0, /* static_pass_number */ 0, /* tv_id */ - PROP_cfg | PROP_ssa, /* properties_required */ + PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ - TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */ + TODO_dump_func + | TODO_verify_ssa + | TODO_rename_vars, /* todo_flags_finish */ + 0 /* letter */ }; - - -#include "gt-tree-ssa-ccp.h"