X-Git-Url: http://git.sourceforge.jp/view?p=pf3gnuchains%2Fgcc-fork.git;a=blobdiff_plain;f=gcc%2Ftree-ssa-ccp.c;h=53050e68429ab9a75177e209feb5487a542c41cd;hp=12d5a61982dd755c3dfb09548d174f4c199c39a4;hb=52f788405a245e52f94b6b16af11fd2fd9321e87;hpb=27335ffdbd00a3c8db8200745a86a2930ff711e8 diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 12d5a61982d..53050e68429 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -1,5 +1,5 @@ /* Conditional constant propagation pass for the GNU compiler. - Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 + Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. Adapted from original RTL SSA-CCP by Daniel Berlin Adapted to GIMPLE trees by Diego Novillo @@ -18,10 +18,164 @@ for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free -Software Foundation, 59 Temple Place - Suite 330, Boston, MA -02111-1307, USA. */ +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +/* Conditional constant propagation (CCP) is based on the SSA + propagation engine (tree-ssa-propagate.c). Constant assignments of + the form VAR = CST are propagated from the assignments into uses of + VAR, which in turn may generate new constants. The simulation uses + a four level lattice to keep track of constant values associated + with SSA names. Given an SSA name V_i, it may take one of the + following values: + + UNINITIALIZED -> This is the default starting value. V_i + has not been processed yet. + + UNDEFINED -> V_i is a local variable whose definition + has not been processed yet. Therefore we + don't yet know if its value is a constant + or not. + + CONSTANT -> V_i has been found to hold a constant + value C. + + VARYING -> V_i cannot take a constant value, or if it + does, it is not possible to determine it + at compile time. + + The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node: + + 1- In ccp_visit_stmt, we are interested in assignments whose RHS + evaluates into a constant and conditional jumps whose predicate + evaluates into a boolean true or false. When an assignment of + the form V_i = CONST is found, V_i's lattice value is set to + CONSTANT and CONST is associated with it. This causes the + propagation engine to add all the SSA edges coming out the + assignment into the worklists, so that statements that use V_i + can be visited. + + If the statement is a conditional with a constant predicate, we + mark the outgoing edges as executable or not executable + depending on the predicate's value. This is then used when + visiting PHI nodes to know when a PHI argument can be ignored. + + + 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the + same constant C, then the LHS of the PHI is set to C. This + evaluation is known as the "meet operation". Since one of the + goals of this evaluation is to optimistically return constant + values as often as possible, it uses two main short cuts: + + - If an argument is flowing in through a non-executable edge, it + is ignored. This is useful in cases like this: + + if (PRED) + a_9 = 3; + else + a_10 = 100; + a_11 = PHI (a_9, a_10) + + If PRED is known to always evaluate to false, then we can + assume that a_11 will always take its value from a_10, meaning + that instead of consider it VARYING (a_9 and a_10 have + different values), we can consider it CONSTANT 100. + + - If an argument has an UNDEFINED value, then it does not affect + the outcome of the meet operation. If a variable V_i has an + UNDEFINED value, it means that either its defining statement + hasn't been visited yet or V_i has no defining statement, in + which case the original symbol 'V' is being used + uninitialized. Since 'V' is a local variable, the compiler + may assume any initial value for it. + + + After propagation, every variable V_i that ends up with a lattice + value of CONSTANT will have the associated constant value in the + array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for + final substitution and folding. + + + Constant propagation in stores and loads (STORE-CCP) + ---------------------------------------------------- + + While CCP has all the logic to propagate constants in GIMPLE + registers, it is missing the ability to associate constants with + stores and loads (i.e., pointer dereferences, structures and + global/aliased variables). We don't keep loads and stores in + SSA, but we do build a factored use-def web for them (in the + virtual operands). + + For instance, consider the following code fragment: + + struct A a; + const int B = 42; + + void foo (int i) + { + if (i > 10) + a.a = 42; + else + { + a.b = 21; + a.a = a.b + 21; + } + + if (a.a != B) + never_executed (); + } + + We should be able to deduce that the predicate 'a.a != B' is always + false. To achieve this, we associate constant values to the SSA + names in the V_MAY_DEF and V_MUST_DEF operands for each store. + Additionally, since we also glob partial loads/stores with the base + symbol, we also keep track of the memory reference where the + constant value was stored (in the MEM_REF field of PROP_VALUE_T). + For instance, + + # a_5 = V_MAY_DEF + a.a = 2; + + # VUSE + x_3 = a.b; + + In the example above, CCP will associate value '2' with 'a_5', but + it would be wrong to replace the load from 'a.b' with '2', because + '2' had been stored into a.a. + + To support STORE-CCP, it is necessary to add a new value to the + constant propagation lattice. When evaluating a load for a memory + reference we can no longer assume a value of UNDEFINED if we + haven't seen a preceding store to the same memory location. + Consider, for instance global variables: + + int A; + + foo (int i) + { + if (i_3 > 10) + A_4 = 3; + # A_5 = PHI (A_4, A_2); + + # VUSE + A.0_6 = A; + + return A.0_6; + } -/* Conditional constant propagation. + The value of A_2 cannot be assumed to be UNDEFINED, as it may have + been defined outside of foo. If we were to assume it UNDEFINED, we + would erroneously optimize the above into 'return 3;'. Therefore, + when doing STORE-CCP, we introduce a fifth lattice value + (UNKNOWN_VAL), which overrides any other value when computing the + meet operation in PHI nodes. + + Though STORE-CCP is not too expensive, it does have to do more work + than regular CCP, so it is only enabled at -O2. Both regular CCP + and STORE-CCP use the exact same algorithm. The only distinction + is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is + set to true. This affects the evaluation of statements and PHI + nodes. References: @@ -45,7 +199,6 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "ggc.h" #include "basic-block.h" #include "output.h" -#include "errors.h" #include "expr.h" #include "function.h" #include "diagnostic.h" @@ -55,6 +208,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "tree-pass.h" #include "tree-ssa-propagate.h" #include "langhooks.h" +#include "target.h" /* Possible lattice values. */ @@ -65,27 +219,29 @@ typedef enum UNKNOWN_VAL, CONSTANT, VARYING -} latticevalue; - -/* Main structure for CCP. Contains the lattice value and, if it's a - constant, the constant value. */ -typedef struct -{ - latticevalue lattice_val; - tree const_val; -} value; +} ccp_lattice_t; -/* This is used to track the current value of each variable. */ -static value *value_vector; +/* Array of propagated constant values. After propagation, + CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If + the constant is held in an SSA name representing a memory store + (i.e., a V_MAY_DEF or V_MUST_DEF), CONST_VAL[I].MEM_REF will + contain the actual memory reference used to store (i.e., the LHS of + the assignment doing the store). */ +static prop_value_t *const_val; +/* True if we are also propagating constants in stores and loads. */ +static bool do_store_ccp; -/* Dump lattice value VAL to file OUTF prefixed by PREFIX. */ +/* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ static void -dump_lattice_value (FILE *outf, const char *prefix, value val) +dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val) { switch (val.lattice_val) { + case UNINITIALIZED: + fprintf (outf, "%sUNINITIALIZED", prefix); + break; case UNDEFINED: fprintf (outf, "%sUNDEFINED", prefix); break; @@ -97,7 +253,7 @@ dump_lattice_value (FILE *outf, const char *prefix, value val) break; case CONSTANT: fprintf (outf, "%sCONSTANT ", prefix); - print_generic_expr (outf, val.const_val, dump_flags); + print_generic_expr (outf, val.value, dump_flags); break; default: gcc_unreachable (); @@ -105,169 +261,200 @@ dump_lattice_value (FILE *outf, const char *prefix, value val) } -/* Return a default value for variable VAR using the following rules: +/* Print lattice value VAL to stderr. */ - 1- Function arguments are considered VARYING. - - 2- Global and static variables that are declared constant are - considered CONSTANT. +void debug_lattice_value (prop_value_t val); - 3- Any other virtually defined variable is considered UNKNOWN_VAL. +void +debug_lattice_value (prop_value_t val) +{ + dump_lattice_value (stderr, "", val); + fprintf (stderr, "\n"); +} - 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. */ -static value -get_default_value (tree var) -{ - value val; - tree sym; +/* The regular is_gimple_min_invariant does a shallow test of the object. + It assumes that full gimplification has happened, or will happen on the + object. For a value coming from DECL_INITIAL, this is not true, so we + have to be more strict ourselves. */ - if (TREE_CODE (var) == SSA_NAME) - sym = SSA_NAME_VAR (var); - else +static bool +ccp_decl_initial_min_invariant (tree t) +{ + if (!is_gimple_min_invariant (t)) + return false; + if (TREE_CODE (t) == ADDR_EXPR) { - gcc_assert (DECL_P (var)); - sym = var; + /* Inline and unroll is_gimple_addressable. */ + while (1) + { + t = TREE_OPERAND (t, 0); + if (is_gimple_id (t)) + return true; + if (!handled_component_p (t)) + return false; + } } + return true; +} - val.lattice_val = UNDEFINED; - val.const_val = NULL_TREE; - if (TREE_CODE (var) == SSA_NAME - && SSA_NAME_VALUE (var) - && is_gimple_min_invariant (SSA_NAME_VALUE (var))) - { - val.lattice_val = CONSTANT; - val.const_val = SSA_NAME_VALUE (var); - } - else if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym)) +/* Compute a default value for variable VAR and store it in the + CONST_VAL array. The following rules are used to get default + values: + + 1- Global and static variables that are declared constant are + considered CONSTANT. + + 2- 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. + + 3- If SSA_NAME_VALUE is set and it is a constant, its value is + used. + + 4- Variables defined by statements other than assignments and PHI + nodes are considered VARYING. + + 5- Variables that are not GIMPLE registers are considered + UNKNOWN_VAL, which is really a stronger version of UNDEFINED. + It's used to avoid the short circuit evaluation implied by + UNDEFINED in ccp_lattice_meet. */ + +static prop_value_t +get_default_value (tree var) +{ + tree sym = SSA_NAME_VAR (var); + prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE }; + + if (!do_store_ccp && !is_gimple_reg (var)) { - /* Function arguments and volatile variables are considered VARYING. */ + /* Short circuit for regular CCP. We are not interested in any + non-register when DO_STORE_CCP is false. */ val.lattice_val = VARYING; } - else if (TREE_STATIC (sym)) + else if (SSA_NAME_VALUE (var) + && is_gimple_min_invariant (SSA_NAME_VALUE (var))) { - /* 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; - } + val.lattice_val = CONSTANT; + val.value = SSA_NAME_VALUE (var); } - else if (!is_gimple_reg (sym)) + else if (TREE_STATIC (sym) + && TREE_READONLY (sym) + && !MTAG_P (sym) + && DECL_INITIAL (sym) + && ccp_decl_initial_min_invariant (DECL_INITIAL (sym))) { - val.const_val = NULL_TREE; - val.lattice_val = UNKNOWN_VAL; + /* Globals and static variables declared 'const' take their + initial value. */ + val.lattice_val = CONSTANT; + val.value = DECL_INITIAL (sym); + val.mem_ref = sym; } 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) + if (IS_EMPTY_STMT (stmt)) + { + /* Variables defined by an empty statement are those used + before being initialized. If VAR is a local variable, we + can assume initially that it is UNDEFINED. If we are + doing STORE-CCP, function arguments and non-register + variables are initially UNKNOWN_VAL, because we cannot + discard the value incoming from outside of this function + (see ccp_lattice_meet for details). */ + if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL) + val.lattice_val = UNDEFINED; + else if (do_store_ccp) + val.lattice_val = UNKNOWN_VAL; + else val.lattice_val = VARYING; } + else if (TREE_CODE (stmt) == MODIFY_EXPR + || TREE_CODE (stmt) == PHI_NODE) + { + /* Any other variable defined by an assignment or a PHI node + is considered UNDEFINED (or UNKNOWN_VAL if VAR is not a + GIMPLE register). */ + val.lattice_val = is_gimple_reg (sym) ? UNDEFINED : UNKNOWN_VAL; + } + else + { + /* Otherwise, VAR will never take on a constant value. */ + val.lattice_val = VARYING; + } } return val; } -/* Get the constant value associated with variable VAR. */ - -static value * -get_value (tree var) -{ - value *val; - gcc_assert (TREE_CODE (var) == SSA_NAME); +/* Get the constant value associated with variable VAR. If + MAY_USE_DEFAULT_P is true, call get_default_value on variables that + have the lattice value UNINITIALIZED. */ - val = &value_vector[SSA_NAME_VERSION (var)]; - if (val->lattice_val == UNINITIALIZED) +static prop_value_t * +get_value (tree var, bool may_use_default_p) +{ + prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; + if (may_use_default_p && val->lattice_val == UNINITIALIZED) *val = get_default_value (var); return val; } -/* Set the lattice value for variable VAR to VAL. Return true if VAL - is different from VAR's previous value. */ +/* Set the value for variable VAR to NEW_VAL. Return true if the new + value is different from VAR's previous value. */ static bool -set_lattice_value (tree var, value val) +set_lattice_value (tree var, prop_value_t new_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) + prop_value_t *old_val = get_value (var, false); + + /* Lattice transitions must always be monotonically increasing in + value. We allow two exceptions: + + 1- If *OLD_VAL and NEW_VAL are the same, return false to + inform the caller that this was a non-transition. + + 2- If we are doing store-ccp (i.e., DOING_STORE_CCP is true), + allow CONSTANT->UNKNOWN_VAL. The UNKNOWN_VAL state is a + special type of UNDEFINED state which prevents the short + circuit evaluation of PHI arguments (see ccp_visit_phi_node + and ccp_lattice_meet). */ + gcc_assert (old_val->lattice_val <= new_val.lattice_val + || (old_val->lattice_val == new_val.lattice_val + && old_val->value == new_val.value + && old_val->mem_ref == new_val.mem_ref) + || (do_store_ccp + && old_val->lattice_val == CONSTANT + && new_val.lattice_val == UNKNOWN_VAL)); + + if (old_val->lattice_val != new_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"); + dump_lattice_value (dump_file, "Lattice value changed to ", new_val); + fprintf (dump_file, ". %sdding SSA edges to worklist.\n", + new_val.lattice_val != UNDEFINED ? "A" : "Not a"); } - *old = val; - return true; + *old_val = new_val; + + /* Transitions UNINITIALIZED -> UNDEFINED are never interesting + for propagation purposes. In these cases return false to + avoid doing useless work. */ + return (new_val.lattice_val != UNDEFINED); } return false; } -/* Set the lattice value for the variable VAR to VARYING. */ - -static void -def_to_varying (tree var) -{ - value val; - val.lattice_val = VARYING; - val.const_val = NULL_TREE; - set_lattice_value (var, val); -} - - -/* Return the likely latticevalue for STMT. +/* Return the likely CCP lattice value for STMT. If STMT has no operands, then return CONSTANT. @@ -277,67 +464,68 @@ def_to_varying (tree var) Else return VARYING. */ -static latticevalue +static ccp_lattice_t likely_value (tree stmt) { - vuse_optype vuses; - int found_constant = 0; + bool found_constant; 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) + + /* If the statement has volatile operands, it won't fold to a + constant value. */ + if (ann->has_volatile_ops) + return VARYING; + + /* If we are not doing store-ccp, statements with loads + and/or stores will never fold into a constant. */ + if (!do_store_ccp + && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) return VARYING; - /* A CALL_EXPR is assumed to be varying. This may be overly conservative, - in the presence of const and pure calls. */ + + /* A CALL_EXPR is assumed to be varying. NOTE: 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); + /* Anything other than assignments and conditional jumps are not + interesting for CCP. */ + if (TREE_CODE (stmt) != MODIFY_EXPR + && TREE_CODE (stmt) != COND_EXPR + && TREE_CODE (stmt) != SWITCH_EXPR) + return VARYING; + + if (is_gimple_min_invariant (get_rhs (stmt))) + return CONSTANT; - FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) + found_constant = false; + FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE|SSA_OP_VUSE) { - value *val = get_value (use); + prop_value_t *val = get_value (use, true); - if (val->lattice_val == UNDEFINED) - return UNDEFINED; + if (val->lattice_val == VARYING) + return VARYING; - if (val->lattice_val == CONSTANT) - found_constant = 1; - } - - vuses = VUSE_OPS (ann); - - if (NUM_VUSES (vuses)) - { - 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); - + { + /* UNKNOWN_VAL is invalid when not doing STORE-CCP. */ + gcc_assert (do_store_ccp); + return UNKNOWN_VAL; + } + if (val->lattice_val == CONSTANT) - found_constant = 1; + found_constant = true; } - return ((found_constant || (!USE_OPS (ann) && !vuses)) ? CONSTANT : VARYING); -} - - -/* Function indicating whether we ought to include information for VAR - when calculating immediate uses. */ + if (found_constant + || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE) + || ZERO_SSA_OPERANDS (stmt, SSA_OP_VUSE)) + return CONSTANT; -static bool -need_imm_uses_for (tree var) -{ - return get_value (var)->lattice_val != VARYING; + return UNDEFINED; } @@ -347,53 +535,39 @@ 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); + const_val = XNEWVEC (prop_value_t, num_ssa_names); + memset (const_val, 0, num_ssa_names * sizeof (*const_val)); /* 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)) { bool is_varying = false; tree stmt = bsi_stmt (i); - ssa_op_iter iter; - tree def; - get_stmt_operands (stmt); + if (likely_value (stmt) == VARYING) - /* 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)) { - if (get_value (def)->lattice_val == VARYING) + tree def; + ssa_op_iter iter; + + /* If the statement will not produce a constant, mark + all its outputs VARYING. */ + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) + get_value (def, false)->lattice_val = VARYING; + + /* Never mark conditional jumps with DONT_SIMULATE_AGAIN, + otherwise the propagator will never add the outgoing + control edges. */ + if (TREE_CODE (stmt) != COND_EXPR + && TREE_CODE (stmt) != SWITCH_EXPR) is_varying = true; } - /* 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; } } @@ -401,304 +575,149 @@ ccp_initialize (void) /* Now process PHI nodes. */ FOR_EACH_BB (bb) { - tree phi, var; - int x; + tree phi; for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) { - value *val = get_value (PHI_RESULT (phi)); + int i; + tree arg; + prop_value_t *val = get_value (PHI_RESULT (phi), false); - for (x = 0; x < PHI_NUM_ARGS (phi); x++) + for (i = 0; i < PHI_NUM_ARGS (phi); i++) { - var = PHI_ARG_DEF (phi, x); + arg = PHI_ARG_DEF (phi, i); - /* If one argument has a V_MAY_DEF, the result is - VARYING. */ - if (TREE_CODE (var) == SSA_NAME) + if (TREE_CODE (arg) == SSA_NAME + && get_value (arg, false)->lattice_val == VARYING) { - 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; - } + val->lattice_val = VARYING; + break; } } 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); } -/* 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 bool -replace_uses_in (tree stmt, bool *replaced_addresses_p) -{ - bool replaced = false; - use_operand_p use; - ssa_op_iter iter; - - if (replaced_addresses_p) - *replaced_addresses_p = false; - - get_stmt_operands (stmt); - - FOR_EACH_SSA_USE_OPERAND (use, stmt, iter, SSA_OP_USE) - { - tree tuse = USE_FROM_PTR (use); - value *val = get_value (tuse); - - if (val->lattice_val != CONSTANT) - continue; +/* Do final substitution of propagated values, cleanup the flowgraph and + free allocated storage. */ - 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; - } - - 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) +static void +ccp_finalize (void) { - 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))) - { - 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; - } + /* Perform substitutions based on the known constant values. */ + substitute_and_fold (const_val, false); - return replaced; + free (const_val); } -/* Perform final substitution and folding. After this pass the program - should still be in SSA form. */ +/* Compute the meet operator between *VAL1 and *VAL2. Store the result + in VAL1. + + any M UNDEFINED = any + any M UNKNOWN_VAL = UNKNOWN_VAL + any M VARYING = VARYING + Ci M Cj = Ci if (i == j) + Ci M Cj = VARYING if (i != j) + + Lattice values UNKNOWN_VAL and UNDEFINED are similar but have + different semantics at PHI nodes. Both values imply that we don't + know whether the variable is constant or not. However, UNKNOWN_VAL + values override all others. For instance, suppose that A is a + global variable: + + +------+ + | | + | / \ + | / \ + | | A_1 = 4 + | \ / + | \ / + | A_3 = PHI (A_2, A_1) + | ... = A_3 + | | + +----+ + + If the edge into A_2 is not executable, the first visit to A_3 will + yield the constant 4. But the second visit to A_3 will be with A_2 + in state UNKNOWN_VAL. We can no longer conclude that A_3 is 4 + because A_2 may have been set in another function. If we had used + the lattice value UNDEFINED, we would have had wrongly concluded + that A_3 is 4. */ + static void -substitute_and_fold (void) +ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2) { - basic_block bb; - unsigned int i; - - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, - "\nSubstituing constants and folding statements\n\n"); - - /* Substitute constants in every statement of every basic block. */ - FOR_EACH_BB (bb) + if (val1->lattice_val == UNDEFINED) { - block_stmt_iterator i; - tree phi; - - /* Propagate our known constants into PHI nodes. */ - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - { - int i; - - for (i = 0; i < PHI_NUM_ARGS (phi); i++) - { - value *new_val; - use_operand_p orig_p = PHI_ARG_DEF_PTR (phi, i); - tree orig = USE_FROM_PTR (orig_p); - - if (! SSA_VAR_P (orig)) - break; - - new_val = get_value (orig); - if (new_val->lattice_val == CONSTANT - && may_propagate_copy (orig, new_val->const_val)) - SET_USE (orig_p, new_val->const_val); - } - } - - for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) - { - bool replaced_address; - tree stmt = bsi_stmt (i); - - /* Skip statements that have been folded already. */ - if (stmt_modified_p (stmt) || !is_exec_stmt (stmt)) - continue; - - /* Replace the statement with its folded version and mark it - folded. */ - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "Line %d: replaced ", get_lineno (stmt)); - print_generic_stmt (dump_file, stmt, TDF_SLIM); - } - - 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); - - /* 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 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)) - { - fprintf (dump_file, " with "); - print_generic_stmt (dump_file, stmt, TDF_SLIM); - fprintf (dump_file, "\n"); - } - } + /* UNDEFINED M any = any */ + *val1 = *val2; } - - /* 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++) + else if (val2->lattice_val == UNDEFINED) { - tree name = ssa_name (i); - value *value; - - if (!name) - continue; - - 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; + /* any M UNDEFINED = any + Nothing to do. VAL1 already contains the value we want. */ + ; } -} - - -/* Free allocated storage. */ - -static void -ccp_finalize (void) -{ - /* Perform substitutions based on the known constant values. */ - substitute_and_fold (); - - free (value_vector); -} - - - -/* Compute the meet operator between VAL1 and VAL2: - - 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 -ccp_lattice_meet (value val1, value val2) -{ - value result; - - /* any M UNDEFINED = any. */ - if (val1.lattice_val == UNDEFINED) - return val2; - else if (val2.lattice_val == UNDEFINED) - return val1; - - /* any M VARYING = VARYING. */ - if (val1.lattice_val == VARYING || val2.lattice_val == VARYING) + else if (val1->lattice_val == UNKNOWN_VAL + || val2->lattice_val == UNKNOWN_VAL) { - result.lattice_val = VARYING; - result.const_val = NULL_TREE; - return result; - } + /* UNKNOWN_VAL values are invalid if we are not doing STORE-CCP. */ + gcc_assert (do_store_ccp); - /* any M UNKNOWN_VAL = UNKNOWN_VAL. */ - if (val1.lattice_val == UNKNOWN_VAL - || val2.lattice_val == UNKNOWN_VAL) + /* any M UNKNOWN_VAL = UNKNOWN_VAL. */ + val1->lattice_val = UNKNOWN_VAL; + val1->value = NULL_TREE; + val1->mem_ref = NULL_TREE; + } + else if (val1->lattice_val == VARYING + || val2->lattice_val == VARYING) { - result.lattice_val = UNKNOWN_VAL; - result.const_val = NULL_TREE; - return result; + /* any M VARYING = VARYING. */ + val1->lattice_val = VARYING; + val1->value = NULL_TREE; + val1->mem_ref = NULL_TREE; } - - /* 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) + else if (val1->lattice_val == CONSTANT + && val2->lattice_val == CONSTANT + && simple_cst_equal (val1->value, val2->value) == 1 + && (!do_store_ccp + || (val1->mem_ref && val2->mem_ref + && operand_equal_p (val1->mem_ref, val2->mem_ref, 0)))) { - result.lattice_val = CONSTANT; - result.const_val = val1.const_val; + /* Ci M Cj = Ci if (i == j) + Ci M Cj = VARYING if (i != j) + + If these two values come from memory stores, make sure that + they come from the same memory reference. */ + val1->lattice_val = CONSTANT; + val1->value = val1->value; + val1->mem_ref = val1->mem_ref; } else { - result.lattice_val = VARYING; - result.const_val = NULL_TREE; + /* Any other combination is VARYING. */ + val1->lattice_val = VARYING; + val1->value = NULL_TREE; + val1->mem_ref = NULL_TREE; } - - return result; } /* 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 + PHI node is determined calling ccp_lattice_meet with all the arguments of the PHI node that are incoming via executable edges. */ static enum ssa_prop_result ccp_visit_phi_node (tree phi) { - value new_val, *old_val; int i; + prop_value_t *old_val, new_val; if (dump_file && (dump_flags & TDF_DETAILS)) { @@ -706,11 +725,11 @@ ccp_visit_phi_node (tree phi) print_generic_expr (dump_file, phi, dump_flags); } - old_val = get_value (PHI_RESULT (phi)); + old_val = get_value (PHI_RESULT (phi), false); switch (old_val->lattice_val) { case VARYING: - return SSA_PROP_NOT_INTERESTING; + return SSA_PROP_VARYING; case CONSTANT: new_val = *old_val; @@ -723,14 +742,15 @@ ccp_visit_phi_node (tree phi) 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; + gcc_assert (do_store_ccp); + + /* FALLTHRU */ case UNDEFINED: case UNINITIALIZED: new_val.lattice_val = UNDEFINED; - new_val.const_val = NULL_TREE; + new_val.value = NULL_TREE; + new_val.mem_ref = NULL_TREE; break; default: @@ -739,7 +759,8 @@ ccp_visit_phi_node (tree phi) for (i = 0; i < PHI_NUM_ARGS (phi); i++) { - /* Compute the meet operator over all the PHI arguments. */ + /* Compute the meet operator over all the PHI arguments flowing + through executable edges. */ edge e = PHI_ARG_EDGE (phi, i); if (dump_file && (dump_flags & TDF_DETAILS)) @@ -754,25 +775,25 @@ ccp_visit_phi_node (tree phi) 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; + tree arg = PHI_ARG_DEF (phi, i); + prop_value_t arg_val; - if (is_gimple_min_invariant (rdef)) + if (is_gimple_min_invariant (arg)) { - val.lattice_val = CONSTANT; - val.const_val = rdef; - rdef_val = &val; + arg_val.lattice_val = CONSTANT; + arg_val.value = arg; + arg_val.mem_ref = NULL_TREE; } else - rdef_val = get_value (rdef); + arg_val = *(get_value (arg, true)); - new_val = ccp_lattice_meet (new_val, *rdef_val); + ccp_lattice_meet (&new_val, &arg_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); + print_generic_expr (dump_file, arg, dump_flags); + dump_lattice_value (dump_file, "\tValue: ", arg_val); fprintf (dump_file, "\n"); } @@ -788,7 +809,8 @@ ccp_visit_phi_node (tree phi) } /* Check for an invalid change from UNKNOWN_VAL to UNDEFINED. */ - if (old_val->lattice_val == UNKNOWN_VAL + if (do_store_ccp + && old_val->lattice_val == UNKNOWN_VAL && new_val.lattice_val == UNDEFINED) return SSA_PROP_NOT_INTERESTING; @@ -821,18 +843,32 @@ ccp_fold (tree stmt) enum tree_code code = TREE_CODE (rhs); 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; + { + /* If the RHS is an SSA_NAME, return its known constant value, + if any. */ + return get_value (rhs, true)->value; + } + else if (do_store_ccp && stmt_makes_single_load (stmt)) + { + /* If the RHS is a memory load, see if the VUSEs associated with + it are a valid constant for that memory load. */ + prop_value_t *val = get_value_loaded_by (stmt, const_val); + if (val && val->mem_ref) + { + if (operand_equal_p (val->mem_ref, rhs, 0)) + return val->value; + + /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a + complex type with a known constant value, return it. */ + if ((TREE_CODE (rhs) == REALPART_EXPR + || TREE_CODE (rhs) == IMAGPART_EXPR) + && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0)) + return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value); + } + return NULL_TREE; + } /* Unary operators. Note that we know the single operand must be a constant. So this should almost always return a @@ -845,32 +881,16 @@ ccp_fold (tree stmt) /* Simplify the operand down to a constant. */ if (TREE_CODE (op0) == SSA_NAME) { - value *val = get_value (op0); + prop_value_t *val = get_value (op0, true); if (val->lattice_val == CONSTANT) - op0 = get_value (op0)->const_val; + op0 = get_value (op0, true)->value; } - 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. */ - if (retval && ! is_gimple_min_invariant (retval)) - return NULL; - - /* If we could not fold the expression, but the arguments are all - constants and gimple values, then build and return the new - expression. - - In some cases the new expression is still something we can - use as a replacement for an argument. This happens with - NOP conversions of types for example. - - In other cases the new expression can not be used as a - replacement for an argument (as it would create non-gimple - code). But the new expression can still be used to derive - other constants. */ - if (! retval && is_gimple_min_invariant (op0)) - return build1 (code, TREE_TYPE (rhs), op0); + if ((code == NOP_EXPR || code == CONVERT_EXPR) + && tree_ssa_useless_type_conversion_1 (TREE_TYPE (rhs), + TREE_TYPE (op0))) + return op0; + return fold_unary (code, TREE_TYPE (rhs), op0); } /* Binary and comparison operators. We know one or both of the @@ -889,41 +909,19 @@ ccp_fold (tree stmt) /* Simplify the operands down to constants when appropriate. */ if (TREE_CODE (op0) == SSA_NAME) { - value *val = get_value (op0); + prop_value_t *val = get_value (op0, true); if (val->lattice_val == CONSTANT) - op0 = val->const_val; + op0 = val->value; } if (TREE_CODE (op1) == SSA_NAME) { - value *val = get_value (op1); + prop_value_t *val = get_value (op1, true); if (val->lattice_val == CONSTANT) - op1 = val->const_val; + op1 = val->value; } - 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. */ - if (retval && ! is_gimple_min_invariant (retval)) - return NULL; - - /* If we could not fold the expression, but the arguments are all - constants and gimple values, then build and return the new - expression. - - In some cases the new expression is still something we can - use as a replacement for an argument. This happens with - NOP conversions of types for example. - - In other cases the new expression can not be used as a - replacement for an argument (as it would create non-gimple - code). But the new expression can still be used to derive - other constants. */ - if (! retval - && is_gimple_min_invariant (op0) - && is_gimple_min_invariant (op1)) - return build (code, TREE_TYPE (rhs), op0, op1); + return fold_binary (code, TREE_TYPE (rhs), op0, op1); } /* We may be able to fold away calls to builtin functions if their @@ -934,24 +932,29 @@ ccp_fold (tree stmt) == FUNCTION_DECL) && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) { - use_optype uses = STMT_USE_OPS (stmt); - if (NUM_USES (uses) != 0) + if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE)) { - tree *orig; - size_t i; + tree *orig, var; + tree fndecl, arglist; + size_t i = 0; + ssa_op_iter iter; + use_operand_p var_p; /* Preserve the original values of every operand. */ - orig = xmalloc (sizeof (tree) * NUM_USES (uses)); - for (i = 0; i < NUM_USES (uses); i++) - orig[i] = USE_OP (uses, i); + orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE)); + FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) + orig[i++] = var; /* Substitute operands with their values and try to fold. */ - replace_uses_in (stmt, NULL); - retval = fold_builtin (rhs, false); + replace_uses_in (stmt, NULL, const_val); + fndecl = get_callee_fndecl (rhs); + arglist = TREE_OPERAND (rhs, 1); + retval = fold_builtin (fndecl, arglist, false); /* Restore operands to their original form. */ - for (i = 0; i < NUM_USES (uses); i++) - SET_USE_OP (uses, i, orig[i]); + i = 0; + FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE) + SET_USE (var_p, orig[i++]); free (orig); } } @@ -967,14 +970,159 @@ ccp_fold (tree stmt) } +/* Return the tree representing the element referenced by T if T is an + ARRAY_REF or COMPONENT_REF into constant aggregates. Return + NULL_TREE otherwise. */ + +static tree +fold_const_aggregate_ref (tree t) +{ + prop_value_t *value; + tree base, ctor, idx, field; + unsigned HOST_WIDE_INT cnt; + tree cfield, cval; + + switch (TREE_CODE (t)) + { + case ARRAY_REF: + /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its + DECL_INITIAL. If BASE is a nested reference into another + ARRAY_REF or COMPONENT_REF, make a recursive call to resolve + the inner reference. */ + base = TREE_OPERAND (t, 0); + switch (TREE_CODE (base)) + { + case VAR_DECL: + if (!TREE_READONLY (base) + || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE + || !targetm.binds_local_p (base)) + return NULL_TREE; + + ctor = DECL_INITIAL (base); + break; + + case ARRAY_REF: + case COMPONENT_REF: + ctor = fold_const_aggregate_ref (base); + break; + + default: + return NULL_TREE; + } + + if (ctor == NULL_TREE + || (TREE_CODE (ctor) != CONSTRUCTOR + && TREE_CODE (ctor) != STRING_CST) + || !TREE_STATIC (ctor)) + return NULL_TREE; + + /* Get the index. If we have an SSA_NAME, try to resolve it + with the current lattice value for the SSA_NAME. */ + idx = TREE_OPERAND (t, 1); + switch (TREE_CODE (idx)) + { + case SSA_NAME: + if ((value = get_value (idx, true)) + && value->lattice_val == CONSTANT + && TREE_CODE (value->value) == INTEGER_CST) + idx = value->value; + else + return NULL_TREE; + break; + + case INTEGER_CST: + break; + + default: + return NULL_TREE; + } + + /* Fold read from constant string. */ + if (TREE_CODE (ctor) == STRING_CST) + { + if ((TYPE_MODE (TREE_TYPE (t)) + == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) + && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) + == MODE_INT) + && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1 + && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0) + return build_int_cst (TREE_TYPE (t), (TREE_STRING_POINTER (ctor) + [TREE_INT_CST_LOW (idx)])); + return NULL_TREE; + } + + /* Whoo-hoo! I'll fold ya baby. Yeah! */ + FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) + if (tree_int_cst_equal (cfield, idx)) + return cval; + break; + + case COMPONENT_REF: + /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its + DECL_INITIAL. If BASE is a nested reference into another + ARRAY_REF or COMPONENT_REF, make a recursive call to resolve + the inner reference. */ + base = TREE_OPERAND (t, 0); + switch (TREE_CODE (base)) + { + case VAR_DECL: + if (!TREE_READONLY (base) + || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE + || !targetm.binds_local_p (base)) + return NULL_TREE; + + ctor = DECL_INITIAL (base); + break; + + case ARRAY_REF: + case COMPONENT_REF: + ctor = fold_const_aggregate_ref (base); + break; + + default: + return NULL_TREE; + } + + if (ctor == NULL_TREE + || TREE_CODE (ctor) != CONSTRUCTOR + || !TREE_STATIC (ctor)) + return NULL_TREE; + + field = TREE_OPERAND (t, 1); + + FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) + if (cfield == field + /* FIXME: Handle bit-fields. */ + && ! DECL_BIT_FIELD (cfield)) + return cval; + break; + + case REALPART_EXPR: + case IMAGPART_EXPR: + { + tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0)); + if (c && TREE_CODE (c) == COMPLEX_CST) + return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c); + break; + } + + default: + break; + } + + return NULL_TREE; +} + /* Evaluate statement STMT. */ -static value +static prop_value_t evaluate_stmt (tree stmt) { - value val; - tree simplified; - latticevalue likelyvalue = likely_value (stmt); + prop_value_t val; + tree simplified = NULL_TREE; + ccp_lattice_t likelyvalue = likely_value (stmt); + + val.mem_ref = NULL_TREE; /* If the statement is likely to have a CONSTANT result, then try to fold the statement to determine the constant value. */ @@ -982,29 +1130,33 @@ evaluate_stmt (tree stmt) simplified = ccp_fold (stmt); /* If the statement is likely to have a VARYING result, then do not bother folding the statement. */ - else if (likelyvalue == VARYING) + if (likelyvalue == VARYING) simplified = get_rhs (stmt); - /* Otherwise the statement is likely to have an UNDEFINED value and - there will be nothing to do. */ - else - simplified = NULL_TREE; + /* If the statement is an ARRAY_REF or COMPONENT_REF into constant + aggregates, extract the referenced constant. Otherwise the + statement is likely to have an UNDEFINED value, and there will be + nothing to do. Note that fold_const_aggregate_ref returns + NULL_TREE if the first case does not match. */ + else if (!simplified) + simplified = fold_const_aggregate_ref (get_rhs (stmt)); if (simplified && is_gimple_min_invariant (simplified)) { /* The statement produced a constant value. */ val.lattice_val = CONSTANT; - val.const_val = simplified; + val.value = simplified; } else { /* The statement produced a nonconstant value. If the statement - 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; + had UNDEFINED operands, then the result of the statement + should be UNDEFINED. Otherwise, the statement is VARYING. */ + if (likelyvalue == UNDEFINED || likelyvalue == UNKNOWN_VAL) + val.lattice_val = likelyvalue; + else + val.lattice_val = VARYING; + + val.value = NULL_TREE; } return val; @@ -1012,57 +1164,46 @@ evaluate_stmt (tree stmt) /* Visit the assignment statement STMT. Set the value of its LHS to the - value computed by the RHS and store LHS in *OUTPUT_P. */ + value computed by the RHS and store LHS in *OUTPUT_P. If STMT + creates virtual definitions, set the value of each new name to that + of the RHS (if we can derive a constant out of the RHS). */ static enum ssa_prop_result visit_assignment (tree stmt, tree *output_p) { - value val; + prop_value_t val; tree lhs, rhs; - vuse_optype vuses; - v_must_def_optype v_must_defs; + enum ssa_prop_result retval; lhs = TREE_OPERAND (stmt, 0); rhs = TREE_OPERAND (stmt, 1); - vuses = STMT_VUSE_OPS (stmt); - v_must_defs = STMT_V_MUST_DEF_OPS (stmt); - - 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); - - /* We require the SSA version number of the lhs for the value_vector. - Make sure we have it. */ - if (TREE_CODE (lhs) != SSA_NAME) - { - /* If we make it here, then stmt only has one definition: - a V_MUST_DEF. */ - lhs = V_MUST_DEF_RESULT (v_must_defs, 0); - } if (TREE_CODE (rhs) == SSA_NAME) { /* For a simple copy operation, we copy the lattice values. */ - value *nval = get_value (rhs); + prop_value_t *nval = get_value (rhs, true); val = *nval; } - else if (DECL_P (rhs) - && NUM_VUSES (vuses) == 1 - && rhs == SSA_NAME_VAR (VUSE_OP (vuses, 0))) + else if (do_store_ccp && stmt_makes_single_load (stmt)) { - /* 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; + /* Same as above, but the RHS is not a gimple register and yet + has a known VUSE. If STMT is loading from the same memory + location that created the SSA_NAMEs for the virtual operands, + we can propagate the value on the RHS. */ + prop_value_t *nval = get_value_loaded_by (stmt, const_val); + + if (nval && nval->mem_ref + && operand_equal_p (nval->mem_ref, rhs, 0)) + val = *nval; + else + val = evaluate_stmt (stmt); } else /* Evaluate the statement. */ val = evaluate_stmt (stmt); /* 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. + value to be a VIEW_CONVERT_EXPR of the old constant value. ??? Also, if this was a definition of a bitfield, we need to widen the constant value into the type of the destination variable. This @@ -1073,46 +1214,91 @@ visit_assignment (tree stmt, tree *output_p) if (TREE_CODE (orig_lhs) == VIEW_CONVERT_EXPR && val.lattice_val == CONSTANT) { - val.const_val = build1 (VIEW_CONVERT_EXPR, - TREE_TYPE (TREE_OPERAND (orig_lhs, 0)), - val.const_val); - orig_lhs = TREE_OPERAND (orig_lhs, 1); + tree w = fold_unary (VIEW_CONVERT_EXPR, + TREE_TYPE (TREE_OPERAND (orig_lhs, 0)), + val.value); + + orig_lhs = TREE_OPERAND (orig_lhs, 0); + if (w && is_gimple_min_invariant (w)) + val.value = w; + else + { + val.lattice_val = VARYING; + val.value = NULL; + } } if (val.lattice_val == CONSTANT && TREE_CODE (orig_lhs) == COMPONENT_REF && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs, 1))) { - tree w = widen_bitfield (val.const_val, TREE_OPERAND (orig_lhs, 1), + tree w = widen_bitfield (val.value, TREE_OPERAND (orig_lhs, 1), orig_lhs); if (w && is_gimple_min_invariant (w)) - val.const_val = w; + val.value = w; else { val.lattice_val = VARYING; - val.const_val = NULL; + val.value = NULL_TREE; + val.mem_ref = NULL_TREE; } } } - /* 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; + retval = SSA_PROP_NOT_INTERESTING; /* Set the lattice value of the statement's output. */ - if (set_lattice_value (lhs, val)) + if (TREE_CODE (lhs) == SSA_NAME) { - *output_p = lhs; - if (val.lattice_val == VARYING) - return SSA_PROP_VARYING; - else - return SSA_PROP_INTERESTING; + /* If STMT is an assignment to an SSA_NAME, we only have one + value to set. */ + if (set_lattice_value (lhs, val)) + { + *output_p = lhs; + if (val.lattice_val == VARYING) + retval = SSA_PROP_VARYING; + else + retval = SSA_PROP_INTERESTING; + } } - else - return SSA_PROP_NOT_INTERESTING; + else if (do_store_ccp && stmt_makes_single_store (stmt)) + { + /* Otherwise, set the names in V_MAY_DEF/V_MUST_DEF operands + to the new constant value and mark the LHS as the memory + reference associated with VAL. */ + ssa_op_iter i; + tree vdef; + bool changed; + + /* Stores cannot take on an UNDEFINED value. */ + if (val.lattice_val == UNDEFINED) + val.lattice_val = UNKNOWN_VAL; + + /* Mark VAL as stored in the LHS of this assignment. */ + val.mem_ref = lhs; + + /* Set the value of every VDEF to VAL. */ + changed = false; + FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS) + changed |= set_lattice_value (vdef, val); + + /* Note that for propagation purposes, we are only interested in + visiting statements that load the exact same memory reference + stored here. Those statements will have the exact same list + of virtual uses, so it is enough to set the output of this + statement to be its first virtual definition. */ + *output_p = first_vdef (stmt); + if (changed) + { + if (val.lattice_val == VARYING) + retval = SSA_PROP_VARYING; + else + retval = SSA_PROP_INTERESTING; + } + } + + return retval; } @@ -1123,7 +1309,7 @@ visit_assignment (tree stmt, tree *output_p) static enum ssa_prop_result visit_cond_stmt (tree stmt, edge *taken_edge_p) { - value val; + prop_value_t val; basic_block block; block = bb_for_stmt (stmt); @@ -1133,7 +1319,7 @@ visit_cond_stmt (tree stmt, edge *taken_edge_p) 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; + *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0; if (*taken_edge_p) return SSA_PROP_INTERESTING; else @@ -1153,27 +1339,17 @@ visit_cond_stmt (tree stmt, edge *taken_edge_p) 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)) { - fprintf (dump_file, "\nVisiting statement: "); - print_generic_stmt (dump_file, stmt, TDF_SLIM); + fprintf (dump_file, "\nVisiting statement:\n"); + print_generic_stmt (dump_file, stmt, dump_flags); fprintf (dump_file, "\n"); } - ann = stmt_ann (stmt); - - 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 (TREE_CODE (stmt) == MODIFY_EXPR) { /* If the statement is an assignment that produces a single output value, evaluate its RHS to see if the lattice value of @@ -1195,30 +1371,36 @@ ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) /* 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); - - /* Mark all V_MAY_DEF operands VARYING. */ - FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_VMAYDEF) - def_to_varying (def); + FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) + { + prop_value_t v = { VARYING, NULL_TREE, NULL_TREE }; + set_lattice_value (def, v); + } return SSA_PROP_VARYING; } -/* Main entry point for SSA Conditional Constant Propagation. - - [ DESCRIBE MAIN ALGORITHM HERE ] */ +/* Main entry point for SSA Conditional Constant Propagation. */ static void -execute_ssa_ccp (void) +execute_ssa_ccp (bool store_ccp) { + do_store_ccp = store_ccp; ccp_initialize (); ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); ccp_finalize (); } +static unsigned int +do_ssa_ccp (void) +{ + execute_ssa_ccp (false); + return 0; +} + + static bool gate_ccp (void) { @@ -1230,22 +1412,60 @@ struct tree_opt_pass pass_ccp = { "ccp", /* name */ gate_ccp, /* gate */ - execute_ssa_ccp, /* execute */ + do_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 */ + PROP_smt_usage, /* properties_destroyed */ 0, /* todo_flags_start */ - TODO_cleanup_cfg | TODO_dump_func | TODO_rename_vars + TODO_cleanup_cfg | TODO_dump_func | TODO_update_ssa | TODO_ggc_collect | TODO_verify_ssa - | TODO_verify_stmts, /* todo_flags_finish */ + | TODO_verify_stmts | TODO_update_smt_usage, /* todo_flags_finish */ 0 /* letter */ }; +static unsigned int +do_ssa_store_ccp (void) +{ + /* If STORE-CCP is not enabled, we just run regular CCP. */ + execute_ssa_ccp (flag_tree_store_ccp != 0); + return 0; +} + +static bool +gate_store_ccp (void) +{ + /* STORE-CCP is enabled only with -ftree-store-ccp, but when + -fno-tree-store-ccp is specified, we should run regular CCP. + That's why the pass is enabled with either flag. */ + return flag_tree_store_ccp != 0 || flag_tree_ccp != 0; +} + + +struct tree_opt_pass pass_store_ccp = +{ + "store_ccp", /* name */ + gate_store_ccp, /* gate */ + do_ssa_store_ccp, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_TREE_STORE_CCP, /* tv_id */ + PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ + 0, /* properties_provided */ + PROP_smt_usage, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | TODO_update_ssa + | TODO_ggc_collect | TODO_verify_ssa + | TODO_cleanup_cfg + | TODO_verify_stmts | TODO_update_smt_usage, /* todo_flags_finish */ + 0 /* letter */ +}; + /* 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. */ @@ -1285,9 +1505,8 @@ widen_bitfield (tree val, tree field, tree var) 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_cst (NULL_TREE, mask))); + wide_val = fold_build2 (BIT_AND_EXPR, TREE_TYPE (var), val, + build_int_cst (TREE_TYPE (var), mask)); } else { @@ -1297,12 +1516,11 @@ widen_bitfield (tree val, tree field, tree var) 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_cst (NULL_TREE, mask))); + wide_val = fold_build2 (BIT_IOR_EXPR, TREE_TYPE (var), val, + build_int_cst (TREE_TYPE (var), mask)); } - return fold (wide_val); + return wide_val; } @@ -1395,9 +1613,9 @@ maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) if (!integer_zerop (elt_offset)) idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); - return build (ARRAY_REF, orig_type, base, idx, min_idx, - size_int (tree_low_cst (elt_size, 1) - / (TYPE_ALIGN_UNIT (elt_type)))); + return build4 (ARRAY_REF, orig_type, base, idx, min_idx, + size_int (tree_low_cst (elt_size, 1) + / (TYPE_ALIGN_UNIT (elt_type)))); } @@ -1458,7 +1676,7 @@ maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, { if (base_is_ptr) base = build1 (INDIRECT_REF, record_type, base); - t = build (COMPONENT_REF, field_type, base, f, NULL_TREE); + t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); return t; } @@ -1498,7 +1716,7 @@ maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, nonzero offset into them. Recurse and hope for a valid match. */ if (base_is_ptr) base = build1 (INDIRECT_REF, record_type, base); - base = build (COMPONENT_REF, field_type, base, f, NULL_TREE); + base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); t = maybe_fold_offset_to_array_ref (base, offset, orig_type); if (t) @@ -1520,7 +1738,7 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that are sometimes added. */ base = fold (base); - STRIP_NOPS (base); + STRIP_TYPE_NOPS (base); TREE_OPERAND (expr, 0) = base; /* One possibility is that the address reduces to a string constant. */ @@ -1548,7 +1766,7 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) /* 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))) + && ccp_decl_initial_min_invariant (DECL_INITIAL (base))) return DECL_INITIAL (base); /* Try folding *(&B+O) to B[X]. */ @@ -1575,7 +1793,7 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) /* We can get here for out-of-range string constant accesses, such as "_"[3]. Bail out of the entire substitution search and arrange for the entire statement to be replaced by a - call to __builtin_trap. In all likelyhood this will all be + call to __builtin_trap. In all likelihood this will all be constant-folded away, but in the meantime we can't leave with something that get_expr_operands can't understand. */ @@ -1585,7 +1803,7 @@ maybe_fold_stmt_indirect (tree expr, tree base, tree offset) && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST) { /* FIXME: Except that this causes problems elsewhere with dead - code not being deleted, and we abort in the rtl expanders + code not being deleted, and we die in the rtl expanders because we failed to remove some ssa_name. In the meantime, just return zero. */ /* FIXME2: This condition should be signaled by @@ -1676,7 +1894,7 @@ maybe_fold_stmt_addition (tree expr) if (TREE_CODE (min_idx) != INTEGER_CST) break; - array_idx = convert (TREE_TYPE (min_idx), array_idx); + array_idx = fold_convert (TREE_TYPE (min_idx), array_idx); if (!integer_zerop (min_idx)) array_idx = int_const_binop (MINUS_EXPR, array_idx, min_idx, 0); @@ -1684,7 +1902,7 @@ maybe_fold_stmt_addition (tree expr) } /* Convert the index to a byte offset. */ - array_idx = convert (sizetype, array_idx); + array_idx = fold_convert (sizetype, array_idx); array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0); /* Update the operands for the next round, or for folding. */ @@ -1708,9 +1926,9 @@ maybe_fold_stmt_addition (tree expr) { if (TYPE_UNSIGNED (TREE_TYPE (op1))) return NULL; - op1 = fold (build1 (NEGATE_EXPR, TREE_TYPE (op1), op1)); + op1 = fold_unary (NEGATE_EXPR, TREE_TYPE (op1), op1); /* ??? In theory fold should always produce another integer. */ - if (TREE_CODE (op1) != INTEGER_CST) + if (op1 == NULL || TREE_CODE (op1) != INTEGER_CST) return NULL; } @@ -1727,6 +1945,14 @@ maybe_fold_stmt_addition (tree expr) return t; } +/* For passing state through walk_tree into fold_stmt_r and its + children. */ + +struct fold_stmt_r_data +{ + bool *changed_p; + bool *inside_addr_expr_p; +}; /* Subroutine of fold_stmt called via walk_tree. We perform several simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ @@ -1734,7 +1960,9 @@ maybe_fold_stmt_addition (tree expr) static tree fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) { - bool *changed_p = data; + struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data; + bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p; + bool *changed_p = fold_stmt_r_data->changed_p; tree expr = *expr_p, t; /* ??? It'd be nice if walk_tree had a pre-order option. */ @@ -1750,13 +1978,23 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) integer_zero_node); break; - /* ??? Could handle ARRAY_REF here, as a variant of INDIRECT_REF. + /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF. We'd only want to bother decomposing an existing ARRAY_REF if the base array is found to have another offset contained within. Otherwise we'd be wasting time. */ + case ARRAY_REF: + /* If we are not processing expressions found within an + ADDR_EXPR, then we can fold constant array references. */ + if (!*inside_addr_expr_p) + t = fold_read_from_constant_string (expr); + else + t = NULL; + break; case ADDR_EXPR: + *inside_addr_expr_p = true; t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); + *inside_addr_expr_p = false; if (t) return t; *walk_subtrees = 0; @@ -1764,7 +2002,7 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) /* Set TREE_INVARIANT properly so that the value is properly considered constant, and so gets propagated as expected. */ if (*changed_p) - recompute_tree_invarant_for_addr_expr (expr); + recompute_tree_invariant_for_addr_expr (expr); return NULL_TREE; case PLUS_EXPR: @@ -1801,6 +2039,10 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) } break; + case TARGET_MEM_REF: + t = maybe_fold_tmr (expr); + break; + default: return NULL_TREE; } @@ -1815,24 +2057,49 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) } -/* 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. */ +/* Return the string length, maximum string length or maximum value of + ARG in LENGTH. + If ARG is an SSA name variable, follow its use-def chains. If LENGTH + is not NULL and, for TYPE == 0, its value is not equal to the length + we determine or if we are unable to determine the length or value, + return false. VISITED is a bitmap of visited variables. + TYPE is 0 if string length should be returned, 1 for maximum string + length and 2 for maximum value ARG can have. */ static bool -get_strlen (tree arg, tree *length, bitmap visited) +get_maxval_strlen (tree arg, tree *length, bitmap visited, int type) { tree var, def_stmt, val; if (TREE_CODE (arg) != SSA_NAME) { - val = c_strlen (arg, 1); + if (type == 2) + { + val = arg; + if (TREE_CODE (val) != INTEGER_CST + || tree_int_cst_sgn (val) < 0) + return false; + } + else + val = c_strlen (arg, 1); if (!val) return false; - if (*length && simple_cst_equal (val, *length) != 1) - return false; + if (*length) + { + if (type > 0) + { + if (TREE_CODE (*length) != INTEGER_CST + || TREE_CODE (val) != INTEGER_CST) + return false; + + if (tree_int_cst_lt (*length, val)) + *length = val; + return true; + } + else if (simple_cst_equal (val, *length) != 1) + return false; + } *length = val; return true; @@ -1850,28 +2117,14 @@ get_strlen (tree arg, tree *length, bitmap visited) { case MODIFY_EXPR: { - tree len, rhs; - + tree 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); - - /* 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; - - *length = len; - return true; - } - - break; + return get_maxval_strlen (rhs, length, visited, type); } case PHI_NODE: @@ -1893,7 +2146,7 @@ get_strlen (tree arg, tree *length, bitmap visited) if (arg == PHI_RESULT (def_stmt)) continue; - if (!get_strlen (arg, length, visited)) + if (!get_maxval_strlen (arg, length, visited, type)) return false; } @@ -1915,9 +2168,9 @@ get_strlen (tree arg, tree *length, bitmap visited) static tree ccp_fold_builtin (tree stmt, tree fn) { - tree result, strlen_val[2]; + tree result, val[3]; tree callee, arglist, a; - int strlen_arg, i; + int arg_mask, i, type; bitmap visited; bool ignore; @@ -1925,22 +2178,22 @@ ccp_fold_builtin (tree stmt, tree fn) /* First try the generic builtin folder. If that succeeds, return the result directly. */ - result = fold_builtin (fn, ignore); + callee = get_callee_fndecl (fn); + arglist = TREE_OPERAND (fn, 1); + result = fold_builtin (callee, arglist, ignore); if (result) - { - if (ignore) - STRIP_NOPS (result); - return result; - } + { + if (ignore) + STRIP_NOPS (result); + return result; + } /* Ignore MD builtins. */ - callee = get_callee_fndecl (fn); if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD) return NULL_TREE; /* If the builtin could not be folded, and it has no argument list, we're done. */ - arglist = TREE_OPERAND (fn, 1); if (!arglist) return NULL_TREE; @@ -1950,11 +2203,31 @@ ccp_fold_builtin (tree stmt, tree fn) case BUILT_IN_STRLEN: case BUILT_IN_FPUTS: case BUILT_IN_FPUTS_UNLOCKED: - strlen_arg = 1; + arg_mask = 1; + type = 0; break; case BUILT_IN_STRCPY: case BUILT_IN_STRNCPY: - strlen_arg = 2; + arg_mask = 2; + type = 0; + break; + case BUILT_IN_MEMCPY_CHK: + case BUILT_IN_MEMPCPY_CHK: + case BUILT_IN_MEMMOVE_CHK: + case BUILT_IN_MEMSET_CHK: + case BUILT_IN_STRNCPY_CHK: + arg_mask = 4; + type = 2; + break; + case BUILT_IN_STRCPY_CHK: + case BUILT_IN_STPCPY_CHK: + arg_mask = 2; + type = 1; + break; + case BUILT_IN_SNPRINTF_CHK: + case BUILT_IN_VSNPRINTF_CHK: + arg_mask = 2; + type = 2; break; default: return NULL_TREE; @@ -1963,15 +2236,15 @@ ccp_fold_builtin (tree stmt, tree fn) /* Try to use the dataflow information gathered by the CCP process. */ visited = BITMAP_ALLOC (NULL); - memset (strlen_val, 0, sizeof (strlen_val)); + memset (val, 0, sizeof (val)); for (i = 0, a = arglist; - strlen_arg; - i++, strlen_arg >>= 1, a = TREE_CHAIN (a)) - if (strlen_arg & 1) + arg_mask; + i++, arg_mask >>= 1, a = TREE_CHAIN (a)) + if (arg_mask & 1) { bitmap_clear (visited); - if (!get_strlen (TREE_VALUE (a), &strlen_val[i], visited)) - strlen_val[i] = NULL_TREE; + if (!get_maxval_strlen (TREE_VALUE (a), &val[i], visited, type)) + val[i] = NULL_TREE; } BITMAP_FREE (visited); @@ -1980,9 +2253,9 @@ ccp_fold_builtin (tree stmt, tree fn) switch (DECL_FUNCTION_CODE (callee)) { case BUILT_IN_STRLEN: - if (strlen_val[0]) + if (val[0]) { - tree new = fold_convert (TREE_TYPE (fn), strlen_val[0]); + tree new = fold_convert (TREE_TYPE (fn), val[0]); /* If the result is not a valid gimple value, or not a cast of a valid gimple value, then we can not use the result. */ @@ -1994,25 +2267,53 @@ ccp_fold_builtin (tree stmt, tree fn) break; case BUILT_IN_STRCPY: - if (strlen_val[1] && is_gimple_val (strlen_val[1])) - result = fold_builtin_strcpy (fn, strlen_val[1]); + if (val[1] && is_gimple_val (val[1])) + result = fold_builtin_strcpy (callee, arglist, val[1]); break; case BUILT_IN_STRNCPY: - if (strlen_val[1] && is_gimple_val (strlen_val[1])) - result = fold_builtin_strncpy (fn, strlen_val[1]); + if (val[1] && is_gimple_val (val[1])) + result = fold_builtin_strncpy (callee, arglist, val[1]); break; case BUILT_IN_FPUTS: result = fold_builtin_fputs (arglist, TREE_CODE (stmt) != MODIFY_EXPR, 0, - strlen_val[0]); + val[0]); break; case BUILT_IN_FPUTS_UNLOCKED: result = fold_builtin_fputs (arglist, TREE_CODE (stmt) != MODIFY_EXPR, 1, - strlen_val[0]); + val[0]); + break; + + case BUILT_IN_MEMCPY_CHK: + case BUILT_IN_MEMPCPY_CHK: + case BUILT_IN_MEMMOVE_CHK: + case BUILT_IN_MEMSET_CHK: + if (val[2] && is_gimple_val (val[2])) + result = fold_builtin_memory_chk (callee, arglist, val[2], ignore, + DECL_FUNCTION_CODE (callee)); + break; + + case BUILT_IN_STRCPY_CHK: + case BUILT_IN_STPCPY_CHK: + if (val[1] && is_gimple_val (val[1])) + result = fold_builtin_stxcpy_chk (callee, arglist, val[1], ignore, + DECL_FUNCTION_CODE (callee)); + break; + + case BUILT_IN_STRNCPY_CHK: + if (val[2] && is_gimple_val (val[2])) + result = fold_builtin_strncpy_chk (arglist, val[2]); + break; + + case BUILT_IN_SNPRINTF_CHK: + case BUILT_IN_VSNPRINTF_CHK: + if (val[1] && is_gimple_val (val[1])) + result = fold_builtin_snprintf_chk (arglist, val[1], + DECL_FUNCTION_CODE (callee)); break; default: @@ -2025,7 +2326,7 @@ ccp_fold_builtin (tree stmt, tree fn) } -/* Fold the statement pointed by STMT_P. In some cases, this function may +/* Fold the statement pointed to by STMT_P. In some cases, this function may replace the whole statement with a new one. Returns true iff folding makes any changes. */ @@ -2033,13 +2334,18 @@ bool fold_stmt (tree *stmt_p) { tree rhs, result, stmt; + struct fold_stmt_r_data fold_stmt_r_data; bool changed = false; + bool inside_addr_expr = false; + + fold_stmt_r_data.changed_p = &changed; + fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; 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)) + if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL)) { *stmt_p = build_function_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], @@ -2069,7 +2375,9 @@ fold_stmt (tree *stmt_p) /* ??? 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. */ + here where we can just smash the call operand. Also + CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and + copied, fold_ternary does not have not information. */ callee = TREE_OPERAND (rhs, 0); if (TREE_CODE (callee) == OBJ_TYPE_REF && lang_hooks.fold_obj_type_ref @@ -2110,6 +2418,38 @@ fold_stmt (tree *stmt_p) return changed; } +/* Perform the minimal folding on statement STMT. Only operations like + *&x created by constant propagation are handled. The statement cannot + be replaced with a new one. */ + +bool +fold_stmt_inplace (tree stmt) +{ + tree old_stmt = stmt, rhs, new_rhs; + struct fold_stmt_r_data fold_stmt_r_data; + bool changed = false; + bool inside_addr_expr = false; + + fold_stmt_r_data.changed_p = &changed; + fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; + + walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL); + gcc_assert (stmt == old_stmt); + + rhs = get_rhs (stmt); + if (!rhs || rhs == stmt) + return changed; + + new_rhs = fold (rhs); + STRIP_USELESS_TYPE_CONVERSION (new_rhs); + if (new_rhs == rhs) + return changed; + + changed |= set_rhs (&stmt, new_rhs); + gcc_assert (stmt == old_stmt); + + return changed; +} /* Convert EXPR into a GIMPLE value suitable for substitution on the RHS of an assignment. Insert the necessary statements before @@ -2126,18 +2466,19 @@ convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr) tmp = get_initialized_tmp_var (expr, &stmts, NULL); pop_gimplify_context (NULL); + if (EXPR_HAS_LOCATION (stmt)) + annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt)); + /* The replacement can expose previously unreferenced variables. */ for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti)) { + tree new_stmt = tsi_stmt (ti); find_new_referenced_vars (tsi_stmt_ptr (ti)); - mark_new_vars_to_rename (tsi_stmt (ti), vars_to_rename); + bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT); + mark_new_vars_to_rename (bsi_stmt (*si_p)); + bsi_next (si_p); } - if (EXPR_HAS_LOCATION (stmt)) - annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt)); - - bsi_insert_before (si_p, stmts, BSI_SAME_STMT); - return tmp; } @@ -2145,7 +2486,7 @@ convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr) /* 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 +static unsigned int execute_fold_all_builtins (void) { bool cfg_changed = false; @@ -2153,17 +2494,26 @@ execute_fold_all_builtins (void) FOR_EACH_BB (bb) { block_stmt_iterator i; - for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) + for (i = bsi_start (bb); !bsi_end_p (i); ) { tree *stmtp = bsi_stmt_ptr (i); + tree old_stmt = *stmtp; tree call = get_rhs (*stmtp); tree callee, result; + enum built_in_function fcode; if (!call || TREE_CODE (call) != CALL_EXPR) - continue; + { + bsi_next (&i); + continue; + } callee = get_callee_fndecl (call); if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) - continue; + { + bsi_next (&i); + continue; + } + fcode = DECL_FUNCTION_CODE (callee); result = ccp_fold_builtin (*stmtp, call); if (!result) @@ -2177,6 +2527,7 @@ execute_fold_all_builtins (void) break; default: + bsi_next (&i); continue; } @@ -2189,11 +2540,15 @@ execute_fold_all_builtins (void) if (!set_rhs (stmtp, result)) { result = convert_to_gimple_builtin (&i, result); - if (result && !set_rhs (stmtp, result)) - abort (); + if (result) + { + bool ok = set_rhs (stmtp, result); + + gcc_assert (ok); + } } - modify_stmt (*stmtp); - if (maybe_clean_eh_stmt (*stmtp) + mark_new_vars_to_rename (*stmtp); + if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp) && tree_purge_dead_eh_edges (bb)) cfg_changed = true; @@ -2203,12 +2558,27 @@ execute_fold_all_builtins (void) print_generic_stmt (dump_file, *stmtp, dump_flags); fprintf (dump_file, "\n"); } + + /* Retry the same statement if it changed into another + builtin, there might be new opportunities now. */ + call = get_rhs (*stmtp); + if (!call || TREE_CODE (call) != CALL_EXPR) + { + bsi_next (&i); + continue; + } + callee = get_callee_fndecl (call); + if (!callee + || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL + || DECL_FUNCTION_CODE (callee) == fcode) + bsi_next (&i); } } /* Delete unreachable blocks. */ if (cfg_changed) cleanup_tree_cfg (); + return 0; } @@ -2227,6 +2597,6 @@ struct tree_opt_pass pass_fold_builtins = 0, /* todo_flags_start */ TODO_dump_func | TODO_verify_ssa - | TODO_rename_vars, /* todo_flags_finish */ + | TODO_update_ssa, /* todo_flags_finish */ 0 /* letter */ };