contains a wild read, the use_rec will be null. */
bool wild_read;
- /* This field is set for const function calls. Const functions
- cannot read memory, but they can read the stack because that is
- where they may get their parms. So having this set is less
- severe than a wild read, it just means that all of the stores to
- the stack are killed rather than all stores. */
- bool stack_read;
+ /* This field is only used for the processing of const functions.
+ These functions cannot read memory, but they can read the stack
+ because that is where they may get their parms. We need to be
+ this conservative because, like the store motion pass, we don't
+ consider CALL_INSN_FUNCTION_USAGE when processing call insns.
+ Moreover, we need to distinguish two cases:
+ 1. Before reload (register elimination), the stores related to
+ outgoing arguments are stack pointer based and thus deemed
+ of non-constant base in this pass. This requires special
+ handling but also means that the frame pointer based stores
+ need not be killed upon encountering a const function call.
+ 2. After reload, the stores related to outgoing arguments can be
+ either stack pointer or hard frame pointer based. This means
+ that we have no other choice than also killing all the frame
+ pointer based stores upon encountering a const function call.
+ This field is set after reload for const function calls. Having
+ this set is less severe than a wild read, it just means that all
+ the frame related stores are killed rather than all the stores. */
+ bool frame_read;
+
+ /* This field is only used for the processing of const functions.
+ It is set if the insn may contain a stack pointer based store. */
+ bool stack_pointer_based;
/* This is true if any of the sets within the store contains a
cselib base. Such stores can only be deleted by the local
}
-/* Return true if X is a constant or one of the registers that behaves
- as a constant over the life of a function. */
+/* Return true if X is a constant or one of the registers that behave
+ as a constant over the life of a function. This is equivalent to
+ !rtx_varies_p for memory addresses. */
static bool
const_or_frame_p (rtx x)
}
else
{
- store_info = pool_alloc (cse_store_info_pool);
+ rtx base_term = find_base_term (XEXP (mem, 0));
+ if (!base_term
+ || (GET_CODE (base_term) == ADDRESS
+ && GET_MODE (base_term) == Pmode
+ && XEXP (base_term, 0) == stack_pointer_rtx))
+ insn_info->stack_pointer_based = true;
insn_info->contains_cselib_groups = true;
+
+ store_info = pool_alloc (cse_store_info_pool);
group_id = -1;
if (dump_file)
{
enum machine_mode store_mode = GET_MODE (store_info->mem);
enum machine_mode read_mode = GET_MODE (read_info->mem);
+ rtx chosen_seq = NULL;
/* Some machines like the x86 have shift insns for each size of
operand. Other machines like the ppc or the ia-64 may only have
for (; access_size <= UNITS_PER_WORD; access_size *= 2)
{
- rtx target, new_reg;
+ rtx target, new_reg, shift_seq, insn;
enum machine_mode new_mode;
+ int cost;
/* Try a wider mode if truncating the store mode to ACCESS_SIZE
bytes requires a real instruction. */
continue;
new_mode = smallest_mode_for_size (access_size * BITS_PER_UNIT,
- GET_MODE_CLASS (read_mode));
+ MODE_INT);
new_reg = gen_reg_rtx (new_mode);
start_sequence ();
target = expand_binop (new_mode, lshr_optab, new_reg,
GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
- if (target == new_reg)
- {
- rtx shift_seq = get_insns ();
- end_sequence ();
+ shift_seq = get_insns ();
+ end_sequence ();
- /* If cost is too great, set target to NULL and
- let the iteration happen. */
- if (shift_seq != NULL)
- {
- int cost = 0;
- rtx insn;
-
- for (insn = shift_seq; insn != NULL_RTX; insn = NEXT_INSN (insn))
- if (INSN_P (insn))
- cost += insn_rtx_cost (PATTERN (insn));
-
- /* The computation up to here is essentially independent
- of the arguments and could be precomputed. It may
- not be worth doing so. We could precompute if
- worthwhile or at least cache the results. The result
- technically depends on SHIFT, ACCESS_SIZE, and
- GET_MODE_CLASS (READ_MODE). But in practice the
- answer will depend only on ACCESS_SIZE. */
-
- if (cost <= COSTS_N_INSNS (1))
- {
- /* We found an acceptable shift. Generate a move to
- take the value from the store and put it into the
- shift pseudo, then shift it, then generate another
- move to put in into the target of the read. */
- start_sequence ();
- emit_move_insn (new_reg, gen_lowpart (new_mode, store_info->rhs));
- emit_insn (shift_seq);
- convert_move (read_reg, new_reg, 1);
+ if (target != new_reg || shift_seq == NULL)
+ continue;
+
+ cost = 0;
+ for (insn = shift_seq; insn != NULL_RTX; insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ cost += insn_rtx_cost (PATTERN (insn));
+
+ /* The computation up to here is essentially independent
+ of the arguments and could be precomputed. It may
+ not be worth doing so. We could precompute if
+ worthwhile or at least cache the results. The result
+ technically depends on both SHIFT and ACCESS_SIZE,
+ but in practice the answer will depend only on ACCESS_SIZE. */
+
+ if (cost > COSTS_N_INSNS (1))
+ continue;
+
+ /* We found an acceptable shift. Generate a move to
+ take the value from the store and put it into the
+ shift pseudo, then shift it, then generate another
+ move to put in into the target of the read. */
+ start_sequence ();
+ emit_move_insn (new_reg, gen_lowpart (new_mode, store_info->rhs));
+ emit_insn (shift_seq);
+ convert_move (read_reg, new_reg, 1);
- if (dump_file)
- {
- fprintf (dump_file, " -- adding extract insn r%d:%s = r%d:%s\n",
- REGNO (new_reg), GET_MODE_NAME (new_mode),
- REGNO (store_info->rhs), GET_MODE_NAME (store_mode));
+ if (dump_file)
+ {
+ fprintf (dump_file, " -- adding extract insn r%d:%s = r%d:%s\n",
+ REGNO (new_reg), GET_MODE_NAME (new_mode),
+ REGNO (store_info->rhs), GET_MODE_NAME (store_mode));
- fprintf (dump_file, " -- with shift of r%d by %d\n",
- REGNO(new_reg), shift);
- fprintf (dump_file, " -- and second extract insn r%d:%s = r%d:%s\n",
- REGNO (read_reg), GET_MODE_NAME (read_mode),
- REGNO (new_reg), GET_MODE_NAME (new_mode));
- }
-
- /* Get the three insn sequence and return it. */
- shift_seq = get_insns ();
- end_sequence ();
- return shift_seq;
- }
- }
+ fprintf (dump_file, " -- with shift of r%d by %d\n",
+ REGNO(new_reg), shift);
+ fprintf (dump_file, " -- and second extract insn r%d:%s = r%d:%s\n",
+ REGNO (read_reg), GET_MODE_NAME (read_mode),
+ REGNO (new_reg), GET_MODE_NAME (new_mode));
}
- else
- /* End the sequence. */
- end_sequence ();
+
+ /* Get the three insn sequence and return it. */
+ chosen_seq = get_insns ();
+ end_sequence ();
+ break;
}
- return NULL;
+ return chosen_seq;
}
if (!dbg_cnt (dse))
return false;
- if (GET_MODE_CLASS (read_mode) != GET_MODE_CLASS (store_mode))
+ if (GET_MODE_CLASS (read_mode) != MODE_INT
+ || GET_MODE_CLASS (store_mode) != MODE_INT)
return false;
/* To get here the read is within the boundaries of the write so
call to get rid of the read. */
if (shift)
{
- if (access_size > UNITS_PER_WORD || FLOAT_MODE_P (store_mode))
+ if (access_size > UNITS_PER_WORD)
return false;
shift_seq = find_shift_sequence (read_reg, access_size, store_info,
if (CALL_P (insn))
{
insn_info->cannot_delete = true;
+
/* Const functions cannot do anything bad i.e. read memory,
- however, they can read their parameters which may have been
- pushed onto the stack. */
+ however, they can read their parameters which may have
+ been pushed onto the stack. */
if (CONST_OR_PURE_CALL_P (insn) && !pure_call_p (insn))
{
insn_info_t i_ptr = active_local_stores;
if (dump_file)
fprintf (dump_file, "const call %d\n", INSN_UID (insn));
+ /* See the head comment of the frame_read field. */
+ if (reload_completed)
+ insn_info->frame_read = true;
+
+ /* Loop over the active stores and remove those which are
+ killed by the const function call. */
while (i_ptr)
{
- store_info_t store_info = i_ptr->store_rec;
+ bool remove_store = false;
- /* Skip the clobbers. */
- while (!store_info->is_set)
- store_info = store_info->next;
+ /* The stack pointer based stores are always killed. */
+ if (i_ptr->stack_pointer_based)
+ remove_store = true;
+
+ /* If the frame is read, the frame related stores are killed. */
+ else if (insn_info->frame_read)
+ {
+ store_info_t store_info = i_ptr->store_rec;
+
+ /* Skip the clobbers. */
+ while (!store_info->is_set)
+ store_info = store_info->next;
- /* Remove the frame related stores. */
- if (store_info->group_id >= 0
- && VEC_index (group_info_t, rtx_group_vec, store_info->group_id)->frame_related)
+ if (store_info->group_id >= 0
+ && VEC_index (group_info_t, rtx_group_vec,
+ store_info->group_id)->frame_related)
+ remove_store = true;
+ }
+
+ if (remove_store)
{
if (dump_file)
dump_insn_info ("removing from active", i_ptr);
}
else
last = i_ptr;
+
i_ptr = i_ptr->next_local_store;
}
-
- insn_info->stack_read = true;
-
- return;
}
- /* Every other call, including pure functions may read memory. */
- add_wild_read (bb_info);
+ else
+ /* Every other call, including pure functions, may read memory. */
+ add_wild_read (bb_info);
+
return;
}
/* Assuming that there are sets in these insns, we cannot delete
them. */
if ((GET_CODE (PATTERN (insn)) == CLOBBER)
- || volatile_insn_p (PATTERN (insn))
+ || volatile_refs_p (PATTERN (insn))
|| (flag_non_call_exceptions && may_trap_p (PATTERN (insn)))
|| (RTX_FRAME_RELATED_P (insn))
|| find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX))
int i;
group_info_t group;
- /* For const function calls kill the stack related stores. */
- if (insn_info->stack_read)
+ /* If this insn reads the frame, kill all the frame related stores. */
+ if (insn_info->frame_read)
{
for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
if (group->process_globally && group->frame_related)
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