/* If-conversion support.
- Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2010
Free Software Foundation, Inc.
This file is part of GCC.
rtx false_expr; /* test for then block insns */
rtx true_prob_val; /* probability of else block */
rtx false_prob_val; /* probability of then block */
- int n_insns;
+ rtx then_last_head = NULL_RTX; /* Last match at the head of THEN */
+ rtx else_last_head = NULL_RTX; /* Last match at the head of ELSE */
+ rtx then_first_tail = NULL_RTX; /* First match at the tail of THEN */
+ rtx else_first_tail = NULL_RTX; /* First match at the tail of ELSE */
+ int then_n_insns, else_n_insns, n_insns;
enum rtx_code false_code;
/* If test is comprised of && or || elements, and we've failed at handling
number of insns and see if it is small enough to convert. */
then_start = first_active_insn (then_bb);
then_end = last_active_insn (then_bb, TRUE);
- n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
+ then_n_insns = ce_info->num_then_insns = count_bb_insns (then_bb);
+ n_insns = then_n_insns;
max = MAX_CONDITIONAL_EXECUTE;
if (else_bb)
{
+ int n_matching;
+
max *= 2;
else_start = first_active_insn (else_bb);
else_end = last_active_insn (else_bb, TRUE);
- n_insns += ce_info->num_else_insns = count_bb_insns (else_bb);
+ else_n_insns = ce_info->num_else_insns = count_bb_insns (else_bb);
+ n_insns += else_n_insns;
+
+ /* Look for matching sequences at the head and tail of the two blocks,
+ and limit the range of insns to be converted if possible. */
+ n_matching = flow_find_cross_jump (then_bb, else_bb,
+ &then_first_tail, &else_first_tail);
+ if (then_first_tail == BB_HEAD (then_bb))
+ then_start = then_end = NULL_RTX;
+ if (else_first_tail == BB_HEAD (else_bb))
+ else_start = else_end = NULL_RTX;
+
+ if (n_matching > 0)
+ {
+ if (then_end)
+ then_end = prev_active_insn (then_first_tail);
+ if (else_end)
+ else_end = prev_active_insn (else_first_tail);
+ n_insns -= 2 * n_matching;
+ }
+
+ if (then_start && else_start)
+ {
+ int longest_match = MIN (then_n_insns - n_matching,
+ else_n_insns - n_matching);
+ n_matching
+ = flow_find_head_matching_sequence (then_bb, else_bb,
+ &then_last_head,
+ &else_last_head,
+ longest_match);
+
+ if (n_matching > 0)
+ {
+ rtx insn;
+
+ /* We won't pass the insns in the head sequence to
+ cond_exec_process_insns, so we need to test them here
+ to make sure that they don't clobber the condition. */
+ for (insn = BB_HEAD (then_bb);
+ insn != NEXT_INSN (then_last_head);
+ insn = NEXT_INSN (insn))
+ if (!LABEL_P (insn) && !NOTE_P (insn)
+ && !DEBUG_INSN_P (insn)
+ && modified_in_p (test_expr, insn))
+ return FALSE;
+ }
+
+ if (then_last_head == then_end)
+ then_start = then_end = NULL_RTX;
+ if (else_last_head == else_end)
+ else_start = else_end = NULL_RTX;
+
+ if (n_matching > 0)
+ {
+ if (then_start)
+ then_start = next_active_insn (then_last_head);
+ if (else_start)
+ else_start = next_active_insn (else_last_head);
+ n_insns -= 2 * n_matching;
+ }
+ }
}
if (n_insns > max)
fprintf (dump_file, "%d insn%s converted to conditional execution.\n",
n_insns, (n_insns == 1) ? " was" : "s were");
- /* Merge the blocks! */
+ /* Merge the blocks! If we had matching sequences, make sure to delete one
+ copy at the appropriate location first: delete the copy in the THEN branch
+ for a tail sequence so that the remaining one is executed last for both
+ branches, and delete the copy in the ELSE branch for a head sequence so
+ that the remaining one is executed first for both branches. */
+ if (then_first_tail)
+ {
+ rtx from = then_first_tail;
+ if (!INSN_P (from))
+ from = next_active_insn (from);
+ delete_insn_chain (from, BB_END (then_bb), false);
+ }
+ if (else_last_head)
+ delete_insn_chain (first_active_insn (else_bb), else_last_head, false);
+
merge_if_block (ce_info);
cond_exec_changed_p = TRUE;
return TRUE;
if (! note)
continue;
set = single_set (insn);
- if (!set || !function_invariant_p (SET_SRC (set)))
+ if (!set || !function_invariant_p (SET_SRC (set))
+ || !function_invariant_p (XEXP (note, 0)))
remove_note (insn, note);
} while (insn != end && (insn = NEXT_INSN (insn)));
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