/* Control flow optimization code for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.
This file is part of GCC.
and cold sections.
Basic block partitioning may result in some jumps that appear to
- be optimizable (or blocks that appear to be mergeable), but which really m
- ust be left untouched (they are required to make it safely across
+ be optimizable (or blocks that appear to be mergeable), but which really
+ must be left untouched (they are required to make it safely across
partition boundaries). See the comments at the top of
bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
return ninsns;
}
-/* Return true iff the condbranches at the end of BB1 and BB2 match. */
-bool
-condjump_equiv_p (struct equiv_info *info, bool call_init)
-{
- basic_block bb1 = info->x_block;
- basic_block bb2 = info->y_block;
- edge b1 = BRANCH_EDGE (bb1);
- edge b2 = BRANCH_EDGE (bb2);
- edge f1 = FALLTHRU_EDGE (bb1);
- edge f2 = FALLTHRU_EDGE (bb2);
- bool reverse, match;
- rtx set1, set2, cond1, cond2;
- rtx src1, src2;
- enum rtx_code code1, code2;
-
- /* Get around possible forwarders on fallthru edges. Other cases
- should be optimized out already. */
- if (FORWARDER_BLOCK_P (f1->dest))
- f1 = single_succ_edge (f1->dest);
-
- if (FORWARDER_BLOCK_P (f2->dest))
- f2 = single_succ_edge (f2->dest);
-
- /* To simplify use of this function, return false if there are
- unneeded forwarder blocks. These will get eliminated later
- during cleanup_cfg. */
- if (FORWARDER_BLOCK_P (f1->dest)
- || FORWARDER_BLOCK_P (f2->dest)
- || FORWARDER_BLOCK_P (b1->dest)
- || FORWARDER_BLOCK_P (b2->dest))
- return false;
-
- if (f1->dest == f2->dest && b1->dest == b2->dest)
- reverse = false;
- else if (f1->dest == b2->dest && b1->dest == f2->dest)
- reverse = true;
- else
- return false;
-
- set1 = pc_set (BB_END (bb1));
- set2 = pc_set (BB_END (bb2));
- if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
- != (XEXP (SET_SRC (set2), 1) == pc_rtx))
- reverse = !reverse;
-
- src1 = SET_SRC (set1);
- src2 = SET_SRC (set2);
- cond1 = XEXP (src1, 0);
- cond2 = XEXP (src2, 0);
- code1 = GET_CODE (cond1);
- if (reverse)
- code2 = reversed_comparison_code (cond2, BB_END (bb2));
- else
- code2 = GET_CODE (cond2);
-
- if (code2 == UNKNOWN)
- return false;
-
- if (call_init && !struct_equiv_init (STRUCT_EQUIV_START | info->mode, info))
- gcc_unreachable ();
- /* Make the sources of the pc sets unreadable so that when we call
- insns_match_p it won't process them.
- The death_notes_match_p from insns_match_p won't see the local registers
- used for the pc set, but that could only cause missed optimizations when
- there are actually condjumps that use stack registers. */
- SET_SRC (set1) = pc_rtx;
- SET_SRC (set2) = pc_rtx;
- /* Verify codes and operands match. */
- if (code1 == code2)
- {
- match = (insns_match_p (BB_END (bb1), BB_END (bb2), info)
- && rtx_equiv_p (&XEXP (cond1, 0), XEXP (cond2, 0), 1, info)
- && rtx_equiv_p (&XEXP (cond1, 1), XEXP (cond2, 1), 1, info));
-
- }
- else if (code1 == swap_condition (code2))
- {
- match = (insns_match_p (BB_END (bb1), BB_END (bb2), info)
- && rtx_equiv_p (&XEXP (cond1, 1), XEXP (cond2, 0), 1, info)
- && rtx_equiv_p (&XEXP (cond1, 0), XEXP (cond2, 1), 1, info));
-
- }
- else
- match = false;
- SET_SRC (set1) = src1;
- SET_SRC (set2) = src2;
- match &= verify_changes (0);
-
- /* If we return true, we will join the blocks. Which means that
- we will only have one branch prediction bit to work with. Thus
- we require the existing branches to have probabilities that are
- roughly similar. */
- if (match
- && !optimize_size
- && maybe_hot_bb_p (bb1)
- && maybe_hot_bb_p (bb2))
- {
- int prob2;
-
- if (b1->dest == b2->dest)
- prob2 = b2->probability;
- else
- /* Do not use f2 probability as f2 may be forwarded. */
- prob2 = REG_BR_PROB_BASE - b2->probability;
-
- /* Fail if the difference in probabilities is greater than 50%.
- This rules out two well-predicted branches with opposite
- outcomes. */
- if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2)
- {
- if (dump_file)
- fprintf (dump_file,
- "Outcomes of branch in bb %i and %i differ too much (%i %i)\n",
- bb1->index, bb2->index, b1->probability, prob2);
-
- match = false;
- }
- }
-
- if (dump_file && match)
- fprintf (dump_file, "Conditionals in bb %i and %i match.\n",
- bb1->index, bb2->index);
-
- if (!match)
- cancel_changes (0);
- return match;
-}
-
/* Return true iff outgoing edges of BB1 and BB2 match, together with
the branch instruction. This means that if we commonize the control
flow before end of the basic block, the semantic remains unchanged.
we require the existing branches to have probabilities that are
roughly similar. */
if (match
- && !optimize_size
- && maybe_hot_bb_p (bb1)
- && maybe_hot_bb_p (bb2))
+ && optimize_bb_for_speed_p (bb1)
+ && optimize_bb_for_speed_p (bb2))
{
int prob2;
/* Don't crossjump if this block ends in a computed jump,
unless we are optimizing for size. */
- if (!optimize_size
+ if (optimize_bb_for_size_p (bb)
&& bb != EXIT_BLOCK_PTR
&& computed_jump_p (BB_END (bb)))
return false;
{
delete_unreachable_blocks ();
- if (cfun->tail_call_emit)
+ if (crtl->tail_call_emit)
fixup_tail_calls ();
return 0;
}
-struct tree_opt_pass pass_jump =
+struct rtl_opt_pass pass_jump =
{
+ {
+ RTL_PASS,
"sibling", /* name */
NULL, /* gate */
rest_of_handle_jump, /* execute */
0, /* properties_destroyed */
TODO_ggc_collect, /* todo_flags_start */
TODO_verify_flow, /* todo_flags_finish */
- 'i' /* letter */
+ }
};
}
-struct tree_opt_pass pass_jump2 =
+struct rtl_opt_pass pass_jump2 =
{
+ {
+ RTL_PASS,
"jump", /* name */
NULL, /* gate */
rest_of_handle_jump2, /* execute */
0, /* properties_destroyed */
TODO_ggc_collect, /* todo_flags_start */
TODO_dump_func | TODO_verify_rtl_sharing,/* todo_flags_finish */
- 'j' /* letter */
+ }
};
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