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ifcvt.c (struct noce_if_info): Add comments to the fields.

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* ifcvt.c (struct noce_if_info): Add comments to the fields.
	Remove the b_unconditional field.
	(noce_try_sign_mask): Do not look at b_unconditional.
	(noce_process_if_block): Do not use merge_if_blocks.  Update
	the CFG here.  Do not set b_unconditional.
	(cond_move_process_if_block): Likewise.
	(find_cond_trap): Likewise.
	(check_cond_move_block): Require simple jump insns at the end
	of the basic block.

From-SVN: r120686
This commit is contained in:
Steven Bosscher 2007-01-11 21:26:02 +00:00
parent 90d715b0a5
commit 2a33a75f60
2 changed files with 107 additions and 53 deletions
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12
gcc/ChangeLog
View File

@ -1,3 +1,15 @@
2007-01-11 Steven Bosscher <steven@gcc.gnu.org>
* ifcvt.c (struct noce_if_info): Add comments to the fields.
Remove the b_unconditional field.
(noce_try_sign_mask): Do not look at b_unconditional.
(noce_process_if_block): Do not use merge_if_blocks. Update
the CFG here. Do not set b_unconditional.
(cond_move_process_if_block): Likewise.
(find_cond_trap): Likewise.
(check_cond_move_block): Require simple jump insns at the end
of the basic block.
2007-01-11 Jan Hubicka <jh@suse.cz>
PR tree-optimization/1046

148
gcc/ifcvt.c
View File

@ -596,12 +596,31 @@ cond_exec_process_if_block (ce_if_block_t * ce_info,
struct noce_if_info
{
/* A basic block that ends in a simple conditional jump. */
basic_block test_bb;
/* The jump that ends TEST_BB. */
rtx jump;
/* The jump condition. */
rtx cond;
/* New insns should be inserted before this one. */
rtx cond_earliest;
/* Insns in the THEN and ELSE block. There is always just this
one insns in those blocks. The insns are single_set insns.
If there was no ELSE block, INSN_B is the last insn before
COND_EARLIEST, or NULL_RTX. In the former case, the insn
operands are still valid, as if INSN_B was moved down below
the jump. */
rtx insn_a, insn_b;
rtx x, a, b;
rtx jump, cond, cond_earliest;
/* True if "b" was originally evaluated unconditionally. */
bool b_unconditional;
/* The SET_SRC of INSN_A and INSN_B. */
rtx a, b;
/* The SET_DEST of INSN_A. */
rtx x;
};
static rtx noce_emit_store_flag (struct noce_if_info *, rtx, int, int);
@ -1877,9 +1896,10 @@ noce_try_sign_mask (struct noce_if_info *if_info)
return FALSE;
/* This is only profitable if T is cheap, or T is unconditionally
executed/evaluated in the original insn sequence. */
executed/evaluated in the original insn sequence. The latter
happens if INSN_B was taken from TEST_BB. */
if (rtx_cost (t, SET) >= COSTS_N_INSNS (2)
&& (!if_info->b_unconditional
&& (BLOCK_FOR_INSN (if_info->insn_b) != if_info->test_bb
|| t != if_info->b))
return FALSE;
@ -2173,6 +2193,7 @@ noce_process_if_block (struct ce_if_block * ce_info)
basic_block test_bb = ce_info->test_bb; /* test block */
basic_block then_bb = ce_info->then_bb; /* THEN */
basic_block else_bb = ce_info->else_bb; /* ELSE or NULL */
basic_block join_bb;
struct noce_if_info if_info;
rtx insn_a, insn_b;
rtx set_a, set_b;
@ -2283,7 +2304,6 @@ noce_process_if_block (struct ce_if_block * ce_info)
if_info.x = x;
if_info.a = a;
if_info.b = b;
if_info.b_unconditional = else_bb == 0;
/* Try optimizations in some approximation of a useful order. */
/* ??? Should first look to see if X is live incoming at all. If it
@ -2364,39 +2384,47 @@ noce_process_if_block (struct ce_if_block * ce_info)
return FALSE;
success:
/* The original sets may now be killed. */
delete_insn (insn_a);
/* Several special cases here: First, we may have reused insn_b above,
in which case insn_b is now NULL. Second, we want to delete insn_b
if it came from the ELSE block, because follows the now correct
write that appears in the TEST block. However, if we got insn_b from
the TEST block, it may in fact be loading data needed for the comparison.
We'll let life_analysis remove the insn if it's really dead. */
if (insn_b && else_bb)
delete_insn (insn_b);
/* The new insns will have been inserted immediately before the jump. We
should be able to remove the jump with impunity, but the condition itself
may have been modified by gcse to be shared across basic blocks. */
delete_insn (jump);
/* If we used a temporary, fix it up now. */
if (orig_x != x)
{
rtx seq;
start_sequence ();
noce_emit_move_insn (orig_x, x);
insn_b = get_insns ();
seq = get_insns ();
set_used_flags (orig_x);
unshare_all_rtl_in_chain (insn_b);
unshare_all_rtl_in_chain (seq);
end_sequence ();
emit_insn_after_setloc (insn_b, BB_END (test_bb), INSN_LOCATOR (insn_a));
emit_insn_before_setloc (seq, BB_END (test_bb), INSN_LOCATOR (insn_a));
}
/* Merge the blocks! */
merge_if_block (ce_info);
/* The original THEN and ELSE blocks may now be removed. The test block
must now jump to the join block. If the test block and the join block
can be merged, do so. */
join_bb = single_succ (then_bb);
if (else_bb)
{
delete_basic_block (else_bb);
num_true_changes++;
}
else
remove_edge (find_edge (test_bb, join_bb));
remove_edge (find_edge (then_bb, join_bb));
redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
delete_basic_block (then_bb);
num_true_changes++;
if (can_merge_blocks_p (test_bb, join_bb))
{
merge_blocks (test_bb, join_bb);
num_true_changes++;
}
num_updated_if_blocks++;
return TRUE;
}
@ -2463,6 +2491,12 @@ check_cond_move_block (basic_block bb, rtx *vals, rtx cond)
return FALSE;
}
/* We can only handle simple jumps at the end of the basic block.
It is almost impossible to update the CFG otherwise. */
insn = BB_END (bb);
if (JUMP_P (insn) && ! onlyjump_p (insn))
return FALSE;
return TRUE;
}
@ -2537,10 +2571,12 @@ cond_move_convert_if_block (struct noce_if_info *if_infop,
static int
cond_move_process_if_block (struct ce_if_block *ce_info)
{
basic_block test_bb = ce_info->test_bb;
basic_block then_bb = ce_info->then_bb;
basic_block else_bb = ce_info->else_bb;
basic_block join_bb;
struct noce_if_info if_info;
rtx jump, cond, insn, seq, loc_insn;
rtx jump, cond, seq, loc_insn;
int max_reg, size, c, i;
rtx *then_vals;
rtx *else_vals;
@ -2624,21 +2660,30 @@ cond_move_process_if_block (struct ce_if_block *ce_info)
}
emit_insn_before_setloc (seq, jump, INSN_LOCATOR (loc_insn));
FOR_BB_INSNS (then_bb, insn)
if (INSN_P (insn) && !JUMP_P (insn))
delete_insn (insn);
join_bb = single_succ (then_bb);
if (else_bb)
{
FOR_BB_INSNS (else_bb, insn)
if (INSN_P (insn) && !JUMP_P (insn))
delete_insn (insn);
delete_basic_block (else_bb);
num_true_changes++;
}
delete_insn (jump);
else
remove_edge (find_edge (test_bb, join_bb));
merge_if_block (ce_info);
remove_edge (find_edge (then_bb, join_bb));
redirect_edge_and_branch_force (single_succ_edge (test_bb), join_bb);
delete_basic_block (then_bb);
num_true_changes++;
if (can_merge_blocks_p (test_bb, join_bb))
{
merge_blocks (test_bb, join_bb);
num_true_changes++;
}
num_updated_if_blocks++;
return TRUE;
}
/* Attempt to convert an IF-THEN or IF-THEN-ELSE block into
straight line code. Return true if successful. */
@ -3201,29 +3246,20 @@ find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
if (seq == NULL)
return FALSE;
num_true_changes++;
/* Emit the new insns before cond_earliest. */
emit_insn_before_setloc (seq, cond_earliest, INSN_LOCATOR (trap));
/* Delete the trap block if possible. */
remove_edge (trap_bb == then_bb ? then_edge : else_edge);
if (EDGE_COUNT (trap_bb->preds) == 0)
delete_basic_block (trap_bb);
/* If the non-trap block and the test are now adjacent, merge them.
Otherwise we must insert a direct branch. */
if (test_bb->next_bb == other_bb)
{
struct ce_if_block new_ce_info;
delete_insn (jump);
memset (&new_ce_info, '\0', sizeof (new_ce_info));
new_ce_info.test_bb = test_bb;
new_ce_info.then_bb = NULL;
new_ce_info.else_bb = NULL;
new_ce_info.join_bb = other_bb;
merge_if_block (&new_ce_info);
delete_basic_block (trap_bb);
num_true_changes++;
}
/* Wire together the blocks again. */
if (current_ir_type () == IR_RTL_CFGLAYOUT)
single_succ_edge (test_bb)->flags |= EDGE_FALLTHRU;
else
{
rtx lab, newjump;
@ -3233,10 +3269,16 @@ find_cond_trap (basic_block test_bb, edge then_edge, edge else_edge)
LABEL_NUSES (lab) += 1;
JUMP_LABEL (newjump) = lab;
emit_barrier_after (newjump);
}
delete_insn (jump);
delete_insn (jump);
if (can_merge_blocks_p (test_bb, other_bb))
{
merge_blocks (test_bb, other_bb);
num_true_changes++;
}
num_updated_if_blocks++;
return TRUE;
}