forked from illumos/gcc
/
cfglayout.c
1431 lines (1230 loc) · 36.7 KB
/
cfglayout.c
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/* Basic block reordering routines for the GNU compiler.
Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "hard-reg-set.h"
#include "obstack.h"
#include "basic-block.h"
#include "insn-config.h"
#include "output.h"
#include "function.h"
#include "cfglayout.h"
#include "cfgloop.h"
#include "target.h"
#include "ggc.h"
#include "alloc-pool.h"
#include "flags.h"
#include "tree-pass.h"
#include "df.h"
#include "vecprim.h"
/* Holds the interesting trailing notes for the function. */
rtx cfg_layout_function_footer;
rtx cfg_layout_function_header;
static rtx skip_insns_after_block (basic_block);
static void record_effective_endpoints (void);
static rtx label_for_bb (basic_block);
static void fixup_reorder_chain (void);
static void change_scope (rtx, tree, tree);
void verify_insn_chain (void);
static void fixup_fallthru_exit_predecessor (void);
static tree insn_scope (const_rtx);
rtx
unlink_insn_chain (rtx first, rtx last)
{
rtx prevfirst = PREV_INSN (first);
rtx nextlast = NEXT_INSN (last);
PREV_INSN (first) = NULL;
NEXT_INSN (last) = NULL;
if (prevfirst)
NEXT_INSN (prevfirst) = nextlast;
if (nextlast)
PREV_INSN (nextlast) = prevfirst;
else
set_last_insn (prevfirst);
if (!prevfirst)
set_first_insn (nextlast);
return first;
}
/* Skip over inter-block insns occurring after BB which are typically
associated with BB (e.g., barriers). If there are any such insns,
we return the last one. Otherwise, we return the end of BB. */
static rtx
skip_insns_after_block (basic_block bb)
{
rtx insn, last_insn, next_head, prev;
next_head = NULL_RTX;
if (bb->next_bb != EXIT_BLOCK_PTR)
next_head = BB_HEAD (bb->next_bb);
for (last_insn = insn = BB_END (bb); (insn = NEXT_INSN (insn)) != 0; )
{
if (insn == next_head)
break;
switch (GET_CODE (insn))
{
case BARRIER:
last_insn = insn;
continue;
case NOTE:
switch (NOTE_KIND (insn))
{
case NOTE_INSN_BLOCK_END:
gcc_unreachable ();
continue;
default:
continue;
break;
}
break;
case CODE_LABEL:
if (NEXT_INSN (insn)
&& JUMP_P (NEXT_INSN (insn))
&& (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
|| GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
{
insn = NEXT_INSN (insn);
last_insn = insn;
continue;
}
break;
default:
break;
}
break;
}
/* It is possible to hit contradictory sequence. For instance:
jump_insn
NOTE_INSN_BLOCK_BEG
barrier
Where barrier belongs to jump_insn, but the note does not. This can be
created by removing the basic block originally following
NOTE_INSN_BLOCK_BEG. In such case reorder the notes. */
for (insn = last_insn; insn != BB_END (bb); insn = prev)
{
prev = PREV_INSN (insn);
if (NOTE_P (insn))
switch (NOTE_KIND (insn))
{
case NOTE_INSN_BLOCK_END:
gcc_unreachable ();
break;
case NOTE_INSN_DELETED:
case NOTE_INSN_DELETED_LABEL:
continue;
default:
reorder_insns (insn, insn, last_insn);
}
}
return last_insn;
}
/* Locate or create a label for a given basic block. */
static rtx
label_for_bb (basic_block bb)
{
rtx label = BB_HEAD (bb);
if (!LABEL_P (label))
{
if (dump_file)
fprintf (dump_file, "Emitting label for block %d\n", bb->index);
label = block_label (bb);
}
return label;
}
/* Locate the effective beginning and end of the insn chain for each
block, as defined by skip_insns_after_block above. */
static void
record_effective_endpoints (void)
{
rtx next_insn;
basic_block bb;
rtx insn;
for (insn = get_insns ();
insn
&& NOTE_P (insn)
&& NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK;
insn = NEXT_INSN (insn))
continue;
/* No basic blocks at all? */
gcc_assert (insn);
if (PREV_INSN (insn))
cfg_layout_function_header =
unlink_insn_chain (get_insns (), PREV_INSN (insn));
else
cfg_layout_function_header = NULL_RTX;
next_insn = get_insns ();
FOR_EACH_BB (bb)
{
rtx end;
if (PREV_INSN (BB_HEAD (bb)) && next_insn != BB_HEAD (bb))
bb->il.rtl->header = unlink_insn_chain (next_insn,
PREV_INSN (BB_HEAD (bb)));
end = skip_insns_after_block (bb);
if (NEXT_INSN (BB_END (bb)) && BB_END (bb) != end)
bb->il.rtl->footer = unlink_insn_chain (NEXT_INSN (BB_END (bb)), end);
next_insn = NEXT_INSN (BB_END (bb));
}
cfg_layout_function_footer = next_insn;
if (cfg_layout_function_footer)
cfg_layout_function_footer = unlink_insn_chain (cfg_layout_function_footer, get_last_insn ());
}
/* Data structures representing mapping of INSN_LOCATOR into scope blocks, line
numbers and files. In order to be GGC friendly we need to use separate
varrays. This also slightly improve the memory locality in binary search.
The _locs array contains locators where the given property change. The
block_locators_blocks contains the scope block that is used for all insn
locator greater than corresponding block_locators_locs value and smaller
than the following one. Similarly for the other properties. */
static VEC(int,heap) *block_locators_locs;
static GTY(()) VEC(tree,gc) *block_locators_blocks;
static VEC(int,heap) *locations_locators_locs;
DEF_VEC_O(location_t);
DEF_VEC_ALLOC_O(location_t,heap);
static VEC(location_t,heap) *locations_locators_vals;
int prologue_locator;
int epilogue_locator;
/* Hold current location information and last location information, so the
datastructures are built lazily only when some instructions in given
place are needed. */
location_t curr_location, last_location;
static tree curr_block, last_block;
static int curr_rtl_loc = -1;
/* Allocate insn locator datastructure. */
void
insn_locators_alloc (void)
{
prologue_locator = epilogue_locator = 0;
block_locators_locs = VEC_alloc (int, heap, 32);
block_locators_blocks = VEC_alloc (tree, gc, 32);
locations_locators_locs = VEC_alloc (int, heap, 32);
locations_locators_vals = VEC_alloc (location_t, heap, 32);
last_location = -1;
curr_location = -1;
curr_block = NULL;
last_block = NULL;
curr_rtl_loc = 0;
}
/* At the end of emit stage, clear current location. */
void
insn_locators_finalize (void)
{
if (curr_rtl_loc >= 0)
epilogue_locator = curr_insn_locator ();
curr_rtl_loc = -1;
}
/* Allocate insn locator datastructure. */
void
insn_locators_free (void)
{
prologue_locator = epilogue_locator = 0;
VEC_free (int, heap, block_locators_locs);
VEC_free (tree,gc, block_locators_blocks);
VEC_free (int, heap, locations_locators_locs);
VEC_free (location_t, heap, locations_locators_vals);
}
/* Set current location. */
void
set_curr_insn_source_location (location_t location)
{
/* IV opts calls into RTL expansion to compute costs of operations. At this
time locators are not initialized. */
if (curr_rtl_loc == -1)
return;
if (location == last_location)
return;
curr_location = location;
}
/* Set current scope block. */
void
set_curr_insn_block (tree b)
{
/* IV opts calls into RTL expansion to compute costs of operations. At this
time locators are not initialized. */
if (curr_rtl_loc == -1)
return;
if (b)
curr_block = b;
}
/* Return current insn locator. */
int
curr_insn_locator (void)
{
if (curr_rtl_loc == -1)
return 0;
if (last_block != curr_block)
{
curr_rtl_loc++;
VEC_safe_push (int, heap, block_locators_locs, curr_rtl_loc);
VEC_safe_push (tree, gc, block_locators_blocks, curr_block);
last_block = curr_block;
}
if (last_location != curr_location)
{
curr_rtl_loc++;
VEC_safe_push (int, heap, locations_locators_locs, curr_rtl_loc);
VEC_safe_push (location_t, heap, locations_locators_vals, &curr_location);
last_location = curr_location;
}
return curr_rtl_loc;
}
static unsigned int
into_cfg_layout_mode (void)
{
cfg_layout_initialize (0);
return 0;
}
static unsigned int
outof_cfg_layout_mode (void)
{
basic_block bb;
FOR_EACH_BB (bb)
if (bb->next_bb != EXIT_BLOCK_PTR)
bb->aux = bb->next_bb;
cfg_layout_finalize ();
return 0;
}
struct rtl_opt_pass pass_into_cfg_layout_mode =
{
{
RTL_PASS,
"into_cfglayout", /* name */
NULL, /* gate */
into_cfg_layout_mode, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
0, /* tv_id */
0, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func, /* todo_flags_finish */
}
};
struct rtl_opt_pass pass_outof_cfg_layout_mode =
{
{
RTL_PASS,
"outof_cfglayout", /* name */
NULL, /* gate */
outof_cfg_layout_mode, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
0, /* tv_id */
0, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func, /* todo_flags_finish */
}
};
/* Return scope resulting from combination of S1 and S2. */
static tree
choose_inner_scope (tree s1, tree s2)
{
if (!s1)
return s2;
if (!s2)
return s1;
if (BLOCK_NUMBER (s1) > BLOCK_NUMBER (s2))
return s1;
return s2;
}
/* Emit lexical block notes needed to change scope from S1 to S2. */
static void
change_scope (rtx orig_insn, tree s1, tree s2)
{
rtx insn = orig_insn;
tree com = NULL_TREE;
tree ts1 = s1, ts2 = s2;
tree s;
while (ts1 != ts2)
{
gcc_assert (ts1 && ts2);
if (BLOCK_NUMBER (ts1) > BLOCK_NUMBER (ts2))
ts1 = BLOCK_SUPERCONTEXT (ts1);
else if (BLOCK_NUMBER (ts1) < BLOCK_NUMBER (ts2))
ts2 = BLOCK_SUPERCONTEXT (ts2);
else
{
ts1 = BLOCK_SUPERCONTEXT (ts1);
ts2 = BLOCK_SUPERCONTEXT (ts2);
}
}
com = ts1;
/* Close scopes. */
s = s1;
while (s != com)
{
rtx note = emit_note_before (NOTE_INSN_BLOCK_END, insn);
NOTE_BLOCK (note) = s;
s = BLOCK_SUPERCONTEXT (s);
}
/* Open scopes. */
s = s2;
while (s != com)
{
insn = emit_note_before (NOTE_INSN_BLOCK_BEG, insn);
NOTE_BLOCK (insn) = s;
s = BLOCK_SUPERCONTEXT (s);
}
}
/* Return lexical scope block locator belongs to. */
static tree
locator_scope (int loc)
{
int max = VEC_length (int, block_locators_locs);
int min = 0;
/* When block_locators_locs was initialized, the pro- and epilogue
insns didn't exist yet and can therefore not be found this way.
But we know that they belong to the outer most block of the
current function.
Without this test, the prologue would be put inside the block of
the first valid instruction in the function and when that first
insn is part of an inlined function then the low_pc of that
inlined function is messed up. Likewise for the epilogue and
the last valid instruction. */
if (loc == prologue_locator || loc == epilogue_locator)
return DECL_INITIAL (cfun->decl);
if (!max || !loc)
return NULL;
while (1)
{
int pos = (min + max) / 2;
int tmp = VEC_index (int, block_locators_locs, pos);
if (tmp <= loc && min != pos)
min = pos;
else if (tmp > loc && max != pos)
max = pos;
else
{
min = pos;
break;
}
}
return VEC_index (tree, block_locators_blocks, min);
}
/* Return lexical scope block insn belongs to. */
static tree
insn_scope (const_rtx insn)
{
return locator_scope (INSN_LOCATOR (insn));
}
/* Return line number of the statement specified by the locator. */
location_t
locator_location (int loc)
{
int max = VEC_length (int, locations_locators_locs);
int min = 0;
while (1)
{
int pos = (min + max) / 2;
int tmp = VEC_index (int, locations_locators_locs, pos);
if (tmp <= loc && min != pos)
min = pos;
else if (tmp > loc && max != pos)
max = pos;
else
{
min = pos;
break;
}
}
return *VEC_index (location_t, locations_locators_vals, min);
}
/* Return source line of the statement that produced this insn. */
int
locator_line (int loc)
{
expanded_location xloc;
if (!loc)
return 0;
else
xloc = expand_location (locator_location (loc));
return xloc.line;
}
/* Return line number of the statement that produced this insn. */
int
insn_line (const_rtx insn)
{
return locator_line (INSN_LOCATOR (insn));
}
/* Return source file of the statement specified by LOC. */
const char *
locator_file (int loc)
{
expanded_location xloc;
if (!loc)
return 0;
else
xloc = expand_location (locator_location (loc));
return xloc.file;
}
/* Return source file of the statement that produced this insn. */
const char *
insn_file (const_rtx insn)
{
return locator_file (INSN_LOCATOR (insn));
}
/* Return true if LOC1 and LOC2 locators have the same location and scope. */
bool
locator_eq (int loc1, int loc2)
{
if (loc1 == loc2)
return true;
if (locator_location (loc1) != locator_location (loc2))
return false;
return locator_scope (loc1) == locator_scope (loc2);
}
/* Rebuild all the NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes based
on the scope tree and the newly reordered instructions. */
void
reemit_insn_block_notes (void)
{
tree cur_block = DECL_INITIAL (cfun->decl);
rtx insn, note;
insn = get_insns ();
if (!active_insn_p (insn))
insn = next_active_insn (insn);
for (; insn; insn = next_active_insn (insn))
{
tree this_block;
/* Avoid putting scope notes between jump table and its label. */
if (JUMP_P (insn)
&& (GET_CODE (PATTERN (insn)) == ADDR_VEC
|| GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
continue;
this_block = insn_scope (insn);
/* For sequences compute scope resulting from merging all scopes
of instructions nested inside. */
if (GET_CODE (PATTERN (insn)) == SEQUENCE)
{
int i;
rtx body = PATTERN (insn);
this_block = NULL;
for (i = 0; i < XVECLEN (body, 0); i++)
this_block = choose_inner_scope (this_block,
insn_scope (XVECEXP (body, 0, i)));
}
if (! this_block)
continue;
if (this_block != cur_block)
{
change_scope (insn, cur_block, this_block);
cur_block = this_block;
}
}
/* change_scope emits before the insn, not after. */
note = emit_note (NOTE_INSN_DELETED);
change_scope (note, cur_block, DECL_INITIAL (cfun->decl));
delete_insn (note);
reorder_blocks ();
}
/* Link the basic blocks in the correct order, compacting the basic
block queue while at it. This also clears the visited flag on
all basic blocks. If STAY_IN_CFGLAYOUT_MODE is false, this function
also clears the basic block header and footer fields.
This function is usually called after a pass (e.g. tracer) finishes
some transformations while in cfglayout mode. The required sequence
of the basic blocks is in a linked list along the bb->aux field.
This functions re-links the basic block prev_bb and next_bb pointers
accordingly, and it compacts and renumbers the blocks. */
void
relink_block_chain (bool stay_in_cfglayout_mode)
{
basic_block bb, prev_bb;
int index;
/* Maybe dump the re-ordered sequence. */
if (dump_file)
{
fprintf (dump_file, "Reordered sequence:\n");
for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
bb;
bb = (basic_block) bb->aux, index++)
{
fprintf (dump_file, " %i ", index);
if (get_bb_original (bb))
fprintf (dump_file, "duplicate of %i ",
get_bb_original (bb)->index);
else if (forwarder_block_p (bb)
&& !LABEL_P (BB_HEAD (bb)))
fprintf (dump_file, "compensation ");
else
fprintf (dump_file, "bb %i ", bb->index);
fprintf (dump_file, " [%i]\n", bb->frequency);
}
}
/* Now reorder the blocks. */
prev_bb = ENTRY_BLOCK_PTR;
bb = ENTRY_BLOCK_PTR->next_bb;
for (; bb; prev_bb = bb, bb = (basic_block) bb->aux)
{
bb->prev_bb = prev_bb;
prev_bb->next_bb = bb;
}
prev_bb->next_bb = EXIT_BLOCK_PTR;
EXIT_BLOCK_PTR->prev_bb = prev_bb;
/* Then, clean up the aux and visited fields. */
FOR_ALL_BB (bb)
{
bb->aux = NULL;
bb->il.rtl->visited = 0;
if (!stay_in_cfglayout_mode)
bb->il.rtl->header = bb->il.rtl->footer = NULL;
}
/* Maybe reset the original copy tables, they are not valid anymore
when we renumber the basic blocks in compact_blocks. If we are
are going out of cfglayout mode, don't re-allocate the tables. */
free_original_copy_tables ();
if (stay_in_cfglayout_mode)
initialize_original_copy_tables ();
/* Finally, put basic_block_info in the new order. */
compact_blocks ();
}
/* Given a reorder chain, rearrange the code to match. */
static void
fixup_reorder_chain (void)
{
basic_block bb;
rtx insn = NULL;
if (cfg_layout_function_header)
{
set_first_insn (cfg_layout_function_header);
insn = cfg_layout_function_header;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
/* First do the bulk reordering -- rechain the blocks without regard to
the needed changes to jumps and labels. */
for (bb = ENTRY_BLOCK_PTR->next_bb; bb; bb = (basic_block) bb->aux)
{
if (bb->il.rtl->header)
{
if (insn)
NEXT_INSN (insn) = bb->il.rtl->header;
else
set_first_insn (bb->il.rtl->header);
PREV_INSN (bb->il.rtl->header) = insn;
insn = bb->il.rtl->header;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
if (insn)
NEXT_INSN (insn) = BB_HEAD (bb);
else
set_first_insn (BB_HEAD (bb));
PREV_INSN (BB_HEAD (bb)) = insn;
insn = BB_END (bb);
if (bb->il.rtl->footer)
{
NEXT_INSN (insn) = bb->il.rtl->footer;
PREV_INSN (bb->il.rtl->footer) = insn;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
}
NEXT_INSN (insn) = cfg_layout_function_footer;
if (cfg_layout_function_footer)
PREV_INSN (cfg_layout_function_footer) = insn;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
set_last_insn (insn);
#ifdef ENABLE_CHECKING
verify_insn_chain ();
#endif
/* Now add jumps and labels as needed to match the blocks new
outgoing edges. */
for (bb = ENTRY_BLOCK_PTR->next_bb; bb ; bb = (basic_block) bb->aux)
{
edge e_fall, e_taken, e;
rtx bb_end_insn;
basic_block nb;
edge_iterator ei;
if (EDGE_COUNT (bb->succs) == 0)
continue;
/* Find the old fallthru edge, and another non-EH edge for
a taken jump. */
e_taken = e_fall = NULL;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_FALLTHRU)
e_fall = e;
else if (! (e->flags & EDGE_EH))
e_taken = e;
bb_end_insn = BB_END (bb);
if (JUMP_P (bb_end_insn))
{
if (any_condjump_p (bb_end_insn))
{
/* If the old fallthru is still next, nothing to do. */
if (bb->aux == e_fall->dest
|| e_fall->dest == EXIT_BLOCK_PTR)
continue;
/* The degenerated case of conditional jump jumping to the next
instruction can happen for jumps with side effects. We need
to construct a forwarder block and this will be done just
fine by force_nonfallthru below. */
if (!e_taken)
;
/* There is another special case: if *neither* block is next,
such as happens at the very end of a function, then we'll
need to add a new unconditional jump. Choose the taken
edge based on known or assumed probability. */
else if (bb->aux != e_taken->dest)
{
rtx note = find_reg_note (bb_end_insn, REG_BR_PROB, 0);
if (note
&& INTVAL (XEXP (note, 0)) < REG_BR_PROB_BASE / 2
&& invert_jump (bb_end_insn,
(e_fall->dest == EXIT_BLOCK_PTR
? NULL_RTX
: label_for_bb (e_fall->dest)), 0))
{
e_fall->flags &= ~EDGE_FALLTHRU;
#ifdef ENABLE_CHECKING
gcc_assert (could_fall_through
(e_taken->src, e_taken->dest));
#endif
e_taken->flags |= EDGE_FALLTHRU;
update_br_prob_note (bb);
e = e_fall, e_fall = e_taken, e_taken = e;
}
}
/* If the "jumping" edge is a crossing edge, and the fall
through edge is non-crossing, leave things as they are. */
else if ((e_taken->flags & EDGE_CROSSING)
&& !(e_fall->flags & EDGE_CROSSING))
continue;
/* Otherwise we can try to invert the jump. This will
basically never fail, however, keep up the pretense. */
else if (invert_jump (bb_end_insn,
(e_fall->dest == EXIT_BLOCK_PTR
? NULL_RTX
: label_for_bb (e_fall->dest)), 0))
{
e_fall->flags &= ~EDGE_FALLTHRU;
#ifdef ENABLE_CHECKING
gcc_assert (could_fall_through
(e_taken->src, e_taken->dest));
#endif
e_taken->flags |= EDGE_FALLTHRU;
update_br_prob_note (bb);
continue;
}
}
else
{
/* Otherwise we have some return, switch or computed
jump. In the 99% case, there should not have been a
fallthru edge. */
gcc_assert (returnjump_p (bb_end_insn) || !e_fall);
continue;
}
}
else
{
/* No fallthru implies a noreturn function with EH edges, or
something similarly bizarre. In any case, we don't need to
do anything. */
if (! e_fall)
continue;
/* If the fallthru block is still next, nothing to do. */
if (bb->aux == e_fall->dest)
continue;
/* A fallthru to exit block. */
if (e_fall->dest == EXIT_BLOCK_PTR)
continue;
}
/* We got here if we need to add a new jump insn. */
nb = force_nonfallthru (e_fall);
if (nb)
{
nb->il.rtl->visited = 1;
nb->aux = bb->aux;
bb->aux = nb;
/* Don't process this new block. */
bb = nb;
/* Make sure new bb is tagged for correct section (same as
fall-thru source, since you cannot fall-throu across
section boundaries). */
BB_COPY_PARTITION (e_fall->src, single_pred (bb));
if (flag_reorder_blocks_and_partition
&& targetm.have_named_sections
&& JUMP_P (BB_END (bb))
&& !any_condjump_p (BB_END (bb))
&& (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
add_reg_note (BB_END (bb), REG_CROSSING_JUMP, NULL_RTX);
}
}
relink_block_chain (/*stay_in_cfglayout_mode=*/false);
/* Annoying special case - jump around dead jumptables left in the code. */
FOR_EACH_BB (bb)
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_FALLTHRU)
break;
if (e && !can_fallthru (e->src, e->dest))
force_nonfallthru (e);
}
/* Ensure goto_locus from edges has some instructions with that locus
in RTL. */
if (!optimize)
FOR_EACH_BB (bb)
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->goto_locus && !(e->flags & EDGE_ABNORMAL))
{
basic_block nb;
rtx end;
insn = BB_END (e->src);
end = PREV_INSN (BB_HEAD (e->src));
while (insn != end
&& (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
insn = PREV_INSN (insn);
if (insn != end
&& locator_eq (INSN_LOCATOR (insn), (int) e->goto_locus))
continue;
if (simplejump_p (BB_END (e->src))
&& INSN_LOCATOR (BB_END (e->src)) == 0)
{
INSN_LOCATOR (BB_END (e->src)) = e->goto_locus;
continue;
}
if (e->dest != EXIT_BLOCK_PTR)
{
insn = BB_HEAD (e->dest);
end = NEXT_INSN (BB_END (e->dest));
while (insn != end && !INSN_P (insn))
insn = NEXT_INSN (insn);
if (insn != end && INSN_LOCATOR (insn)
&& locator_eq (INSN_LOCATOR (insn), (int) e->goto_locus))
continue;
}
nb = split_edge (e);
if (!INSN_P (BB_END (nb)))
BB_END (nb) = emit_insn_after_noloc (gen_nop (), BB_END (nb),
nb);
INSN_LOCATOR (BB_END (nb)) = e->goto_locus;
}
}
}
/* Perform sanity checks on the insn chain.
1. Check that next/prev pointers are consistent in both the forward and
reverse direction.
2. Count insns in chain, going both directions, and check if equal.
3. Check that get_last_insn () returns the actual end of chain. */
void
verify_insn_chain (void)
{
rtx x, prevx, nextx;
int insn_cnt1, insn_cnt2;
for (prevx = NULL, insn_cnt1 = 1, x = get_insns ();
x != 0;
prevx = x, insn_cnt1++, x = NEXT_INSN (x))
gcc_assert (PREV_INSN (x) == prevx);
gcc_assert (prevx == get_last_insn ());
for (nextx = NULL, insn_cnt2 = 1, x = get_last_insn ();
x != 0;
nextx = x, insn_cnt2++, x = PREV_INSN (x))
gcc_assert (NEXT_INSN (x) == nextx);
gcc_assert (insn_cnt1 == insn_cnt2);
}
/* If we have assembler epilogues, the block falling through to exit must
be the last one in the reordered chain when we reach final. Ensure
that this condition is met. */
static void
fixup_fallthru_exit_predecessor (void)
{
edge e;
edge_iterator ei;
basic_block bb = NULL;
/* This transformation is not valid before reload, because we might
separate a call from the instruction that copies the return
value. */
gcc_assert (reload_completed);
FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
if (e->flags & EDGE_FALLTHRU)
bb = e->src;