/* Control flow graph building code for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 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 2, or (at your option) any later
+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
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
-
-/* find_basic_blocks divides the current function's rtl into basic
- blocks and constructs the CFG. The blocks are recorded in the
- basic_block_info array; the CFG exists in the edge structures
- referenced by the blocks.
-
- find_basic_blocks also finds any unreachable loops and deletes them.
-
- Available functionality:
- - CFG construction
- find_basic_blocks
- - Local CFG construction
- find_sub_basic_blocks
- */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
\f
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "hard-reg-set.h"
#include "output.h"
#include "function.h"
#include "except.h"
+#include "expr.h"
#include "toplev.h"
#include "timevar.h"
+#include "sbitmap.h"
-#include "obstack.h"
-static int count_basic_blocks PARAMS ((rtx));
-static void find_basic_blocks_1 PARAMS ((rtx));
-static rtx find_label_refs PARAMS ((rtx, rtx));
-static void make_edges PARAMS ((rtx, int, int, int));
-static void make_label_edge PARAMS ((sbitmap *, basic_block,
- rtx, int));
-static void make_eh_edge PARAMS ((sbitmap *, basic_block, rtx));
-static void find_bb_boundaries PARAMS ((basic_block));
-static void compute_outgoing_frequencies PARAMS ((basic_block));
-
-/* Count the basic blocks of the function. */
-
-static int
-count_basic_blocks (f)
- rtx f;
-{
- rtx insn;
- RTX_CODE prev_code;
- int count = 0;
- int saw_abnormal_edge = 0;
-
- prev_code = JUMP_INSN;
- for (insn = f; insn; insn = NEXT_INSN (insn))
- {
- enum rtx_code code = GET_CODE (insn);
-
- if (code == CODE_LABEL
- || (GET_RTX_CLASS (code) == 'i'
- && (prev_code == JUMP_INSN
- || prev_code == BARRIER
- || saw_abnormal_edge)))
- {
- saw_abnormal_edge = 0;
- count++;
- }
-
- /* Record whether this insn created an edge. */
- if (code == CALL_INSN)
- {
- rtx note;
-
- /* If there is a nonlocal goto label and the specified
- region number isn't -1, we have an edge. */
- if (nonlocal_goto_handler_labels
- && ((note = find_reg_note (insn, REG_EH_REGION, NULL_RTX)) == 0
- || INTVAL (XEXP (note, 0)) >= 0))
- saw_abnormal_edge = 1;
-
- else if (can_throw_internal (insn))
- saw_abnormal_edge = 1;
- }
- else if (flag_non_call_exceptions
- && code == INSN
- && can_throw_internal (insn))
- saw_abnormal_edge = 1;
-
- if (code != NOTE)
- prev_code = code;
- }
+static void make_edges (basic_block, basic_block, int);
+static void make_label_edge (sbitmap, basic_block, rtx, int);
+static void find_bb_boundaries (basic_block);
+static void compute_outgoing_frequencies (basic_block);
+\f
+/* Return true if insn is something that should be contained inside basic
+ block. */
- /* The rest of the compiler works a bit smoother when we don't have to
- check for the edge case of do-nothing functions with no basic blocks. */
- if (count == 0)
+bool
+inside_basic_block_p (const_rtx insn)
+{
+ switch (GET_CODE (insn))
{
- emit_insn (gen_rtx_USE (VOIDmode, const0_rtx));
- count = 1;
+ case CODE_LABEL:
+ /* Avoid creating of basic block for jumptables. */
+ return (NEXT_INSN (insn) == 0
+ || !JUMP_P (NEXT_INSN (insn))
+ || (GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_VEC
+ && GET_CODE (PATTERN (NEXT_INSN (insn))) != ADDR_DIFF_VEC));
+
+ case JUMP_INSN:
+ return (GET_CODE (PATTERN (insn)) != ADDR_VEC
+ && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC);
+
+ case CALL_INSN:
+ case INSN:
+ case DEBUG_INSN:
+ return true;
+
+ case BARRIER:
+ case NOTE:
+ return false;
+
+ default:
+ gcc_unreachable ();
}
-
- return count;
}
-/* Scan a list of insns for labels referred to other than by jumps.
- This is used to scan the alternatives of a call placeholder. */
-static rtx
-find_label_refs (f, lvl)
- rtx f;
- rtx lvl;
-{
- rtx insn;
-
- for (insn = f; insn; insn = NEXT_INSN (insn))
- if (INSN_P (insn) && GET_CODE (insn) != JUMP_INSN)
- {
- rtx note;
+/* Return true if INSN may cause control flow transfer, so it should be last in
+ the basic block. */
- /* Make a list of all labels referred to other than by jumps
- (which just don't have the REG_LABEL notes).
+bool
+control_flow_insn_p (const_rtx insn)
+{
+ switch (GET_CODE (insn))
+ {
+ case NOTE:
+ case CODE_LABEL:
+ case DEBUG_INSN:
+ return false;
+
+ case JUMP_INSN:
+ /* Jump insn always causes control transfer except for tablejumps. */
+ return (GET_CODE (PATTERN (insn)) != ADDR_VEC
+ && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC);
+
+ case CALL_INSN:
+ /* Noreturn and sibling call instructions terminate the basic blocks
+ (but only if they happen unconditionally). */
+ if ((SIBLING_CALL_P (insn)
+ || find_reg_note (insn, REG_NORETURN, 0))
+ && GET_CODE (PATTERN (insn)) != COND_EXEC)
+ return true;
+
+ /* Call insn may return to the nonlocal goto handler. */
+ if (can_nonlocal_goto (insn))
+ return true;
+ break;
- Make a special exception for labels followed by an ADDR*VEC,
- as this would be a part of the tablejump setup code.
+ case INSN:
+ /* Treat trap instructions like noreturn calls (same provision). */
+ if (GET_CODE (PATTERN (insn)) == TRAP_IF
+ && XEXP (PATTERN (insn), 0) == const1_rtx)
+ return true;
+ if (!cfun->can_throw_non_call_exceptions)
+ return false;
+ break;
- Make a special exception to registers loaded with label
- values just before jump insns that use them. */
+ case BARRIER:
+ /* It is nonsense to reach barrier when looking for the
+ end of basic block, but before dead code is eliminated
+ this may happen. */
+ return false;
- for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_LABEL)
- {
- rtx lab = XEXP (note, 0), next;
-
- if ((next = next_nonnote_insn (lab)) != NULL
- && GET_CODE (next) == JUMP_INSN
- && (GET_CODE (PATTERN (next)) == ADDR_VEC
- || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
- ;
- else if (GET_CODE (lab) == NOTE)
- ;
- else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
- && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
- ;
- else
- lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
- }
- }
+ default:
+ gcc_unreachable ();
+ }
- return lvl;
+ return can_throw_internal (insn);
}
+
\f
/* Create an edge between two basic blocks. FLAGS are auxiliary information
about the edge that is accumulated between calls. */
/* Create an edge from a basic block to a label. */
static void
-make_label_edge (edge_cache, src, label, flags)
- sbitmap *edge_cache;
- basic_block src;
- rtx label;
- int flags;
+make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags)
{
- if (GET_CODE (label) != CODE_LABEL)
- abort ();
+ gcc_assert (LABEL_P (label));
/* If the label was never emitted, this insn is junk, but avoid a
crash trying to refer to BLOCK_FOR_INSN (label). This can happen
/* Create the edges generated by INSN in REGION. */
-static void
-make_eh_edge (edge_cache, src, insn)
- sbitmap *edge_cache;
- basic_block src;
- rtx insn;
+void
+rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn)
{
- int is_call = (GET_CODE (insn) == CALL_INSN ? EDGE_ABNORMAL_CALL : 0);
- rtx handlers, i;
+ eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn);
- handlers = reachable_handlers (insn);
+ if (lp)
+ {
+ rtx label = lp->landing_pad;
- for (i = handlers; i; i = XEXP (i, 1))
- make_label_edge (edge_cache, src, XEXP (i, 0),
- EDGE_ABNORMAL | EDGE_EH | is_call);
+ /* During initial rtl generation, use the post_landing_pad. */
+ if (label == NULL)
+ {
+ gcc_assert (lp->post_landing_pad);
+ label = label_rtx (lp->post_landing_pad);
+ }
- free_INSN_LIST_list (&handlers);
+ make_label_edge (edge_cache, src, label,
+ EDGE_ABNORMAL | EDGE_EH
+ | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0));
+ }
}
-/* Identify the edges between basic blocks MIN to MAX.
- NONLOCAL_LABEL_LIST is a list of non-local labels in the function. Blocks
- that are otherwise unreachable may be reachable with a non-local goto.
+/* States of basic block as seen by find_many_sub_basic_blocks. */
+enum state {
+ /* Basic blocks created via split_block belong to this state.
+ make_edges will examine these basic blocks to see if we need to
+ create edges going out of them. */
+ BLOCK_NEW = 0,
+
+ /* Basic blocks that do not need examining belong to this state.
+ These blocks will be left intact. In particular, make_edges will
+ not create edges going out of these basic blocks. */
+ BLOCK_ORIGINAL,
+
+ /* Basic blocks that may need splitting (due to a label appearing in
+ the middle, etc) belong to this state. After splitting them,
+ make_edges will create edges going out of them as needed. */
+ BLOCK_TO_SPLIT
+};
+
+#define STATE(BB) (enum state) ((size_t) (BB)->aux)
+#define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
- BB_EH_END is an array indexed by basic block number in which we record
- the list of exception regions active at the end of the basic block. */
+/* Used internally by purge_dead_tablejump_edges, ORed into state. */
+#define BLOCK_USED_BY_TABLEJUMP 32
+#define FULL_STATE(BB) ((size_t) (BB)->aux)
+
+/* Identify the edges going out of basic blocks between MIN and MAX,
+ inclusive, that have their states set to BLOCK_NEW or
+ BLOCK_TO_SPLIT.
+
+ UPDATE_P should be nonzero if we are updating CFG and zero if we
+ are building CFG from scratch. */
static void
-make_edges (label_value_list, min, max, update_p)
- rtx label_value_list;
- int min, max, update_p;
+make_edges (basic_block min, basic_block max, int update_p)
{
- int i;
- sbitmap *edge_cache = NULL;
-
- /* Assume no computed jump; revise as we create edges. */
- current_function_has_computed_jump = 0;
+ basic_block bb;
+ sbitmap edge_cache = NULL;
/* Heavy use of computed goto in machine-generated code can lead to
nearly fully-connected CFGs. In that case we spend a significant
amount of time searching the edge lists for duplicates. */
- if (forced_labels || label_value_list)
- {
- edge_cache = sbitmap_vector_alloc (n_basic_blocks, n_basic_blocks);
- sbitmap_vector_zero (edge_cache, n_basic_blocks);
+ if (forced_labels || cfun->cfg->max_jumptable_ents > 100)
+ edge_cache = sbitmap_alloc (last_basic_block);
- if (update_p)
- for (i = min; i <= max; ++i)
- {
- edge e;
- for (e = BASIC_BLOCK (i)->succ; e ; e = e->succ_next)
- if (e->dest != EXIT_BLOCK_PTR)
- SET_BIT (edge_cache[i], e->dest->index);
- }
- }
+ /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block
+ is always the entry. */
+ if (min == ENTRY_BLOCK_PTR->next_bb)
+ make_edge (ENTRY_BLOCK_PTR, min, EDGE_FALLTHRU);
- /* By nature of the way these get numbered, block 0 is always the entry. */
- if (min == 0)
- cached_make_edge (edge_cache, ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
-
- for (i = min; i <= max; ++i)
+ FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
{
- basic_block bb = BASIC_BLOCK (i);
rtx insn, x;
enum rtx_code code;
- int force_fallthru = 0;
+ edge e;
+ edge_iterator ei;
+
+ if (STATE (bb) == BLOCK_ORIGINAL)
+ continue;
- if (GET_CODE (bb->head) == CODE_LABEL
- && LABEL_ALTERNATE_NAME (bb->head))
+ /* If we have an edge cache, cache edges going out of BB. */
+ if (edge_cache)
+ {
+ sbitmap_zero (edge_cache);
+ if (update_p)
+ {
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (e->dest != EXIT_BLOCK_PTR)
+ SET_BIT (edge_cache, e->dest->index);
+ }
+ }
+
+ if (LABEL_P (BB_HEAD (bb))
+ && LABEL_ALT_ENTRY_P (BB_HEAD (bb)))
cached_make_edge (NULL, ENTRY_BLOCK_PTR, bb, 0);
/* Examine the last instruction of the block, and discover the
ways we can leave the block. */
- insn = bb->end;
+ insn = BB_END (bb);
code = GET_CODE (insn);
/* A branch. */
{
rtx tmp;
- /* Recognize exception handling placeholders. */
- if (GET_CODE (PATTERN (insn)) == RESX)
- make_eh_edge (edge_cache, bb, insn);
-
/* Recognize a non-local goto as a branch outside the
current function. */
- else if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
+ if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
;
- /* ??? Recognize a tablejump and do the right thing. */
- else if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
- && (tmp = NEXT_INSN (tmp)) != NULL_RTX
- && GET_CODE (tmp) == JUMP_INSN
- && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
- || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
+ /* Recognize a tablejump and do the right thing. */
+ else if (tablejump_p (insn, NULL, &tmp))
{
rtvec vec;
int j;
&& GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
make_label_edge (edge_cache, bb,
XEXP (XEXP (SET_SRC (tmp), 2), 0), 0);
-
-#ifdef CASE_DROPS_THROUGH
- /* Silly VAXen. The ADDR_VEC is going to be in the way of
- us naturally detecting fallthru into the next block. */
- force_fallthru = 1;
-#endif
}
/* If this is a computed jump, then mark it as reaching
- everything on the label_value_list and forced_labels list. */
+ everything on the forced_labels list. */
else if (computed_jump_p (insn))
{
- current_function_has_computed_jump = 1;
-
- for (x = label_value_list; x; x = XEXP (x, 1))
- make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
-
for (x = forced_labels; x; x = XEXP (x, 1))
make_label_edge (edge_cache, bb, XEXP (x, 0), EDGE_ABNORMAL);
}
else if (returnjump_p (insn))
cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, 0);
+ /* Recognize asm goto and do the right thing. */
+ else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
+ {
+ int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
+ for (i = 0; i < n; ++i)
+ make_label_edge (edge_cache, bb,
+ XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0);
+ }
+
/* Otherwise, we have a plain conditional or unconditional jump. */
else
{
- if (! JUMP_LABEL (insn))
- abort ();
+ gcc_assert (JUMP_LABEL (insn));
make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
}
}
- /* If this is a sibling call insn, then this is in effect a
- combined call and return, and so we need an edge to the
- exit block. No need to worry about EH edges, since we
- wouldn't have created the sibling call in the first place. */
-
+ /* If this is a sibling call insn, then this is in effect a combined call
+ and return, and so we need an edge to the exit block. No need to
+ worry about EH edges, since we wouldn't have created the sibling call
+ in the first place. */
if (code == CALL_INSN && SIBLING_CALL_P (insn))
cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR,
- EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
+ EDGE_SIBCALL | EDGE_ABNORMAL);
/* If this is a CALL_INSN, then mark it as reaching the active EH
handler for this CALL_INSN. If we're handling non-call
exceptions then any insn can reach any of the active handlers.
-
Also mark the CALL_INSN as reaching any nonlocal goto handler. */
-
- else if (code == CALL_INSN || flag_non_call_exceptions)
+ else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions)
{
/* Add any appropriate EH edges. */
- make_eh_edge (edge_cache, bb, insn);
+ rtl_make_eh_edge (edge_cache, bb, insn);
if (code == CALL_INSN && nonlocal_goto_handler_labels)
{
/* ??? This could be made smarter: in some cases it's possible
to tell that certain calls will not do a nonlocal goto.
-
For example, if the nested functions that do the nonlocal
gotos do not have their addresses taken, then only calls to
those functions or to other nested functions that use them
could possibly do nonlocal gotos. */
- /* We do know that a REG_EH_REGION note with a value less
- than 0 is guaranteed not to perform a non-local goto. */
- rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
- if (!note || INTVAL (XEXP (note, 0)) >= 0)
+ if (can_nonlocal_goto (insn))
for (x = nonlocal_goto_handler_labels; x; x = XEXP (x, 1))
make_label_edge (edge_cache, bb, XEXP (x, 0),
EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
}
/* Find out if we can drop through to the next block. */
- insn = next_nonnote_insn (insn);
- if (!insn || (i + 1 == n_basic_blocks && force_fallthru))
+ insn = NEXT_INSN (insn);
+ e = find_edge (bb, EXIT_BLOCK_PTR);
+ if (e && e->flags & EDGE_FALLTHRU)
+ insn = NULL;
+
+ while (insn
+ && NOTE_P (insn)
+ && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
+ insn = NEXT_INSN (insn);
+
+ if (!insn)
cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR, EDGE_FALLTHRU);
- else if (i + 1 < n_basic_blocks)
+ else if (bb->next_bb != EXIT_BLOCK_PTR)
{
- rtx tmp = BLOCK_HEAD (i + 1);
- if (GET_CODE (tmp) == NOTE)
- tmp = next_nonnote_insn (tmp);
- if (force_fallthru || insn == tmp)
- cached_make_edge (edge_cache, bb, BASIC_BLOCK (i + 1), EDGE_FALLTHRU);
+ if (insn == BB_HEAD (bb->next_bb))
+ cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU);
}
}
sbitmap_vector_free (edge_cache);
}
\f
-/* Find all basic blocks of the function whose first insn is F.
-
- Collect and return a list of labels whose addresses are taken. This
- will be used in make_edges for use with computed gotos. */
-
static void
-find_basic_blocks_1 (f)
- rtx f;
+mark_tablejump_edge (rtx label)
{
- rtx insn, next;
- int i = 0;
- rtx bb_note = NULL_RTX;
- rtx lvl = NULL_RTX;
- rtx trll = NULL_RTX;
- rtx head = NULL_RTX;
- rtx end = NULL_RTX;
-
- /* We process the instructions in a slightly different way than we did
- previously. This is so that we see a NOTE_BASIC_BLOCK after we have
- closed out the previous block, so that it gets attached at the proper
- place. Since this form should be equivalent to the previous,
- count_basic_blocks continues to use the old form as a check. */
-
- for (insn = f; insn; insn = next)
- {
- enum rtx_code code = GET_CODE (insn);
-
- next = NEXT_INSN (insn);
-
- switch (code)
- {
- case NOTE:
- {
- int kind = NOTE_LINE_NUMBER (insn);
-
- /* Look for basic block notes with which to keep the
- basic_block_info pointers stable. Unthread the note now;
- we'll put it back at the right place in create_basic_block.
- Or not at all if we've already found a note in this block. */
- if (kind == NOTE_INSN_BASIC_BLOCK)
- {
- if (bb_note == NULL_RTX)
- bb_note = insn;
- else
- next = delete_insn (insn);
- }
- break;
- }
-
- case CODE_LABEL:
- /* A basic block starts at a label. If we've closed one off due
- to a barrier or some such, no need to do it again. */
- if (head != NULL_RTX)
- {
- create_basic_block_structure (i++, head, end, bb_note);
- bb_note = NULL_RTX;
- }
-
- head = end = insn;
- break;
-
- case JUMP_INSN:
- /* A basic block ends at a jump. */
- if (head == NULL_RTX)
- head = insn;
- else
- {
- /* ??? Make a special check for table jumps. The way this
- happens is truly and amazingly gross. We are about to
- create a basic block that contains just a code label and
- an addr*vec jump insn. Worse, an addr_diff_vec creates
- its own natural loop.
-
- Prevent this bit of brain damage, pasting things together
- correctly in make_edges.
-
- The correct solution involves emitting the table directly
- on the tablejump instruction as a note, or JUMP_LABEL. */
-
- if (GET_CODE (PATTERN (insn)) == ADDR_VEC
- || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
- {
- head = end = NULL;
- n_basic_blocks--;
- break;
- }
- }
- end = insn;
- goto new_bb_inclusive;
-
- case BARRIER:
- /* A basic block ends at a barrier. It may be that an unconditional
- jump already closed the basic block -- no need to do it again. */
- if (head == NULL_RTX)
- break;
- goto new_bb_exclusive;
-
- case CALL_INSN:
- {
- /* Record whether this call created an edge. */
- rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
- int region = (note ? INTVAL (XEXP (note, 0)) : 0);
-
- if (GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
- {
- /* Scan each of the alternatives for label refs. */
- lvl = find_label_refs (XEXP (PATTERN (insn), 0), lvl);
- lvl = find_label_refs (XEXP (PATTERN (insn), 1), lvl);
- lvl = find_label_refs (XEXP (PATTERN (insn), 2), lvl);
- /* Record its tail recursion label, if any. */
- if (XEXP (PATTERN (insn), 3) != NULL_RTX)
- trll = alloc_EXPR_LIST (0, XEXP (PATTERN (insn), 3), trll);
- }
-
- /* A basic block ends at a call that can either throw or
- do a non-local goto. */
- if ((nonlocal_goto_handler_labels && region >= 0)
- || can_throw_internal (insn))
- {
- new_bb_inclusive:
- if (head == NULL_RTX)
- head = insn;
- end = insn;
-
- new_bb_exclusive:
- create_basic_block_structure (i++, head, end, bb_note);
- head = end = NULL_RTX;
- bb_note = NULL_RTX;
- break;
- }
- }
- /* Fall through. */
-
- case INSN:
- /* Non-call exceptions generate new blocks just like calls. */
- if (flag_non_call_exceptions && can_throw_internal (insn))
- goto new_bb_inclusive;
-
- if (head == NULL_RTX)
- head = insn;
- end = insn;
- break;
-
- default:
- abort ();
- }
-
- if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
- {
- rtx note;
-
- /* Make a list of all labels referred to other than by jumps.
-
- Make a special exception for labels followed by an ADDR*VEC,
- as this would be a part of the tablejump setup code.
-
- Make a special exception to registers loaded with label
- values just before jump insns that use them. */
-
- for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_LABEL)
- {
- rtx lab = XEXP (note, 0), next;
-
- if ((next = next_nonnote_insn (lab)) != NULL
- && GET_CODE (next) == JUMP_INSN
- && (GET_CODE (PATTERN (next)) == ADDR_VEC
- || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
- ;
- else if (GET_CODE (lab) == NOTE)
- ;
- else if (GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
- && find_reg_note (NEXT_INSN (insn), REG_LABEL, lab))
- ;
- else
- lvl = alloc_EXPR_LIST (0, XEXP (note, 0), lvl);
- }
- }
- }
+ basic_block bb;
- if (head != NULL_RTX)
- create_basic_block_structure (i++, head, end, bb_note);
- else if (bb_note)
- delete_insn (bb_note);
-
- if (i != n_basic_blocks)
- abort ();
-
- label_value_list = lvl;
- tail_recursion_label_list = trll;
+ gcc_assert (LABEL_P (label));
+ /* See comment in make_label_edge. */
+ if (INSN_UID (label) == 0)
+ return;
+ bb = BLOCK_FOR_INSN (label);
+ SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP);
}
-
-/* Find basic blocks of the current function.
- F is the first insn of the function and NREGS the number of register
- numbers in use. */
-
-void
-find_basic_blocks (f, nregs, file)
- rtx f;
- int nregs ATTRIBUTE_UNUSED;
- FILE *file ATTRIBUTE_UNUSED;
+static void
+purge_dead_tablejump_edges (basic_block bb, rtx table)
{
- int max_uid;
- timevar_push (TV_CFG);
-
- basic_block_for_insn = 0;
-
- /* Flush out existing data. */
- if (basic_block_info != NULL)
+ rtx insn = BB_END (bb), tmp;
+ rtvec vec;
+ int j;
+ edge_iterator ei;
+ edge e;
+
+ if (GET_CODE (PATTERN (table)) == ADDR_VEC)
+ vec = XVEC (PATTERN (table), 0);
+ else
+ vec = XVEC (PATTERN (table), 1);
+
+ for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
+ mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0));
+
+ /* Some targets (eg, ARM) emit a conditional jump that also
+ contains the out-of-range target. Scan for these and
+ add an edge if necessary. */
+ if ((tmp = single_set (insn)) != NULL
+ && SET_DEST (tmp) == pc_rtx
+ && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
+ && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
+ mark_tablejump_edge (XEXP (XEXP (SET_SRC (tmp), 2), 0));
+
+ for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
{
- int i;
-
- clear_edges ();
-
- /* Clear bb->aux on all extant basic blocks. We'll use this as a
- tag for reuse during create_basic_block, just in case some pass
- copies around basic block notes improperly. */
- for (i = 0; i < n_basic_blocks; ++i)
- BASIC_BLOCK (i)->aux = NULL;
-
- VARRAY_FREE (basic_block_info);
+ if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP)
+ SET_STATE (e->dest, FULL_STATE (e->dest)
+ & ~(size_t) BLOCK_USED_BY_TABLEJUMP);
+ else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH)))
+ {
+ remove_edge (e);
+ continue;
+ }
+ ei_next (&ei);
}
-
- n_basic_blocks = count_basic_blocks (f);
-
- /* Size the basic block table. The actual structures will be allocated
- by find_basic_blocks_1, since we want to keep the structure pointers
- stable across calls to find_basic_blocks. */
- /* ??? This whole issue would be much simpler if we called find_basic_blocks
- exactly once, and thereafter we don't have a single long chain of
- instructions at all until close to the end of compilation when we
- actually lay them out. */
-
- VARRAY_BB_INIT (basic_block_info, n_basic_blocks, "basic_block_info");
-
- find_basic_blocks_1 (f);
-
- /* Record the block to which an insn belongs. */
- /* ??? This should be done another way, by which (perhaps) a label is
- tagged directly with the basic block that it starts. It is used for
- more than that currently, but IMO that is the only valid use. */
-
- max_uid = get_max_uid ();
-#ifdef AUTO_INC_DEC
- /* Leave space for insns life_analysis makes in some cases for auto-inc.
- These cases are rare, so we don't need too much space. */
- max_uid += max_uid / 10;
-#endif
-
- compute_bb_for_insn (max_uid);
-
- /* Discover the edges of our cfg. */
- make_edges (label_value_list, 0, n_basic_blocks - 1, 0);
-
- /* Do very simple cleanup now, for the benefit of code that runs between
- here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns. */
- tidy_fallthru_edges ();
-
-#ifdef ENABLE_CHECKING
- verify_flow_info ();
-#endif
- timevar_pop (TV_CFG);
}
-\f
-/* State of basic block as seen by find_sub_basic_blocks. */
-enum state
- {
- BLOCK_NEW = 0,
- BLOCK_ORIGINAL,
- BLOCK_TO_SPLIT
- };
-#define STATE(bb) (enum state)(size_t)(bb)->aux
-#define SET_STATE(bb, state) (bb)->aux = (void *)(state)
/* Scan basic block BB for possible BB boundaries inside the block
and create new basic blocks in the progress. */
static void
-find_bb_boundaries (bb)
- basic_block bb;
+find_bb_boundaries (basic_block bb)
{
- rtx insn = bb->head;
- rtx end = bb->end;
+ basic_block orig_bb = bb;
+ rtx insn = BB_HEAD (bb);
+ rtx end = BB_END (bb), x;
+ rtx table;
rtx flow_transfer_insn = NULL_RTX;
edge fallthru = NULL;
- if (insn == bb->end)
+ if (insn == BB_END (bb))
return;
- if (GET_CODE (insn) == CODE_LABEL)
+ if (LABEL_P (insn))
insn = NEXT_INSN (insn);
/* Scan insn chain and try to find new basic block boundaries. */
{
enum rtx_code code = GET_CODE (insn);
- switch (code)
+ /* In case we've previously seen an insn that effects a control
+ flow transfer, split the block. */
+ if ((flow_transfer_insn || code == CODE_LABEL)
+ && inside_basic_block_p (insn))
{
- case BARRIER:
- if (!flow_transfer_insn)
- abort ();
- break;
-
- /* On code label, split current basic block. */
- case CODE_LABEL:
fallthru = split_block (bb, PREV_INSN (insn));
if (flow_transfer_insn)
- bb->end = flow_transfer_insn;
+ {
+ BB_END (bb) = flow_transfer_insn;
+
+ /* Clean up the bb field for the insns between the blocks. */
+ for (x = NEXT_INSN (flow_transfer_insn);
+ x != BB_HEAD (fallthru->dest);
+ x = NEXT_INSN (x))
+ if (!BARRIER_P (x))
+ set_block_for_insn (x, NULL);
+ }
+
bb = fallthru->dest;
remove_edge (fallthru);
flow_transfer_insn = NULL_RTX;
- if (LABEL_ALTERNATE_NAME (insn))
+ if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
make_edge (ENTRY_BLOCK_PTR, bb, 0);
- break;
-
- case INSN:
- case JUMP_INSN:
- case CALL_INSN:
- /* In case we've previously split an insn that effects a control
- flow transfer, move the block header to proper place. */
- if (flow_transfer_insn)
- {
- fallthru = split_block (bb, PREV_INSN (insn));
- bb->end = flow_transfer_insn;
- bb = fallthru->dest;
- remove_edge (fallthru);
- flow_transfer_insn = NULL_RTX;
- }
-
- /* We need some special care for those expressions. */
- if (code == JUMP_INSN)
- {
- if (GET_CODE (PATTERN (insn)) == ADDR_VEC
- || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
- abort ();
- flow_transfer_insn = insn;
- }
- else if (code == CALL_INSN)
- {
- rtx note;
- if (nonlocal_goto_handler_labels
- && (!(note = find_reg_note (insn, REG_EH_REGION, NULL_RTX))
- || INTVAL (XEXP (note, 0)) >= 0))
- flow_transfer_insn = insn;
- else if (can_throw_internal (insn))
- flow_transfer_insn = insn;
- else if (SIBLING_CALL_P (insn))
- flow_transfer_insn = insn;
- else if (find_reg_note (insn, REG_NORETURN, 0))
- flow_transfer_insn = insn;
- }
- else if (flag_non_call_exceptions && can_throw_internal (insn))
- flow_transfer_insn = insn;
- break;
-
- default:
- break;
}
+ else if (code == BARRIER)
+ {
+ /* __builtin_unreachable () may cause a barrier to be emitted in
+ the middle of a BB. We need to split it in the same manner as
+ if the barrier were preceded by a control_flow_insn_p insn. */
+ if (!flow_transfer_insn)
+ flow_transfer_insn = prev_nonnote_insn_bb (insn);
+ }
+
+ if (control_flow_insn_p (insn))
+ flow_transfer_insn = insn;
if (insn == end)
break;
insn = NEXT_INSN (insn);
return and barrier, or possibly other sequence not behaving like
ordinary jump, we need to take care and move basic block boundary. */
if (flow_transfer_insn)
- bb->end = flow_transfer_insn;
+ {
+ BB_END (bb) = flow_transfer_insn;
+
+ /* Clean up the bb field for the insns that do not belong to BB. */
+ x = flow_transfer_insn;
+ while (x != end)
+ {
+ x = NEXT_INSN (x);
+ if (!BARRIER_P (x))
+ set_block_for_insn (x, NULL);
+ }
+ }
/* We've possibly replaced the conditional jump by conditional jump
followed by cleanup at fallthru edge, so the outgoing edges may
be dead. */
purge_dead_edges (bb);
+
+ /* purge_dead_edges doesn't handle tablejump's, but if we have split the
+ basic block, we might need to kill some edges. */
+ if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table))
+ purge_dead_tablejump_edges (bb, table);
}
/* Assume that frequency of basic block B is known. Compute frequencies
and probabilities of outgoing edges. */
static void
-compute_outgoing_frequencies (b)
- basic_block b;
+compute_outgoing_frequencies (basic_block b)
{
edge e, f;
- if (b->succ && b->succ->succ_next && !b->succ->succ_next->succ_next)
+ edge_iterator ei;
+
+ if (EDGE_COUNT (b->succs) == 2)
{
- rtx note = find_reg_note (b->end, REG_BR_PROB, NULL);
+ rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL);
int probability;
- if (!note)
- return;
- probability = INTVAL (XEXP (find_reg_note (b->end,
- REG_BR_PROB, NULL), 0));
- e = BRANCH_EDGE (b);
- e->probability = probability;
- e->count = ((b->count * probability + REG_BR_PROB_BASE / 2)
- / REG_BR_PROB_BASE);
- f = FALLTHRU_EDGE (b);
- f->probability = REG_BR_PROB_BASE - probability;
- f->count = b->count - e->count;
+ if (note)
+ {
+ probability = INTVAL (XEXP (note, 0));
+ e = BRANCH_EDGE (b);
+ e->probability = probability;
+ e->count = ((b->count * probability + REG_BR_PROB_BASE / 2)
+ / REG_BR_PROB_BASE);
+ f = FALLTHRU_EDGE (b);
+ f->probability = REG_BR_PROB_BASE - probability;
+ f->count = b->count - e->count;
+ return;
+ }
}
- if (b->succ && !b->succ->succ_next)
+
+ if (single_succ_p (b))
{
- e = b->succ;
+ e = single_succ_edge (b);
e->probability = REG_BR_PROB_BASE;
e->count = b->count;
+ return;
}
+ guess_outgoing_edge_probabilities (b);
+ if (b->count)
+ FOR_EACH_EDGE (e, ei, b->succs)
+ e->count = ((b->count * e->probability + REG_BR_PROB_BASE / 2)
+ / REG_BR_PROB_BASE);
}
-/* Assume that someone emitted code with control flow instructions to the
- basic block. Update the data structure. */
+/* Assume that some pass has inserted labels or control flow
+ instructions within a basic block. Split basic blocks as needed
+ and create edges. */
void
-find_many_sub_basic_blocks (blocks)
- sbitmap blocks;
+find_many_sub_basic_blocks (sbitmap blocks)
{
- int i;
- int min, max;
+ basic_block bb, min, max;
- for (i = 0; i < n_basic_blocks; i++)
- {
- SET_STATE (BASIC_BLOCK (i),
- TEST_BIT (blocks, i)
- ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
- }
+ FOR_EACH_BB (bb)
+ SET_STATE (bb,
+ TEST_BIT (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
- for (i = 0; i < n_basic_blocks; i++)
- {
- basic_block bb = BASIC_BLOCK (i);
- if (STATE (bb) == BLOCK_TO_SPLIT)
- find_bb_boundaries (bb);
- }
+ FOR_EACH_BB (bb)
+ if (STATE (bb) == BLOCK_TO_SPLIT)
+ find_bb_boundaries (bb);
- for (i = 0; i < n_basic_blocks; i++)
- if (STATE (BASIC_BLOCK (i)) != BLOCK_ORIGINAL)
+ FOR_EACH_BB (bb)
+ if (STATE (bb) != BLOCK_ORIGINAL)
break;
- min = max = i;
- for (; i < n_basic_blocks; i++)
- if (STATE (BASIC_BLOCK (i)) != BLOCK_ORIGINAL)
- max = i;
+
+ min = max = bb;
+ for (; bb != EXIT_BLOCK_PTR; bb = bb->next_bb)
+ if (STATE (bb) != BLOCK_ORIGINAL)
+ max = bb;
/* Now re-scan and wire in all edges. This expect simple (conditional)
jumps at the end of each new basic blocks. */
- make_edges (NULL, min, max, 1);
+ make_edges (min, max, 1);
/* Update branch probabilities. Expect only (un)conditional jumps
to be created with only the forward edges. */
- for (i = min; i <= max; i++)
- {
- edge e;
- basic_block b = BASIC_BLOCK (i);
-
- if (STATE (b) == BLOCK_ORIGINAL)
- continue;
- if (STATE (b) == BLOCK_NEW)
- {
- b->count = 0;
- b->frequency = 0;
- for (e = b->pred; e; e=e->pred_next)
- {
- b->count += e->count;
- b->frequency += EDGE_FREQUENCY (e);
- }
- }
- compute_outgoing_frequencies (b);
- }
- for (i = 0; i < n_basic_blocks; i++)
- SET_STATE (BASIC_BLOCK (i), 0);
-}
-
-/* Like above but for single basic block only. */
-
-void
-find_sub_basic_blocks (bb)
- basic_block bb;
-{
- int i;
- int min, max;
- basic_block next = (bb->index == n_basic_blocks - 1
- ? NULL : BASIC_BLOCK (bb->index + 1));
-
- min = bb->index;
- find_bb_boundaries (bb);
- max = (next ? next->index : n_basic_blocks) - 1;
+ if (profile_status != PROFILE_ABSENT)
+ FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
+ {
+ edge e;
+ edge_iterator ei;
- /* Now re-scan and wire in all edges. This expect simple (conditional)
- jumps at the end of each new basic blocks. */
- make_edges (NULL, min, max, 1);
+ if (STATE (bb) == BLOCK_ORIGINAL)
+ continue;
+ if (STATE (bb) == BLOCK_NEW)
+ {
+ bb->count = 0;
+ bb->frequency = 0;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ bb->count += e->count;
+ bb->frequency += EDGE_FREQUENCY (e);
+ }
+ }
- /* Update branch probabilities. Expect only (un)conditional jumps
- to be created with only the forward edges. */
- for (i = min; i <= max; i++)
- {
- edge e;
- basic_block b = BASIC_BLOCK (i);
+ compute_outgoing_frequencies (bb);
+ }
- if (i != min)
- {
- b->count = 0;
- b->frequency = 0;
- for (e = b->pred; e; e=e->pred_next)
- {
- b->count += e->count;
- b->frequency += EDGE_FREQUENCY (e);
- }
- }
- compute_outgoing_frequencies (b);
- }
+ FOR_EACH_BB (bb)
+ SET_STATE (bb, 0);
}
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