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flow.c (flow_delete_insn, [...]): Export.

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* flow.c (flow_delete_insn, make_edge, remove_edge): Export.
        * basic-block.h: Declare them.
        * emit-rtl.h (active_insn_p): New.
        (next_active_insn, prev_active_insn): Use it.
        * rtl.h: Declare it.
        * function.c (emit_return_into_block): New.
        (thread_prologue_and_epilogue_insns): Insert return insns instead
        of epilogues when possible.
        * jump.c (jump_optimize_1): Remove code to insert a return insn
        on the fallthru to the exit block.

From-SVN: r31826
This commit is contained in:
Richard Henderson 2000-02-06 05:01:03 -08:00 committed by Richard Henderson
parent 52a75c3c22
commit 69732dcb9c
7 changed files with 143 additions and 58 deletions
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13
gcc/ChangeLog
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@ -1,3 +1,16 @@
2000-02-06 Richard Henderson <rth@cygnus.com>
* flow.c (flow_delete_insn, make_edge, remove_edge): Export.
* basic-block.h: Declare them.
* emit-rtl.h (active_insn_p): New.
(next_active_insn, prev_active_insn): Use it.
* rtl.h: Declare it.
* function.c (emit_return_into_block): New.
(thread_prologue_and_epilogue_insns): Insert return insns instead
of epilogues when possible.
* jump.c (jump_optimize_1): Remove code to insert a return insn
on the fallthru to the exit block.
2000-02-06 Richard Henderson <rth@cygnus.com>
* simplify-rtx.c (simplify_relational_operation): Canonicalize

4
gcc/basic-block.h
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@ -222,7 +222,11 @@ extern void insert_insn_on_edge PARAMS ((rtx, edge));
extern void commit_edge_insertions PARAMS ((void));
extern void remove_fake_edges PARAMS ((void));
extern void add_noreturn_fake_exit_edges PARAMS ((void));
extern rtx flow_delete_insn PARAMS ((rtx));
extern void flow_delete_insn_chain PARAMS ((rtx, rtx));
extern void make_edge PARAMS ((sbitmap *, basic_block,
basic_block, int));
extern void remove_edge PARAMS ((edge));
/* Structure to hold information for each natural loop. */

25
gcc/emit-rtl.c
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@ -2084,6 +2084,17 @@ prev_real_insn (insn)
does not look inside SEQUENCEs. Until reload has completed, this is the
same as next_real_insn. */
int
active_insn_p (insn)
rtx insn;
{
return (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == JUMP_INSN
|| (GET_CODE (insn) == INSN
&& (! reload_completed
|| (GET_CODE (PATTERN (insn)) != USE
&& GET_CODE (PATTERN (insn)) != CLOBBER))));
}
rtx
next_active_insn (insn)
rtx insn;
@ -2091,12 +2102,7 @@ next_active_insn (insn)
while (insn)
{
insn = NEXT_INSN (insn);
if (insn == 0
|| GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == JUMP_INSN
|| (GET_CODE (insn) == INSN
&& (! reload_completed
|| (GET_CODE (PATTERN (insn)) != USE
&& GET_CODE (PATTERN (insn)) != CLOBBER))))
if (insn == 0 || active_insn_p (insn))
break;
}
@ -2114,12 +2120,7 @@ prev_active_insn (insn)
while (insn)
{
insn = PREV_INSN (insn);
if (insn == 0
|| GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == JUMP_INSN
|| (GET_CODE (insn) == INSN
&& (! reload_completed
|| (GET_CODE (PATTERN (insn)) != USE
&& GET_CODE (PATTERN (insn)) != CLOBBER))))
if (insn == 0 || active_insn_p (insn))
break;
}

10
gcc/flow.c
View File

@ -285,8 +285,6 @@ static rtx find_basic_blocks_1 PARAMS ((rtx));
static void create_basic_block PARAMS ((int, rtx, rtx, rtx));
static void clear_edges PARAMS ((void));
static void make_edges PARAMS ((rtx));
static void make_edge PARAMS ((sbitmap *, basic_block,
basic_block, int));
static void make_label_edge PARAMS ((sbitmap *, basic_block,
rtx, int));
static void make_eh_edge PARAMS ((sbitmap *, eh_nesting_info *,
@ -302,7 +300,6 @@ static void delete_eh_regions PARAMS ((void));
static int can_delete_note_p PARAMS ((rtx));
static int delete_block PARAMS ((basic_block));
static void expunge_block PARAMS ((basic_block));
static rtx flow_delete_insn PARAMS ((rtx));
static int can_delete_label_p PARAMS ((rtx));
static int merge_blocks_move_predecessor_nojumps PARAMS ((basic_block,
basic_block));
@ -346,7 +343,6 @@ static void count_reg_sets_1 PARAMS ((rtx));
static void count_reg_sets PARAMS ((rtx));
static void count_reg_references PARAMS ((rtx));
static void invalidate_mems_from_autoinc PARAMS ((rtx));
static void remove_edge PARAMS ((edge));
static void remove_fake_successors PARAMS ((basic_block));
static void flow_nodes_print PARAMS ((const char *, const sbitmap, FILE *));
static void flow_exits_print PARAMS ((const char *, const edge *, int, FILE *));
@ -1056,7 +1052,7 @@ make_edges (label_value_list)
/* Create an edge between two basic blocks. FLAGS are auxiliary information
about the edge that is accumulated between calls. */
static void
void
make_edge (edge_cache, src, dst, flags)
sbitmap *edge_cache;
basic_block src, dst;
@ -1982,7 +1978,7 @@ expunge_block (b)
/* Delete INSN by patching it out. Return the next insn. */
static rtx
rtx
flow_delete_insn (insn)
rtx insn;
{
@ -6215,7 +6211,7 @@ find_edge_index (edge_list, pred, succ)
}
/* This function will remove an edge from the flow graph. */
static void
void
remove_edge (e)
edge e;
{

109
gcc/function.c
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@ -271,6 +271,7 @@ static int all_blocks PARAMS ((tree, tree *));
can always export `prologue_epilogue_contains'. */
static int *record_insns PARAMS ((rtx)) ATTRIBUTE_UNUSED;
static int contains PARAMS ((rtx, int *));
static void emit_return_into_block PARAMS ((basic_block));
static void put_addressof_into_stack PARAMS ((rtx, struct hash_table *));
static boolean purge_addressof_1 PARAMS ((rtx *, rtx, int, int,
struct hash_table *));
@ -6577,6 +6578,27 @@ prologue_epilogue_contains (insn)
return 0;
}
/* Insert gen_return at the end of block BB. This also means updating
block_for_insn appropriately. */
static void
emit_return_into_block (bb)
basic_block bb;
{
rtx p, end;
end = emit_jump_insn_after (gen_return (), bb->end);
p = NEXT_INSN (bb->end);
while (1)
{
set_block_for_insn (p, bb);
if (p == end)
break;
p = NEXT_INSN (p);
}
bb->end = end;
}
/* Generate the prologue and epilogue RTL if the machine supports it. Thread
this into place with notes indicating where the prologue ends and where
the epilogue begins. Update the basic block information when possible. */
@ -6629,6 +6651,93 @@ thread_prologue_and_epilogue_insns (f)
if (e == NULL)
goto epilogue_done;
#ifdef HAVE_return
if (optimize && HAVE_return)
{
/* If we're allowed to generate a simple return instruction,
then by definition we don't need a full epilogue. Examine
the block that falls through to EXIT. If it does not
contain any code, examine its predecessors and try to
emit (conditional) return instructions. */
basic_block last;
edge e_next;
rtx label;
for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
if (e->flags & EDGE_FALLTHRU)
break;
if (e == NULL)
goto epilogue_done;
last = e->src;
/* Verify that there are no active instructions in the last block. */
label = last->end;
while (label && GET_CODE (label) != CODE_LABEL)
{
if (active_insn_p (label))
break;
label = PREV_INSN (label);
}
if (last->head == label && GET_CODE (label) == CODE_LABEL)
{
for (e = last->pred; e ; e = e_next)
{
basic_block bb = e->src;
rtx jump;
e_next = e->pred_next;
if (bb == ENTRY_BLOCK_PTR)
continue;
jump = bb->end;
if (GET_CODE (jump) != JUMP_INSN)
continue;
/* If we have an unconditional jump, we can replace that
with a simple return instruction. */
if (simplejump_p (jump))
{
emit_return_into_block (bb);
flow_delete_insn (jump);
}
/* If we have a conditional jump, we can try to replace
that with a conditional return instruction. */
else if (condjump_p (jump))
{
rtx ret, *loc;
ret = SET_SRC (PATTERN (jump));
if (GET_CODE (XEXP (ret, 1)) == LABEL_REF)
loc = &XEXP (ret, 1);
else
loc = &XEXP (ret, 2);
ret = gen_rtx_RETURN (VOIDmode);
if (! validate_change (jump, loc, ret, 0))
continue;
if (JUMP_LABEL (jump))
LABEL_NUSES (JUMP_LABEL (jump))--;
}
else
continue;
/* Fix up the CFG for the successful change we just made. */
remove_edge (e);
make_edge (NULL, bb, EXIT_BLOCK_PTR, 0);
}
}
/* Emit a return insn for the exit fallthru block. Whether
this is still reachable will be determined later. */
emit_barrier_after (last->end);
emit_return_into_block (last);
goto epilogue_done;
}
#endif
#ifdef HAVE_epilogue
if (HAVE_epilogue)
{

39
gcc/jump.c
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@ -232,25 +232,6 @@ jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, mark_labels_only)
last_insn = delete_unreferenced_labels (f);
#ifdef HAVE_return
if (optimize && HAVE_return)
{
/* If we fall through to the epilogue, see if we can insert a RETURN insn
in front of it. If the machine allows it at this point (we might be
after reload for a leaf routine), it will improve optimization for it
to be there. */
insn = get_last_insn ();
while (insn && GET_CODE (insn) == NOTE)
insn = PREV_INSN (insn);
if (insn && GET_CODE (insn) != BARRIER)
{
emit_jump_insn (gen_return ());
emit_barrier ();
}
}
#endif
if (noop_moves)
delete_noop_moves (f);
@ -2142,26 +2123,6 @@ jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, mark_labels_only)
}
}
#ifdef HAVE_return
if (HAVE_return)
{
/* If we fall through to the epilogue, see if we can insert a RETURN insn
in front of it. If the machine allows it at this point (we might be
after reload for a leaf routine), it will improve optimization for it
to be there. We do this both here and at the start of this pass since
the RETURN might have been deleted by some of our optimizations. */
insn = get_last_insn ();
while (insn && GET_CODE (insn) == NOTE)
insn = PREV_INSN (insn);
if (insn && GET_CODE (insn) != BARRIER)
{
emit_jump_insn (gen_return ());
emit_barrier ();
}
}
#endif
/* CAN_REACH_END is persistent for each function. Once set it should
not be cleared. This is especially true for the case where we
delete the NOTE_FUNCTION_END note. CAN_REACH_END is cleared by

1
gcc/rtl.h
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@ -1051,6 +1051,7 @@ extern rtx prev_real_insn PARAMS ((rtx));
extern rtx next_real_insn PARAMS ((rtx));
extern rtx prev_active_insn PARAMS ((rtx));
extern rtx next_active_insn PARAMS ((rtx));
extern int active_insn_p PARAMS ((rtx));
extern rtx prev_label PARAMS ((rtx));
extern rtx next_label PARAMS ((rtx));
extern rtx next_cc0_user PARAMS ((rtx));