+2014-05-13 Zhenqiang Chen <zhenqiang.chen@linaro.org>
+
+ * Makefile.in: add shrink-wrap.o.
+ * config/i386/i386.c: include "shrink-wrap.h"
+ * function.c: Likewise.
+ (requires_stack_frame_p, next_block_for_reg,
+ move_insn_for_shrink_wrap, prepare_shrink_wrap,
+ dup_block_and_redirect): Move to shrink-wrap.c
+ (thread_prologue_and_epilogue_insns): Extract three code segments
+ as functions in shrink-wrap.c
+ * function.h: Move #ifdef HAVE_simple_return ... #endif block to
+ shrink-wrap.h
+ * shrink-wrap.c: New file.
+ * shrink-wrap.h: New file.
+
2014-05-12 David Wohlferd <dw@LimeGreenSocks.com>
* doc/extend.texi: Reflect current numbers of pragmas. Remove
sel-sched-dump.o \
sel-sched.o \
sese.o \
+ shrink-wrap.o \
simplify-rtx.o \
sparseset.o \
sreal.o \
#include "pass_manager.h"
#include "target-globals.h"
#include "tree-vectorizer.h"
+#include "shrink-wrap.h"
static rtx legitimize_dllimport_symbol (rtx, bool);
static rtx legitimize_pe_coff_extern_decl (rtx, bool);
#include "df.h"
#include "params.h"
#include "bb-reorder.h"
+#include "shrink-wrap.h"
/* So we can assign to cfun in this file. */
#undef cfun
return 0;
}
-#ifdef HAVE_simple_return
-
-/* Return true if INSN requires the stack frame to be set up.
- PROLOGUE_USED contains the hard registers used in the function
- prologue. SET_UP_BY_PROLOGUE is the set of registers we expect the
- prologue to set up for the function. */
-bool
-requires_stack_frame_p (rtx insn, HARD_REG_SET prologue_used,
- HARD_REG_SET set_up_by_prologue)
-{
- df_ref *df_rec;
- HARD_REG_SET hardregs;
- unsigned regno;
-
- if (CALL_P (insn))
- return !SIBLING_CALL_P (insn);
-
- /* We need a frame to get the unique CFA expected by the unwinder. */
- if (cfun->can_throw_non_call_exceptions && can_throw_internal (insn))
- return true;
-
- CLEAR_HARD_REG_SET (hardregs);
- for (df_rec = DF_INSN_DEFS (insn); *df_rec; df_rec++)
- {
- rtx dreg = DF_REF_REG (*df_rec);
-
- if (!REG_P (dreg))
- continue;
-
- add_to_hard_reg_set (&hardregs, GET_MODE (dreg),
- REGNO (dreg));
- }
- if (hard_reg_set_intersect_p (hardregs, prologue_used))
- return true;
- AND_COMPL_HARD_REG_SET (hardregs, call_used_reg_set);
- for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
- if (TEST_HARD_REG_BIT (hardregs, regno)
- && df_regs_ever_live_p (regno))
- return true;
-
- for (df_rec = DF_INSN_USES (insn); *df_rec; df_rec++)
- {
- rtx reg = DF_REF_REG (*df_rec);
-
- if (!REG_P (reg))
- continue;
-
- add_to_hard_reg_set (&hardregs, GET_MODE (reg),
- REGNO (reg));
- }
- if (hard_reg_set_intersect_p (hardregs, set_up_by_prologue))
- return true;
-
- return false;
-}
-
-/* See whether BB has a single successor that uses [REGNO, END_REGNO),
- and if BB is its only predecessor. Return that block if so,
- otherwise return null. */
-
-static basic_block
-next_block_for_reg (basic_block bb, int regno, int end_regno)
-{
- edge e, live_edge;
- edge_iterator ei;
- bitmap live;
- int i;
-
- live_edge = NULL;
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- live = df_get_live_in (e->dest);
- for (i = regno; i < end_regno; i++)
- if (REGNO_REG_SET_P (live, i))
- {
- if (live_edge && live_edge != e)
- return NULL;
- live_edge = e;
- }
- }
-
- /* We can sometimes encounter dead code. Don't try to move it
- into the exit block. */
- if (!live_edge || live_edge->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
- return NULL;
-
- /* Reject targets of abnormal edges. This is needed for correctness
- on ports like Alpha and MIPS, whose pic_offset_table_rtx can die on
- exception edges even though it is generally treated as call-saved
- for the majority of the compilation. Moving across abnormal edges
- isn't going to be interesting for shrink-wrap usage anyway. */
- if (live_edge->flags & EDGE_ABNORMAL)
- return NULL;
-
- if (EDGE_COUNT (live_edge->dest->preds) > 1)
- return NULL;
-
- return live_edge->dest;
-}
-
-/* Try to move INSN from BB to a successor. Return true on success.
- USES and DEFS are the set of registers that are used and defined
- after INSN in BB. */
-
-static bool
-move_insn_for_shrink_wrap (basic_block bb, rtx insn,
- const HARD_REG_SET uses,
- const HARD_REG_SET defs)
-{
- rtx set, src, dest;
- bitmap live_out, live_in, bb_uses, bb_defs;
- unsigned int i, dregno, end_dregno, sregno, end_sregno;
- basic_block next_block;
-
- /* Look for a simple register copy. */
- set = single_set (insn);
- if (!set)
- return false;
- src = SET_SRC (set);
- dest = SET_DEST (set);
- if (!REG_P (dest) || !REG_P (src))
- return false;
-
- /* Make sure that the source register isn't defined later in BB. */
- sregno = REGNO (src);
- end_sregno = END_REGNO (src);
- if (overlaps_hard_reg_set_p (defs, GET_MODE (src), sregno))
- return false;
-
- /* Make sure that the destination register isn't referenced later in BB. */
- dregno = REGNO (dest);
- end_dregno = END_REGNO (dest);
- if (overlaps_hard_reg_set_p (uses, GET_MODE (dest), dregno)
- || overlaps_hard_reg_set_p (defs, GET_MODE (dest), dregno))
- return false;
-
- /* See whether there is a successor block to which we could move INSN. */
- next_block = next_block_for_reg (bb, dregno, end_dregno);
- if (!next_block)
- return false;
-
- /* At this point we are committed to moving INSN, but let's try to
- move it as far as we can. */
- do
- {
- live_out = df_get_live_out (bb);
- live_in = df_get_live_in (next_block);
- bb = next_block;
-
- /* Check whether BB uses DEST or clobbers DEST. We need to add
- INSN to BB if so. Either way, DEST is no longer live on entry,
- except for any part that overlaps SRC (next loop). */
- bb_uses = &DF_LR_BB_INFO (bb)->use;
- bb_defs = &DF_LR_BB_INFO (bb)->def;
- if (df_live)
- {
- for (i = dregno; i < end_dregno; i++)
- {
- if (REGNO_REG_SET_P (bb_uses, i) || REGNO_REG_SET_P (bb_defs, i)
- || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
- next_block = NULL;
- CLEAR_REGNO_REG_SET (live_out, i);
- CLEAR_REGNO_REG_SET (live_in, i);
- }
-
- /* Check whether BB clobbers SRC. We need to add INSN to BB if so.
- Either way, SRC is now live on entry. */
- for (i = sregno; i < end_sregno; i++)
- {
- if (REGNO_REG_SET_P (bb_defs, i)
- || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
- next_block = NULL;
- SET_REGNO_REG_SET (live_out, i);
- SET_REGNO_REG_SET (live_in, i);
- }
- }
- else
- {
- /* DF_LR_BB_INFO (bb)->def does not comprise the DF_REF_PARTIAL and
- DF_REF_CONDITIONAL defs. So if DF_LIVE doesn't exist, i.e.
- at -O1, just give up searching NEXT_BLOCK. */
- next_block = NULL;
- for (i = dregno; i < end_dregno; i++)
- {
- CLEAR_REGNO_REG_SET (live_out, i);
- CLEAR_REGNO_REG_SET (live_in, i);
- }
-
- for (i = sregno; i < end_sregno; i++)
- {
- SET_REGNO_REG_SET (live_out, i);
- SET_REGNO_REG_SET (live_in, i);
- }
- }
-
- /* If we don't need to add the move to BB, look for a single
- successor block. */
- if (next_block)
- next_block = next_block_for_reg (next_block, dregno, end_dregno);
- }
- while (next_block);
-
- /* BB now defines DEST. It only uses the parts of DEST that overlap SRC
- (next loop). */
- for (i = dregno; i < end_dregno; i++)
- {
- CLEAR_REGNO_REG_SET (bb_uses, i);
- SET_REGNO_REG_SET (bb_defs, i);
- }
-
- /* BB now uses SRC. */
- for (i = sregno; i < end_sregno; i++)
- SET_REGNO_REG_SET (bb_uses, i);
-
- emit_insn_after (PATTERN (insn), bb_note (bb));
- delete_insn (insn);
- return true;
-}
-
-/* Look for register copies in the first block of the function, and move
- them down into successor blocks if the register is used only on one
- path. This exposes more opportunities for shrink-wrapping. These
- kinds of sets often occur when incoming argument registers are moved
- to call-saved registers because their values are live across one or
- more calls during the function. */
-
-static void
-prepare_shrink_wrap (basic_block entry_block)
-{
- rtx insn, curr, x;
- HARD_REG_SET uses, defs;
- df_ref *ref;
-
- CLEAR_HARD_REG_SET (uses);
- CLEAR_HARD_REG_SET (defs);
- FOR_BB_INSNS_REVERSE_SAFE (entry_block, insn, curr)
- if (NONDEBUG_INSN_P (insn)
- && !move_insn_for_shrink_wrap (entry_block, insn, uses, defs))
- {
- /* Add all defined registers to DEFs. */
- for (ref = DF_INSN_DEFS (insn); *ref; ref++)
- {
- x = DF_REF_REG (*ref);
- if (REG_P (x) && HARD_REGISTER_P (x))
- SET_HARD_REG_BIT (defs, REGNO (x));
- }
-
- /* Add all used registers to USESs. */
- for (ref = DF_INSN_USES (insn); *ref; ref++)
- {
- x = DF_REF_REG (*ref);
- if (REG_P (x) && HARD_REGISTER_P (x))
- SET_HARD_REG_BIT (uses, REGNO (x));
- }
- }
-}
-
-#endif
-
#ifdef HAVE_return
/* Insert use of return register before the end of BB. */
also means updating block_for_insn appropriately. SIMPLE_P is
the same as in gen_return_pattern and passed to it. */
-static void
+void
emit_return_into_block (bool simple_p, basic_block bb)
{
rtx jump, pat;
JUMP_LABEL (returnjump) = ret_rtx;
}
-#ifdef HAVE_simple_return
-/* Create a copy of BB instructions and insert at BEFORE. Redirect
- preds of BB to COPY_BB if they don't appear in NEED_PROLOGUE. */
-static void
-dup_block_and_redirect (basic_block bb, basic_block copy_bb, rtx before,
- bitmap_head *need_prologue)
-{
- edge_iterator ei;
- edge e;
- rtx insn = BB_END (bb);
-
- /* We know BB has a single successor, so there is no need to copy a
- simple jump at the end of BB. */
- if (simplejump_p (insn))
- insn = PREV_INSN (insn);
-
- start_sequence ();
- duplicate_insn_chain (BB_HEAD (bb), insn);
- if (dump_file)
- {
- unsigned count = 0;
- for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
- if (active_insn_p (insn))
- ++count;
- fprintf (dump_file, "Duplicating bb %d to bb %d, %u active insns.\n",
- bb->index, copy_bb->index, count);
- }
- insn = get_insns ();
- end_sequence ();
- emit_insn_before (insn, before);
-
- /* Redirect all the paths that need no prologue into copy_bb. */
- for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
- if (!bitmap_bit_p (need_prologue, e->src->index))
- {
- int freq = EDGE_FREQUENCY (e);
- copy_bb->count += e->count;
- copy_bb->frequency += EDGE_FREQUENCY (e);
- e->dest->count -= e->count;
- if (e->dest->count < 0)
- e->dest->count = 0;
- e->dest->frequency -= freq;
- if (e->dest->frequency < 0)
- e->dest->frequency = 0;
- redirect_edge_and_branch_force (e, copy_bb);
- continue;
- }
- else
- ei_next (&ei);
-}
-#endif
-
#if defined (HAVE_return) || defined (HAVE_simple_return)
/* Return true if there are any active insns between HEAD and TAIL. */
-static bool
+bool
active_insn_between (rtx head, rtx tail)
{
while (tail)
/* LAST_BB is a block that exits, and empty of active instructions.
Examine its predecessors for jumps that can be converted to
(conditional) returns. */
-static vec<edge>
+vec<edge>
convert_jumps_to_returns (basic_block last_bb, bool simple_p,
vec<edge> unconverted ATTRIBUTE_UNUSED)
{
}
/* Emit a return insn for the exit fallthru block. */
-static basic_block
+basic_block
emit_return_for_exit (edge exit_fallthru_edge, bool simple_p)
{
basic_block last_bb = exit_fallthru_edge->src;
bool inserted;
#ifdef HAVE_simple_return
vec<edge> unconverted_simple_returns = vNULL;
- bool nonempty_prologue;
bitmap_head bb_flags;
- unsigned max_grow_size;
#endif
rtx returnjump;
rtx seq ATTRIBUTE_UNUSED, epilogue_end ATTRIBUTE_UNUSED;
prologue/epilogue is emitted only around those parts of the
function that require it. */
- nonempty_prologue = false;
- for (seq = prologue_seq; seq; seq = NEXT_INSN (seq))
- if (!NOTE_P (seq) || NOTE_KIND (seq) != NOTE_INSN_PROLOGUE_END)
- {
- nonempty_prologue = true;
- break;
- }
-
- if (flag_shrink_wrap && HAVE_simple_return
- && (targetm.profile_before_prologue () || !crtl->profile)
- && nonempty_prologue && !crtl->calls_eh_return)
- {
- HARD_REG_SET prologue_clobbered, prologue_used, live_on_edge;
- struct hard_reg_set_container set_up_by_prologue;
- rtx p_insn;
- vec<basic_block> vec;
- basic_block bb;
- bitmap_head bb_antic_flags;
- bitmap_head bb_on_list;
- bitmap_head bb_tail;
-
- if (dump_file)
- fprintf (dump_file, "Attempting shrink-wrapping optimization.\n");
-
- /* Compute the registers set and used in the prologue. */
- CLEAR_HARD_REG_SET (prologue_clobbered);
- CLEAR_HARD_REG_SET (prologue_used);
- for (p_insn = prologue_seq; p_insn; p_insn = NEXT_INSN (p_insn))
- {
- HARD_REG_SET this_used;
- if (!NONDEBUG_INSN_P (p_insn))
- continue;
-
- CLEAR_HARD_REG_SET (this_used);
- note_uses (&PATTERN (p_insn), record_hard_reg_uses,
- &this_used);
- AND_COMPL_HARD_REG_SET (this_used, prologue_clobbered);
- IOR_HARD_REG_SET (prologue_used, this_used);
- note_stores (PATTERN (p_insn), record_hard_reg_sets,
- &prologue_clobbered);
- }
-
- prepare_shrink_wrap (entry_edge->dest);
-
- bitmap_initialize (&bb_antic_flags, &bitmap_default_obstack);
- bitmap_initialize (&bb_on_list, &bitmap_default_obstack);
- bitmap_initialize (&bb_tail, &bitmap_default_obstack);
-
- /* Find the set of basic blocks that require a stack frame,
- and blocks that are too big to be duplicated. */
-
- vec.create (n_basic_blocks_for_fn (cfun));
-
- CLEAR_HARD_REG_SET (set_up_by_prologue.set);
- add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
- STACK_POINTER_REGNUM);
- add_to_hard_reg_set (&set_up_by_prologue.set, Pmode, ARG_POINTER_REGNUM);
- if (frame_pointer_needed)
- add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
- HARD_FRAME_POINTER_REGNUM);
- if (pic_offset_table_rtx)
- add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
- PIC_OFFSET_TABLE_REGNUM);
- if (crtl->drap_reg)
- add_to_hard_reg_set (&set_up_by_prologue.set,
- GET_MODE (crtl->drap_reg),
- REGNO (crtl->drap_reg));
- if (targetm.set_up_by_prologue)
- targetm.set_up_by_prologue (&set_up_by_prologue);
-
- /* We don't use a different max size depending on
- optimize_bb_for_speed_p because increasing shrink-wrapping
- opportunities by duplicating tail blocks can actually result
- in an overall decrease in code size. */
- max_grow_size = get_uncond_jump_length ();
- max_grow_size *= PARAM_VALUE (PARAM_MAX_GROW_COPY_BB_INSNS);
-
- FOR_EACH_BB_FN (bb, cfun)
- {
- rtx insn;
- unsigned size = 0;
-
- FOR_BB_INSNS (bb, insn)
- if (NONDEBUG_INSN_P (insn))
- {
- if (requires_stack_frame_p (insn, prologue_used,
- set_up_by_prologue.set))
- {
- if (bb == entry_edge->dest)
- goto fail_shrinkwrap;
- bitmap_set_bit (&bb_flags, bb->index);
- vec.quick_push (bb);
- break;
- }
- else if (size <= max_grow_size)
- {
- size += get_attr_min_length (insn);
- if (size > max_grow_size)
- bitmap_set_bit (&bb_on_list, bb->index);
- }
- }
- }
-
- /* Blocks that really need a prologue, or are too big for tails. */
- bitmap_ior_into (&bb_on_list, &bb_flags);
-
- /* For every basic block that needs a prologue, mark all blocks
- reachable from it, so as to ensure they are also seen as
- requiring a prologue. */
- while (!vec.is_empty ())
- {
- basic_block tmp_bb = vec.pop ();
-
- FOR_EACH_EDGE (e, ei, tmp_bb->succs)
- if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
- && bitmap_set_bit (&bb_flags, e->dest->index))
- vec.quick_push (e->dest);
- }
-
- /* Find the set of basic blocks that need no prologue, have a
- single successor, can be duplicated, meet a max size
- requirement, and go to the exit via like blocks. */
- vec.quick_push (EXIT_BLOCK_PTR_FOR_FN (cfun));
- while (!vec.is_empty ())
- {
- basic_block tmp_bb = vec.pop ();
-
- FOR_EACH_EDGE (e, ei, tmp_bb->preds)
- if (single_succ_p (e->src)
- && !bitmap_bit_p (&bb_on_list, e->src->index)
- && can_duplicate_block_p (e->src))
- {
- edge pe;
- edge_iterator pei;
-
- /* If there is predecessor of e->src which doesn't
- need prologue and the edge is complex,
- we might not be able to redirect the branch
- to a copy of e->src. */
- FOR_EACH_EDGE (pe, pei, e->src->preds)
- if ((pe->flags & EDGE_COMPLEX) != 0
- && !bitmap_bit_p (&bb_flags, pe->src->index))
- break;
- if (pe == NULL && bitmap_set_bit (&bb_tail, e->src->index))
- vec.quick_push (e->src);
- }
- }
-
- /* Now walk backwards from every block that is marked as needing
- a prologue to compute the bb_antic_flags bitmap. Exclude
- tail blocks; They can be duplicated to be used on paths not
- needing a prologue. */
- bitmap_clear (&bb_on_list);
- bitmap_and_compl (&bb_antic_flags, &bb_flags, &bb_tail);
- FOR_EACH_BB_FN (bb, cfun)
- {
- if (!bitmap_bit_p (&bb_antic_flags, bb->index))
- continue;
- FOR_EACH_EDGE (e, ei, bb->preds)
- if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
- && bitmap_set_bit (&bb_on_list, e->src->index))
- vec.quick_push (e->src);
- }
- while (!vec.is_empty ())
- {
- basic_block tmp_bb = vec.pop ();
- bool all_set = true;
-
- bitmap_clear_bit (&bb_on_list, tmp_bb->index);
- FOR_EACH_EDGE (e, ei, tmp_bb->succs)
- if (!bitmap_bit_p (&bb_antic_flags, e->dest->index))
- {
- all_set = false;
- break;
- }
-
- if (all_set)
- {
- bitmap_set_bit (&bb_antic_flags, tmp_bb->index);
- FOR_EACH_EDGE (e, ei, tmp_bb->preds)
- if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
- && bitmap_set_bit (&bb_on_list, e->src->index))
- vec.quick_push (e->src);
- }
- }
- /* Find exactly one edge that leads to a block in ANTIC from
- a block that isn't. */
- if (!bitmap_bit_p (&bb_antic_flags, entry_edge->dest->index))
- FOR_EACH_BB_FN (bb, cfun)
- {
- if (!bitmap_bit_p (&bb_antic_flags, bb->index))
- continue;
- FOR_EACH_EDGE (e, ei, bb->preds)
- if (!bitmap_bit_p (&bb_antic_flags, e->src->index))
- {
- if (entry_edge != orig_entry_edge)
- {
- entry_edge = orig_entry_edge;
- if (dump_file)
- fprintf (dump_file, "More than one candidate edge.\n");
- goto fail_shrinkwrap;
- }
- if (dump_file)
- fprintf (dump_file, "Found candidate edge for "
- "shrink-wrapping, %d->%d.\n", e->src->index,
- e->dest->index);
- entry_edge = e;
- }
- }
-
- if (entry_edge != orig_entry_edge)
- {
- /* Test whether the prologue is known to clobber any register
- (other than FP or SP) which are live on the edge. */
- CLEAR_HARD_REG_BIT (prologue_clobbered, STACK_POINTER_REGNUM);
- if (frame_pointer_needed)
- CLEAR_HARD_REG_BIT (prologue_clobbered, HARD_FRAME_POINTER_REGNUM);
- REG_SET_TO_HARD_REG_SET (live_on_edge,
- df_get_live_in (entry_edge->dest));
- if (hard_reg_set_intersect_p (live_on_edge, prologue_clobbered))
- {
- entry_edge = orig_entry_edge;
- if (dump_file)
- fprintf (dump_file,
- "Shrink-wrapping aborted due to clobber.\n");
- }
- }
- if (entry_edge != orig_entry_edge)
- {
- crtl->shrink_wrapped = true;
- if (dump_file)
- fprintf (dump_file, "Performing shrink-wrapping.\n");
-
- /* Find tail blocks reachable from both blocks needing a
- prologue and blocks not needing a prologue. */
- if (!bitmap_empty_p (&bb_tail))
- FOR_EACH_BB_FN (bb, cfun)
- {
- bool some_pro, some_no_pro;
- if (!bitmap_bit_p (&bb_tail, bb->index))
- continue;
- some_pro = some_no_pro = false;
- FOR_EACH_EDGE (e, ei, bb->preds)
- {
- if (bitmap_bit_p (&bb_flags, e->src->index))
- some_pro = true;
- else
- some_no_pro = true;
- }
- if (some_pro && some_no_pro)
- vec.quick_push (bb);
- else
- bitmap_clear_bit (&bb_tail, bb->index);
- }
- /* Find the head of each tail. */
- while (!vec.is_empty ())
- {
- basic_block tbb = vec.pop ();
-
- if (!bitmap_bit_p (&bb_tail, tbb->index))
- continue;
-
- while (single_succ_p (tbb))
- {
- tbb = single_succ (tbb);
- bitmap_clear_bit (&bb_tail, tbb->index);
- }
- }
- /* Now duplicate the tails. */
- if (!bitmap_empty_p (&bb_tail))
- FOR_EACH_BB_REVERSE_FN (bb, cfun)
- {
- basic_block copy_bb, tbb;
- rtx insert_point;
- int eflags;
-
- if (!bitmap_clear_bit (&bb_tail, bb->index))
- continue;
-
- /* Create a copy of BB, instructions and all, for
- use on paths that don't need a prologue.
- Ideal placement of the copy is on a fall-thru edge
- or after a block that would jump to the copy. */
- FOR_EACH_EDGE (e, ei, bb->preds)
- if (!bitmap_bit_p (&bb_flags, e->src->index)
- && single_succ_p (e->src))
- break;
- if (e)
- {
- /* Make sure we insert after any barriers. */
- rtx end = get_last_bb_insn (e->src);
- copy_bb = create_basic_block (NEXT_INSN (end),
- NULL_RTX, e->src);
- BB_COPY_PARTITION (copy_bb, e->src);
- }
- else
- {
- /* Otherwise put the copy at the end of the function. */
- copy_bb = create_basic_block (NULL_RTX, NULL_RTX,
- EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb);
- BB_COPY_PARTITION (copy_bb, bb);
- }
-
- insert_point = emit_note_after (NOTE_INSN_DELETED,
- BB_END (copy_bb));
- emit_barrier_after (BB_END (copy_bb));
-
- tbb = bb;
- while (1)
- {
- dup_block_and_redirect (tbb, copy_bb, insert_point,
- &bb_flags);
- tbb = single_succ (tbb);
- if (tbb == EXIT_BLOCK_PTR_FOR_FN (cfun))
- break;
- e = split_block (copy_bb, PREV_INSN (insert_point));
- copy_bb = e->dest;
- }
-
- /* Quiet verify_flow_info by (ab)using EDGE_FAKE.
- We have yet to add a simple_return to the tails,
- as we'd like to first convert_jumps_to_returns in
- case the block is no longer used after that. */
- eflags = EDGE_FAKE;
- if (CALL_P (PREV_INSN (insert_point))
- && SIBLING_CALL_P (PREV_INSN (insert_point)))
- eflags = EDGE_SIBCALL | EDGE_ABNORMAL;
- make_single_succ_edge (copy_bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
- eflags);
-
- /* verify_flow_info doesn't like a note after a
- sibling call. */
- delete_insn (insert_point);
- if (bitmap_empty_p (&bb_tail))
- break;
- }
- }
-
- fail_shrinkwrap:
- bitmap_clear (&bb_tail);
- bitmap_clear (&bb_antic_flags);
- bitmap_clear (&bb_on_list);
- vec.release ();
- }
+ try_shrink_wrapping (&entry_edge, orig_entry_edge, &bb_flags, prologue_seq);
#endif
if (split_prologue_seq != NULL_RTX)
exit_fallthru_edge = find_fallthru_edge (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds);
- /* If we're allowed to generate a simple return instruction, then by
- definition we don't need a full epilogue. If the last basic
- block before the exit block does not contain active instructions,
- examine its predecessors and try to emit (conditional) return
- instructions. */
#ifdef HAVE_simple_return
if (entry_edge != orig_entry_edge)
- {
- if (optimize)
- {
- unsigned i, last;
-
- /* convert_jumps_to_returns may add to preds of the exit block
- (but won't remove). Stop at end of current preds. */
- last = EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds);
- for (i = 0; i < last; i++)
- {
- e = EDGE_I (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds, i);
- if (LABEL_P (BB_HEAD (e->src))
- && !bitmap_bit_p (&bb_flags, e->src->index)
- && !active_insn_between (BB_HEAD (e->src), BB_END (e->src)))
- unconverted_simple_returns
- = convert_jumps_to_returns (e->src, true,
- unconverted_simple_returns);
- }
- }
-
- if (exit_fallthru_edge != NULL
- && EDGE_COUNT (exit_fallthru_edge->src->preds) != 0
- && !bitmap_bit_p (&bb_flags, exit_fallthru_edge->src->index))
- {
- basic_block last_bb;
-
- last_bb = emit_return_for_exit (exit_fallthru_edge, true);
- returnjump = BB_END (last_bb);
- exit_fallthru_edge = NULL;
- }
- }
+ exit_fallthru_edge
+ = get_unconverted_simple_return (exit_fallthru_edge, bb_flags,
+ &unconverted_simple_returns,
+ &returnjump);
#endif
#ifdef HAVE_return
if (HAVE_return)
}
#ifdef HAVE_simple_return
- /* If there were branches to an empty LAST_BB which we tried to
- convert to conditional simple_returns, but couldn't for some
- reason, create a block to hold a simple_return insn and redirect
- those remaining edges. */
- if (!unconverted_simple_returns.is_empty ())
- {
- basic_block simple_return_block_hot = NULL;
- basic_block simple_return_block_cold = NULL;
- edge pending_edge_hot = NULL;
- edge pending_edge_cold = NULL;
- basic_block exit_pred;
- int i;
-
- gcc_assert (entry_edge != orig_entry_edge);
-
- /* See if we can reuse the last insn that was emitted for the
- epilogue. */
- if (returnjump != NULL_RTX
- && JUMP_LABEL (returnjump) == simple_return_rtx)
- {
- e = split_block (BLOCK_FOR_INSN (returnjump), PREV_INSN (returnjump));
- if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
- simple_return_block_hot = e->dest;
- else
- simple_return_block_cold = e->dest;
- }
-
- /* Also check returns we might need to add to tail blocks. */
- FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
- if (EDGE_COUNT (e->src->preds) != 0
- && (e->flags & EDGE_FAKE) != 0
- && !bitmap_bit_p (&bb_flags, e->src->index))
- {
- if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
- pending_edge_hot = e;
- else
- pending_edge_cold = e;
- }
-
- /* Save a pointer to the exit's predecessor BB for use in
- inserting new BBs at the end of the function. Do this
- after the call to split_block above which may split
- the original exit pred. */
- exit_pred = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
-
- FOR_EACH_VEC_ELT (unconverted_simple_returns, i, e)
- {
- basic_block *pdest_bb;
- edge pending;
-
- if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
- {
- pdest_bb = &simple_return_block_hot;
- pending = pending_edge_hot;
- }
- else
- {
- pdest_bb = &simple_return_block_cold;
- pending = pending_edge_cold;
- }
-
- if (*pdest_bb == NULL && pending != NULL)
- {
- emit_return_into_block (true, pending->src);
- pending->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);
- *pdest_bb = pending->src;
- }
- else if (*pdest_bb == NULL)
- {
- basic_block bb;
- rtx start;
-
- bb = create_basic_block (NULL, NULL, exit_pred);
- BB_COPY_PARTITION (bb, e->src);
- start = emit_jump_insn_after (gen_simple_return (),
- BB_END (bb));
- JUMP_LABEL (start) = simple_return_rtx;
- emit_barrier_after (start);
-
- *pdest_bb = bb;
- make_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
- }
- redirect_edge_and_branch_force (e, *pdest_bb);
- }
- unconverted_simple_returns.release ();
- }
-
- if (entry_edge != orig_entry_edge)
- {
- FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
- if (EDGE_COUNT (e->src->preds) != 0
- && (e->flags & EDGE_FAKE) != 0
- && !bitmap_bit_p (&bb_flags, e->src->index))
- {
- emit_return_into_block (true, e->src);
- e->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);
- }
- }
+ convert_to_simple_return (entry_edge, orig_entry_edge, bb_flags, returnjump,
+ unconverted_simple_returns);
#endif
#ifdef HAVE_sibcall_epilogue
extern int get_next_funcdef_no (void);
extern int get_last_funcdef_no (void);
-#ifdef HAVE_simple_return
-extern bool requires_stack_frame_p (rtx, HARD_REG_SET, HARD_REG_SET);
-#endif
-
extern rtx get_hard_reg_initial_val (enum machine_mode, unsigned int);
extern rtx has_hard_reg_initial_val (enum machine_mode, unsigned int);
extern rtx get_hard_reg_initial_reg (rtx);
--- /dev/null
+/* Expands front end tree to back end RTL for GCC.
+ Copyright (C) 1987-2014 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/>. */
+
+/* This file handles shrink-wrapping related optimizations. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "rtl-error.h"
+#include "tree.h"
+#include "stor-layout.h"
+#include "varasm.h"
+#include "stringpool.h"
+#include "flags.h"
+#include "except.h"
+#include "function.h"
+#include "expr.h"
+#include "optabs.h"
+#include "libfuncs.h"
+#include "regs.h"
+#include "hard-reg-set.h"
+#include "insn-config.h"
+#include "recog.h"
+#include "output.h"
+#include "hashtab.h"
+#include "tm_p.h"
+#include "langhooks.h"
+#include "target.h"
+#include "common/common-target.h"
+#include "gimple-expr.h"
+#include "gimplify.h"
+#include "tree-pass.h"
+#include "predict.h"
+#include "df.h"
+#include "params.h"
+#include "bb-reorder.h"
+#include "shrink-wrap.h"
+
+
+#ifdef HAVE_simple_return
+
+/* Return true if INSN requires the stack frame to be set up.
+ PROLOGUE_USED contains the hard registers used in the function
+ prologue. SET_UP_BY_PROLOGUE is the set of registers we expect the
+ prologue to set up for the function. */
+bool
+requires_stack_frame_p (rtx insn, HARD_REG_SET prologue_used,
+ HARD_REG_SET set_up_by_prologue)
+{
+ df_ref *df_rec;
+ HARD_REG_SET hardregs;
+ unsigned regno;
+
+ if (CALL_P (insn))
+ return !SIBLING_CALL_P (insn);
+
+ /* We need a frame to get the unique CFA expected by the unwinder. */
+ if (cfun->can_throw_non_call_exceptions && can_throw_internal (insn))
+ return true;
+
+ CLEAR_HARD_REG_SET (hardregs);
+ for (df_rec = DF_INSN_DEFS (insn); *df_rec; df_rec++)
+ {
+ rtx dreg = DF_REF_REG (*df_rec);
+
+ if (!REG_P (dreg))
+ continue;
+
+ add_to_hard_reg_set (&hardregs, GET_MODE (dreg),
+ REGNO (dreg));
+ }
+ if (hard_reg_set_intersect_p (hardregs, prologue_used))
+ return true;
+ AND_COMPL_HARD_REG_SET (hardregs, call_used_reg_set);
+ for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+ if (TEST_HARD_REG_BIT (hardregs, regno)
+ && df_regs_ever_live_p (regno))
+ return true;
+
+ for (df_rec = DF_INSN_USES (insn); *df_rec; df_rec++)
+ {
+ rtx reg = DF_REF_REG (*df_rec);
+
+ if (!REG_P (reg))
+ continue;
+
+ add_to_hard_reg_set (&hardregs, GET_MODE (reg),
+ REGNO (reg));
+ }
+ if (hard_reg_set_intersect_p (hardregs, set_up_by_prologue))
+ return true;
+
+ return false;
+}
+
+/* See whether BB has a single successor that uses [REGNO, END_REGNO),
+ and if BB is its only predecessor. Return that block if so,
+ otherwise return null. */
+
+static basic_block
+next_block_for_reg (basic_block bb, int regno, int end_regno)
+{
+ edge e, live_edge;
+ edge_iterator ei;
+ bitmap live;
+ int i;
+
+ live_edge = NULL;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ live = df_get_live_in (e->dest);
+ for (i = regno; i < end_regno; i++)
+ if (REGNO_REG_SET_P (live, i))
+ {
+ if (live_edge && live_edge != e)
+ return NULL;
+ live_edge = e;
+ }
+ }
+
+ /* We can sometimes encounter dead code. Don't try to move it
+ into the exit block. */
+ if (!live_edge || live_edge->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ return NULL;
+
+ /* Reject targets of abnormal edges. This is needed for correctness
+ on ports like Alpha and MIPS, whose pic_offset_table_rtx can die on
+ exception edges even though it is generally treated as call-saved
+ for the majority of the compilation. Moving across abnormal edges
+ isn't going to be interesting for shrink-wrap usage anyway. */
+ if (live_edge->flags & EDGE_ABNORMAL)
+ return NULL;
+
+ if (EDGE_COUNT (live_edge->dest->preds) > 1)
+ return NULL;
+
+ return live_edge->dest;
+}
+
+/* Try to move INSN from BB to a successor. Return true on success.
+ USES and DEFS are the set of registers that are used and defined
+ after INSN in BB. */
+
+static bool
+move_insn_for_shrink_wrap (basic_block bb, rtx insn,
+ const HARD_REG_SET uses,
+ const HARD_REG_SET defs)
+{
+ rtx set, src, dest;
+ bitmap live_out, live_in, bb_uses, bb_defs;
+ unsigned int i, dregno, end_dregno, sregno, end_sregno;
+ basic_block next_block;
+
+ /* Look for a simple register copy. */
+ set = single_set (insn);
+ if (!set)
+ return false;
+ src = SET_SRC (set);
+ dest = SET_DEST (set);
+ if (!REG_P (dest) || !REG_P (src))
+ return false;
+
+ /* Make sure that the source register isn't defined later in BB. */
+ sregno = REGNO (src);
+ end_sregno = END_REGNO (src);
+ if (overlaps_hard_reg_set_p (defs, GET_MODE (src), sregno))
+ return false;
+
+ /* Make sure that the destination register isn't referenced later in BB. */
+ dregno = REGNO (dest);
+ end_dregno = END_REGNO (dest);
+ if (overlaps_hard_reg_set_p (uses, GET_MODE (dest), dregno)
+ || overlaps_hard_reg_set_p (defs, GET_MODE (dest), dregno))
+ return false;
+
+ /* See whether there is a successor block to which we could move INSN. */
+ next_block = next_block_for_reg (bb, dregno, end_dregno);
+ if (!next_block)
+ return false;
+
+ /* At this point we are committed to moving INSN, but let's try to
+ move it as far as we can. */
+ do
+ {
+ live_out = df_get_live_out (bb);
+ live_in = df_get_live_in (next_block);
+ bb = next_block;
+
+ /* Check whether BB uses DEST or clobbers DEST. We need to add
+ INSN to BB if so. Either way, DEST is no longer live on entry,
+ except for any part that overlaps SRC (next loop). */
+ bb_uses = &DF_LR_BB_INFO (bb)->use;
+ bb_defs = &DF_LR_BB_INFO (bb)->def;
+ if (df_live)
+ {
+ for (i = dregno; i < end_dregno; i++)
+ {
+ if (REGNO_REG_SET_P (bb_uses, i) || REGNO_REG_SET_P (bb_defs, i)
+ || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
+ next_block = NULL;
+ CLEAR_REGNO_REG_SET (live_out, i);
+ CLEAR_REGNO_REG_SET (live_in, i);
+ }
+
+ /* Check whether BB clobbers SRC. We need to add INSN to BB if so.
+ Either way, SRC is now live on entry. */
+ for (i = sregno; i < end_sregno; i++)
+ {
+ if (REGNO_REG_SET_P (bb_defs, i)
+ || REGNO_REG_SET_P (&DF_LIVE_BB_INFO (bb)->gen, i))
+ next_block = NULL;
+ SET_REGNO_REG_SET (live_out, i);
+ SET_REGNO_REG_SET (live_in, i);
+ }
+ }
+ else
+ {
+ /* DF_LR_BB_INFO (bb)->def does not comprise the DF_REF_PARTIAL and
+ DF_REF_CONDITIONAL defs. So if DF_LIVE doesn't exist, i.e.
+ at -O1, just give up searching NEXT_BLOCK. */
+ next_block = NULL;
+ for (i = dregno; i < end_dregno; i++)
+ {
+ CLEAR_REGNO_REG_SET (live_out, i);
+ CLEAR_REGNO_REG_SET (live_in, i);
+ }
+
+ for (i = sregno; i < end_sregno; i++)
+ {
+ SET_REGNO_REG_SET (live_out, i);
+ SET_REGNO_REG_SET (live_in, i);
+ }
+ }
+
+ /* If we don't need to add the move to BB, look for a single
+ successor block. */
+ if (next_block)
+ next_block = next_block_for_reg (next_block, dregno, end_dregno);
+ }
+ while (next_block);
+
+ /* BB now defines DEST. It only uses the parts of DEST that overlap SRC
+ (next loop). */
+ for (i = dregno; i < end_dregno; i++)
+ {
+ CLEAR_REGNO_REG_SET (bb_uses, i);
+ SET_REGNO_REG_SET (bb_defs, i);
+ }
+
+ /* BB now uses SRC. */
+ for (i = sregno; i < end_sregno; i++)
+ SET_REGNO_REG_SET (bb_uses, i);
+
+ emit_insn_after (PATTERN (insn), bb_note (bb));
+ delete_insn (insn);
+ return true;
+}
+
+/* Look for register copies in the first block of the function, and move
+ them down into successor blocks if the register is used only on one
+ path. This exposes more opportunities for shrink-wrapping. These
+ kinds of sets often occur when incoming argument registers are moved
+ to call-saved registers because their values are live across one or
+ more calls during the function. */
+
+void
+prepare_shrink_wrap (basic_block entry_block)
+{
+ rtx insn, curr, x;
+ HARD_REG_SET uses, defs;
+ df_ref *ref;
+
+ CLEAR_HARD_REG_SET (uses);
+ CLEAR_HARD_REG_SET (defs);
+ FOR_BB_INSNS_REVERSE_SAFE (entry_block, insn, curr)
+ if (NONDEBUG_INSN_P (insn)
+ && !move_insn_for_shrink_wrap (entry_block, insn, uses, defs))
+ {
+ /* Add all defined registers to DEFs. */
+ for (ref = DF_INSN_DEFS (insn); *ref; ref++)
+ {
+ x = DF_REF_REG (*ref);
+ if (REG_P (x) && HARD_REGISTER_P (x))
+ SET_HARD_REG_BIT (defs, REGNO (x));
+ }
+
+ /* Add all used registers to USESs. */
+ for (ref = DF_INSN_USES (insn); *ref; ref++)
+ {
+ x = DF_REF_REG (*ref);
+ if (REG_P (x) && HARD_REGISTER_P (x))
+ SET_HARD_REG_BIT (uses, REGNO (x));
+ }
+ }
+}
+
+/* Create a copy of BB instructions and insert at BEFORE. Redirect
+ preds of BB to COPY_BB if they don't appear in NEED_PROLOGUE. */
+void
+dup_block_and_redirect (basic_block bb, basic_block copy_bb, rtx before,
+ bitmap_head *need_prologue)
+{
+ edge_iterator ei;
+ edge e;
+ rtx insn = BB_END (bb);
+
+ /* We know BB has a single successor, so there is no need to copy a
+ simple jump at the end of BB. */
+ if (simplejump_p (insn))
+ insn = PREV_INSN (insn);
+
+ start_sequence ();
+ duplicate_insn_chain (BB_HEAD (bb), insn);
+ if (dump_file)
+ {
+ unsigned count = 0;
+ for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
+ if (active_insn_p (insn))
+ ++count;
+ fprintf (dump_file, "Duplicating bb %d to bb %d, %u active insns.\n",
+ bb->index, copy_bb->index, count);
+ }
+ insn = get_insns ();
+ end_sequence ();
+ emit_insn_before (insn, before);
+
+ /* Redirect all the paths that need no prologue into copy_bb. */
+ for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei));)
+ if (!bitmap_bit_p (need_prologue, e->src->index))
+ {
+ int freq = EDGE_FREQUENCY (e);
+ copy_bb->count += e->count;
+ copy_bb->frequency += EDGE_FREQUENCY (e);
+ e->dest->count -= e->count;
+ if (e->dest->count < 0)
+ e->dest->count = 0;
+ e->dest->frequency -= freq;
+ if (e->dest->frequency < 0)
+ e->dest->frequency = 0;
+ redirect_edge_and_branch_force (e, copy_bb);
+ continue;
+ }
+ else
+ ei_next (&ei);
+}
+
+
+/* Try to perform a kind of shrink-wrapping, making sure the
+ prologue/epilogue is emitted only around those parts of the
+ function that require it. */
+
+void
+try_shrink_wrapping (edge *entry_edge, edge orig_entry_edge,
+ bitmap_head *bb_flags, rtx prologue_seq)
+{
+ edge e;
+ edge_iterator ei;
+ bool nonempty_prologue = false;
+ unsigned max_grow_size;
+ rtx seq;
+
+ for (seq = prologue_seq; seq; seq = NEXT_INSN (seq))
+ if (!NOTE_P (seq) || NOTE_KIND (seq) != NOTE_INSN_PROLOGUE_END)
+ {
+ nonempty_prologue = true;
+ break;
+ }
+
+ if (flag_shrink_wrap && HAVE_simple_return
+ && (targetm.profile_before_prologue () || !crtl->profile)
+ && nonempty_prologue && !crtl->calls_eh_return)
+ {
+ HARD_REG_SET prologue_clobbered, prologue_used, live_on_edge;
+ struct hard_reg_set_container set_up_by_prologue;
+ rtx p_insn;
+ vec<basic_block> vec;
+ basic_block bb;
+ bitmap_head bb_antic_flags;
+ bitmap_head bb_on_list;
+ bitmap_head bb_tail;
+
+ if (dump_file)
+ fprintf (dump_file, "Attempting shrink-wrapping optimization.\n");
+
+ /* Compute the registers set and used in the prologue. */
+ CLEAR_HARD_REG_SET (prologue_clobbered);
+ CLEAR_HARD_REG_SET (prologue_used);
+ for (p_insn = prologue_seq; p_insn; p_insn = NEXT_INSN (p_insn))
+ {
+ HARD_REG_SET this_used;
+ if (!NONDEBUG_INSN_P (p_insn))
+ continue;
+
+ CLEAR_HARD_REG_SET (this_used);
+ note_uses (&PATTERN (p_insn), record_hard_reg_uses,
+ &this_used);
+ AND_COMPL_HARD_REG_SET (this_used, prologue_clobbered);
+ IOR_HARD_REG_SET (prologue_used, this_used);
+ note_stores (PATTERN (p_insn), record_hard_reg_sets,
+ &prologue_clobbered);
+ }
+
+ prepare_shrink_wrap ((*entry_edge)->dest);
+
+ bitmap_initialize (&bb_antic_flags, &bitmap_default_obstack);
+ bitmap_initialize (&bb_on_list, &bitmap_default_obstack);
+ bitmap_initialize (&bb_tail, &bitmap_default_obstack);
+
+ /* Find the set of basic blocks that require a stack frame,
+ and blocks that are too big to be duplicated. */
+
+ vec.create (n_basic_blocks_for_fn (cfun));
+
+ CLEAR_HARD_REG_SET (set_up_by_prologue.set);
+ add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
+ STACK_POINTER_REGNUM);
+ add_to_hard_reg_set (&set_up_by_prologue.set, Pmode, ARG_POINTER_REGNUM);
+ if (frame_pointer_needed)
+ add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
+ HARD_FRAME_POINTER_REGNUM);
+ if (pic_offset_table_rtx)
+ add_to_hard_reg_set (&set_up_by_prologue.set, Pmode,
+ PIC_OFFSET_TABLE_REGNUM);
+ if (crtl->drap_reg)
+ add_to_hard_reg_set (&set_up_by_prologue.set,
+ GET_MODE (crtl->drap_reg),
+ REGNO (crtl->drap_reg));
+ if (targetm.set_up_by_prologue)
+ targetm.set_up_by_prologue (&set_up_by_prologue);
+
+ /* We don't use a different max size depending on
+ optimize_bb_for_speed_p because increasing shrink-wrapping
+ opportunities by duplicating tail blocks can actually result
+ in an overall decrease in code size. */
+ max_grow_size = get_uncond_jump_length ();
+ max_grow_size *= PARAM_VALUE (PARAM_MAX_GROW_COPY_BB_INSNS);
+
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ rtx insn;
+ unsigned size = 0;
+
+ FOR_BB_INSNS (bb, insn)
+ if (NONDEBUG_INSN_P (insn))
+ {
+ if (requires_stack_frame_p (insn, prologue_used,
+ set_up_by_prologue.set))
+ {
+ if (bb == (*entry_edge)->dest)
+ goto fail_shrinkwrap;
+ bitmap_set_bit (bb_flags, bb->index);
+ vec.quick_push (bb);
+ break;
+ }
+ else if (size <= max_grow_size)
+ {
+ size += get_attr_min_length (insn);
+ if (size > max_grow_size)
+ bitmap_set_bit (&bb_on_list, bb->index);
+ }
+ }
+ }
+
+ /* Blocks that really need a prologue, or are too big for tails. */
+ bitmap_ior_into (&bb_on_list, bb_flags);
+
+ /* For every basic block that needs a prologue, mark all blocks
+ reachable from it, so as to ensure they are also seen as
+ requiring a prologue. */
+ while (!vec.is_empty ())
+ {
+ basic_block tmp_bb = vec.pop ();
+
+ FOR_EACH_EDGE (e, ei, tmp_bb->succs)
+ if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
+ && bitmap_set_bit (bb_flags, e->dest->index))
+ vec.quick_push (e->dest);
+ }
+
+ /* Find the set of basic blocks that need no prologue, have a
+ single successor, can be duplicated, meet a max size
+ requirement, and go to the exit via like blocks. */
+ vec.quick_push (EXIT_BLOCK_PTR_FOR_FN (cfun));
+ while (!vec.is_empty ())
+ {
+ basic_block tmp_bb = vec.pop ();
+
+ FOR_EACH_EDGE (e, ei, tmp_bb->preds)
+ if (single_succ_p (e->src)
+ && !bitmap_bit_p (&bb_on_list, e->src->index)
+ && can_duplicate_block_p (e->src))
+ {
+ edge pe;
+ edge_iterator pei;
+
+ /* If there is predecessor of e->src which doesn't
+ need prologue and the edge is complex,
+ we might not be able to redirect the branch
+ to a copy of e->src. */
+ FOR_EACH_EDGE (pe, pei, e->src->preds)
+ if ((pe->flags & EDGE_COMPLEX) != 0
+ && !bitmap_bit_p (bb_flags, pe->src->index))
+ break;
+ if (pe == NULL && bitmap_set_bit (&bb_tail, e->src->index))
+ vec.quick_push (e->src);
+ }
+ }
+
+ /* Now walk backwards from every block that is marked as needing
+ a prologue to compute the bb_antic_flags bitmap. Exclude
+ tail blocks; They can be duplicated to be used on paths not
+ needing a prologue. */
+ bitmap_clear (&bb_on_list);
+ bitmap_and_compl (&bb_antic_flags, bb_flags, &bb_tail);
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ if (!bitmap_bit_p (&bb_antic_flags, bb->index))
+ continue;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
+ && bitmap_set_bit (&bb_on_list, e->src->index))
+ vec.quick_push (e->src);
+ }
+ while (!vec.is_empty ())
+ {
+ basic_block tmp_bb = vec.pop ();
+ bool all_set = true;
+
+ bitmap_clear_bit (&bb_on_list, tmp_bb->index);
+ FOR_EACH_EDGE (e, ei, tmp_bb->succs)
+ if (!bitmap_bit_p (&bb_antic_flags, e->dest->index))
+ {
+ all_set = false;
+ break;
+ }
+
+ if (all_set)
+ {
+ bitmap_set_bit (&bb_antic_flags, tmp_bb->index);
+ FOR_EACH_EDGE (e, ei, tmp_bb->preds)
+ if (!bitmap_bit_p (&bb_antic_flags, e->src->index)
+ && bitmap_set_bit (&bb_on_list, e->src->index))
+ vec.quick_push (e->src);
+ }
+ }
+ /* Find exactly one edge that leads to a block in ANTIC from
+ a block that isn't. */
+ if (!bitmap_bit_p (&bb_antic_flags, (*entry_edge)->dest->index))
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ if (!bitmap_bit_p (&bb_antic_flags, bb->index))
+ continue;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (!bitmap_bit_p (&bb_antic_flags, e->src->index))
+ {
+ if (*entry_edge != orig_entry_edge)
+ {
+ *entry_edge = orig_entry_edge;
+ if (dump_file)
+ fprintf (dump_file, "More than one candidate edge.\n");
+ goto fail_shrinkwrap;
+ }
+ if (dump_file)
+ fprintf (dump_file, "Found candidate edge for "
+ "shrink-wrapping, %d->%d.\n", e->src->index,
+ e->dest->index);
+ *entry_edge = e;
+ }
+ }
+
+ if (*entry_edge != orig_entry_edge)
+ {
+ /* Test whether the prologue is known to clobber any register
+ (other than FP or SP) which are live on the edge. */
+ CLEAR_HARD_REG_BIT (prologue_clobbered, STACK_POINTER_REGNUM);
+ if (frame_pointer_needed)
+ CLEAR_HARD_REG_BIT (prologue_clobbered, HARD_FRAME_POINTER_REGNUM);
+ REG_SET_TO_HARD_REG_SET (live_on_edge,
+ df_get_live_in ((*entry_edge)->dest));
+ if (hard_reg_set_intersect_p (live_on_edge, prologue_clobbered))
+ {
+ *entry_edge = orig_entry_edge;
+ if (dump_file)
+ fprintf (dump_file,
+ "Shrink-wrapping aborted due to clobber.\n");
+ }
+ }
+ if (*entry_edge != orig_entry_edge)
+ {
+ crtl->shrink_wrapped = true;
+ if (dump_file)
+ fprintf (dump_file, "Performing shrink-wrapping.\n");
+
+ /* Find tail blocks reachable from both blocks needing a
+ prologue and blocks not needing a prologue. */
+ if (!bitmap_empty_p (&bb_tail))
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ bool some_pro, some_no_pro;
+ if (!bitmap_bit_p (&bb_tail, bb->index))
+ continue;
+ some_pro = some_no_pro = false;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ if (bitmap_bit_p (bb_flags, e->src->index))
+ some_pro = true;
+ else
+ some_no_pro = true;
+ }
+ if (some_pro && some_no_pro)
+ vec.quick_push (bb);
+ else
+ bitmap_clear_bit (&bb_tail, bb->index);
+ }
+ /* Find the head of each tail. */
+ while (!vec.is_empty ())
+ {
+ basic_block tbb = vec.pop ();
+
+ if (!bitmap_bit_p (&bb_tail, tbb->index))
+ continue;
+
+ while (single_succ_p (tbb))
+ {
+ tbb = single_succ (tbb);
+ bitmap_clear_bit (&bb_tail, tbb->index);
+ }
+ }
+ /* Now duplicate the tails. */
+ if (!bitmap_empty_p (&bb_tail))
+ FOR_EACH_BB_REVERSE_FN (bb, cfun)
+ {
+ basic_block copy_bb, tbb;
+ rtx insert_point;
+ int eflags;
+
+ if (!bitmap_clear_bit (&bb_tail, bb->index))
+ continue;
+
+ /* Create a copy of BB, instructions and all, for
+ use on paths that don't need a prologue.
+ Ideal placement of the copy is on a fall-thru edge
+ or after a block that would jump to the copy. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (!bitmap_bit_p (bb_flags, e->src->index)
+ && single_succ_p (e->src))
+ break;
+ if (e)
+ {
+ /* Make sure we insert after any barriers. */
+ rtx end = get_last_bb_insn (e->src);
+ copy_bb = create_basic_block (NEXT_INSN (end),
+ NULL_RTX, e->src);
+ BB_COPY_PARTITION (copy_bb, e->src);
+ }
+ else
+ {
+ /* Otherwise put the copy at the end of the function. */
+ copy_bb = create_basic_block (NULL_RTX, NULL_RTX,
+ EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb);
+ BB_COPY_PARTITION (copy_bb, bb);
+ }
+
+ insert_point = emit_note_after (NOTE_INSN_DELETED,
+ BB_END (copy_bb));
+ emit_barrier_after (BB_END (copy_bb));
+
+ tbb = bb;
+ while (1)
+ {
+ dup_block_and_redirect (tbb, copy_bb, insert_point,
+ bb_flags);
+ tbb = single_succ (tbb);
+ if (tbb == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ break;
+ e = split_block (copy_bb, PREV_INSN (insert_point));
+ copy_bb = e->dest;
+ }
+
+ /* Quiet verify_flow_info by (ab)using EDGE_FAKE.
+ We have yet to add a simple_return to the tails,
+ as we'd like to first convert_jumps_to_returns in
+ case the block is no longer used after that. */
+ eflags = EDGE_FAKE;
+ if (CALL_P (PREV_INSN (insert_point))
+ && SIBLING_CALL_P (PREV_INSN (insert_point)))
+ eflags = EDGE_SIBCALL | EDGE_ABNORMAL;
+ make_single_succ_edge (copy_bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
+ eflags);
+
+ /* verify_flow_info doesn't like a note after a
+ sibling call. */
+ delete_insn (insert_point);
+ if (bitmap_empty_p (&bb_tail))
+ break;
+ }
+ }
+
+ fail_shrinkwrap:
+ bitmap_clear (&bb_tail);
+ bitmap_clear (&bb_antic_flags);
+ bitmap_clear (&bb_on_list);
+ vec.release ();
+ }
+}
+
+/* If we're allowed to generate a simple return instruction, then by
+ definition we don't need a full epilogue. If the last basic
+ block before the exit block does not contain active instructions,
+ examine its predecessors and try to emit (conditional) return
+ instructions. */
+
+edge
+get_unconverted_simple_return (edge exit_fallthru_edge, bitmap_head bb_flags,
+ vec<edge> *unconverted_simple_returns,
+ rtx *returnjump)
+{
+ if (optimize)
+ {
+ unsigned i, last;
+
+ /* convert_jumps_to_returns may add to preds of the exit block
+ (but won't remove). Stop at end of current preds. */
+ last = EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds);
+ for (i = 0; i < last; i++)
+ {
+ edge e = EDGE_I (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds, i);
+ if (LABEL_P (BB_HEAD (e->src))
+ && !bitmap_bit_p (&bb_flags, e->src->index)
+ && !active_insn_between (BB_HEAD (e->src), BB_END (e->src)))
+ *unconverted_simple_returns
+ = convert_jumps_to_returns (e->src, true,
+ *unconverted_simple_returns);
+ }
+ }
+
+ if (exit_fallthru_edge != NULL
+ && EDGE_COUNT (exit_fallthru_edge->src->preds) != 0
+ && !bitmap_bit_p (&bb_flags, exit_fallthru_edge->src->index))
+ {
+ basic_block last_bb;
+
+ last_bb = emit_return_for_exit (exit_fallthru_edge, true);
+ *returnjump = BB_END (last_bb);
+ exit_fallthru_edge = NULL;
+ }
+ return exit_fallthru_edge;
+}
+
+/* If there were branches to an empty LAST_BB which we tried to
+ convert to conditional simple_returns, but couldn't for some
+ reason, create a block to hold a simple_return insn and redirect
+ those remaining edges. */
+
+void
+convert_to_simple_return (edge entry_edge, edge orig_entry_edge,
+ bitmap_head bb_flags, rtx returnjump,
+ vec<edge> unconverted_simple_returns)
+{
+ edge e;
+ edge_iterator ei;
+
+ if (!unconverted_simple_returns.is_empty ())
+ {
+ basic_block simple_return_block_hot = NULL;
+ basic_block simple_return_block_cold = NULL;
+ edge pending_edge_hot = NULL;
+ edge pending_edge_cold = NULL;
+ basic_block exit_pred;
+ int i;
+
+ gcc_assert (entry_edge != orig_entry_edge);
+
+ /* See if we can reuse the last insn that was emitted for the
+ epilogue. */
+ if (returnjump != NULL_RTX
+ && JUMP_LABEL (returnjump) == simple_return_rtx)
+ {
+ e = split_block (BLOCK_FOR_INSN (returnjump), PREV_INSN (returnjump));
+ if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
+ simple_return_block_hot = e->dest;
+ else
+ simple_return_block_cold = e->dest;
+ }
+
+ /* Also check returns we might need to add to tail blocks. */
+ FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
+ if (EDGE_COUNT (e->src->preds) != 0
+ && (e->flags & EDGE_FAKE) != 0
+ && !bitmap_bit_p (&bb_flags, e->src->index))
+ {
+ if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
+ pending_edge_hot = e;
+ else
+ pending_edge_cold = e;
+ }
+
+ /* Save a pointer to the exit's predecessor BB for use in
+ inserting new BBs at the end of the function. Do this
+ after the call to split_block above which may split
+ the original exit pred. */
+ exit_pred = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
+
+ FOR_EACH_VEC_ELT (unconverted_simple_returns, i, e)
+ {
+ basic_block *pdest_bb;
+ edge pending;
+
+ if (BB_PARTITION (e->src) == BB_HOT_PARTITION)
+ {
+ pdest_bb = &simple_return_block_hot;
+ pending = pending_edge_hot;
+ }
+ else
+ {
+ pdest_bb = &simple_return_block_cold;
+ pending = pending_edge_cold;
+ }
+
+ if (*pdest_bb == NULL && pending != NULL)
+ {
+ emit_return_into_block (true, pending->src);
+ pending->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);
+ *pdest_bb = pending->src;
+ }
+ else if (*pdest_bb == NULL)
+ {
+ basic_block bb;
+ rtx start;
+
+ bb = create_basic_block (NULL, NULL, exit_pred);
+ BB_COPY_PARTITION (bb, e->src);
+ start = emit_jump_insn_after (gen_simple_return (),
+ BB_END (bb));
+ JUMP_LABEL (start) = simple_return_rtx;
+ emit_barrier_after (start);
+
+ *pdest_bb = bb;
+ make_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
+ }
+ redirect_edge_and_branch_force (e, *pdest_bb);
+ }
+ unconverted_simple_returns.release ();
+ }
+
+ if (entry_edge != orig_entry_edge)
+ {
+ FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds)
+ if (EDGE_COUNT (e->src->preds) != 0
+ && (e->flags & EDGE_FAKE) != 0
+ && !bitmap_bit_p (&bb_flags, e->src->index))
+ {
+ emit_return_into_block (true, e->src);
+ e->flags &= ~(EDGE_FALLTHRU | EDGE_FAKE);
+ }
+ }
+}
+
+#endif
--- /dev/null
+/* Structure for saving state for a nested function.
+ Copyright (C) 1989-2014 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/>. */
+
+#ifndef GCC_SHRINK_WRAP_H
+#define GCC_SHRINK_WRAP_H
+
+#include "hashtab.h"
+#include "vec.h"
+#include "machmode.h"
+
+#ifdef HAVE_simple_return
+/* In function.c. */
+extern void emit_return_into_block (bool simple_p, basic_block bb);
+extern bool active_insn_between (rtx head, rtx tail);
+extern vec<edge> convert_jumps_to_returns (basic_block last_bb, bool simple_p,
+ vec<edge> unconverted);
+extern basic_block emit_return_for_exit (edge exit_fallthru_edge,
+ bool simple_p);
+
+/* In shrink-wrap.c. */
+extern bool requires_stack_frame_p (rtx, HARD_REG_SET, HARD_REG_SET);
+extern void prepare_shrink_wrap (basic_block entry_block);
+extern void dup_block_and_redirect (basic_block bb, basic_block copy_bb,
+ rtx before, bitmap_head *need_prologue);
+extern void try_shrink_wrapping (edge *entry_edge, edge orig_entry_edge,
+ bitmap_head *bb_flags, rtx prologue_seq);
+extern edge get_unconverted_simple_return (edge, bitmap_head,
+ vec<edge> *, rtx *);
+extern void convert_to_simple_return (edge entry_edge, edge orig_entry_edge,
+ bitmap_head bb_flags, rtx returnjump,
+ vec<edge> unconverted_simple_returns);
+#endif
+
+#endif /* GCC_SHRINK_WRAP_H */
+
+
projects / thirdparty / gcc.git / commitdiff
