/* RTL dead code elimination.
- Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011
+ Free Software Foundation, Inc.
This file is part of GCC.
#include "tree-pass.h"
#include "dbgcnt.h"
#include "tm_p.h"
+#include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */
/* -------------------------------------------------------------------------
return false;
default:
- if (volatile_refs_p (body))
- return false;
-
- if (flag_non_call_exceptions && may_trap_p (body))
- return false;
-
- return true;
+ return !volatile_refs_p (body);
}
}
&& !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)))
return find_call_stack_args (insn, false, fast, arg_stores);
+ /* Don't delete jumps, notes and the like. */
if (!NONJUMP_INSN_P (insn))
return false;
- /* Similarly, we cannot delete other insns that can throw either. */
- if (df_in_progress && flag_non_call_exceptions && can_throw_internal (insn))
+ /* Don't delete insns that can throw. */
+ if (!insn_nothrow_p (insn))
return false;
body = PATTERN (insn);
switch (GET_CODE (body))
{
case USE:
+ case VAR_LOCATION:
return false;
case CLOBBER:
}
+/* Return true if store to MEM, starting OFF bytes from stack pointer,
+ is a call argument store, and clear corresponding bits from SP_BYTES
+ bitmap if it is. */
+
+static bool
+check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off,
+ HOST_WIDE_INT max_sp_off, bitmap sp_bytes)
+{
+ HOST_WIDE_INT byte;
+ for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++)
+ {
+ if (byte < min_sp_off
+ || byte >= max_sp_off
+ || !bitmap_clear_bit (sp_bytes, byte - min_sp_off))
+ return false;
+ }
+ return true;
+}
+
+
/* Try to find all stack stores of CALL_INSN arguments if
ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found
and it is therefore safe to eliminate the call, return true,
if (GET_CODE (XEXP (p, 0)) == USE
&& MEM_P (XEXP (XEXP (p, 0), 0)))
{
- rtx mem = XEXP (XEXP (p, 0), 0), addr, size;
- HOST_WIDE_INT off = 0;
- size = MEM_SIZE (mem);
- if (size == NULL_RTX)
+ rtx mem = XEXP (XEXP (p, 0), 0), addr;
+ HOST_WIDE_INT off = 0, size;
+ if (!MEM_SIZE_KNOWN_P (mem))
return false;
+ size = MEM_SIZE (mem);
addr = XEXP (mem, 0);
if (GET_CODE (addr) == PLUS
&& REG_P (XEXP (addr, 0))
return false;
}
min_sp_off = MIN (min_sp_off, off);
- max_sp_off = MAX (max_sp_off, off + INTVAL (size));
+ max_sp_off = MAX (max_sp_off, off + size);
}
if (min_sp_off >= max_sp_off)
set = single_set (DF_REF_INSN (defs->ref));
off += INTVAL (XEXP (SET_SRC (set), 1));
}
- for (byte = off; byte < off + INTVAL (MEM_SIZE (mem)); byte++)
+ for (byte = off; byte < off + MEM_SIZE (mem); byte++)
{
if (!bitmap_set_bit (sp_bytes, byte - min_sp_off))
gcc_unreachable ();
for (insn = PREV_INSN (call_insn); insn; insn = prev_insn)
{
rtx set, mem, addr;
- HOST_WIDE_INT off, byte;
+ HOST_WIDE_INT off;
if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn)))
prev_insn = NULL_RTX;
if (CALL_P (insn))
break;
- if (!INSN_P (insn))
+ if (!NONDEBUG_INSN_P (insn))
continue;
set = single_set (insn);
break;
}
- if (GET_MODE_SIZE (GET_MODE (mem)) == 0)
+ if (GET_MODE_SIZE (GET_MODE (mem)) == 0
+ || !check_argument_store (mem, off, min_sp_off,
+ max_sp_off, sp_bytes))
break;
- for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++)
- {
- if (byte < min_sp_off
- || byte >= max_sp_off
- || !bitmap_clear_bit (sp_bytes, byte - min_sp_off))
- break;
- }
-
if (!deletable_insn_p (insn, fast, NULL))
break;
}
-/* Delete all REG_EQUAL notes of the registers INSN writes, to prevent
- bad dangling REG_EQUAL notes. */
+/* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN
+ writes to. */
static void
-delete_corresponding_reg_eq_notes (rtx insn)
+remove_reg_equal_equiv_notes_for_defs (rtx insn)
{
df_ref *def_rec;
+
for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
- {
- df_ref def = *def_rec;
- unsigned int regno = DF_REF_REGNO (def);
- /* This loop is a little tricky. We cannot just go down the
- chain because it is being modified by the actions in the
- loop. So we just get the head. We plan to drain the list
- anyway. */
- while (DF_REG_EQ_USE_CHAIN (regno))
+ remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (*def_rec));
+}
+
+/* Scan all BBs for debug insns and reset those that reference values
+ defined in unmarked insns. */
+
+static void
+reset_unmarked_insns_debug_uses (void)
+{
+ basic_block bb;
+ rtx insn, next;
+
+ FOR_EACH_BB_REVERSE (bb)
+ FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next)
+ if (DEBUG_INSN_P (insn))
{
- df_ref eq_use = DF_REG_EQ_USE_CHAIN (regno);
- rtx noted_insn = DF_REF_INSN (eq_use);
- rtx note = find_reg_note (noted_insn, REG_EQUAL, NULL_RTX);
- if (!note)
- note = find_reg_note (noted_insn, REG_EQUIV, NULL_RTX);
-
- /* This assert is generally triggered when someone deletes a
- REG_EQUAL or REG_EQUIV note by hacking the list manually
- rather than calling remove_note. */
- gcc_assert (note);
- remove_note (noted_insn, note);
+ df_ref *use_rec;
+
+ for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++)
+ {
+ df_ref use = *use_rec;
+ struct df_link *defs;
+ for (defs = DF_REF_CHAIN (use); defs; defs = defs->next)
+ {
+ rtx ref_insn;
+ if (DF_REF_IS_ARTIFICIAL (defs->ref))
+ continue;
+ ref_insn = DF_REF_INSN (defs->ref);
+ if (!marked_insn_p (ref_insn))
+ break;
+ }
+ if (!defs)
+ continue;
+ /* ??? FIXME could we propagate the values assigned to
+ each of the DEFs? */
+ INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
+ df_insn_rescan_debug_internal (insn);
+ break;
+ }
}
- }
}
-
/* Delete every instruction that hasn't been marked. */
static void
FOR_EACH_BB_REVERSE (bb)
FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next)
- if (INSN_P (insn))
+ if (NONDEBUG_INSN_P (insn))
{
/* Always delete no-op moves. */
if (noop_move_p (insn))
if (dump_file)
fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn));
- /* Before we delete the insn we have to delete REG_EQUAL notes
+ /* Before we delete the insn we have to remove the REG_EQUAL notes
for the destination regs in order to avoid dangling notes. */
- delete_corresponding_reg_eq_notes (insn);
+ remove_reg_equal_equiv_notes_for_defs (insn);
/* If a pure or const call is deleted, this may make the cfg
have unreachable blocks. We rememeber this and call
FOR_EACH_BB (bb)
{
FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev)
- if (INSN_P (insn))
+ if (NONDEBUG_INSN_P (insn))
{
/* Don't mark argument stores now. They will be marked
if needed when the associated CALL is marked. */
FOR_ALL_BB (bb)
{
- for (use_rec = df_get_artificial_uses (bb->index);
+ for (use_rec = df_get_artificial_uses (bb->index);
*use_rec; use_rec++)
for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next)
if (! DF_REF_IS_ARTIFICIAL (defs->ref))
struct df_link *defs;
df_ref *use_rec;
+ if (DEBUG_INSN_P (insn))
+ return;
+
for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++)
{
df_ref use = *use_rec;
}
VEC_free (rtx, heap, worklist);
+ if (MAY_HAVE_DEBUG_INSNS)
+ reset_unmarked_insns_debug_uses ();
+
/* Before any insns are deleted, we must remove the chains since
they are not bidirectional. */
df_remove_problem (df_chain);
{
{
RTL_PASS,
- "dce", /* name */
- gate_ud_dce, /* gate */
- rest_of_handle_ud_dce, /* execute */
+ "ud_dce", /* name */
+ gate_ud_dce, /* gate */
+ rest_of_handle_ud_dce, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func |
TODO_df_finish | TODO_verify_rtl_sharing |
TODO_ggc_collect /* todo_flags_finish */
}
artificial uses. */
static bool
-byte_dce_process_block (basic_block bb, bool redo_out, bitmap au)
+word_dce_process_block (basic_block bb, bool redo_out)
{
bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack);
rtx insn;
bool block_changed;
- df_ref *def_rec;
if (redo_out)
{
set. */
edge e;
edge_iterator ei;
- df_confluence_function_n con_fun_n = df_byte_lr->problem->con_fun_n;
- bitmap_clear (DF_BYTE_LR_OUT (bb));
+ df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n;
+ bitmap_clear (DF_WORD_LR_OUT (bb));
FOR_EACH_EDGE (e, ei, bb->succs)
(*con_fun_n) (e);
}
if (dump_file)
{
fprintf (dump_file, "processing block %d live out = ", bb->index);
- df_print_byte_regset (dump_file, DF_BYTE_LR_OUT (bb));
+ df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb));
}
- bitmap_copy (local_live, DF_BYTE_LR_OUT (bb));
-
- df_byte_lr_simulate_artificial_refs_at_end (bb, local_live);
+ bitmap_copy (local_live, DF_WORD_LR_OUT (bb));
FOR_BB_INSNS_REVERSE (bb, insn)
- if (INSN_P (insn))
+ if (NONDEBUG_INSN_P (insn))
{
- /* The insn is needed if there is someone who uses the output. */
- for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
- {
- df_ref def = *def_rec;
- unsigned int last;
- unsigned int dregno = DF_REF_REGNO (def);
- unsigned int start = df_byte_lr_get_regno_start (dregno);
- unsigned int len = df_byte_lr_get_regno_len (dregno);
-
- unsigned int sb;
- unsigned int lb;
- /* This is one of the only places where DF_MM_MAY should
- be used for defs. Need to make sure that we are
- checking for all of the bits that may be used. */
-
- if (!df_compute_accessed_bytes (def, DF_MM_MAY, &sb, &lb))
- {
- start += sb;
- len = lb - sb;
- }
-
- if (bitmap_bit_p (au, dregno))
- {
- mark_insn (insn, true);
- goto quickexit;
- }
-
- last = start + len;
- while (start < last)
- if (bitmap_bit_p (local_live, start++))
- {
- mark_insn (insn, true);
- goto quickexit;
- }
- }
-
- quickexit:
-
+ bool any_changed;
/* No matter if the instruction is needed or not, we remove
any regno in the defs from the live set. */
- df_byte_lr_simulate_defs (insn, local_live);
+ any_changed = df_word_lr_simulate_defs (insn, local_live);
+ if (any_changed)
+ mark_insn (insn, true);
/* On the other hand, we do not allow the dead uses to set
anything in local_live. */
if (marked_insn_p (insn))
- df_byte_lr_simulate_uses (insn, local_live);
+ df_word_lr_simulate_uses (insn, local_live);
if (dump_file)
{
- fprintf (dump_file, "finished processing insn %d live out = ",
+ fprintf (dump_file, "finished processing insn %d live out = ",
INSN_UID (insn));
- df_print_byte_regset (dump_file, local_live);
+ df_print_word_regset (dump_file, local_live);
}
}
-
- df_byte_lr_simulate_artificial_refs_at_top (bb, local_live);
- block_changed = !bitmap_equal_p (local_live, DF_BYTE_LR_IN (bb));
+ block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb));
if (block_changed)
- bitmap_copy (DF_BYTE_LR_IN (bb), local_live);
+ bitmap_copy (DF_WORD_LR_IN (bb), local_live);
+
BITMAP_FREE (local_live);
return block_changed;
}
FOR_BB_INSNS_REVERSE (bb, insn)
if (INSN_P (insn))
{
- bool needed = false;
+ bool needed = marked_insn_p (insn);
/* The insn is needed if there is someone who uses the output. */
- for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
- if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec))
- || bitmap_bit_p (au, DF_REF_REGNO (*def_rec)))
- {
- needed = true;
- break;
- }
-
- if (needed)
- mark_insn (insn, true);
-
+ if (!needed)
+ for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
+ if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec))
+ || bitmap_bit_p (au, DF_REF_REGNO (*def_rec)))
+ {
+ needed = true;
+ mark_insn (insn, true);
+ break;
+ }
+
/* No matter if the instruction is needed or not, we remove
any regno in the defs from the live set. */
df_simulate_defs (insn, local_live);
/* On the other hand, we do not allow the dead uses to set
anything in local_live. */
- if (marked_insn_p (insn))
+ if (needed)
df_simulate_uses (insn, local_live);
}
-
+
df_simulate_finalize_backwards (bb, local_live);
block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb));
}
-/* Perform fast DCE once initialization is done. If BYTE_LEVEL is
- true, use the byte level dce, otherwise do it at the pseudo
+/* Perform fast DCE once initialization is done. If WORD_LEVEL is
+ true, use the word level dce, otherwise do it at the pseudo
level. */
static void
-fast_dce (bool byte_level)
+fast_dce (bool word_level)
{
int *postorder = df_get_postorder (DF_BACKWARD);
int n_blocks = df_get_n_blocks (DF_BACKWARD);
df_simulate_fixup_sets has the disadvantage of calling
bb_has_eh_pred once per insn, so we cache the information
here. */
- bitmap au = df->regular_block_artificial_uses;
- bitmap au_eh = df->eh_block_artificial_uses;
+ bitmap au = &df->regular_block_artificial_uses;
+ bitmap au_eh = &df->eh_block_artificial_uses;
int i;
prescan_insns_for_dce (true);
continue;
}
- if (byte_level)
- local_changed
- = byte_dce_process_block (bb, bitmap_bit_p (redo_out, index),
- bb_has_eh_pred (bb) ? au_eh : au);
+ if (word_level)
+ local_changed
+ = word_dce_process_block (bb, bitmap_bit_p (redo_out, index));
else
- local_changed
+ local_changed
= dce_process_block (bb, bitmap_bit_p (redo_out, index),
bb_has_eh_pred (bb) ? au_eh : au);
bitmap_set_bit (processed, index);
-
+
if (local_changed)
{
edge e;
bitmap_set_bit (redo_out, e->src->index);
}
}
-
+
if (global_changed)
{
/* Turn off the RUN_DCE flag to prevent recursive calls to
sbitmap_zero (marked);
bitmap_clear (processed);
bitmap_clear (redo_out);
-
+
/* We do not need to rescan any instructions. We only need
to redo the dataflow equations for the blocks that had a
change at the top of the block. Then we need to redo the
- iteration. */
- if (byte_level)
- df_analyze_problem (df_byte_lr, all_blocks, postorder, n_blocks);
+ iteration. */
+ if (word_level)
+ df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks);
else
df_analyze_problem (df_lr, all_blocks, postorder, n_blocks);
/* Fast byte level DCE. */
-static unsigned int
-rest_of_handle_fast_byte_dce (void)
+void
+run_word_dce (void)
{
- df_byte_lr_add_problem ();
+ int old_flags;
+
+ if (!flag_dce)
+ return;
+
+ timevar_push (TV_DCE);
+ old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN);
+ df_word_lr_add_problem ();
init_dce (true);
fast_dce (true);
fini_dce (true);
- return 0;
+ df_set_flags (old_flags);
+ timevar_pop (TV_DCE);
}
{
{
RTL_PASS,
- "dce", /* name */
+ "rtl_dce", /* name */
gate_fast_dce, /* gate */
rest_of_handle_fast_dce, /* execute */
NULL, /* sub */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func |
- TODO_df_finish | TODO_verify_rtl_sharing |
- TODO_ggc_collect /* todo_flags_finish */
- }
-};
-
-struct rtl_opt_pass pass_fast_rtl_byte_dce =
-{
- {
- RTL_PASS,
- "byte-dce", /* name */
- gate_fast_dce, /* gate */
- rest_of_handle_fast_byte_dce, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_DCE, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func |
TODO_df_finish | TODO_verify_rtl_sharing |
TODO_ggc_collect /* todo_flags_finish */
}
OSDN Git Service
