/* Standard problems for dataflow support routines.
Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
- 2008, 2009, 2010 Free Software Foundation, Inc.
+ 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
Originally contributed by Michael P. Hayes
(m.hayes@elec.canterbury.ac.nz, mhayes@redhat.com)
Major rewrite contributed by Danny Berlin (dberlin@dberlin.org)
#include "basic-block.h"
#include "sbitmap.h"
#include "bitmap.h"
+#include "target.h"
#include "timevar.h"
#include "df.h"
#include "except.h"
for (; link; link = link->next)
{
fprintf (file, "%c%d(bb %d insn %d) ",
- DF_REF_REG_DEF_P (link->ref) ? 'd' : 'u',
+ DF_REF_REG_DEF_P (link->ref)
+ ? 'd'
+ : (DF_REF_FLAGS (link->ref) & DF_REF_IN_NOTE) ? 'e' : 'u',
DF_REF_ID (link->ref),
DF_REF_BBNO (link->ref),
- DF_REF_IS_ARTIFICIAL (link->ref) ? -1 : DF_REF_INSN_UID (link->ref));
+ DF_REF_IS_ARTIFICIAL (link->ref)
+ ? -1 : DF_REF_INSN_UID (link->ref));
}
fprintf (file, "}");
}
return true;
}
+
+/* Node of a linked list of uses of dead REGs in debug insns. */
+struct dead_debug_use
+{
+ df_ref use;
+ struct dead_debug_use *next;
+};
+
+/* Linked list of the above, with a bitmap of the REGs in the
+ list. */
+struct dead_debug
+{
+ struct dead_debug_use *head;
+ bitmap used;
+ bitmap to_rescan;
+};
+
+static void dead_debug_reset (struct dead_debug *, unsigned int);
+
+
/* Set the REG_UNUSED notes for the multiword hardreg defs in INSN
based on the bits in LIVE. Do not generate notes for registers in
artificial uses. DO_NOT_GEN is updated so that REG_DEAD notes are
static void
df_set_unused_notes_for_mw (rtx insn, struct df_mw_hardreg *mws,
bitmap live, bitmap do_not_gen,
- bitmap artificial_uses)
+ bitmap artificial_uses,
+ struct dead_debug *debug)
{
unsigned int r;
{
unsigned int regno = mws->start_regno;
df_set_note (REG_UNUSED, insn, mws->mw_reg);
+ dead_debug_reset (debug, regno);
#ifdef REG_DEAD_DEBUGGING
df_print_note ("adding 1: ", insn, REG_NOTES (insn));
&& !bitmap_bit_p (artificial_uses, r))
{
df_set_note (REG_UNUSED, insn, regno_reg_rtx[r]);
+ dead_debug_reset (debug, r);
#ifdef REG_DEAD_DEBUGGING
df_print_note ("adding 2: ", insn, REG_NOTES (insn));
#endif
static void
df_create_unused_note (rtx insn, df_ref def,
- bitmap live, bitmap artificial_uses)
+ bitmap live, bitmap artificial_uses,
+ struct dead_debug *debug)
{
unsigned int dregno = DF_REF_REGNO (def);
rtx reg = (DF_REF_LOC (def))
? *DF_REF_REAL_LOC (def): DF_REF_REG (def);
df_set_note (REG_UNUSED, insn, reg);
+ dead_debug_reset (debug, dregno);
#ifdef REG_DEAD_DEBUGGING
df_print_note ("adding 3: ", insn, REG_NOTES (insn));
#endif
return;
}
-/* Node of a linked list of uses of dead REGs in debug insns. */
-struct dead_debug_use
-{
- df_ref use;
- struct dead_debug_use *next;
-};
-
-/* Linked list of the above, with a bitmap of the REGs in the
- list. */
-struct dead_debug
-{
- struct dead_debug_use *head;
- bitmap used;
- bitmap to_rescan;
-};
/* Initialize DEBUG to an empty list, and clear USED, if given. */
static inline void
}
}
+/* Reset DEBUG_INSNs with pending uses of DREGNO. */
+static void
+dead_debug_reset (struct dead_debug *debug, unsigned int dregno)
+{
+ struct dead_debug_use **tailp = &debug->head;
+ struct dead_debug_use *cur;
+ rtx insn;
+
+ if (!debug->used || !bitmap_clear_bit (debug->used, dregno))
+ return;
+
+ while ((cur = *tailp))
+ {
+ if (DF_REF_REGNO (cur->use) == dregno)
+ {
+ *tailp = cur->next;
+ insn = DF_REF_INSN (cur->use);
+ INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
+ if (debug->to_rescan == NULL)
+ debug->to_rescan = BITMAP_ALLOC (NULL);
+ bitmap_set_bit (debug->to_rescan, INSN_UID (insn));
+ XDELETE (cur);
+ }
+ else
+ tailp = &(*tailp)->next;
+ }
+}
+
/* Add USE to DEBUG. It must be a dead reference to UREGNO in a debug
insn. Create a bitmap for DEBUG as needed. */
static inline void
&& !df_ignore_stack_reg (mws->start_regno))
df_set_unused_notes_for_mw (insn,
mws, live, do_not_gen,
- artificial_uses);
+ artificial_uses, &debug);
mws_rec++;
}
if (!DF_REF_FLAGS_IS_SET (def, DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))
{
df_create_unused_note (insn,
- def, live, artificial_uses);
+ def, live, artificial_uses, &debug);
bitmap_set_bit (do_not_gen, dregno);
}
if (DF_MWS_REG_DEF_P (mws))
df_set_unused_notes_for_mw (insn,
mws, live, do_not_gen,
- artificial_uses);
+ artificial_uses, &debug);
mws_rec++;
}
df_ref def = *def_rec;
unsigned int dregno = DF_REF_REGNO (def);
df_create_unused_note (insn,
- def, live, artificial_uses);
+ def, live, artificial_uses, &debug);
if (!DF_REF_FLAGS_IS_SET (def, DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))
bitmap_set_bit (do_not_gen, dregno);
}
}
+/* Find the set of uses for INSN. This includes partial defs. */
+
+static void
+df_simulate_find_uses (rtx insn, bitmap uses)
+{
+ df_ref *rec;
+ unsigned int uid = INSN_UID (insn);
+
+ for (rec = DF_INSN_UID_DEFS (uid); *rec; rec++)
+ {
+ df_ref def = *rec;
+ if (DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL))
+ bitmap_set_bit (uses, DF_REF_REGNO (def));
+ }
+ for (rec = DF_INSN_UID_USES (uid); *rec; rec++)
+ {
+ df_ref use = *rec;
+ bitmap_set_bit (uses, DF_REF_REGNO (use));
+ }
+}
+
/* Find the set of real DEFs, which are not clobbers, for INSN. */
void
{
rtx reg = XEXP (link, 0);
int regno = REGNO (reg);
- if (regno < FIRST_PSEUDO_REGISTER)
- {
- int n = hard_regno_nregs[regno][GET_MODE (reg)];
- while (--n >= 0)
- bitmap_clear_bit (live, regno + n);
- }
+ if (HARD_REGISTER_NUM_P (regno))
+ bitmap_clear_range (live, regno,
+ hard_regno_nregs[regno][GET_MODE (reg)]);
else
bitmap_clear_bit (live, regno);
}
}
df_simulate_fixup_sets (bb, live);
}
+\f
+/* Used by the next two functions to encode information about the
+ memory references we found. */
+#define MEMREF_NORMAL 1
+#define MEMREF_VOLATILE 2
+
+/* A subroutine of can_move_insns_across_p called through for_each_rtx.
+ Return either MEMREF_NORMAL or MEMREF_VOLATILE if a memory is found. */
+
+static int
+find_memory (rtx *px, void *data ATTRIBUTE_UNUSED)
+{
+ rtx x = *px;
+
+ if (GET_CODE (x) == ASM_OPERANDS && MEM_VOLATILE_P (x))
+ return MEMREF_VOLATILE;
+
+ if (!MEM_P (x))
+ return 0;
+ if (MEM_VOLATILE_P (x))
+ return MEMREF_VOLATILE;
+ if (MEM_READONLY_P (x))
+ return 0;
+
+ return MEMREF_NORMAL;
+}
+
+/* A subroutine of can_move_insns_across_p called through note_stores.
+ DATA points to an integer in which we set either the bit for
+ MEMREF_NORMAL or the bit for MEMREF_VOLATILE if we find a MEM
+ of either kind. */
+
+static void
+find_memory_stores (rtx x, const_rtx pat ATTRIBUTE_UNUSED,
+ void *data ATTRIBUTE_UNUSED)
+{
+ int *pflags = (int *)data;
+ if (GET_CODE (x) == SUBREG)
+ x = XEXP (x, 0);
+ /* Treat stores to SP as stores to memory, this will prevent problems
+ when there are references to the stack frame. */
+ if (x == stack_pointer_rtx)
+ *pflags |= MEMREF_VOLATILE;
+ if (!MEM_P (x))
+ return;
+ *pflags |= MEM_VOLATILE_P (x) ? MEMREF_VOLATILE : MEMREF_NORMAL;
+}
+
+/* Scan BB backwards, using df_simulate functions to keep track of
+ lifetimes, up to insn POINT. The result is stored in LIVE. */
+
+void
+simulate_backwards_to_point (basic_block bb, regset live, rtx point)
+{
+ rtx insn;
+ bitmap_copy (live, df_get_live_out (bb));
+ df_simulate_initialize_backwards (bb, live);
+
+ /* Scan and update life information until we reach the point we're
+ interested in. */
+ for (insn = BB_END (bb); insn != point; insn = PREV_INSN (insn))
+ df_simulate_one_insn_backwards (bb, insn, live);
+}
+
+/* Return true if it is safe to move a group of insns, described by
+ the range FROM to TO, backwards across another group of insns,
+ described by ACROSS_FROM to ACROSS_TO. It is assumed that there
+ are no insns between ACROSS_TO and FROM, but they may be in
+ different basic blocks; MERGE_BB is the block from which the
+ insns will be moved. The caller must pass in a regset MERGE_LIVE
+ which specifies the registers live after TO.
+
+ This function may be called in one of two cases: either we try to
+ move identical instructions from all successor blocks into their
+ predecessor, or we try to move from only one successor block. If
+ OTHER_BRANCH_LIVE is nonnull, it indicates that we're dealing with
+ the second case. It should contain a set of registers live at the
+ end of ACROSS_TO which must not be clobbered by moving the insns.
+ In that case, we're also more careful about moving memory references
+ and trapping insns.
+
+ We return false if it is not safe to move the entire group, but it
+ may still be possible to move a subgroup. PMOVE_UPTO, if nonnull,
+ is set to point at the last moveable insn in such a case. */
+
+bool
+can_move_insns_across (rtx from, rtx to, rtx across_from, rtx across_to,
+ basic_block merge_bb, regset merge_live,
+ regset other_branch_live, rtx *pmove_upto)
+{
+ rtx insn, next, max_to;
+ bitmap merge_set, merge_use, local_merge_live;
+ bitmap test_set, test_use;
+ unsigned i, fail = 0;
+ bitmap_iterator bi;
+ int memrefs_in_across = 0;
+ int mem_sets_in_across = 0;
+ bool trapping_insns_in_across = false;
+
+ if (pmove_upto != NULL)
+ *pmove_upto = NULL_RTX;
+
+ /* Find real bounds, ignoring debug insns. */
+ while (!NONDEBUG_INSN_P (from) && from != to)
+ from = NEXT_INSN (from);
+ while (!NONDEBUG_INSN_P (to) && from != to)
+ to = PREV_INSN (to);
+
+ for (insn = across_to; ; insn = next)
+ {
+ if (NONDEBUG_INSN_P (insn))
+ {
+ memrefs_in_across |= for_each_rtx (&PATTERN (insn), find_memory,
+ NULL);
+ note_stores (PATTERN (insn), find_memory_stores,
+ &mem_sets_in_across);
+ /* This is used just to find sets of the stack pointer. */
+ memrefs_in_across |= mem_sets_in_across;
+ trapping_insns_in_across |= may_trap_p (PATTERN (insn));
+ }
+ next = PREV_INSN (insn);
+ if (insn == across_from)
+ break;
+ }
+
+ /* Collect:
+ MERGE_SET = set of registers set in MERGE_BB
+ MERGE_USE = set of registers used in MERGE_BB and live at its top
+ MERGE_LIVE = set of registers live at the point inside the MERGE
+ range that we've reached during scanning
+ TEST_SET = set of registers set between ACROSS_FROM and ACROSS_END.
+ TEST_USE = set of registers used between ACROSS_FROM and ACROSS_END,
+ and live before ACROSS_FROM. */
+
+ merge_set = BITMAP_ALLOC (®_obstack);
+ merge_use = BITMAP_ALLOC (®_obstack);
+ local_merge_live = BITMAP_ALLOC (®_obstack);
+ test_set = BITMAP_ALLOC (®_obstack);
+ test_use = BITMAP_ALLOC (®_obstack);
+
+ /* Compute the set of registers set and used in the ACROSS range. */
+ if (other_branch_live != NULL)
+ bitmap_copy (test_use, other_branch_live);
+ df_simulate_initialize_backwards (merge_bb, test_use);
+ for (insn = across_to; ; insn = next)
+ {
+ if (NONDEBUG_INSN_P (insn))
+ {
+ df_simulate_find_defs (insn, test_set);
+ df_simulate_defs (insn, test_use);
+ df_simulate_uses (insn, test_use);
+ }
+ next = PREV_INSN (insn);
+ if (insn == across_from)
+ break;
+ }
+
+ /* Compute an upper bound for the amount of insns moved, by finding
+ the first insn in MERGE that sets a register in TEST_USE, or uses
+ a register in TEST_SET. We also check for calls, trapping operations,
+ and memory references. */
+ max_to = NULL_RTX;
+ for (insn = from; ; insn = next)
+ {
+ if (CALL_P (insn))
+ break;
+ if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_EPILOGUE_BEG)
+ break;
+ if (NONDEBUG_INSN_P (insn))
+ {
+ if (may_trap_or_fault_p (PATTERN (insn))
+ && (trapping_insns_in_across || other_branch_live != NULL))
+ break;
+
+ /* We cannot move memory stores past each other, or move memory
+ reads past stores, at least not without tracking them and
+ calling true_dependence on every pair.
+
+ If there is no other branch and no memory references or
+ sets in the ACROSS range, we can move memory references
+ freely, even volatile ones.
+
+ Otherwise, the rules are as follows: volatile memory
+ references and stores can't be moved at all, and any type
+ of memory reference can't be moved if there are volatile
+ accesses or stores in the ACROSS range. That leaves
+ normal reads, which can be moved, as the trapping case is
+ dealt with elsewhere. */
+ if (other_branch_live != NULL || memrefs_in_across != 0)
+ {
+ int mem_ref_flags = 0;
+ int mem_set_flags = 0;
+ note_stores (PATTERN (insn), find_memory_stores, &mem_set_flags);
+ mem_ref_flags = for_each_rtx (&PATTERN (insn), find_memory,
+ NULL);
+ /* Catch sets of the stack pointer. */
+ mem_ref_flags |= mem_set_flags;
+
+ if ((mem_ref_flags | mem_set_flags) & MEMREF_VOLATILE)
+ break;
+ if ((memrefs_in_across & MEMREF_VOLATILE) && mem_ref_flags != 0)
+ break;
+ if (mem_set_flags != 0
+ || (mem_sets_in_across != 0 && mem_ref_flags != 0))
+ break;
+ }
+ df_simulate_find_uses (insn, merge_use);
+ /* We're only interested in uses which use a value live at
+ the top, not one previously set in this block. */
+ bitmap_and_compl_into (merge_use, merge_set);
+ df_simulate_find_defs (insn, merge_set);
+ if (bitmap_intersect_p (merge_set, test_use)
+ || bitmap_intersect_p (merge_use, test_set))
+ break;
+#ifdef HAVE_cc0
+ if (!sets_cc0_p (insn))
+#endif
+ max_to = insn;
+ }
+ next = NEXT_INSN (insn);
+ if (insn == to)
+ break;
+ }
+ if (max_to != to)
+ fail = 1;
+
+ if (max_to == NULL_RTX || (fail && pmove_upto == NULL))
+ goto out;
+
+ /* Now, lower this upper bound by also taking into account that
+ a range of insns moved across ACROSS must not leave a register
+ live at the end that will be clobbered in ACROSS. We need to
+ find a point where TEST_SET & LIVE == 0.
+
+ Insns in the MERGE range that set registers which are also set
+ in the ACROSS range may still be moved as long as we also move
+ later insns which use the results of the set, and make the
+ register dead again. This is verified by the condition stated
+ above. We only need to test it for registers that are set in
+ the moved region.
+
+ MERGE_LIVE is provided by the caller and holds live registers after
+ TO. */
+ bitmap_copy (local_merge_live, merge_live);
+ for (insn = to; insn != max_to; insn = PREV_INSN (insn))
+ df_simulate_one_insn_backwards (merge_bb, insn, local_merge_live);
+
+ /* We're not interested in registers that aren't set in the moved
+ region at all. */
+ bitmap_and_into (local_merge_live, merge_set);
+ for (;;)
+ {
+ if (NONDEBUG_INSN_P (insn))
+ {
+ if (!bitmap_intersect_p (test_set, local_merge_live)
+#ifdef HAVE_cc0
+ && !sets_cc0_p (insn)
+#endif
+ )
+ {
+ max_to = insn;
+ break;
+ }
+
+ df_simulate_one_insn_backwards (merge_bb, insn,
+ local_merge_live);
+ }
+ if (insn == from)
+ {
+ fail = 1;
+ goto out;
+ }
+ insn = PREV_INSN (insn);
+ }
+
+ if (max_to != to)
+ fail = 1;
+ if (pmove_upto)
+ *pmove_upto = max_to;
+
+ /* For small register class machines, don't lengthen lifetimes of
+ hard registers before reload. */
+ if (! reload_completed
+ && targetm.small_register_classes_for_mode_p (VOIDmode))
+ {
+ EXECUTE_IF_SET_IN_BITMAP (merge_set, 0, i, bi)
+ {
+ if (i < FIRST_PSEUDO_REGISTER
+ && ! fixed_regs[i]
+ && ! global_regs[i])
+ fail = 1;
+ }
+ }
+
+ out:
+ BITMAP_FREE (merge_set);
+ BITMAP_FREE (merge_use);
+ BITMAP_FREE (local_merge_live);
+ BITMAP_FREE (test_set);
+ BITMAP_FREE (test_use);
+
+ return !fail;
+}
\f
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