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2011-03-09 Bernd Schmidt <bernds@codesourcery.com>
Issue #10649
gcc/
* dwarf2out.c (dwarf2out_begin_epilogue): Accept simplejumps
as well as returnjumps.
* cfganal.c (set_edge_can_fallthru_flag): Revert previous change
that tried to keep epilogue blocks adjacent.
2011-02-03 Bernd Schmidt <bernds@codesourcery.com>
gcc/
* function.c (prepare_shrink_wrap): New function.
(thread_prologue_and_epilogue_insns): Call it.
=== modified file 'gcc/cfganal.c'
--- old/gcc/cfganal.c 2011-02-08 10:51:58 +0000
+++ new/gcc/cfganal.c 2011-03-10 14:55:10 +0000
@@ -271,37 +271,6 @@
EDGE_SUCC (bb, 0)->flags |= EDGE_CAN_FALLTHRU;
EDGE_SUCC (bb, 1)->flags |= EDGE_CAN_FALLTHRU;
}
- /* dwarf2out expects that a NOTE_INSN_EPILOGUE_BEGIN is always paired
- with a return or a sibcall. Ensure that this remains the case if
- they are in different basic blocks. */
- FOR_EACH_BB (bb)
- {
- edge e;
- edge_iterator ei;
- rtx insn, end;
-
- end = BB_END (bb);
- FOR_BB_INSNS (bb, insn)
- if (GET_CODE (insn) == NOTE
- && NOTE_KIND (insn) == NOTE_INSN_EPILOGUE_BEG
- && !(CALL_P (end) && SIBLING_CALL_P (end))
- && !returnjump_p (end))
- {
- basic_block other_bb = NULL;
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- if (e->flags & EDGE_FALLTHRU)
- other_bb = e->dest;
- else
- e->flags &= ~EDGE_CAN_FALLTHRU;
- }
- FOR_EACH_EDGE (e, ei, other_bb->preds)
- {
- if (!(e->flags & EDGE_FALLTHRU))
- e->flags &= ~EDGE_CAN_FALLTHRU;
- }
- }
- }
}
/* Find unreachable blocks. An unreachable block will have 0 in
=== modified file 'gcc/dwarf2out.c'
--- old/gcc/dwarf2out.c 2011-02-08 10:51:58 +0000
+++ new/gcc/dwarf2out.c 2011-03-10 14:55:10 +0000
@@ -2782,10 +2782,10 @@
dwarf2out_frame_debug_expr (insn, label);
}
-/* Determine if we need to save and restore CFI information around this
- epilogue. If SIBCALL is true, then this is a sibcall epilogue. If
- we do need to save/restore, then emit the save now, and insert a
- NOTE_INSN_CFA_RESTORE_STATE at the appropriate place in the stream. */
+/* Determine if we need to save and restore CFI information around
+ this epilogue. If we do need to save/restore, then emit the save
+ now, and insert a NOTE_INSN_CFA_RESTORE_STATE at the appropriate
+ place in the stream. */
void
dwarf2out_begin_epilogue (rtx insn)
@@ -2800,8 +2800,10 @@
if (!INSN_P (i))
continue;
- /* Look for both regular and sibcalls to end the block. */
- if (returnjump_p (i))
+ /* Look for both regular and sibcalls to end the block. Various
+ optimization passes may cause us to jump to a common epilogue
+ tail, so we also accept simplejumps. */
+ if (returnjump_p (i) || simplejump_p (i))
break;
if (CALL_P (i) && SIBLING_CALL_P (i))
break;
=== modified file 'gcc/function.c'
--- old/gcc/function.c 2011-02-08 10:51:58 +0000
+++ new/gcc/function.c 2011-03-10 14:55:10 +0000
@@ -5038,6 +5038,127 @@
return true;
return false;
}
+
+/* Look for sets of call-saved registers 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;
+ FOR_BB_INSNS_SAFE (entry_block, insn, curr)
+ {
+ basic_block next_bb;
+ edge e, live_edge;
+ edge_iterator ei;
+ rtx set, scan;
+ unsigned destreg, srcreg;
+
+ if (!NONDEBUG_INSN_P (insn))
+ continue;
+ set = single_set (insn);
+ if (!set)
+ continue;
+
+ if (!REG_P (SET_SRC (set)) || !REG_P (SET_DEST (set)))
+ continue;
+ srcreg = REGNO (SET_SRC (set));
+ destreg = REGNO (SET_DEST (set));
+ if (hard_regno_nregs[srcreg][GET_MODE (SET_SRC (set))] > 1
+ || hard_regno_nregs[destreg][GET_MODE (SET_DEST (set))] > 1)
+ continue;
+
+ next_bb = entry_block;
+ scan = insn;
+
+ for (;;)
+ {
+ live_edge = NULL;
+ FOR_EACH_EDGE (e, ei, next_bb->succs)
+ {
+ if (REGNO_REG_SET_P (df_get_live_in (e->dest), destreg))
+ {
+ if (live_edge)
+ {
+ live_edge = NULL;
+ break;
+ }
+ live_edge = e;
+ }
+ }
+ if (!live_edge)
+ break;
+ /* We can sometimes encounter dead code. Don't try to move it
+ into the exit block. */
+ if (live_edge->dest == EXIT_BLOCK_PTR)
+ break;
+ if (EDGE_COUNT (live_edge->dest->preds) > 1)
+ break;
+ while (scan != BB_END (next_bb))
+ {
+ scan = NEXT_INSN (scan);
+ if (NONDEBUG_INSN_P (scan))
+ {
+ rtx link;
+ HARD_REG_SET set_regs;
+
+ CLEAR_HARD_REG_SET (set_regs);
+ note_stores (PATTERN (scan), record_hard_reg_sets,
+ &set_regs);
+ if (CALL_P (scan))
+ IOR_HARD_REG_SET (set_regs, call_used_reg_set);
+ for (link = REG_NOTES (scan); link; link = XEXP (link, 1))
+ if (REG_NOTE_KIND (link) == REG_INC)
+ record_hard_reg_sets (XEXP (link, 0), NULL, &set_regs);
+
+ if (TEST_HARD_REG_BIT (set_regs, srcreg)
+ || reg_referenced_p (SET_DEST (set),
+ PATTERN (scan)))
+ {
+ scan = NULL_RTX;
+ break;
+ }
+ if (CALL_P (scan))
+ {
+ rtx link = CALL_INSN_FUNCTION_USAGE (scan);
+ while (link)
+ {
+ rtx tmp = XEXP (link, 0);
+ if (GET_CODE (tmp) == USE
+ && reg_referenced_p (SET_DEST (set), tmp))
+ break;
+ link = XEXP (link, 1);
+ }
+ if (link)
+ {
+ scan = NULL_RTX;
+ break;
+ }
+ }
+ }
+ }
+ if (!scan)
+ break;
+ next_bb = live_edge->dest;
+ }
+
+ if (next_bb != entry_block)
+ {
+ rtx after = BB_HEAD (next_bb);
+ while (!NOTE_P (after)
+ || NOTE_KIND (after) != NOTE_INSN_BASIC_BLOCK)
+ after = NEXT_INSN (after);
+ emit_insn_after (PATTERN (insn), after);
+ delete_insn (insn);
+ }
+ }
+}
+
#endif
#ifdef HAVE_return
@@ -5215,6 +5336,8 @@
bitmap_head bb_antic_flags;
bitmap_head bb_on_list;
+ prepare_shrink_wrap (entry_edge->dest);
+
bitmap_initialize (&bb_antic_flags, &bitmap_default_obstack);
bitmap_initialize (&bb_on_list, &bitmap_default_obstack);
|
