re PR rtl-optimization/13931 (combiner much slower on big basic blocks)

	PR rtl-optimization/13931
	* combine.c: Revert patch of 2003-05-14, and:
	(try_combine): Only set elim_i1 and elim_i2 if the destination is
	completely killed in the appropriate insn.
	(distribute_notes): Don't skip multiple hard register test for
	elim_i1 and elim_i2.

From-SVN: r105275

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9d7fc4e7a8cc77d0ee3b14858bf9c9ed5c0952a2..8fa4b88a3afa01bcef4b3bca7022ca7d1ea13fef 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2005-10-11  Ian Lance Taylor  <ian@airs.com>
+
+       PR rtl-optimization/13931
+       * combine.c: Revert patch of 2003-05-14, and:
+       (try_combine): Only set elim_i1 and elim_i2 if the destination is
+       completely killed in the appropriate insn.
+       (distribute_notes): Don't skip multiple hard register test for
+       elim_i1 and elim_i2.
+
 2005-10-11  Richard Henderson  <rth@redhat.com>
 
        PR c/24255

diff --git a/gcc/combine.c b/gcc/combine.c
index 4ab0f18097e2ddc2ff05de1650381a0f9ba302c1..3be34e4b44d5be6288a52b98531d9a2a68c89d16 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -53,6 +53,10 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
    flow.c aren't completely updated:
 
    - reg_live_length is not updated
+   - reg_n_refs is not adjusted in the rare case when a register is
+     no longer required in a computation
+   - there are extremely rare cases (see distribute_regnotes) when a
+     REG_DEAD note is lost
    - a LOG_LINKS entry that refers to an insn with multiple SETs may be
      removed because there is no way to know which register it was
      linking
@@ -410,7 +414,7 @@ static void reg_dead_at_p_1 (rtx, rtx, void *);
 static int reg_dead_at_p (rtx, rtx);
 static void move_deaths (rtx, rtx, int, rtx, rtx *);
 static int reg_bitfield_target_p (rtx, rtx);
-static void distribute_notes (rtx, rtx, rtx, rtx);
+static void distribute_notes (rtx, rtx, rtx, rtx, rtx, rtx);
 static void distribute_links (rtx);
 static void mark_used_regs_combine (rtx);
 static int insn_cuid (rtx);
@@ -1730,6 +1734,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
   rtx i2pat;
   /* Indicates if I2DEST or I1DEST is in I2SRC or I1_SRC.  */
   int i2dest_in_i2src = 0, i1dest_in_i1src = 0, i2dest_in_i1src = 0;
+  int i2dest_killed = 0, i1dest_killed = 0;
   int i1_feeds_i3 = 0;
   /* Notes that must be added to REG_NOTES in I3 and I2.  */
   rtx new_i3_notes, new_i2_notes;
@@ -1838,6 +1843,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
 
              added_sets_2 = added_sets_1 = 0;
              i2dest = SET_SRC (PATTERN (i3));
+             i2dest_killed = dead_or_set_p (i2, i2dest);
 
              /* Replace the dest in I2 with our dest and make the resulting
                 insn the new pattern for I3.  Then skip to where we
@@ -1912,6 +1918,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
       subst_low_cuid = INSN_CUID (i2);
       added_sets_2 = added_sets_1 = 0;
       i2dest = SET_DEST (temp);
+      i2dest_killed = dead_or_set_p (i2, i2dest);
 
       SUBST (SET_SRC (temp),
             immed_double_const (lo, hi, GET_MODE (SET_DEST (temp))));
@@ -1982,6 +1989,8 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
   i2dest_in_i2src = reg_overlap_mentioned_p (i2dest, i2src);
   i1dest_in_i1src = i1 && reg_overlap_mentioned_p (i1dest, i1src);
   i2dest_in_i1src = i1 && reg_overlap_mentioned_p (i2dest, i1src);
+  i2dest_killed = dead_or_set_p (i2, i2dest);
+  i1dest_killed = i1 && dead_or_set_p (i1, i1dest);
 
   /* See if I1 directly feeds into I3.  It does if I1DEST is not used
      in I2SRC.  */
@@ -2737,7 +2746,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
          REG_N_DEATHS (REGNO (XEXP (note, 0)))++;
 
       distribute_notes (new_other_notes, undobuf.other_insn,
-                       undobuf.other_insn, NULL_RTX);
+                       undobuf.other_insn, NULL_RTX, NULL_RTX, NULL_RTX);
     }
 #ifdef HAVE_cc0
   /* If I2 is the CC0 setter and I3 is the CC0 user then check whether
@@ -2812,6 +2821,17 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
     rtx i3links, i2links, i1links = 0;
     rtx midnotes = 0;
     unsigned int regno;
+    /* Compute which registers we expect to eliminate.  newi2pat may be setting
+       either i3dest or i2dest, so we must check it.  Also, i1dest may be the
+       same as i3dest, in which case newi2pat may be setting i1dest.  */
+    rtx elim_i2 = ((newi2pat && reg_set_p (i2dest, newi2pat))
+                  || i2dest_in_i2src || i2dest_in_i1src
+                  || !i2dest_killed
+                  ? 0 : i2dest);
+    rtx elim_i1 = (i1 == 0 || i1dest_in_i1src
+                  || (newi2pat && reg_set_p (i1dest, newi2pat))
+                  || !i1dest_killed
+                  ? 0 : i1dest);
 
     /* Get the old REG_NOTES and LOG_LINKS from all our insns and
        clear them.  */
@@ -2936,13 +2956,17 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
 
     /* Distribute all the LOG_LINKS and REG_NOTES from I1, I2, and I3.  */
     if (i3notes)
-      distribute_notes (i3notes, i3, i3, newi2pat ? i2 : NULL_RTX);
+      distribute_notes (i3notes, i3, i3, newi2pat ? i2 : NULL_RTX,
+                       elim_i2, elim_i1);
     if (i2notes)
-      distribute_notes (i2notes, i2, i3, newi2pat ? i2 : NULL_RTX);
+      distribute_notes (i2notes, i2, i3, newi2pat ? i2 : NULL_RTX,
+                       elim_i2, elim_i1);
     if (i1notes)
-      distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL_RTX);
+      distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL_RTX,
+                       elim_i2, elim_i1);
     if (midnotes)
-      distribute_notes (midnotes, NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
+      distribute_notes (midnotes, NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
+                       elim_i2, elim_i1);
 
     /* Distribute any notes added to I2 or I3 by recog_for_combine.  We
        know these are REG_UNUSED and want them to go to the desired insn,
@@ -2955,7 +2979,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
          if (REG_P (XEXP (temp, 0)))
            REG_N_DEATHS (REGNO (XEXP (temp, 0)))++;
 
-       distribute_notes (new_i2_notes, i2, i2, NULL_RTX);
+       distribute_notes (new_i2_notes, i2, i2, NULL_RTX, NULL_RTX, NULL_RTX);
       }
 
     if (new_i3_notes)
@@ -2964,7 +2988,7 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
          if (REG_P (XEXP (temp, 0)))
            REG_N_DEATHS (REGNO (XEXP (temp, 0)))++;
 
-       distribute_notes (new_i3_notes, i3, i3, NULL_RTX);
+       distribute_notes (new_i3_notes, i3, i3, NULL_RTX, NULL_RTX, NULL_RTX);
       }
 
     /* If I3DEST was used in I3SRC, it really died in I3.  We may need to
@@ -2982,11 +3006,12 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
        if (newi2pat && reg_set_p (i3dest_killed, newi2pat))
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed,
                                               NULL_RTX),
-                           NULL_RTX, i2, NULL_RTX);
+                           NULL_RTX, i2, NULL_RTX, elim_i2, elim_i1);
        else
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i3dest_killed,
                                               NULL_RTX),
-                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
+                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
+                           elim_i2, elim_i1);
       }
 
     if (i2dest_in_i2src)
@@ -2996,10 +3021,11 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
 
        if (newi2pat && reg_set_p (i2dest, newi2pat))
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX),
-                           NULL_RTX, i2, NULL_RTX);
+                           NULL_RTX, i2, NULL_RTX, NULL_RTX, NULL_RTX);
        else
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i2dest, NULL_RTX),
-                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
+                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
+                           NULL_RTX, NULL_RTX);
       }
 
     if (i1dest_in_i1src)
@@ -3009,10 +3035,11 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
 
        if (newi2pat && reg_set_p (i1dest, newi2pat))
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX),
-                           NULL_RTX, i2, NULL_RTX);
+                           NULL_RTX, i2, NULL_RTX, NULL_RTX, NULL_RTX);
        else
          distribute_notes (gen_rtx_EXPR_LIST (REG_DEAD, i1dest, NULL_RTX),
-                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX);
+                           NULL_RTX, i3, newi2pat ? i2 : NULL_RTX,
+                           NULL_RTX, NULL_RTX);
       }
 
     distribute_links (i3links);
@@ -11906,11 +11933,16 @@ reg_bitfield_target_p (rtx x, rtx body)
    as appropriate.  I3 and I2 are the insns resulting from the combination
    insns including FROM (I2 may be zero).
 
+   ELIM_I2 and ELIM_I1 are either zero or registers that we know will
+   not need REG_DEAD notes because they are being substituted for.  This
+   saves searching in the most common cases.
+
    Each note in the list is either ignored or placed on some insns, depending
    on the type of note.  */
 
 static void
-distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
+distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2, rtx elim_i2,
+                 rtx elim_i1)
 {
   rtx note, next_note;
   rtx tem;
@@ -12188,6 +12220,11 @@ distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
                   && reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
            place = i2;
 
+         if (place == 0
+             && (rtx_equal_p (XEXP (note, 0), elim_i2)
+                 || rtx_equal_p (XEXP (note, 0), elim_i1)))
+           break;
+
          if (place == 0)
            {
              basic_block bb = this_basic_block;
@@ -12249,7 +12286,8 @@ distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
                          PATTERN (tem) = pc_rtx;
                          REG_NOTES (tem) = NULL;
 
-                         distribute_notes (old_notes, tem, tem, NULL_RTX);
+                         distribute_notes (old_notes, tem, tem, NULL_RTX,
+                                           NULL_RTX, NULL_RTX);
                          distribute_links (LOG_LINKS (tem));
 
                          SET_INSN_DELETED (tem);
@@ -12263,7 +12301,8 @@ distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
                              REG_NOTES (cc0_setter) = NULL;
 
                              distribute_notes (old_notes, cc0_setter,
-                                               cc0_setter, NULL_RTX);
+                                               cc0_setter, NULL_RTX,
+                                               NULL_RTX, NULL_RTX);
                              distribute_links (LOG_LINKS (cc0_setter));
 
                              SET_INSN_DELETED (cc0_setter);
@@ -12398,7 +12437,7 @@ distribute_notes (rtx notes, rtx from_insn, rtx i3, rtx i2)
                                = gen_rtx_EXPR_LIST (REG_DEAD, piece, NULL_RTX);
 
                              distribute_notes (new_note, place, place,
-                                               NULL_RTX);
+                                               NULL_RTX, NULL_RTX, NULL_RTX);
                            }
                          else if (! refers_to_regno_p (i, i + 1,
                                                        PATTERN (place), 0)