[PATCH] Postreload DF fix (PR middle-end/78540)

[Jakub Jelinek]

Hi!

On the following case we ICE in DF checking, because
reload_combine_recognize_pattern starts with apply_change_group
that in the end on success calls df_insn_rescan, but if it is successful,
we then remove_reg_equal_equiv_notes and nothing rescans the notes.

Fixed by rescanning just the notes if anything changed.
remove_reg_equal_equiv_notes is right now only used in postreload
(this spot) and in the combiner (where we df_insn_rescan shortly afterwards,
thus we are fine with remove_reg_equal_equiv_notes itself not rescanning
anything).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-11-28  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/78540
        * rtl.h (remove_reg_equal_equiv_notes): Return bool instead of void.
        * rtlanal.c (remove_reg_equal_equiv_notes): Return true if any
        note has been removed.
        * postreload.c (reload_combine_recognize_pattern): If
        remove_reg_equal_equiv_notes returns true, call df_notes_rescan.

        * gcc.dg/pr78540.c: New test.

--- gcc/rtl.h.jj        2016-11-23 16:47:36.000000000 +0100
+++ gcc/rtl.h   2016-11-28 17:44:44.647327866 +0100
@@ -3057,7 +3057,7 @@ extern void add_int_reg_note (rtx_insn *
 extern void add_shallow_copy_of_reg_note (rtx_insn *, rtx);
 extern rtx duplicate_reg_note (rtx);
 extern void remove_note (rtx_insn *, const_rtx);
-extern void remove_reg_equal_equiv_notes (rtx_insn *);
+extern bool remove_reg_equal_equiv_notes (rtx_insn *);
 extern void remove_reg_equal_equiv_notes_for_regno (unsigned int);
 extern int side_effects_p (const_rtx);
 extern int volatile_refs_p (const_rtx);
--- gcc/rtlanal.c.jj    2016-11-28 10:59:06.000000000 +0100
+++ gcc/rtlanal.c       2016-11-28 17:45:37.592716718 +0100
@@ -2351,22 +2351,28 @@ remove_note (rtx_insn *insn, const_rtx n
     }
 }
 
-/* Remove REG_EQUAL and/or REG_EQUIV notes if INSN has such notes.  */
+/* Remove REG_EQUAL and/or REG_EQUIV notes if INSN has such notes.
+   Return true if any note has been removed.  */
 
-void
+bool
 remove_reg_equal_equiv_notes (rtx_insn *insn)
 {
   rtx *loc;
+  bool ret = false;
 
   loc = &REG_NOTES (insn);
   while (*loc)
     {
       enum reg_note kind = REG_NOTE_KIND (*loc);
       if (kind == REG_EQUAL || kind == REG_EQUIV)
-       *loc = XEXP (*loc, 1);
+       {
+         *loc = XEXP (*loc, 1);
+         ret = true;
+       }
       else
        loc = &XEXP (*loc, 1);
     }
+  return ret;
 }
 
 /* Remove all REG_EQUAL and REG_EQUIV notes referring to REGNO.  */
--- gcc/postreload.c.jj 2016-11-18 20:04:26.000000000 +0100
+++ gcc/postreload.c    2016-11-28 17:47:19.081409275 +0100
@@ -1192,10 +1192,11 @@ reload_combine_recognize_pattern (rtx_in
              /* Delete the reg-reg addition.  */
              delete_insn (insn);
 
-             if (reg_state[regno].offset != const0_rtx)
-               /* Previous REG_EQUIV / REG_EQUAL notes for PREV
-                  are now invalid.  */
-               remove_reg_equal_equiv_notes (prev);
+             if (reg_state[regno].offset != const0_rtx
+                 /* Previous REG_EQUIV / REG_EQUAL notes for PREV
+                    are now invalid.  */
+                 && remove_reg_equal_equiv_notes (prev))
+               df_notes_rescan (prev);
 
              reg_state[regno].use_index = RELOAD_COMBINE_MAX_USES;
              return true;
--- gcc/testsuite/gcc.dg/pr78540.c.jj   2016-11-28 17:53:32.769595232 +0100
+++ gcc/testsuite/gcc.dg/pr78540.c      2016-11-28 17:53:16.000000000 +0100
@@ -0,0 +1,27 @@
+/* PR middle-end/78540 */
+/* { dg-do compile { target int128 } } */
+/* { dg-options "-O2 -Wno-psabi" } */
+/* { dg-additional-options "-march=core2" { target i?86-*-* x86_64-*-* } } */
+
+typedef unsigned __int128 V __attribute__ ((vector_size (64)));
+V g;
+
+static inline V
+foo (V a)
+{
+  V b, c;
+  c[0] = 0;
+  a += 2281559097;
+  c ^= 0;
+  b[0] = 0;
+  return 1 + c + b + a;
+}
+
+V
+bar ()
+{
+  V a = g, b = g;
+  a[1] ^= 1;
+  b[foo (a)[0] & 3] |= 1;
+  return b;
+}

        Jakub