Re: [PATCH] Fix PR 51505

[Paolo Bonzini <bonzini at gnu dot org>]

On 01/29/2012 04:09 PM, Eric Botcazou wrote:
> > > As discussed in Bugzilla, this is the patch implementing Paolo's
> > > suggestion of killing REG_EQUAL/REG_EQUIV notes from df_kill_notes.  The
> > > code assumes there is at most one such note per insn.
> >
> > That's wrong though and wreaks havoc during reload, e.g.:
> >
> > (insn 169 60 62 4 (set (reg:TF 158)
> >          (mem/c:TF (plus:SI (reg/f:SI 101 %sfp)
> >                  (const_int -16 [0xfffffffffffffff0])) [3 S16 A64]))
> > 960513-1.c:13 97 {*movtf_insn_sp32}
> >       (expr_list:REG_EQUIV (mem/c:TF (plus:SI (reg/f:SI 101 %sfp)
> >                  (const_int -16 [0xfffffffffffffff0])) [3 S16 A64])
> >          (expr_list:REG_EQUAL (mult:TF (reg/v:TF 110 [ d ])
> >                  (reg:TF 154))
> >              (nil))))
> >
> > because the REG_EQUIV note disappears behind reload's back and it isn't
> > prepared for that.  This is the cause of the following regression on SPARC:
> >
> > FAIL: gcc.c-torture/execute/960513-1.c execution,  -Os
>
> As well as:
>
> FAIL: gcc.c-torture/execute/stdarg-2.c execution,  -O2
> FAIL: gcc.c-torture/execute/stdarg-2.c execution,  -O3 -fomit-frame-pointer
> FAIL: gcc.c-torture/execute/stdarg-2.c execution,  -O3 -g
> FAIL: gcc.c-torture/execute/stdarg-2.c execution,  -Os
> FAIL: gcc.c-torture/execute/stdarg-2.c
> execution,  -O2 -flto -flto-partition=none
> FAIL: gcc.c-torture/execute/stdarg-2.c execution,  -O2 -flto
>
> for the exact same reason.

Does this help?

Paolo

2012-01-30  Paolo Bonzini  <bonzini@gnu.org>

	* df-problems.c (df_kill_notes): Check that the use refers
	to the note under examination.

Index: df-problems.c
===================================================================
--- df-problems.c	(revision 183693)
+++ df-problems.c	(working copy)
@@ -2814,8 +2814,10 @@ df_kill_notes (rtx insn, bitmap live)
 	      {
 		df_ref use = *use_rec;
 		if (DF_REF_REGNO (use) > FIRST_PSEUDO_REGISTER
+		    && DF_REF_LOC (use)
 		    && (DF_REF_FLAGS (use) & DF_REF_IN_NOTE)
-		    && ! bitmap_bit_p (live, DF_REF_REGNO (use)))
+		    && ! bitmap_bit_p (live, DF_REF_REGNO (use))
+		    && loc_mentioned_in_p (DF_REF_LOC (use), XEXP (link, 0)))
 		  {
 		    deleted = true;
 		    break;