On Mon, Dec 3, 2012 at 9:19 PM, Steven Bosscher wrote:
>> So the compiler doesn't bootstrap with the gcse.c patch you posted earlier in
>> the thread? Still this seems too bold to me, the note datum could be a
>> constant and should be preserved in this case.
>
> You mean the patch at
> http://gcc.gnu.org/ml/gcc-patches/2012-11/msg02275.html right?
>
> I haven't tried that other patch. I'll test that one.
>
...
>> The cse.c hunk is OK then.
>
> Thanks, I'll commit it separately.
This is what I'll commit in a second.
A new proposed cprop.c change will follow later.
Ciao!
Steven
* gcse.c (struct reg_use): Remove unused struct.
(gcse_emit_move_after): Do not create REG_EQUAL notes that reference
the SET_DEST of the instruction the note would be attached to.
* cse.c (cse_main): Add the DF_NOTE problem.
Index: gcse.c
===================================================================
--- gcse.c (revision 194084)
+++ gcse.c (working copy)
@@ -255,8 +255,6 @@ int flag_rerun_cse_after_global_opts;
/* An obstack for our working variables. */
static struct obstack gcse_obstack;
-struct reg_use {rtx reg_rtx; };
-
/* Hash table of expressions. */
struct expr
@@ -2491,23 +2489,27 @@ gcse_emit_move_after (rtx dest, rtx src, rtx insn)
rtx new_rtx;
rtx set = single_set (insn), set2;
rtx note;
- rtx eqv;
+ rtx eqv = NULL_RTX;
/* This should never fail since we're creating a reg->reg copy
we've verified to be valid. */
new_rtx = emit_insn_after (gen_move_insn (dest, src), insn);
- /* Note the equivalence for local CSE pass. */
+ /* Note the equivalence for local CSE pass. Take the note from the old
+ set if there was one. Otherwise record the SET_SRC from the old set
+ unless DEST is also an operand of the SET_SRC. */
set2 = single_set (new_rtx);
if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
return new_rtx;
if ((note = find_reg_equal_equiv_note (insn)))
eqv = XEXP (note, 0);
- else
+ else if (! REG_P (dest)
+ || ! reg_mentioned_p (dest, SET_SRC (set)))
eqv = SET_SRC (set);
- set_unique_reg_note (new_rtx, REG_EQUAL, copy_insn_1 (eqv));
+ if (eqv != NULL_RTX)
+ set_unique_reg_note (new_rtx, REG_EQUAL, copy_insn_1 (eqv));
return new_rtx;
}
Index: cse.c
===================================================================
--- cse.c (revision 194084)
+++ cse.c (working copy)
@@ -6520,6 +6520,7 @@ cse_main (rtx f ATTRIBUTE_UNUSED, int nregs)
int i, n_blocks;
df_set_flags (DF_LR_RUN_DCE);
+ df_note_add_problem ();
df_analyze ();
df_set_flags (DF_DEFER_INSN_RESCAN);
