From: "Ulrich Weigand" <uweigand@de.ibm.com>
To: rth@redhat.com (Richard Henderson)
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 0/2] Convert s390 to atomic optabs, v2
Date: Mon, 06 Aug 2012 16:44:00 -0000 [thread overview]
Message-ID: <201208061643.q76GhkfS022897@d06av02.portsmouth.uk.ibm.com> (raw)
In-Reply-To: <5019BA68.5070709@redhat.com> from "Richard Henderson" at Aug 01, 2012 04:23:20 PM
Richard Henderson wrote:
While the first set of changes looks good to me, I don't understand those:
> @@ -4728,7 +4733,12 @@ init_alignment_context (struct alignment_context *ac, rtx mem,
> ac->aligned = (MEM_ALIGN (mem) >= GET_MODE_BITSIZE (SImode));
>
> if (ac->aligned)
> - ac->memsi = adjust_address (mem, SImode, 0); /* Memory is aligned. */
> + {
> + ac->memsi = adjust_address (mem, SImode, 0); /* Memory is aligned. */
> + ac->shift = const0_rtx;
> + ac->modemask = GEN_INT (GET_MODE_MASK (mode));
> + ac->modemaski = GEN_INT (~GET_MODE_MASK (mode));
> + }
> else
> {
> /* Alignment is unknown. */
> @@ -4755,15 +4765,17 @@ init_alignment_context (struct alignment_context *ac, rtx mem,
> ac->shift = expand_simple_binop (SImode, MINUS, ac->shift, byteoffset,
> NULL_RTX, 1, OPTAB_DIRECT);
>
> + /* Shift is the byte count, but we need the bitcount. */
> + ac->shift = expand_simple_binop (SImode, ASHIFT, ac->shift, GEN_INT (3),
> + NULL_RTX, 1, OPTAB_DIRECT);
> +
> + /* Calculate masks. */
> + ac->modemask = expand_simple_binop (SImode, ASHIFT,
> + GEN_INT (GET_MODE_MASK (mode)),
> + ac->shift, NULL_RTX, 1, OPTAB_DIRECT);
> + ac->modemaski = expand_simple_unop (SImode, NOT, ac->modemask,
> + NULL_RTX, 1);
> }
> - /* Shift is the byte count, but we need the bitcount. */
> - ac->shift = expand_simple_binop (SImode, MULT, ac->shift, GEN_INT (BITS_PER_UNIT),
> - NULL_RTX, 1, OPTAB_DIRECT);
> - /* Calculate masks. */
> - ac->modemask = expand_simple_binop (SImode, ASHIFT,
> - GEN_INT (GET_MODE_MASK (mode)), ac->shift,
> - NULL_RTX, 1, OPTAB_DIRECT);
> - ac->modemaski = expand_simple_unop (SImode, NOT, ac->modemask, NULL_RTX, 1);
> }
>
> /* A subroutine of s390_expand_cs_hqi. Insert INS into VAL. If possible,
> @@ -4781,7 +4793,7 @@ s390_two_part_insv (struct alignment_context *ac, rtx *seq1, rtx *seq2,
> start_sequence ();
> tmp = copy_to_mode_reg (SImode, val);
> if (s390_expand_insv (tmp, GEN_INT (GET_MODE_BITSIZE (mode)),
> - const0_rtx, ins))
> + GEN_INT (32 - GET_MODE_BITSIZE (mode)), ins))
> {
> *seq1 = NULL;
> *seq2 = get_insns ();
"aligned" accesses do involve the *most significant* part of the word
(on a big-endian machine), which means ac->shift has to be set to
modesize (outer) - modesize (inner), and expand_insv needs to be
called with bitpos 0 (due to bits-big-endian).
When reverting this part of your patch (and together with the EQ/NE fix
pointed out here: http://gcc.gnu.org/ml/gcc-patches/2012-08/msg00170.html),
I can complete a bootstrap/testing cycle without regressions.
(There's still code being generated that looks a bit inefficient, but that's
a different story.)
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com
prev parent reply other threads:[~2012-08-06 16:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-29 21:32 [CFT] s390: Convert from sync to atomic optabs Richard Henderson
2012-07-30 14:19 ` Ulrich Weigand
2012-07-30 15:12 ` Richard Henderson
2012-07-30 15:51 ` Ulrich Weigand
2012-07-30 18:53 ` Richard Henderson
2012-07-30 22:33 ` [PATCH 0/2] Convert s390 to atomic optabs, v2 Richard Henderson
2012-07-30 22:33 ` [PATCH 1/2] s390: Reorg s390_expand_insv Richard Henderson
2012-07-30 22:36 ` [PATCH 2/2] s390: Convert from sync to atomic optabs Richard Henderson
2012-08-06 18:34 ` Ulrich Weigand
2012-08-06 18:51 ` Richard Henderson
2012-08-06 19:45 ` Richard Henderson
2012-08-06 22:40 ` s390: Avoid CAS boolean output inefficiency Richard Henderson
2012-08-07 17:02 ` Ulrich Weigand
2012-08-07 22:13 ` Richard Henderson
2012-08-08 18:05 ` Ulrich Weigand
2012-08-09 16:55 ` Eric Botcazou
2012-07-31 9:11 ` [PATCH 0/2] Convert s390 to atomic optabs, v2 Richard Guenther
2012-07-31 15:27 ` Andrew MacLeod
2012-07-31 16:07 ` Richard Henderson
2012-08-01 8:41 ` Richard Guenther
2012-08-01 15:59 ` Richard Henderson
2012-08-01 17:14 ` Richard Guenther
2012-08-01 19:42 ` Richard Henderson
2012-07-31 18:36 ` Ulrich Weigand
2012-07-31 19:54 ` Richard Henderson
2012-08-01 23:23 ` Richard Henderson
2012-08-03 12:20 ` Ulrich Weigand
2012-08-03 14:21 ` Ulrich Weigand
2012-08-06 16:44 ` Ulrich Weigand [this message]
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