From: Tom de Vries <Tom_deVries@mentor.com>
To: Richard Henderson <rth@redhat.com>
Cc: Steve Ellcey <sellcey@mips.com>,
Andrew Pinski <pinskia@gmail.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Fix PR55876 - Make generation of paradoxical subreg in widen_operand more robust
Date: Mon, 14 Jan 2013 14:44:00 -0000 [thread overview]
Message-ID: <50F3C179.1030705@mentor.com> (raw)
In-Reply-To: <50EB0A5D.1000302@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 1178 bytes --]
On 07/01/13 18:48, Richard Henderson wrote:
> On 01/07/2013 02:16 AM, Tom de Vries wrote:
>> - /* If MODE is no wider than a single word, we return a paradoxical
>> - SUBREG. */
>> + /* If MODE is no wider than a single word, we return a
>> + lowpart or paradoxical SUBREG. */
>> if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD)
>> - return gen_rtx_SUBREG (mode, force_reg (GET_MODE (op), op), 0);
>> + {
>> + if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (op)))
>> + return gen_lowpart_SUBREG (mode, op);
>> + else
>> + return gen_rtx_SUBREG (mode, force_reg (GET_MODE (op), op), 0);
>> + }
>
> Is there any good reason we're using gen_rtx_SUBREG directly here?
> Seems like this sort of logic would be present in plain gen_lowpart,
> generating the paradoxical subreg that we want.
>
Ah, didn't realize that. Attached patch uses gen_lowpart.
Bootstrapped and reg-tested on x86_64.
Build and reg-tested on mips64, -mabi=n32 and -mabi=64.
OK for trunk?
Thanks,
- Tom
2013-01-14 Tom de Vries <tom@codesourcery.com>
PR target/55876
* optabs.c (widen_operand): Use gen_lowpart instead of gen_rtx_SUBREG.
Update comment.
[-- Attachment #2: widen_operand-paradoxical-subreg.4.patch --]
[-- Type: text/x-patch, Size: 778 bytes --]
Index: gcc/optabs.c
===================================================================
--- gcc/optabs.c (revision 194898)
+++ gcc/optabs.c (working copy)
@@ -327,10 +327,10 @@ widen_operand (rtx op, enum machine_mode
&& SUBREG_PROMOTED_UNSIGNED_P (op) == unsignedp))
return convert_modes (mode, oldmode, op, unsignedp);
- /* If MODE is no wider than a single word, we return a paradoxical
+ /* If MODE is no wider than a single word, we return a lowpart or paradoxical
SUBREG. */
if (GET_MODE_SIZE (mode) <= UNITS_PER_WORD)
- return gen_rtx_SUBREG (mode, force_reg (GET_MODE (op), op), 0);
+ return gen_lowpart (mode, force_reg (GET_MODE (op), op));
/* Otherwise, get an object of MODE, clobber it, and set the low-order
part to OP. */
next prev parent reply other threads:[~2013-01-14 14:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <50EA9FDD.6000803@mentor.com>
2013-01-07 10:16 ` Tom de Vries
2013-01-07 17:48 ` Richard Henderson
2013-01-14 14:44 ` Tom de Vries [this message]
2013-01-15 17:12 ` Richard Henderson
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