From: Richard Sandiford <richard.sandiford@arm.com>
To: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 1/3] expr: Allow scalar_int_mode target mode when converting a constant
Date: Fri, 24 Jul 2020 15:14:53 +0100 [thread overview]
Message-ID: <mpt7dutq9sy.fsf@arm.com> (raw)
In-Reply-To: <20200722094855.dbpua4635rmncz2d@jozef-acer-manjaro> (Jozef Lawrynowicz's message of "Wed, 22 Jul 2020 10:48:55 +0100")
Jozef Lawrynowicz <jozef.l@mittosystems.com> writes:
> On Wed, Jul 22, 2020 at 09:33:47AM +0100, Richard Sandiford wrote:
>> Jozef Lawrynowicz <jozef.l@mittosystems.com> writes:
>> > is_int_mode does not allow MODE_PARTIAL_INT modes, so convert_modes was
>> > not allowing a constant value to be converted to a MODE_PARTIAL_INT for
>> > use as operand 2 in patterns such as ashlpsi3. The constant had
>> > to be copied into a register before it could be used, but now can be
>> > used directly as an operand without any copying.
>>
>> Yeah. I guess this dates back to when MODE_PARTIAL_INTs didn't have
>> a known precision.
>
> Is that what the section on MODE_PARTIAL_INT in the description for the
> "subreg" RTX refers to? From "14.8 Registers and Memory" of gccint:
>
> A MODE_PARTIAL_INT mode behaves as if it were as wide as the corresponding
> MODE_INT mode, except that it has an unknown number of undefined bits.
Yeah. Before d8487c949ad5 the number of significant bits in a partial
mode was hidden from target-independent code.
> If so, that whole section seems out of date. I can work on getting it
> fixed up.
Sounds good :-)
Thanks,
Richard
next prev parent reply other threads:[~2020-07-24 14:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 18:17 [PATCH 0/3] MSP430: Improve code-generation for shift instructions Jozef Lawrynowicz
2020-07-21 18:24 ` [PATCH 1/3] expr: Allow scalar_int_mode target mode when converting a constant Jozef Lawrynowicz
2020-07-22 8:33 ` Richard Sandiford
2020-07-22 9:48 ` Jozef Lawrynowicz
2020-07-24 14:14 ` Richard Sandiford [this message]
2020-07-21 18:26 ` [PATCH 2/3] expmed: Fix possible use of NULL_RTX return value from emit_store_flag Jozef Lawrynowicz
2020-07-22 8:38 ` Richard Sandiford
2020-07-21 18:29 ` [PATCH 3/3] MSP430: Simplify and extend shift instruction patterns Jozef Lawrynowicz
2020-08-07 10:55 ` ping " Jozef Lawrynowicz
2020-08-25 19:16 ` Jeff Law
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