From: Richard Sandiford <richard.sandiford@arm.com>
To: Jeff Law <law@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [19/23] rtlanal: Add some new helper classes
Date: Mon, 14 Dec 2020 16:37:37 +0000 [thread overview]
Message-ID: <mpt8sa0uywe.fsf@arm.com> (raw)
In-Reply-To: <eba74cb5-f342-eac8-78d4-4895f2ff56b4@redhat.com> (Jeff Law's message of "Sun, 13 Dec 2020 10:30:47 -0700")
Jeff Law <law@redhat.com> writes:
> On 11/13/20 1:20 AM, Richard Sandiford via Gcc-patches wrote:
>> This patch adds some classes for gathering the list of registers
>> and memory that are read and written by an instruction, along
>> with various properties about the accesses. In some ways it's
>> similar to the information that DF collects for registers,
>> but extended to memory. The main reason for using it instead
>> of DF is that it can analyse tentative changes to instructions
>> before they've been committed.
>>
>> The classes also collect general information about the instruction,
>> since it's cheap to do and helps to avoid multiple walks of the same
>> RTL pattern.
>>
>> I've tried to optimise the code quite a bit, since with later patches
>> it becomes relatively performance-sensitive. See the discussion in
>> the comments for the trade-offs involved.
>>
>> I put the declarations in a new rtlanal.h header file since it
>> seemed a bit excessive to put so much new inline stuff in rtl.h.
>>
>> gcc/
>> * rtlanal.h: New file.
>> (MEM_REGNO): New constant.
>> (rtx_obj_flags): New namespace.
>> (rtx_obj_reference, rtx_properties): New classes.
>> (growing_rtx_properties, vec_rtx_properties_base): Likewise.
>> (vec_rtx_properties): New alias.
>> * rtlanal.c: Include it.
>> (rtx_properties::try_to_add_reg): New function.
>> (rtx_properties::try_to_add_dest): Likewise.
>> (rtx_properties::try_to_add_src): Likewise.
>> (rtx_properties::try_to_add_pattern): Likewise.
>> (rtx_properties::try_to_add_insn): Likewise.
>> (vec_rtx_properties_base::grow): Likewise.
> One might argue at least some of these should become first class
> properties of insns but then we have the joy of keeping them up-to-date
> as transformations are made. It also reminds me a bit of the old
> var_ann stuff we had in the tree SSA implementation.
Yeah. The RTL SSA insn info does store these properties, but that has
the advantage of being new code and so can require all updates to go
through new interfaces. I agree that ideally we'd store the information
directly in RTL insns instead.
I guess one question is where we would store the new flags. In some
ways it might be easier to do that after any future split of rtx_insn
and rtx, since we could then use a smaller code field and potentially
replace the mode field. (Things like :TI markers for VLIW bundles
could use a separate flag instead.)
It might even be possible to do the update fairly cheaply, if we made
the generators record static flags for the fixed part of the pattern
and only computed the operand information dynamically.
Thanks,
Richard
next prev parent reply other threads:[~2020-12-14 16:37 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 8:10 [00/23] Make fwprop use an on-the-side RTL SSA representation Richard Sandiford
2020-11-13 8:11 ` [01/23] vec: Silence clang warning Richard Sandiford
2020-11-25 19:58 ` Jeff Law
2020-11-13 8:12 ` [02/23] rtlanal: Remove noop_move_p REG_EQUAL condition Richard Sandiford
2020-11-25 20:00 ` Jeff Law
2020-11-13 8:12 ` [03/23] reginfo: Add a global_reg_set Richard Sandiford
2020-11-25 20:01 ` Jeff Law
2020-11-13 8:13 ` [04/23] Move iterator_range to a new iterator-utils.h file Richard Sandiford
2020-11-25 20:02 ` Jeff Law
2020-11-13 8:13 ` [05/23] Add more iterator utilities Richard Sandiford
2020-11-25 20:12 ` Jeff Law
2020-11-13 8:14 ` [06/23] Add an RAII class for managing obstacks Richard Sandiford
2020-11-25 20:15 ` Jeff Law
2020-11-13 8:14 ` [07/23] Add a class that multiplexes two pointer types Richard Sandiford
2020-11-25 20:23 ` Jeff Law
2020-11-26 16:15 ` Richard Sandiford
2020-11-30 1:28 ` Jeff Law
2020-11-25 23:33 ` Martin Sebor
2020-11-26 17:06 ` Richard Sandiford
2020-11-27 18:12 ` Richard Sandiford
2020-11-28 0:17 ` Martin Sebor
2020-12-17 0:17 ` Richard Sandiford
2020-12-17 14:21 ` Tom Tromey
2020-12-17 15:38 ` Richard Sandiford
2020-12-17 15:44 ` Nathan Sidwell
2021-01-04 15:32 ` Jeff Law
2020-11-13 8:15 ` [08/23] Add an alternative splay tree implementation Richard Sandiford
2020-12-02 20:36 ` Jeff Law
2020-12-17 0:29 ` Richard Sandiford
2021-01-04 15:27 ` Jeff Law
2021-01-01 8:25 ` Andreas Schwab
2021-01-04 14:53 ` Richard Sandiford
2021-01-04 15:02 ` Andreas Schwab
2021-01-04 15:42 ` Richard Sandiford
2021-01-05 12:13 ` Richard Biener
2020-11-13 8:15 ` [09/23] Add a cut-down version of std::span (array_slice) Richard Sandiford
2020-11-30 19:56 ` Jeff Law
2022-08-03 15:13 ` Martin Jambor
2022-08-03 15:31 ` Richard Sandiford
2022-08-10 16:03 ` Martin Jambor
2022-08-11 6:58 ` Richard Biener
2022-08-16 7:59 ` Richard Sandiford
2020-11-13 8:16 ` [10/23] Tweak the way that is_a is implemented Richard Sandiford
2020-12-02 5:15 ` Jeff Law
2020-11-13 8:16 ` [11/23] Split update_cfg_for_uncondjump out of combine Richard Sandiford
2020-11-30 6:14 ` Jeff Law
2020-11-13 8:17 ` [12/23] Export print-rtl.c:print_insn_with_notes Richard Sandiford
2020-11-25 20:24 ` Jeff Law
2020-11-13 8:18 ` [13/23] recog: Split out a register_asm_p function Richard Sandiford
2020-11-25 20:24 ` Jeff Law
2020-11-13 8:18 ` [14/23] simplify-rtx: Put simplify routines into a class Richard Sandiford
2020-11-30 19:54 ` Jeff Law
2020-11-13 8:19 ` [15/23] recog: Add a validate_change_xveclen function Richard Sandiford
2020-11-30 20:03 ` Jeff Law
2020-11-13 8:19 ` [16/23] recog: Add a way of temporarily undoing changes Richard Sandiford
2020-11-25 20:27 ` Jeff Law
2020-12-17 0:22 ` Richard Sandiford
2020-11-13 8:20 ` [17/23] recog: Add a class for propagating into insns Richard Sandiford
2020-12-03 22:32 ` Jeff Law
2020-11-13 8:20 ` [18/23] recog: Add an RAII class for undoing insn changes Richard Sandiford
2020-11-25 20:27 ` Jeff Law
2020-11-13 8:20 ` [19/23] rtlanal: Add some new helper classes Richard Sandiford
2020-12-13 17:30 ` Jeff Law
2020-12-14 16:37 ` Richard Sandiford [this message]
2020-12-14 20:02 ` Jeff Law
2020-11-13 8:21 ` [20/23] rtlanal: Add simple_regno_set Richard Sandiford
2020-11-25 20:31 ` Jeff Law
2020-12-17 0:47 ` Richard Sandiford
2021-01-04 15:28 ` Jeff Law
2020-11-13 8:22 ` [21/23] doc: Add documentation for rtl-ssa Richard Sandiford
2020-11-30 6:26 ` Jeff Law
2020-11-13 8:23 ` [PATCH 22/23] Add rtl-ssa Richard Sandiford
2020-12-16 3:31 ` Jeff Law
2020-12-17 0:33 ` Richard Sandiford
2020-12-19 20:01 ` Jeff Law
2020-11-13 8:24 ` [PATCH 23/23] fwprop: Rewrite to use RTL SSA Richard Sandiford
2020-12-16 3:52 ` Jeff Law
2020-12-17 0:34 ` Richard Sandiford
2020-11-25 19:58 ` [00/23] Make fwprop use an on-the-side RTL SSA representation Jeff Law
2020-11-26 16:03 ` Richard Sandiford
2020-11-27 15:56 ` Michael Matz
2020-11-27 16:31 ` Richard Sandiford
2020-11-30 21:13 ` Jeff Law
2020-12-01 0:03 ` Michael Matz
2020-12-01 10:15 ` Richard Sandiford
2020-12-02 0:25 ` Jeff Law
2020-11-30 6:45 ` Jeff Law
2020-11-30 14:12 ` Richard Sandiford
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