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From: Vineet Gupta <vineetg@rivosinc.com>
To: Andrew Waterman <andrew@sifive.com>, Sergei Lewis <slewis@rivosinc.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 2/2] riscv: vectorised mem* and str* functions
Date: Thu, 2 Feb 2023 16:13:15 -0800	[thread overview]
Message-ID: <b25ff49a-166f-876a-5533-4ee3f4c515a6@rivosinc.com> (raw)
In-Reply-To: <CA++6G0DbRQ=RFNPAW94-L6ynTHxECUb6sxaXUMwq-pP_8NfbUQ@mail.gmail.com>



On 2/1/23 11:03, Andrew Waterman wrote:
>> +#ifndef __riscv_strict_align
> strict-align is not the right thing to check here.  As the RVA profile
> document explains, all RVA-compliant implementations must support
> misaligned loads and stores (so strict-align will be false), but they
> might execute extremely slowly (e.g., via trap and emulate), and so
> this approach will unduly penalize some implementations.

FWIW, the proposed __riscv_strict_align if generated can have 2 possible 
values:
  - 1 (explicit -mstrict-align used in build)
  - 2 cpu tune param indicated unaligned access is slow (like with 
trap-n-emulate)

So if theory code can still be written to cater to that.

-Vineet

  reply	other threads:[~2023-02-03  0:13 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-01  9:52 [PATCH 1/2] riscv: sysdeps support for vectorised functions Sergei Lewis
2023-02-01  9:52 ` [PATCH 2/2] riscv: vectorised mem* and str* functions Sergei Lewis
2023-02-01 15:33   ` Jeff Law
2023-02-01 16:42     ` Florian Weimer
2023-02-01 17:07       ` Jeff Law
2023-02-02  9:34         ` Sergei Lewis
2023-02-06 12:49         ` Sergei Lewis
2023-02-01 17:17     ` Adhemerval Zanella Netto
2023-02-01 17:38   ` Adhemerval Zanella Netto
2023-02-01 18:13     ` Noah Goldstein
2023-02-02 10:02     ` Sergei Lewis
2023-02-02 14:26       ` Adhemerval Zanella Netto
2023-02-02 15:20         ` Sergei Lewis
2023-02-02 15:35           ` Sergei Lewis
2023-02-03 11:35           ` Adhemerval Zanella Netto
2023-02-03 14:04             ` Sergei Lewis
2023-02-01 18:11   ` Noah Goldstein
2023-02-01 18:13   ` Andrew Waterman
2023-02-01 19:03   ` Andrew Waterman
2023-02-03  0:13     ` Vineet Gupta [this message]
2023-02-03  0:51       ` Andrew Waterman
2023-05-03  2:11   ` Yun Hsiang

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