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From: Andrew Jones <ajones@ventanamicro.com>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: linux-riscv@lists.infradead.org, palmer@dabbelt.com,
	christoph.muellner@vrull.eu, conor@kernel.org,
	philipp.tomsich@vrull.eu, jszhang@kernel.org
Subject: Re: [PATCH v4 4/5] RISC-V: add infrastructure to allow different str* implementations
Date: Wed, 11 Jan 2023 13:34:36 +0100	[thread overview]
Message-ID: <20230111123436.6qq3syh24prrs7o7@orel> (raw)
In-Reply-To: <20230110111647.vg4fdclz4hzcuaj3@orel>

On Tue, Jan 10, 2023 at 12:16:47PM +0100, Andrew Jones wrote:
> On Tue, Jan 10, 2023 at 11:46:40AM +0100, Heiko Stübner wrote:
> > Hi Andrew,
> > 
> > Am Dienstag, 10. Januar 2023, 10:39:36 CET schrieb Andrew Jones:
> > > On Mon, Jan 09, 2023 at 07:17:54PM +0100, Heiko Stuebner wrote:
> > > > From: Heiko Stuebner <heiko.stuebner@vrull.eu>
> > > > 
> > > > Depending on supported extensions on specific RISC-V cores,
> > > > optimized str* functions might make sense.
> > > > 
> > > > This adds basic infrastructure to allow patching the function calls
> > > > via alternatives later on.
> > > > 
> > > > The Linux kernel provides standard implementations for string functions
> > > > but when architectures want to extend them, they need to provide their
> > > > own.
> > > 
> > > And the compiler provides builtins. In the previous series it appeared
> > > to be a bad idea to compile the kernel with the compiler's builtins
> > > disabled. How will the optimized string functions which will be based
> > > on this patch be selected?
> > 
> > yep, the consensus seemingly was that the compiler knows best when
> > to use builtins for some cases (which is probably correct), hence the move
> > away from the inline bases.
> > 
> > So I guess the first decision is the compiler's wether to use a builtin or
> > the kernel string function (same as for mem*) .

Hi Heiko,

Thinking about this some more, I'd still like to understand how/when the
compiler makes this choice. Are compiler flags involved? Or do some
heuristics dictate the choice?

Thanks,
drew

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  reply	other threads:[~2023-01-11 12:34 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-09 18:17 [PATCH v4 0/5] Zbb string optimizations and call support in alternatives Heiko Stuebner
2023-01-09 18:17 ` [PATCH v4 1/5] RISC-V: move some stray __RISCV_INSN_FUNCS definitions from kprobes Heiko Stuebner
2023-01-09 20:53   ` Conor Dooley
2023-01-11 15:14     ` Heiko Stübner
2023-01-10  8:32   ` Andrew Jones
2023-01-09 18:17 ` [PATCH v4 2/5] RISC-V: add helpers for J-type immediate handling Heiko Stuebner
2023-01-09 22:22   ` Conor Dooley
2023-01-10  8:44   ` Andrew Jones
2023-01-10  8:54     ` Conor Dooley
2023-01-11 14:43       ` Jisheng Zhang
2023-01-09 18:17 ` [PATCH v4 3/5] RISC-V: fix jal addresses in patched alternatives Heiko Stuebner
2023-01-10  9:28   ` Andrew Jones
2023-01-11 17:15     ` Jisheng Zhang
2023-01-11 13:18   ` Jisheng Zhang
2023-01-11 13:53     ` Heiko Stübner
2023-01-11 14:15     ` Andrew Jones
2023-01-11 14:44       ` Jisheng Zhang
2023-01-09 18:17 ` [PATCH v4 4/5] RISC-V: add infrastructure to allow different str* implementations Heiko Stuebner
2023-01-09 22:37   ` Conor Dooley
2023-01-09 23:31     ` Heiko Stübner
2023-01-10  9:39   ` Andrew Jones
2023-01-10 10:46     ` Heiko Stübner
2023-01-10 11:16       ` Andrew Jones
2023-01-11 12:34         ` Andrew Jones [this message]
     [not found]           ` <CAEg0e7gJgpoiGjfLeedba0-r=dCE1Z_qkU53w_+-cVjsuqaC3A@mail.gmail.com>
2023-01-11 13:42             ` Philipp Tomsich
2023-01-11 13:47             ` Andrew Jones
2023-01-10 12:13   ` Andrew Jones
2023-01-11 12:30     ` Andrew Jones
2023-01-12 16:05     ` Heiko Stübner
2023-01-09 18:17 ` [PATCH v4 5/5] RISC-V: add zbb support to string functions Heiko Stuebner
2023-01-09 20:39   ` Conor Dooley
2023-01-10  9:57   ` Andrew Jones
2023-01-10 10:14     ` Conor Dooley
2023-01-12 11:21       ` Heiko Stübner
2023-01-12 12:06         ` Conor Dooley
2023-01-12 12:28           ` Heiko Stübner
2023-01-11 12:24   ` Andrew Jones
2023-01-11 14:27     ` Christoph Müllner
2023-01-11 15:16       ` Andrew Jones
2023-01-11 15:22       ` Jeff Law
2023-01-12 22:05     ` Heiko Stübner
2023-01-11 13:24 ` [PATCH v4 0/5] Zbb string optimizations and call support in alternatives Jisheng Zhang

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