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From: Richard Sandiford <richard.sandiford@linaro.org>
To: Michael Collison <Michael.Collison@arm.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,  nd <nd@arm.com>
Subject: Re: [PATCH 1/2][Aarch64] Improve FP to int conversions
Date: Sat, 19 May 2018 09:26:00 -0000	[thread overview]
Message-ID: <87lgcgm293.fsf@linaro.org> (raw)
In-Reply-To: <VI1PR08MB3053855D2D7D38769BB81EFF95900@VI1PR08MB3053.eurprd08.prod.outlook.com>	(Michael Collison's message of "Fri, 18 May 2018 20:34:58 +0000")

Michael Collison <Michael.Collison@arm.com> writes:
> This patch improves additional cases of FP to integer conversions.
>
> Example 1:
>
> unsigned long
> f7 (double x)
> {
>   return (unsigned) y;
> }
>
>
> At -O2
>
> Trunk generates:
>
> f7:
> 	fcvtzu	w0, d0
> 	uxtw	x0, w0
> 	ret
>
> With the patch we can merge the zero-extend and reduce the sequence to one instruction at -O2
>
> f7:
> 	fcvtzu	x0, d0
> 	ret

Thanks for doing this, patch looks good to me FWIW.  I think the
patch actually uses "fcvtzu w0, d0", which unlike "fcvtzu x0, d0"
preserves the rtl semantics exactly.

> +/* { dg-final { scan-assembler "fcvtzu\\tw\[0-9\]+, d\[0-9\]+" } } */
> +/* { dg-final { scan-assembler "fcvtzu\\tw\[0-9\]+, s\[0-9\]+" } } */

Just wanted to plug curly-brace quoting, which avoids the extra backslashes:

/* { dg-final { scan-assembler {fcvtzu\tw[0-9]+, d[0-9]+} } } */
/* { dg-final { scan-assembler {fcvtzu\tw[0-9]+, s[0-9]+} } } */

Either's fine though -- don't respin for that. :-)

Richard

  reply	other threads:[~2018-05-19  9:19 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 20:35 Michael Collison
2018-05-19  9:26 ` Richard Sandiford [this message]
2018-05-21 16:57 ` Richard Earnshaw (lists)

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