From: Richard Henderson <rth@redhat.com>
To: Jeff Law <law@redhat.com>,
Andrew Jenner <andrew@codesourcery.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Explicit register earlyclobber fix
Date: Tue, 22 Sep 2015 19:31:00 -0000 [thread overview]
Message-ID: <5601A9FD.3020302@redhat.com> (raw)
In-Reply-To: <5601A978.9040107@redhat.com>
On 09/22/2015 12:18 PM, Jeff Law wrote:
> On 09/22/2015 01:15 PM, Richard Henderson wrote:
>>> And doesn't it have to be =& and always at the start for an asm constraint?
>>> For operands in patterns, we have to consider operand alternatives, but that's
>>> not on issue here.
>>
>> Technically we do support alternatives on asms. Not usefully except for CISC,
>> since all alternatives have to use the same output pattern, but one can write
>> things like
>>
>> asm("add %0,%1" : "=r,m"(x) : "rim,ri"(y))
> Wow, learn something every day. In that case, I think we do have to search a
> little harder than just peeking at the first two letters of the constraint :(
We wouldn't be. He's adding this check at the beginning of each alternative.
So why would we want to search the entire rest of the string now?
r~
next prev parent reply other threads:[~2015-09-22 19:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 16:03 Andrew Jenner
2015-09-22 19:16 ` Richard Henderson
2015-09-22 19:18 ` Jeff Law
2015-09-22 19:20 ` Richard Henderson
2015-09-22 19:31 ` Jeff Law
2015-09-22 19:31 ` Richard Henderson [this message]
2015-09-22 19:56 ` Jeff Law
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