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Re: [PATCH v2 6/6] i386: Implement asm flag outputs
- From: "H. Peter Anvin" <hpa at zytor dot com>
- To: Jeff Law <law at redhat dot com>, Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Cc: torvalds at linux-foundation dot org
- Date: Wed, 20 May 2015 09:25:43 -0700
- Subject: Re: [PATCH v2 6/6] i386: Implement asm flag outputs
- Authentication-results: sourceware.org; auth=none
- References: <1431034740-5375-7-git-send-email-rth at redhat dot com> <1431704235-9239-1-git-send-email-rth at redhat dot com> <555CB473 dot 30306 at redhat dot com>
Well, these kinds of asm are inherently target specific, but I did already ask for a cpp symbol to indicate this faculty us available.
On May 20, 2015 9:21:07 AM PDT, Jeff Law <law@redhat.com> wrote:
>On 05/15/2015 09:37 AM, Richard Henderson wrote:
>> Version 2 includes proper test cases and documentation.
>> Hopefully the documentation even makes sense. Suggestions
>> and improvements there gratefully appreciated.
>>
>>
>> r~
>> ---
>> gcc/config/i386/constraints.md | 5 ++
>> gcc/config/i386/i386.c | 137
>+++++++++++++++++++++++++++--
>> gcc/doc/extend.texi | 76 ++++++++++++++++
>> gcc/testsuite/gcc.target/i386/asm-flag-0.c | 15 ++++
>> gcc/testsuite/gcc.target/i386/asm-flag-1.c | 18 ++++
>> gcc/testsuite/gcc.target/i386/asm-flag-2.c | 16 ++++
>> gcc/testsuite/gcc.target/i386/asm-flag-3.c | 22 +++++
>> gcc/testsuite/gcc.target/i386/asm-flag-4.c | 20 +++++
>> gcc/testsuite/gcc.target/i386/asm-flag-5.c | 19 ++++
>> 9 files changed, 321 insertions(+), 7 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-0.c
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-1.c
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-2.c
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-3.c
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-4.c
>> create mode 100644 gcc/testsuite/gcc.target/i386/asm-flag-5.c
>It all seems to make sense. Obviously you'll need a ChangeLog and the
>usual testing before committing.
>
>I won't stress much if this needs a bit of further tweaking as the
>kernel folks start to exploit the capability and we find weaknesses in
>the implementation.
>
>What I don't see is any way to know if the target supports asm flag
>outputs. Are we expecting the kernel folks to do some kind of test
>then
>enable/disable based on the result?
>
>I'm going to assume the mapping of the constraints to the actual modes
>and codes is correct.
>
>
>Jeff
--
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