llvm dev - Feb 2010 - [LLVMdev] Metadata

On Thu, Feb 11, 2010 at 10:54 PM, David Greene <dag at cray.com>
wrote:
> On Thursday 11 February 2010 16:31:16 Garrison Venn wrote:
>> I don't think the lang ref metadata grammar section
>> (http://llvm.org/docs/LangRef.html#metadata) has been fully updated
with
>> how !dbg metadata is used in
>> http://llvm.org/docs/SourceLevelDebugging.html. At least to me it is
not
>> clear. In my mind I translate the phrase "LLVM IR allows metadata
to be
>> attached to instructions " into a grammar depicted in
>> SourceLevelDebugging.html. I was going to ask about this, but I'll
let you
>> instead. :-)
>
> But that's not even a grammar.
>
> I simply want to know what the syntax is for specifying metadata on an
> instruction.  From what I gather, it is this:
>
> <instruction> ',' <MetadataSpec>
>
> <MetadataSpec>: '!' <ID> '!' <ID>
>
> <ID>: [a-zA-Z_][a-zA-Z0-9_]*
>
> And the second <ID> needs to be the name of a metadata node:
>
> '!' <ID> '=' METADATA '!' '{'
<MDNodeList> '}'
>
> And MDNodeList contains a list of stuff like integer values, strings and so
> on.
>
> Is that basically right?  So I would have to do this:
>
>        %r8 = load <2 x double>* %r6, align 16, !nontemporal !0
> [...]
> !0 = metadata !{ i32 1 }
I guess, that's what I described in the example in previous email :).
In this case, your metadata is just an integer one. In my example, my
metadata was a collection of 4 values.
> I would really rather not have to specify the entirely redundant !0.  Just
the
> fact that the instruction has metadata with index/name
"nontemporal" should
> be enough.
-
Devang

On Thu, Feb 11, 2010 at 3:36 PM, Devang Patel <devang.patel at gmail.com>
wrote:
> On Thu, Feb 11, 2010 at 10:54 PM, David Greene <dag at cray.com>
wrote:
>> On Thursday 11 February 2010 16:31:16 Garrison Venn wrote:
>>> I don't think the lang ref metadata grammar section
>>> (http://llvm.org/docs/LangRef.html#metadata) has been fully updated
with
>>> how !dbg metadata is used in
>>> http://llvm.org/docs/SourceLevelDebugging.html. At least to me it
is not
>>> clear. In my mind I translate the phrase "LLVM IR allows
metadata to be
>>> attached to instructions " into a grammar depicted in
>>> SourceLevelDebugging.html. I was going to ask about this, but
I'll let you
>>> instead. :-)
>>
>> But that's not even a grammar.
>>
>> I simply want to know what the syntax is for specifying metadata on an
>> instruction.  From what I gather, it is this:
>>
>> <instruction> ',' <MetadataSpec>
>>
>> <MetadataSpec>: '!' <ID> '!' <ID>
>>
>> <ID>: [a-zA-Z_][a-zA-Z0-9_]*
>>
>> And the second <ID> needs to be the name of a metadata node:
>>
>> '!' <ID> '=' METADATA '!' '{'
<MDNodeList> '}'
>>
>> And MDNodeList contains a list of stuff like integer values, strings
and so
>> on.
>>
>> Is that basically right?  So I would have to do this:
>>
>>        %r8 = load <2 x double>* %r6, align 16, !nontemporal !0
>> [...]
>> !0 = metadata !{ i32 1 }
>
> I guess, that's what I described in the example in previous email :).
> In this case, your metadata is just an integer one. In my example, my
> metadata was a collection of 4 values.
So David would write what he wants as:

  %r8 = load <2 x double>* %r6, align 16, !nontemporal !{ i32 1 }

?
>> I would really rather not have to specify the entirely redundant !0.
 Just the
>> fact that the instruction has metadata with index/name
"nontemporal" should
>> be enough.
>
> -
> Devang
>
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On Thu, Feb 11, 2010 at 11:47 PM, Jeffrey Yasskin <jyasskin at google.com>
wrote:
>
>  %r8 = load <2 x double>* %r6, align 16, !nontemporal !{ i32 1 }
>
> ?
This is what a call, inlined metadata. The asm parser at the moment
won't handle this. It expects stand alone metadata.

-
Devang