llvm dev - Feb 2011 - [LLVMdev] reference to %llvm.dbg.variable in source level debug docs

Hello
I'm reading http://llvm.org/docs/SourceLevelDebugging.html and some
things aren't clear.

There are a couple of references made to %llvm.dbg.variable, which
isn't defined anywhere. It it an intrinsic? A global? Could it be a
relic from the old debug info docs (where it *is* defined?). The same
goes for llvm.dbg.derivedtype and llvm.dbg.subrange which are also
referenced but not defined.

Additionally, there's this definition:

"""
 void %llvm.dbg.declare(metadata, metadata)

This intrinsic provides information about a local element (ex.
variable.) The first argument is metadata holding alloca for the
variable.. The second argument is the %llvm.dbg.variable containing
the description of the variable.
"""

I see all uses of llvm.dbg.declare having values/types as first
argument, not metadata. What am I missing?
Thanks in advance,
Eli

On Feb 1, 2011, at 3:58 AM, Eli Bendersky wrote:
> Hello
> I'm reading http://llvm.org/docs/SourceLevelDebugging.html and some
> things aren't clear.
> 
> There are a couple of references made to %llvm.dbg.variable, which
> isn't defined anywhere. It it an intrinsic? A global? Could it be a
> relic from the old debug info docs (where it *is* defined?). The same
> goes for llvm.dbg.derivedtype and llvm.dbg.subrange which are also
> referenced but not defined.
It was a stale reference. I fixed the docs.
> 
> Additionally, there's this definition:
> 
> """
>  void %llvm.dbg.declare(metadata, metadata)
> 
> This intrinsic provides information about a local element (ex.
> variable.) The first argument is metadata holding alloca for the
> variable.. The second argument is the %llvm.dbg.variable containing
> the description of the variable.
> """
> 
> I see all uses of llvm.dbg.declare having values/types as first
> argument, not metadata. What am I missing?
I am seeing 
  call void @llvm.dbg.declare(metadata !{i32* %argc.addr}, metadata !12), !dbg
!13

?
-
Devang

>> There are a couple of references made to %llvm.dbg.variable, which
>> isn't defined anywhere. It it an intrinsic? A global? Could it be a
>> relic from the old debug info docs (where it *is* defined?). The same
>> goes for llvm.dbg.derivedtype and llvm.dbg.subrange which are also
>> referenced but not defined.
>
> It was a stale reference. I fixed the docs.
Thanks. Is llvm.dbg.derivedtype.type also a stale reference? It's
mentioned in "Derived type descriptors" but isn't described or
defined
anywhere.
>> Additionally, there's this definition:
>>
>> """
>>  void %llvm.dbg.declare(metadata, metadata)
>>
>> This intrinsic provides information about a local element (ex.
>> variable.) The first argument is metadata holding alloca for the
>> variable.. The second argument is the %llvm.dbg.variable containing
>> the description of the variable.
>> """
>>
>> I see all uses of llvm.dbg.declare having values/types as first
>> argument, not metadata. What am I missing?
>
> I am seeing
>  call void @llvm.dbg.declare(metadata !{i32* %argc.addr}, metadata !12),
!dbg !13
In the example IR of http://llvm.org/docs/SourceLevelDebugging.html,
section "Object lifetimes and scoping", there is:

call void @llvm.dbg.declare({}* %2, metadata !12), !dbg !14

Which isn't exactly like the llvm.dbg.declare intrinsic is defined -
in the definition the first argument is also metadata.
Indeed, generating IR from C files using trunk clang, I also see:

call void @llvm.dbg.declare(metadata !{i32* %a.addr}, metadata !22), !dbg !23

Which is different from what
http://llvm.org/docs/SourceLevelDebugging.html shows.

Eli