llvm dev - Aug 2020 - TableGen trace facility

Well, I was hinting at LLVM_DEBUG messages. You can pretty much dump all
"actions" Tablegen would take to process a .td file, which should
suffice,
IMO.


On Wed, Aug 5, 2020 at 5:59 PM Paul C. Anagnostopoulos <paul at
windfall.com>
wrote:
> Your reply suggests that there is a way to see debug messages from
> TableGen. Is that what you meant? If so, can you explain how that works?
> (Sorry, I should know the answer to this question, but I'm quite the
> newbie.)
>
> At 8/5/2020 04:15 AM, Madhur Amilkanthwar wrote:
> >Hi Paul,
> >If all you care about is debugging then for now we can just emit a few
> more debug messages which would help to "trace" the flow. To
distinguish
> traces you can prefix it with some known string. I don't think you
really
> need a 'trace' tag in the language spec for this.
> >
> >Debugging Tablegen has always been a nightmare and I don't think we
can
> ever reach a stage where we can start a debugger and debug statements in
> .td files step-by-step. This is far from reality unless we fundamentally
> change the language.
>
>
-- 
*Disclaimer: Views, concerns, thoughts, questions, ideas expressed in this
mail are of my own and my employer has no take in it. *
Thank You.
Madhur D. Amilkanthwar
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I'm sorry, I still don't understand. I presume you are talking about the
LLVM_DEBUG() macro that is enabled with the -debug option. But there are no uses
of LLVM_DEBUG() in the TableGen base files. Wouldn't the base
"compiler" have to display the information we're talking about? Or
is it sufficient to use LLVM_DEBUG() in the target-specific files?

At 8/5/2020 08:40 AM, Madhur Amilkanthwar wrote:
>Well, I was hinting at LLVM_DEBUG messages. You can pretty much dump all
"actions" Tablegen would take to process a .td file, which should
suffice, IMO.
>
>
>On Wed, Aug 5, 2020 at 5:59 PM Paul C. Anagnostopoulos <<mailto:paul
at windfall.com>paul at windfall.com> wrote:
>Your reply suggests that there is a way to see debug messages from TableGen.
Is that what you meant? If so, can you explain how that works? (Sorry, I should
know the answer to this question, but I'm quite the newbie.)
>
>At 8/5/2020 04:15 AM, Madhur Amilkanthwar wrote:
>>Hi Paul,
>>If all you care about is debugging then for now we can just emit a few
more debug messages which would help to "trace" the flow. To
distinguish traces you can prefix it with some known string. I don't think
you really need a 'trace' tag in the language spec for this.
>>
>>Debugging Tablegen has always been a nightmare and I don't think we
can ever reach a stage where we can start a debugger and debug statements in .td
files step-by-step. This is far from reality unless we fundamentally change the
language.

Hi Paul,

On Wed, Aug 5, 2020 at 4:04 PM Paul C. Anagnostopoulos
<paul at windfall.com> wrote:
> I'm sorry, I still don't understand. I presume you are talking
about the LLVM_DEBUG() macro that is enabled with the -debug option. But there
are no uses of LLVM_DEBUG() in the TableGen base files. Wouldn't the base
"compiler" have to display the information we're talking about? Or
is it sufficient to use LLVM_DEBUG() in the target-specific files?
Trying to interpret what Madhur is saying, maybe adding some uses of
LLVM_DEBUG() to TableGen would be a good idea.

Cheers,
Nicolai

>
> At 8/5/2020 08:40 AM, Madhur Amilkanthwar wrote:
> >Well, I was hinting at LLVM_DEBUG messages. You can pretty much dump
all "actions" Tablegen would take to process a .td file, which should
suffice, IMO.
> >
> >
> >On Wed, Aug 5, 2020 at 5:59 PM Paul C. Anagnostopoulos
<<mailto:paul at windfall.com>paul at windfall.com> wrote:
> >Your reply suggests that there is a way to see debug messages from
TableGen. Is that what you meant? If so, can you explain how that works? (Sorry,
I should know the answer to this question, but I'm quite the newbie.)
> >
> >At 8/5/2020 04:15 AM, Madhur Amilkanthwar wrote:
> >>Hi Paul,
> >>If all you care about is debugging then for now we can just emit a
few more debug messages which would help to "trace" the flow. To
distinguish traces you can prefix it with some known string. I don't think
you really need a 'trace' tag in the language spec for this.
> >>
> >>Debugging Tablegen has always been a nightmare and I don't
think we can ever reach a stage where we can start a debugger and debug
statements in .td files step-by-step. This is far from reality unless we
fundamentally change the language.
>

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aber vergiss niemals, wie sie sein sollte.