[P4-dev] p4c compiler output in .p4i

hemant at mnkcg.com hemant at mnkcg.com
Thu Jun 8 17:18:41 EDT 2017


Han,

 

Great, thanks!

 

Hemant

 

From: Han Wang [mailto:hw342 at cornell.edu] 
Sent: Thursday, June 08, 2017 5:16 PM
To: hemant at mnkcg.com
Cc: p4-dev <p4-dev at lists.p4.org>
Subject: Re: [P4-dev] p4c compiler output in .p4i

 

Hi Hemant,

 

You can use the —top4 flag in p4c-bm2-ss and p4test to dump IR as inlined comments in p4 program, see slide 32 in compiler-design.pptx

 

Han

 

On Jun 8, 2017, at 2:01 PM, <hemant at mnkcg.com <mailto:hemant at mnkcg.com> > <hemant at mnkcg.com <mailto:hemant at mnkcg.com> > wrote:

 

Hi Han,

 

Got it.  I found the tools/driver/p4_src/p4c.bmv2.cfg and see the p4i is part of the preprocessor setup.  Thanks to Mihai for replying too.  About IR, what support does the current p4c compiler have for outputting IR?  Isn’t JSON output pending to be developed?

 

Thanks,

 

Hemant

 

From: Han Wang [mailto:hanwang at barefootnetworks.com] 
Sent: Thursday, June 08, 2017 4:48 PM
To: hemant at mnkcg.com <mailto:hemant at mnkcg.com> 
Cc: p4-dev <p4-dev at lists.p4.org <mailto:p4-dev at lists.p4.org> >
Subject: Re: [P4-dev] p4c compiler output in .p4i

 

Hi Hemant,

 

p4c is a compiler driver that invokes the other components of the p4 tool chain to process a p4 program. Specifically, for bmv2, the compiler driver invokes preprocessor and p4c-bm2-ss to generate the output json configuration for bmv2.

 

You can use the -### flag or --test-only flag to find out which commands are invoked by p4c compiler driver.

 

In this case, the .p4i file is the output of the preprocessor step.

 

Han

 

On Jun 8, 2017, at 1:40 PM,  <mailto:hemant at mnkcg.com> hemant at mnkcg.com wrote:

 

The compiler-design slides included with the docs for the p4c compiler do not include some details.  Thus a question:

 

When I use p4c to compile P4-16 code in a .p4 file, the compiler outputs a .p4i file.  Looking at this file, it looks like IR (Intermediate Representation) to me – am I correct?   It would be good to describe this output file in the docs.

 

Thanks,

 

Hemant

 

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