Add support for verify statements in bmv2 backend #234
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With version 2.1, the bmv2 JSON supports declaring parser errors as well as verify statements in the parser's body. See https://github.com/p4lang/behavioral-model/pull/259/files#diff-418314966c57fea403ba29bf6b0793c7 for more information. In this pull request, we add a visitor pass which assigns a numerical value to each error declared in the P4 input. The mapping error name <-> value is added to the JSON under the 'errors' key. verify statements are then handled when converting parser states to JSON, as per the bmv2 JSON description. Later on, we will be able to handle references to error constants in expressions in controls. This will be done by substituting the numerical value for the error constant in expressions, and otherwise using regular bmv2 expressions. The error code produced by the parser will need to be exposed as a metadata field though. So for now only references to error constants in verify statements are supported.
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@mbudiu-vmw please let me know if I didn't implement this in a satisfactory way |
mihaibudiu
requested changes
Jan 16, 2017
| } | ||
| { | ||
| auto error = mce->arguments->at(1); | ||
| BUG_CHECK(error->is<IR::Member>(), "Error when processing verify"); |
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Maybe this should be an ::error instead of a bug. One can declare variables with an error type, and one could use here an expression with an error result. The ::error message should indicate that only constant error values are supported in verify.
ChrisDodd
approved these changes
Jan 16, 2017
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@ChrisDodd I was going to add the requested fix today... I guess I'll open a new PR |
antoninbas
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Jan 19, 2017
As requested in review for PR #234
antoninbas
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Jan 19, 2017
As requested in review for PR #234
ChrisDodd
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As requested in review for PR #234
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With version 2.1, the bmv2 JSON supports declaring parser errors as well
as verify statements in the parser's body. See
https://github.com/p4lang/behavioral-model/pull/259/files#diff-418314966c57fea403ba29bf6b0793c7
for more information.
In this pull request, we add a visitor pass which assigns a numerical
value to each error declared in the P4 input. The mapping error name <->
value is added to the JSON under the 'errors' key. verify statements are
then handled when converting parser states to JSON, as per the bmv2 JSON
description.
Later on, we will be able to handle references to error constants in
expressions in controls. This will be done by substituting the numerical
value for the error constant in expressions, and otherwise using regular
bmv2 expressions. The error code produced by the parser will need to be
exposed as a metadata field though. So for now only references to error
constants in verify statements are supported.