P4C
The P4 Compiler
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Public Member Functions | List of all members
BFN::AddParserPad Class Reference

Add "padding" (additional states/extract fields) to parsers to meet minimum parse depth requirements. More...

Inheritance diagram for BFN::AddParserPad:
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Public Member Functions

 AddParserPad (const std::set< cstring > &structs, const std::map< const IR::P4Parser *, std::map< cstring, int > > &stateSize, const std::map< const IR::P4Parser *, ParserEnforceDepthReq::ParserPadReq > &padReq, const std::map< cstring, int > &headerPadAmt, const std::map< const IR::P4Parser *, gress_t > &allParsers, const std::map< const IR::P4Control *, gress_t > &allDeparsers, const std::map< const IR::P4Control *, gress_t > &allMauPipes, const std::map< const IR::P4Control *, std::set< const IR::P4Parser * > > &deparserParser, const std::map< const IR::P4Control *, std::set< const IR::P4Parser * > > &mauPipeParser, int ctrShiftAmt)
 
- Public Member Functions inherited from P4::Modifier
const IR::Node * apply_visitor (const IR::Node *n, const char *name=0) override
 
profile_t init_apply (const IR::Node *root) override
 
virtual void loop_revisit (const IR::Node *)
 
virtual void postorder (IR::Node *)
 
virtual bool preorder (IR::Node *)
 
virtual void revisit (const IR::Node *, const IR::Node *)
 
void revisit_visited ()
 
bool visit_in_progress (const IR::Node *) const
 
void visitAgain () const override
 
void visitOnce () const override
 
- Public Member Functions inherited from P4::Visitor
virtual bool check_global (cstring)
 
virtual void clear_globals ()
 
virtual Visitor * clone () const
 
virtual ControlFlowVisitor * controlFlowVisitor ()
 
virtual void end_apply ()
 
virtual void end_apply (const IR::Node *root)
 
virtual void erase_global (cstring)
 
template<class T>
const T * findContext () const
 
template<class T>
const T * findContext (const Context *&c) const
 
template<class T>
const T * findOrigCtxt () const
 
template<class T>
const T * findOrigCtxt (const Context *&c) const
 
virtual Visitor & flow_clone ()
 
virtual void flow_merge (Visitor &)
 
virtual bool flow_merge_closure (Visitor &)
 
virtual void flow_merge_global_from (cstring)
 
virtual void flow_merge_global_to (cstring)
 
const Context * getChildContext () const
 
int getChildrenVisited () const
 
const Context * getContext () const
 
int getContextDepth () const
 
const IR::Node * getCurrentNode () const
 
template<class T>
const T * getCurrentNode () const
 
const IR::Node * getOriginal () const
 
template<class T>
const T * getOriginal () const
 
template<class T>
const T * getParent () const
 
virtual bool has_flow_joins () const
 
profile_t init_apply (const IR::Node *root, const Context *parent_context)
 
template<class T>
bool isInContext () const
 
template<class T>
bool isInContext (const Context *&c) const
 
bool isInContext (const IR::Node *n) const
 
virtual const char * name () const
 
template<class T>
void parallel_visit (const IR::Vector< T > &v, const char *name, int cidx)
 
template<class T>
void parallel_visit (const IR::Vector< T > &v, const char *name=0)
 
template<class T>
void parallel_visit (IR::Vector< T > &v, const char *name, int cidx)
 
template<class T>
void parallel_visit (IR::Vector< T > &v, const char *name=0)
 
void print_context () const
 
const Visitor & setCalledBy (const Visitor *visitor)
 
void setName (const char *name)
 
void visit (const IR::Node &n, const char *name, int cidx)
 
void visit (const IR::Node &n, const char *name=0)
 
void visit (const IR::Node *&n, const char *name, int cidx)
 
void visit (const IR::Node *&n, const char *name=0)
 
void visit (const IR::Node *const &n, const char *name, int cidx)
 
void visit (const IR::Node *const &n, const char *name=0)
 
void visit (IR::Node &n, const char *name, int cidx)
 
void visit (IR::Node &n, const char *name=0)
 
void visit (IR::Node *&, const char *=0, int=0)
 
template<class T, typename = std::enable_if_t<Util::has_SourceInfo_v<T> && !std::is_pointer_v<T>>, class... Args>
void warn (const int kind, const char *format, const T &node, Args &&...args)
 The const ref variant of the above.
 
template<class T, typename = std::enable_if_t<Util::has_SourceInfo_v<T>>, class... Args>
void warn (const int kind, const char *format, const T *node, Args &&...args)
 
bool warning_enabled (int warning_kind) const
 

Additional Inherited Members

- Public Types inherited from P4::Visitor
typedef Visitor_Context Context
 
- Static Public Member Functions inherited from P4::Visitor
static cstring demangle (const char *)
 
static bool warning_enabled (const Visitor *visitor, int warning_kind)
 
- Public Attributes inherited from P4::Visitor
const Visitor * called_by = nullptr
 
cstring internalName
 
SplitFlowVisit_base *& split_link
 
SplitFlowVisit_base * split_link_mem = nullptr
 
- Protected Member Functions inherited from P4::Visitor
virtual void init_join_flows (const IR::Node *)
 
virtual bool join_flows (const IR::Node *)
 
virtual void post_join_flows (const IR::Node *, const IR::Node *)
 
void visit_children (const IR::Node *, std::function< void()> fn)
 
- Protected Attributes inherited from P4::Modifier
bool forceClone = false
 
- Protected Attributes inherited from P4::Visitor
bool dontForwardChildrenBeforePreorder = false
 
bool joinFlows = false
 
bool visitDagOnce = true
 

Detailed Description

Add "padding" (additional states/extract fields) to parsers to meet minimum parse depth requirements.

For parsers with struct headers, padding uses a counter to count the bytes remaining to meet the minimum depth requirement. For non-struct headers, padding adds additional bytes to the header to meet the depth requirement.

This pass does not calculate padding requirements. Instead, these are calculated by IdentifyPadRequirements.

For programs that don't meet the minimum parse depth requirement, this pass:

  • Non-struct headers (i.e., a P4 "header" is passed into the parser):
    • Creates a clone of the header with an additional field to meet the minimum parse depth.
    • Replaces references to the original header with the padded header when used in a pipe requiring parser min-depth padding.
  • Struct headers (i.e., a P4 "struct" is passed into the parser):
    • Adds a blob header to store data parsed in padding states.
    • Adds a stack of blob headers to each header struct to meet parse depth requirements.
    • For each parser that doesn't meet parse depth requirements:
      • Adds a counter.
      • Initializes the counter in the start state to the parse depth minus the number of bytes parsed in the state.
      • Decrements the counter in each state by the nubmer of bytes parsed.
      • Adds padding states that read data and decrement the counter until the counter is <= 0.
      • Replaces accept/reject transitions to transitions to the new padding states.
      • Adds emit statements to the deparser for the blob header stack.